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<meta name="robots" content="INDEX,FOLLOW,NOARCHIVE" /><meta name="citation_inbook_title" content="Webvision: The Organization of the Retina and Visual System [Internet]" /><meta name="citation_title" content="Crystalline Lens and Cataract" /><meta name="citation_publisher" content="University of Utah Health Sciences Center" /><meta name="citation_date" content="2017/08/15" /><meta name="citation_author" content="Joah F. Aliancy" /><meta name="citation_author" content="Nick Mamalis" /><meta name="citation_pmid" content="29356473" /><meta name="citation_fulltext_html_url" content="https://www.ncbi.nlm.nih.gov/books/NBK476171/" /><link rel="schema.DC" href="http://purl.org/DC/elements/1.0/" /><meta name="DC.Title" content="Crystalline Lens and Cataract" /><meta name="DC.Type" content="Text" /><meta name="DC.Publisher" content="University of Utah Health Sciences Center" /><meta name="DC.Contributor" content="Joah F. Aliancy" /><meta name="DC.Contributor" content="Nick Mamalis" /><meta name="DC.Date" content="2017/08/15" /><meta name="DC.Identifier" content="https://www.ncbi.nlm.nih.gov/books/NBK476171/" /><meta name="description" content="The lens of the eye is a biconvex, relatively acellular, optically transparent intraocular structure that with the cornea serves to transmit light to the retina with minimal light scattering (Figure 1a). Early anatomists viewed the lens as the location of meaningful visualization. We now know that this is the function of the retina, with the lens serving as a conduit of light transmission and focus to the retina. The lens can change shape with the aid of the ciliary muscles, thereby changing the focal distance to the retina and bringing the image into sharp focus on the retina. This adjustment of the lens is known as accommodation (similar to the focusing of a photographic camera via movement of its lenses). The lens is flatter on its anterior side than on its posterior side. (Figure 1b)." /><meta name="og:title" content="Crystalline Lens and Cataract" /><meta name="og:type" content="book" /><meta name="og:description" content="The lens of the eye is a biconvex, relatively acellular, optically transparent intraocular structure that with the cornea serves to transmit light to the retina with minimal light scattering (Figure 1a). Early anatomists viewed the lens as the location of meaningful visualization. We now know that this is the function of the retina, with the lens serving as a conduit of light transmission and focus to the retina. The lens can change shape with the aid of the ciliary muscles, thereby changing the focal distance to the retina and bringing the image into sharp focus on the retina. This adjustment of the lens is known as accommodation (similar to the focusing of a photographic camera via movement of its lenses). The lens is flatter on its anterior side than on its posterior side. (Figure 1b)." /><meta name="og:url" content="https://www.ncbi.nlm.nih.gov/books/NBK476171/" /><meta name="og:site_name" content="NCBI Bookshelf" /><meta name="og:image" content="https://www.ncbi.nlm.nih.gov/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-webvision-lrg.png" /><meta name="twitter:card" content="summary" /><meta name="twitter:site" content="@ncbibooks" /><meta name="bk-non-canon-loc" content="/books/n/webvision/lens_cataract/" /><link rel="canonical" href="https://www.ncbi.nlm.nih.gov/books/NBK476171/" /><link rel="stylesheet" href="/corehtml/pmc/css/figpopup.css" type="text/css" media="screen" /><link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books.min.css" type="text/css" /><link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books_print.min.css" type="text/css" media="print" /><style type="text/css">p a.figpopup{display:inline !important} .bk_tt {font-family: monospace} .first-line-outdent .bk_ref {display: inline} .body-content h2, .body-content .h2 {border-bottom: 1px solid #97B0C8} .body-content h2.inline {border-bottom: none} a.page-toc-label , .jig-ncbismoothscroll a {text-decoration:none;border:0 !important} .temp-labeled-list .graphic {display:inline-block !important} .temp-labeled-list img{width:100%}</style><script type="text/javascript" src="/corehtml/pmc/js/jquery.hoverIntent.min.js"> </script><script type="text/javascript" src="/corehtml/pmc/js/common.min.js?_=3.18"> </script><script type="text/javascript" src="/corehtml/pmc/js/large-obj-scrollbars.min.js"> </script><script type="text/javascript">window.name="mainwindow";</script><script type="text/javascript" src="/corehtml/pmc/js/bookshelf/2.26/book-toc.min.js"> </script><script type="text/javascript" src="/corehtml/pmc/js/bookshelf/2.26/books.min.js"> </script><meta name="book-collection" content="NONE" />
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<div class="pre-content"><div><div class="bk_prnt"><p class="small">NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.</p><p>Kolb H, Fernandez E, Jones B, et al., editors. Webvision: The Organization of the Retina and Visual System [Internet]. Salt Lake City (UT): University of Utah Health Sciences Center; 1995-. </p></div><div class="iconblock clearfix whole_rhythm no_top_margin bk_noprnt"><a class="img_link icnblk_img" title="Table of Contents Page" href="/books/n/webvision/"><img class="source-thumb" src="/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-webvision-lrg.png" alt="Cover of Webvision" height="100px" width="80px" /></a><div class="icnblk_cntnt eight_col"><h2>Webvision: The Organization of the Retina and Visual System [Internet].</h2><a data-jig="ncbitoggler" href="#__NBK476171_dtls__">Show details</a><div style="display:none" class="ui-widget" id="__NBK476171_dtls__"><div>Kolb H, Fernandez E, Jones B, et al., editors.</div><div>Salt Lake City (UT): <a href="http://webvision.med.utah.edu/" ref="pagearea=page-banner&targetsite=external&targetcat=link&targettype=publisher">University of Utah Health Sciences Center</a>; 1995-.</div></div><div class="half_rhythm"><ul class="inline_list"><li style="margin-right:1em"><a class="bk_cntns" href="/books/n/webvision/">Contents</a></li></ul></div><div class="bk_noprnt"><form method="get" action="/books/n/webvision/" id="bk_srch"><div class="bk_search"><label for="bk_term" class="offscreen_noflow">Search term</label><input type="text" title="Search this book" id="bk_term" name="term" value="" data-jig="ncbiclearbutton" /> <input type="submit" class="jig-ncbibutton" value="Search this book" submit="false" style="padding: 0.1em 0.4em;" /></div></form></div></div><div class="icnblk_cntnt two_col"><div class="pagination bk_noprnt"><a class="active page_link prev" href="/books/n/webvision/anteriorsegment/" title="Previous page in this title">< Prev</a><a class="active page_link next" href="/books/n/webvision/intraocular_lenses/" title="Next page in this title">Next ></a></div></div></div></div></div>
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<div class="main-content lit-style" itemscope="itemscope" itemtype="http://schema.org/CreativeWork"><div class="meta-content fm-sec"><h1 id="_NBK476171_"><span class="title" itemprop="name">Crystalline Lens and Cataract</span></h1><p class="contrib-group"><span itemprop="author">Joah F. Aliancy</span>, MD and <span itemprop="author">Nick Mamalis</span>, MD.</p><a data-jig="ncbitoggler" href="#__NBK476171_ai__" style="border:0;text-decoration:none">Author Information and Affiliations</a><div style="display:none" class="ui-widget" id="__NBK476171_ai__"><p class="contrib-group"><h4>Authors</h4><span itemprop="author">Joah F. Aliancy</span>, MD<sup><img src="/corehtml/pmc/pmcgifs/corrauth.gif" alt="corresponding author" /></sup><sup>1</sup><sup>,<a href="#lens_cataract.Tc.an1" class="bk_pop">*</a></sup> and <span itemprop="author">Nick Mamalis</span>, MD<sup><img src="/corehtml/pmc/pmcgifs/corrauth.gif" alt="corresponding author" /></sup><sup>1</sup><sup>,<a href="#lens_cataract.Tc.an2" class="bk_pop">†</a></sup>.</p><h4>Affiliations</h4><div class="affiliation"><sup>1</sup> John A. Moran Eye Center, University of Utah School of Medicine, Salt Lake City<div><span class="email-label">Email: </span><a href="mailto:dev@null" data-email="ude.hatu@ycnaila.haoj" class="oemail">ude.hatu@ycnaila.haoj</a><div><span class="email-label">Email: </span><a href="mailto:dev@null" data-email="ude.hatu.csh@silamam.kcin" class="oemail">ude.hatu.csh@silamam.kcin</a></div></div></div><div><sup><img src="/corehtml/pmc/pmcgifs/corrauth.gif" alt="corresponding author" /></sup>Corresponding author.</div></div><p class="small">Created: <span itemprop="datePublished">August 15, 2017</span>.</p></div><div class="jig-ncbiinpagenav body-content whole_rhythm" data-jigconfig="allHeadingLevels: ['h2'],smoothScroll: false" itemprop="text"><div id="lens_cataract.Introduction" itemprop="description"><h2 id="_lens_cataract_Introduction_">Introduction</h2><p>The lens of the eye is a biconvex, relatively acellular, optically transparent intraocular structure that with the cornea serves to transmit light to the retina with minimal light scattering (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F1a/?report=objectonly" target="object" rid-figpopup="figlenscataractF1a" rid-ob="figoblenscataractF1a">Figure 1a</a>). Early anatomists viewed the lens as the location of meaningful visualization. We now know that this is the function of the retina, with the lens serving as a conduit of light transmission and focus to the retina. The lens can change shape with the aid of the ciliary muscles, thereby changing the <a href="https://en.wikipedia.org/wiki/Focal_distance" ref="pagearea=abstract&targetsite=external&targetcat=link&targettype=uri">focal distance</a> to the retina and bringing the image into sharp focus on the retina. This adjustment of the lens is known as <a href="https://en.wikipedia.org/wiki/Accommodation_(eye)" ref="pagearea=abstract&targetsite=external&targetcat=link&targettype=uri">accommodation</a> (similar to the focusing of a photographic camera via movement of its <a href="https://en.wikipedia.org/wiki/Photographic_lens" ref="pagearea=abstract&targetsite=external&targetcat=link&targettype=uri">lenses</a>). The lens is flatter on its anterior side than on its posterior side. (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F1b/?report=objectonly" target="object" rid-figpopup="figlenscataractF1b" rid-ob="figoblenscataractF1b">Figure 1b</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF1a" co-legend-rid="figlgndlenscataractF1a"><a href="/books/NBK476171/figure/lens_cataract.F1a/?report=objectonly" target="object" title="Figure 1a. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF1a" rid-ob="figoblenscataractF1a"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image003.gif" src-large="/books/NBK476171/bin/lens_cataract-Image003.jpg" alt="Figure 1a. . A human eyeball cut in half to show the lens and the passage of light through it from the object ahead to the focus on the retina." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF1a"><h4 id="lens_cataract.F1a"><a href="/books/NBK476171/figure/lens_cataract.F1a/?report=objectonly" target="object" rid-ob="figoblenscataractF1a">Figure 1a. </a></h4><p class="float-caption no_bottom_margin">A human eyeball cut in half to show the lens and the passage of light through it from the object ahead to the focus on the retina. </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF1b" co-legend-rid="figlgndlenscataractF1b"><a href="/books/NBK476171/figure/lens_cataract.F1b/?report=objectonly" target="object" title="Figure 1b. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF1b" rid-ob="figoblenscataractF1b"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image004.gif" src-large="/books/NBK476171/bin/lens_cataract-Image004.jpg" alt="Figure 1b. . Histological section of normal crystalline lens (H&E stain, X2)." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF1b"><h4 id="lens_cataract.F1b"><a href="/books/NBK476171/figure/lens_cataract.F1b/?report=objectonly" target="object" rid-ob="figoblenscataractF1b">Figure 1b. </a></h4><p class="float-caption no_bottom_margin">Histological section of normal crystalline lens (H&E stain, X2). The sectioned iris is shown (<i>iris</i>) but the <i>ciliary body</i> is mostly out of the plane of the section. Notice the lens is flatter anteriorally, facing the cornea (<i>cornea</i>). </p></div></div></div><div id="lens_cataract.Development_of_the_lens"><h2 id="_lens_cataract_Development_of_the_lens_">Development of the lens</h2><p>The mature lens originates from surface ectoderm and develops through a highly organized process correlated with the neuroectoderm germ cell layer. Early in embryogenesis the diencephalon, neuroectoderm derived tissue, forms two outpouchings called the optic vesicles. The optic vesicles induce formation of the immature lenticular cells when they come in contact with surface ectoderm. The immature lenticular cells thicken to form the lens placode. Concurrently, the optic vesicles invaginate causing an indentation on the lens placode called the lens pit (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F2a/?report=objectonly" target="object" rid-figpopup="figlenscataractF2a" rid-ob="figoblenscataractF2a">Figure 2a</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF2a" co-legend-rid="figlgndlenscataractF2a"><a href="/books/NBK476171/figure/lens_cataract.F2a/?report=objectonly" target="object" title="Figure 2a. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF2a" rid-ob="figoblenscataractF2a"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image005.gif" src-large="/books/NBK476171/bin/lens_cataract-Image005.jpg" alt="Figure 2a. . A cartoon to show the development of the eye from the embryonic neural tube." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF2a"><h4 id="lens_cataract.F2a"><a href="/books/NBK476171/figure/lens_cataract.F2a/?report=objectonly" target="object" rid-ob="figoblenscataractF2a">Figure 2a. </a></h4><p class="float-caption no_bottom_margin">A cartoon to show the development of the eye from the embryonic neural tube. 1. <i>Optic vesicles</i> form from the <i>neural tube</i>. 2. The <i>optic cup</i> forms by invagination, as the <i>retina</i> folds back upon the pigment epithelium. The developing optic cup induces the <a href="/books/NBK476171/figure/lens_cataract.F2a/?report=objectonly" target="object" rid-ob="figoblenscataractF2a">(more...)</a></p></div></div><p>At this point, the lens vesicle is made up of a single layer of cells enveloped within an outer basement membrane. This basement membrane will eventually form the lens capsule. While encased in the basement membrane, the cells in the posterior pole of the lens vesicle extend anteriorly to form the primary lens fibers (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F2b/?report=objectonly" target="object" rid-figpopup="figlenscataractF2b" rid-ob="figoblenscataractF2b">Figure 2b</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF2b" co-legend-rid="figlgndlenscataractF2b"><a href="/books/NBK476171/figure/lens_cataract.F2b/?report=objectonly" target="object" title="Figure 2b. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF2b" rid-ob="figoblenscataractF2b"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image006.gif" src-large="/books/NBK476171/bin/lens_cataract-Image006.jpg" alt="Figure 2b. . Embryonic lens." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF2b"><h4 id="lens_cataract.F2b"><a href="/books/NBK476171/figure/lens_cataract.F2b/?report=objectonly" target="object" rid-ob="figoblenscataractF2b">Figure 2b. </a></h4><p class="float-caption no_bottom_margin"><i>Embryonic lens</i>. <i>Lens vesicle</i> posterior epithelial cells (<i>pec</i>) elongate to form the primary lens fibers (H&E stain, X10). </p></div></div><p>The anterior cells become the lens epithelial cells, while the primary lens fibers collectively form the embryonic nucleus. Subsequently, secondary lens fibers begin to elongate from the lens epithelial cells to form the fetal nucleus during the gestation period and continue to grow multiple layers. As the secondary lens fibers elongate from the equator, they form Y-shaped sutures by meeting anteriorly and posteriorly during fetal growth. The secondary lens fibers eventually grow to form the adult nucleus with new layers of lens fibers forming the lenticular cortex. During lenticular development, the hyaloid artery delivers nutrition and growth factors through the tunica vasculosa lentis, a vascular structure that envelopes the lens nucleus. However, this structure undergoes involution prior to birth to resemble the avascular lens seen in the adult. A firm understanding of the embryology and development of the lens will provide great insight into the pathology associated with cataract formation.</p><p><a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F3/?report=objectonly" target="object" rid-figpopup="figlenscataractF3" rid-ob="figoblenscataractF3">Figure 3</a> shows a stained section of the adult human lens with anterior part of the lens in the top section and the posterior part in the lower section.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF3" co-legend-rid="figlgndlenscataractF3"><a href="/books/NBK476171/figure/lens_cataract.F3/?report=objectonly" target="object" title="Figure 3. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF3" rid-ob="figoblenscataractF3"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image007.gif" src-large="/books/NBK476171/bin/lens_cataract-Image007.jpg" alt="Figure 3. . Layers of the lens." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF3"><h4 id="lens_cataract.F3"><a href="/books/NBK476171/figure/lens_cataract.F3/?report=objectonly" target="object" rid-ob="figoblenscataractF3">Figure 3. </a></h4><p class="float-caption no_bottom_margin">Layers of the lens. Upper section is through the anterior <i>lens capsule</i> showing lens epithelial cells, <i>lec</i>, and lens fibers, <i>lf</i>. Lower section is of the posterior lens capsule, <i>plc</i> and cortical fibers (<i>cf</i>). (H&E stain, X40). </p></div></div><p>The lens is composed of 4 structures: capsule, epithelium, cortex and nucleus (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F3/?report=objectonly" target="object" rid-figpopup="figlenscataractF3" rid-ob="figoblenscataractF3">Figure 3</a>). The capsule is the basement membrane with type VI collagen elaborated by the epithelium layer, and stains positively with Periodic acid-Schiff (PAS) stain. It is optically clear and acellular. The lens is held in place by zonular fibers, otherwise known as the zonules of Zinn (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F4/?report=objectonly" target="object" rid-figpopup="figlenscataractF4" rid-ob="figoblenscataractF4">Figure 4</a>). These elastic fibers originate from the nonpigmented epithelium layer of the ciliary body and articulate with the outer layer of the capsule, the capsular lamellar layer. There is a reduction of zonular tension with contraction of the ciliary muscle leading to a more spherical shape allowing focus on more proximal objects. This process is called accommodation.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF4" co-legend-rid="figlgndlenscataractF4"><a href="/books/NBK476171/figure/lens_cataract.F4/?report=objectonly" target="object" title="Figure 4. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF4" rid-ob="figoblenscataractF4"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image008.gif" src-large="/books/NBK476171/bin/lens_cataract-Image008.jpg" alt="Figure 4. . Scanning electron micrograph of zonular fibers." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF4"><h4 id="lens_cataract.F4"><a href="/books/NBK476171/figure/lens_cataract.F4/?report=objectonly" target="object" rid-ob="figoblenscataractF4">Figure 4. </a></h4><p class="float-caption no_bottom_margin">Scanning electron micrograph of <i>zonular fibers</i>. The fibers originate from the nonpigmented epithelium layer of the <i>ciliary body</i> and insert into the lens capsule. </p></div></div><p>The lens epithelium has mitotically active cells that undergo further differentiation via an elongation process, increase in intracellular protein and loss of organelles. These cells are arranged in one layer across the posterior aspect of the anterior capsule. The equatorial bow region of the lens is where lens epithelial cells elongate to form lens fiber cells (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F5/?report=objectonly" target="object" rid-figpopup="figlenscataractF5" rid-ob="figoblenscataractF5">Figure 5</a>). Terminal differentiation of the epithelium eventually leads to the fiber layers of both the cortex and nucleus, with older fibers being located more centrally.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF5" co-legend-rid="figlgndlenscataractF5"><a href="/books/NBK476171/figure/lens_cataract.F5/?report=objectonly" target="object" title="Figure 5. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF5" rid-ob="figoblenscataractF5"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image009.gif" src-large="/books/NBK476171/bin/lens_cataract-Image009.jpg" alt="Figure 5. . Lens bow region." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF5"><h4 id="lens_cataract.F5"><a href="/books/NBK476171/figure/lens_cataract.F5/?report=objectonly" target="object" rid-ob="figoblenscataractF5">Figure 5. </a></h4><p class="float-caption no_bottom_margin"><i>Lens bow region</i>. Lens epithelial cells (<i>ec</i>) originating from the equatorial region elongate to form new <i>lens fibers</i> (H&E stain, X10). </p></div></div><p>While the nucleus is denser, histologically, there is no distinction between the cortex and nucleus (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F5/?report=objectonly" target="object" rid-figpopup="figlenscataractF5" rid-ob="figoblenscataractF5">Figure 5</a>). The only appreciable difference is age, with older layers located more centrally. Interestingly, as the cortex and nucleus layers grow, the overall diopter strength of the lens increases owing to the increased diameter and curvature of the lens. The lack of organelles within the nucleus and cortex serves to provide an optically clear media for light transmission. The adult lens is almost three times the mass of its corresponding neonatal version, 90 mg to 250 mg.</p><p>In the adult, the lens lacks vascularity or innervation thus the metabolic demands of the lens are met by a constant flow of aqueous humor that serves as a conduit for both removal of waste and the delivery of nutrients.</p></div><div id="lens_cataract.Cataract_formation_and_typ"><h2 id="_lens_cataract_Cataract_formation_and_typ_">Cataract formation and types of cataracts</h2><div id="lens_cataract.Congenital_cataracts"><h3>Congenital cataracts</h3><p>Congenital cataracts are lenticular opacities that cause significant light scattering at birth or are noted shortly after (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F6/?report=objectonly" target="object" rid-figpopup="figlenscataractF6" rid-ob="figoblenscataractF6">Figure 6</a>). An estimated 200,000 children worldwide are blind as a result of congenital cataracts, with an incidence of 40,000 in developing countries (<a class="bk_pop" href="#lens_cataract.REF.1" data-bk-pop-others="lens_cataract.REF.2">1, 2</a>). In regards to laterality, the prevalence appears to be the same for unilateral vs. bilateral (<a class="bk_pop" href="#lens_cataract.REF.2">2</a>). Surgical intervention for both unilateral and bilateral cataract is paramount to prevent long term deprivation amblyopia or visual loss (<a class="bk_pop" href="#lens_cataract.REF.3" data-bk-pop-others="lens_cataract.REF.4">3, 4</a>). Amblyopia is defined as a dysfunction in visual processing, characterized by poor visual acuity in one or both eyes and abnormal binocular depth perception (<a class="bk_pop" href="#lens_cataract.REF.5">5</a>). While both unilateral and bilateral cataracts are critical to detect, the long term severity of bilateral visual deprivation appears to be less than its unilateral counterpart (<a class="bk_pop" href="#lens_cataract.REF.6">6</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF6" co-legend-rid="figlgndlenscataractF6"><a href="/books/NBK476171/figure/lens_cataract.F6/?report=objectonly" target="object" title="Figure 6. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF6" rid-ob="figoblenscataractF6"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image010.gif" src-large="/books/NBK476171/bin/lens_cataract-Image010.jpg" alt="Figure 6. . Clinical photograph of an eye with a dilated pupil to show a congenital cataract in the original fetal lens nucleus." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF6"><h4 id="lens_cataract.F6"><a href="/books/NBK476171/figure/lens_cataract.F6/?report=objectonly" target="object" rid-ob="figoblenscataractF6">Figure 6. </a></h4><p class="float-caption no_bottom_margin">Clinical photograph of an eye with a dilated pupil to show a congenital cataract in the original fetal lens nucleus. </p></div></div></div><div id="lens_cataract.Nuclear_cataracts"><h3>Nuclear cataracts</h3><p>A common cause of visual impairment in older adults is age-related cataract, which is subcategorized as nuclear, cortical or subcapsular in type. Cumulative incidence of nuclear, cortical and posterior cortical are 29.7%, 22.9% and 8.4% respectively (<a class="bk_pop" href="#lens_cataract.REF.7" data-bk-pop-others="lens_cataract.REF.8">7, 8</a>). Nuclear cataract is the most common age-related problem (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F7/?report=objectonly" target="object" rid-figpopup="figlenscataractF7" rid-ob="figoblenscataractF7">Figure 7</a>, <a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F8/?report=objectonly" target="object" rid-figpopup="figlenscataractF8" rid-ob="figoblenscataractF8">Figure 8</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF7" co-legend-rid="figlgndlenscataractF7"><a href="/books/NBK476171/figure/lens_cataract.F7/?report=objectonly" target="object" title="Figure 7. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF7" rid-ob="figoblenscataractF7"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image011.gif" src-large="/books/NBK476171/bin/lens_cataract-Image011.jpg" alt="Figure 7. . Sagittal section of part of the eyeball to show a mature nuclear sclerotic cataract, nsc; retina (retina); cornea, (c)." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF7"><h4 id="lens_cataract.F7"><a href="/books/NBK476171/figure/lens_cataract.F7/?report=objectonly" target="object" rid-ob="figoblenscataractF7">Figure 7. </a></h4><p class="float-caption no_bottom_margin">Sagittal section of part of the eyeball to show a mature nuclear sclerotic cataract, <i>nsc</i>; retina (<i>retina</i>); cornea, (<i>c</i>). </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF8" co-legend-rid="figlgndlenscataractF8"><a href="/books/NBK476171/figure/lens_cataract.F8/?report=objectonly" target="object" title="Figure 8. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF8" rid-ob="figoblenscataractF8"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image012.gif" src-large="/books/NBK476171/bin/lens_cataract-Image012.jpg" alt="Figure 8. . Posterior view of a nuclear sclerotic cataract using the Miyake-Apple technique of removing the back part of the eyeball." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF8"><h4 id="lens_cataract.F8"><a href="/books/NBK476171/figure/lens_cataract.F8/?report=objectonly" target="object" rid-ob="figoblenscataractF8">Figure 8. </a></h4><p class="float-caption no_bottom_margin">Posterior view of a nuclear sclerotic cataract using the Miyake-Apple technique of removing the back part of the eyeball. </p></div></div><p>With age, nuclear fibers become more compacted and cause increased light scattering. As a result, sclerotic lens nuclei decrease in transparency and result in visual aberrations and annoying glare at night. Clinically, the sclerotic nuclear lens changes in color, from a clear transparent material to yellow or orange, eventually even to brown (brunescent) if left to mature (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F9/?report=objectonly" target="object" rid-figpopup="figlenscataractF9" rid-ob="figoblenscataractF9">Figure 9</a>). Histologically, nuclear sclerotic lenses are characterized by a dense homogenous material.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF9" co-legend-rid="figlgndlenscataractF9"><a href="/books/NBK476171/figure/lens_cataract.F9/?report=objectonly" target="object" title="Figure 9. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF9" rid-ob="figoblenscataractF9"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image013.gif" src-large="/books/NBK476171/bin/lens_cataract-Image013.jpg" alt="Figure 9. . Isolated brunescent cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF9"><h4 id="lens_cataract.F9"><a href="/books/NBK476171/figure/lens_cataract.F9/?report=objectonly" target="object" rid-ob="figoblenscataractF9">Figure 9. </a></h4><p class="float-caption no_bottom_margin">Isolated brunescent cataract. Nuclear sclerotic cataract has a deep brown color with age. </p></div></div><p>Aging causes the lenticular material to increase in overall size and become more amorphous. As the lens fibers continue to age, the nucleus becomes more compact and less pliable decreasing the ability of the lens to effectively accommodate. The increased coloration is due to protein aggregation in the nuclear lens, decreasing its transparency and leading to various symptoms including visual impairment, decrease in contrast sensitivity, dull color perception and a myopic shift.</p><p>As the cataract continues to mature, the cortical material begins to liquefy and the nucleus increases in opacity. A hyper-mature cataract is the final stage of the aging process. The liquefied cortex is resorbed, and the dense nucleus sinks within the capsular bag. If left untreated, proteinaceous material can leak across the capsular lining and cause trabecular meshwork (TM) obstruction leading to a phacolytic glaucomatous reaction. This inflammatory reaction is mediated by macrophages that respond to the leakage of lenticular protein and contribute to the TM obstruction. Changes within the lens nucleus do not occur independent of the other lenticular structure, instead, cortical subcapsular cataracts may and typically do occur simultaneously. However, nuclear sclerotic cataract is by far the most common age-related lenticular opacity.</p><p><a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F10/?report=objectonly" target="object" rid-figpopup="figlenscataractF10" rid-ob="figoblenscataractF10">Figure 10</a> shows a photograph of a patient’s eye with dense mature cataract that has both nuclear and cortical (see below) components. Obviously, the patient was “blind” in this eye, and this cataract needed to be removed to restore sight to the eye.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF10" co-legend-rid="figlgndlenscataractF10"><a href="/books/NBK476171/figure/lens_cataract.F10/?report=objectonly" target="object" title="Figure 10. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF10" rid-ob="figoblenscataractF10"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image014.gif" src-large="/books/NBK476171/bin/lens_cataract-Image014.jpg" alt="Figure 10. . Photograph of a patient’s right eye with a dense mature cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF10"><h4 id="lens_cataract.F10"><a href="/books/NBK476171/figure/lens_cataract.F10/?report=objectonly" target="object" rid-ob="figoblenscataractF10">Figure 10. </a></h4><p class="float-caption no_bottom_margin">Photograph of a patient’s right eye with a dense mature cataract. Courtesy of James Gilmore, Photography department at the Moran Eye Center. </p></div></div></div><div id="lens_cataract.Cortical_cataracts"><h3>Cortical cataracts</h3><p>As in nuclear sclerotic lens changes, aging can cause similar degenerative changes in the lens cortex. The opacities formed within the lens cortex are quite unique. Sharp clear fluid clefts, resembling opaque spokes within the lens cortex, are seen. <a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F11/?report=objectonly" target="object" rid-figpopup="figlenscataractF11" rid-ob="figoblenscataractF11">Figure 11</a> and <a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F12/?report=objectonly" target="object" rid-figpopup="figlenscataractF12" rid-ob="figoblenscataractF12">Figure 12</a> show the typical appearance of cortical cataract shown from the front (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F11/?report=objectonly" target="object" rid-figpopup="figlenscataractF11" rid-ob="figoblenscataractF11">Figure 11</a>) and the back (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F12/?report=objectonly" target="object" rid-figpopup="figlenscataractF12" rid-ob="figoblenscataractF12">Figure 12</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF11" co-legend-rid="figlgndlenscataractF11"><a href="/books/NBK476171/figure/lens_cataract.F11/?report=objectonly" target="object" title="Figure 11. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF11" rid-ob="figoblenscataractF11"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image015.gif" src-large="/books/NBK476171/bin/lens_cataract-Image015.jpg" alt="Figure 11. . Clinical photograph of a cortical cataract with prominent cortical fluid clefts (black lines)." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF11"><h4 id="lens_cataract.F11"><a href="/books/NBK476171/figure/lens_cataract.F11/?report=objectonly" target="object" rid-ob="figoblenscataractF11">Figure 11. </a></h4><p class="float-caption no_bottom_margin">Clinical photograph of a cortical cataract with prominent cortical fluid clefts (black lines). </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF12" co-legend-rid="figlgndlenscataractF12"><a href="/books/NBK476171/figure/lens_cataract.F12/?report=objectonly" target="object" title="Figure 12. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF12" rid-ob="figoblenscataractF12"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image016.gif" src-large="/books/NBK476171/bin/lens_cataract-Image016.jpg" alt="Figure 12. . Posterior view of a cortical cataract using the Miyake-Apple technique to display the lens." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF12"><h4 id="lens_cataract.F12"><a href="/books/NBK476171/figure/lens_cataract.F12/?report=objectonly" target="object" rid-ob="figoblenscataractF12">Figure 12. </a></h4><p class="float-caption no_bottom_margin">Posterior view of a cortical cataract using the Miyake-Apple technique to display the lens. The fluid clefts are obvious (black lines). </p></div></div><p>Histologically, cortical cataracts are characterized by an accumulation of pink staining eosinophilic fluid between cortical fibers (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F13/?report=objectonly" target="object" rid-figpopup="figlenscataractF13" rid-ob="figoblenscataractF13">Figure 13</a>). This fluid accumulation causes shifts between lenticular cells leading to displacement and degeneration of bordering cells. The shift accounts for the spokes seen clinically (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F11/?report=objectonly" target="object" rid-figpopup="figlenscataractF11" rid-ob="figoblenscataractF11">Figure 11</a>, <a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F12/?report=objectonly" target="object" rid-figpopup="figlenscataractF12" rid-ob="figoblenscataractF12">Figure 12</a>). Globules of proteinaceous material, called Morgagnian globules, may be released from the degeneration of the cortical lens cells (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F14/?report=objectonly" target="object" rid-figpopup="figlenscataractF14" rid-ob="figoblenscataractF14">Figure 14</a>). As the cortical cataract continues to mature, the entire cortical region can be replaced by these globules and thus becomes a mature Morgagnian cataract (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F15/?report=objectonly" target="object" rid-figpopup="figlenscataractF15" rid-ob="figoblenscataractF15">Figure 15</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF13" co-legend-rid="figlgndlenscataractF13"><a href="/books/NBK476171/figure/lens_cataract.F13/?report=objectonly" target="object" title="Figure 13. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF13" rid-ob="figoblenscataractF13"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image017.gif" src-large="/books/NBK476171/bin/lens_cataract-Image017.jpg" alt="Figure 13. . Cortical cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF13"><h4 id="lens_cataract.F13"><a href="/books/NBK476171/figure/lens_cataract.F13/?report=objectonly" target="object" rid-ob="figoblenscataractF13">Figure 13. </a></h4><p class="float-caption no_bottom_margin">Cortical cataract. Histology of early liquified cortical changes displaying accumulation of eosinophilic fluid (pink background) between the lenticular fibers. (H&E stain, X10). </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF14" co-legend-rid="figlgndlenscataractF14"><a href="/books/NBK476171/figure/lens_cataract.F14/?report=objectonly" target="object" title="Figure 14. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF14" rid-ob="figoblenscataractF14"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image018.gif" src-large="/books/NBK476171/bin/lens_cataract-Image018.jpg" alt="Figure 14. . Histology of advanced cortical cataract displaying extensive protein breakdown forming Morgagnian globules (Mg, arrows)." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF14"><h4 id="lens_cataract.F14"><a href="/books/NBK476171/figure/lens_cataract.F14/?report=objectonly" target="object" rid-ob="figoblenscataractF14">Figure 14. </a></h4><p class="float-caption no_bottom_margin">Histology of advanced cortical cataract displaying extensive protein breakdown forming Morgagnian globules (<i>Mg</i>, arrows). (H&E stain, X10). </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF15" co-legend-rid="figlgndlenscataractF15"><a href="/books/NBK476171/figure/lens_cataract.F15/?report=objectonly" target="object" title="Figure 15. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF15" rid-ob="figoblenscataractF15"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image019.gif" src-large="/books/NBK476171/bin/lens_cataract-Image019.jpg" alt="Figure 15. . Morgagnian cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF15"><h4 id="lens_cataract.F15"><a href="/books/NBK476171/figure/lens_cataract.F15/?report=objectonly" target="object" rid-ob="figoblenscataractF15">Figure 15. </a></h4><p class="float-caption no_bottom_margin">Morgagnian cataract. A hypermature cataract with a liquified cortex (<i>c</i>) and a dense nuclear cataract (<i>dnc</i>). </p></div></div><p>Another characteristic appearance of the cortical cataract is a Christmas tree cataract. This occurs when crystals form within the deep cortex. These crystals are typically composed of cholesterol, lipids, calcium or other compounds. Interestingly, Christmas tree cataracts do not typically cause significant visual impairment.</p><p>While a cortical cataract can occur independently of a nuclear sclerotic cataract, biomechanical changes within the lens nucleus can actually induce cataractous changes in the lens cortex. The ability to effectively accommodate decreases with age, in general. The altered biomechanics between the sclerotic nucleus and cortex creates residual sheer stress and results in parallel micro-ridges at the area of lamellar separation. This process helps to explain the histologic patterns seen in cortical cataracts.</p></div><div id="lens_cataract.Posterior_subcapsular_cata"><h3>Posterior subcapsular cataract</h3><p>Posterior subcapsular cataracts (PSC) develop due to the posterior migration of lens epithelial cells in response to external stimulus. Although most cases are spontaneous, PSC also can develop secondarily to metabolic causes, such as diabetes, inflammation, uveitis, or from long-term topical or systemic corticosteroid use. PSC tend to occur in younger patients and progress more quickly than the other cataract subtypes. The opacity is located at the posterior pole of the lens on the anterior surface of the posterior capsule (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F16/?report=objectonly" target="object" rid-figpopup="figlenscataractF16" rid-ob="figoblenscataractF16">Figure 16</a>, <a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F17/?report=objectonly" target="object" rid-figpopup="figlenscataractF17" rid-ob="figoblenscataractF17">Figure 17</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF16" co-legend-rid="figlgndlenscataractF16"><a href="/books/NBK476171/figure/lens_cataract.F16/?report=objectonly" target="object" title="Figure 16. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF16" rid-ob="figoblenscataractF16"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image020.gif" src-large="/books/NBK476171/bin/lens_cataract-Image020.jpg" alt="Figure 16. . Slit lamp clinical photograph of a focal opacified area (white granular appearance) of posterior subcapsular cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF16"><h4 id="lens_cataract.F16"><a href="/books/NBK476171/figure/lens_cataract.F16/?report=objectonly" target="object" rid-ob="figoblenscataractF16">Figure 16. </a></h4><p class="float-caption no_bottom_margin">Slit lamp clinical photograph of a focal opacified area (white granular appearance) of posterior subcapsular cataract. </p></div></div><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF17" co-legend-rid="figlgndlenscataractF17"><a href="/books/NBK476171/figure/lens_cataract.F17/?report=objectonly" target="object" title="Figure 17. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF17" rid-ob="figoblenscataractF17"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image021.gif" src-large="/books/NBK476171/bin/lens_cataract-Image021.jpg" alt="Figure 17. . Retroillumination clinical photograph of a focal granular area (arrows) of a posterior subcapsular cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF17"><h4 id="lens_cataract.F17"><a href="/books/NBK476171/figure/lens_cataract.F17/?report=objectonly" target="object" rid-ob="figoblenscataractF17">Figure 17. </a></h4><p class="float-caption no_bottom_margin">Retroillumination clinical photograph of a focal granular area (arrows) of a posterior subcapsular cataract. </p></div></div><p>An ultrastructural study involving 13 eyes with PSC showed the changes that took place as lens epithelial cells migrated from the equator of the lens to the PSC region. The study concluded that there was a mitotic change as cells migrated towards the posterior pole. The equatorial region cells resembled normal lens epithelial cells but the cells near the PSC showed increased mitotic activity. The authors suggested that the cells were responding to some type of noxious stimuli at the posterior pole. The resultant activity caused the cells to mature into lens fibers or enlarge into bladder-like cells called Wedl cells and the formation of PSC (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F18/?report=objectonly" target="object" rid-figpopup="figlenscataractF18" rid-ob="figoblenscataractF18">Figure 18</a>). The migrating cells probably contribute to cataract formation by secreting extracellular materials, cytolysis, cell dissolution, and possibly release of lysosomal enzymes (<a class="bk_pop" href="#lens_cataract.REF.9">9</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF18" co-legend-rid="figlgndlenscataractF18"><a href="/books/NBK476171/figure/lens_cataract.F18/?report=objectonly" target="object" title="Figure 18. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF18" rid-ob="figoblenscataractF18"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image022.gif" src-large="/books/NBK476171/bin/lens_cataract-Image022.jpg" alt="Figure 18. . Bladder cells (bc) or Wedl cells." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF18"><h4 id="lens_cataract.F18"><a href="/books/NBK476171/figure/lens_cataract.F18/?report=objectonly" target="object" rid-ob="figoblenscataractF18">Figure 18. </a></h4><p class="float-caption no_bottom_margin">Bladder cells (<i>bc</i>) or Wedl cells. Swollen lens epithelial cells that have migrated posteriorally to the posterior capsule in a subcapsular cataract (H&E stain, X20). </p></div></div></div><div id="lens_cataract.Anterior_subcapsular_catar"><h3>Anterior subcapsular cataract</h3><p>Anterior subcapsular cataracts (ASC) develop because of the degeneration of anterior lens epithelial cells. They can develop secondary to trauma, medical treatment iatrogenic causes, or spontaneously. The area of damage causes a migration of lens epithelial cells into the area and subsequent transformation of the cells into myofibroblasts in a process known as fibrous metaplasia. This results in an opacity on the anterior surface of the lens beneath the anterior capsule.</p><p>In one of the first studies on ASC, 5 lenses with ASC were examined by light and electron microscopy and confirmed the ability of the lens epithelium to undergo transformation to a fibrous plaque. The lens epithelial cells lost their normal cuboidal shape and elongated into a more spindle-shaped cell (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F19/?report=objectonly" target="object" rid-figpopup="figlenscataractF19" rid-ob="figoblenscataractF19">Figure 19</a>: a, b, c). These cells were found frequently to be in contact with one another, resulting in the fibrous plaque known as ASC. This process can be broken down into two phases: a proliferative and a degenerative phase. The proliferative phase was most evident near the periphery of the plaque, showing numerous spindle-shaped cells and mitotically active cells. It is followed by a degenerative phase, which results in an almost structure-less hyaline mass with fewer spindle-shaped cells (<a class="bk_pop" href="#lens_cataract.REF.10">10</a>).</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF19" co-legend-rid="figlgndlenscataractF19"><a href="/books/NBK476171/figure/lens_cataract.F19/?report=objectonly" target="object" title="Figure 19. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF19" rid-ob="figoblenscataractF19"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image023.gif" src-large="/books/NBK476171/bin/lens_cataract-Image023.jpg" alt="Figure 19. . Electron micrographs of the anterior lens epithelial cells in anterior subcapsular cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF19"><h4 id="lens_cataract.F19"><a href="/books/NBK476171/figure/lens_cataract.F19/?report=objectonly" target="object" rid-ob="figoblenscataractF19">Figure 19. </a></h4><p class="float-caption no_bottom_margin">Electron micrographs of the anterior lens epithelial cells in anterior subcapsular cataract. a) Low magnification view of the anterior epithelial cells lying in basement membrane. X440. b) Higher magnification of spindle-shaped epithelial cells that will <a href="/books/NBK476171/figure/lens_cataract.F19/?report=objectonly" target="object" rid-ob="figoblenscataractF19">(more...)</a></p></div></div><p>Although the cause of ASC is varied, an association between ASC and the formation of synechiae after trauma or inflammation has been hypothesized. The synechiae would form between the posterior iris and anterior lens capsule, resulting in a stagnation of aqueous humor and accumulation of toxic metabolites that could produce a toxic effect on anterior lens epithelium (<a class="bk_pop" href="#lens_cataract.REF.10">10</a>).</p></div><div id="lens_cataract.Traumatic_cataract"><h3>Traumatic cataract</h3><p>Direct injury to the head or eye can cause significant mechanical disruption and lead to cataract formation. A Vossius ring can occur if the insult caused the posterior iris pigment epithelium to imprint on the lens capsule. The pigment deposition may abate and resolve completely with time. Severe blunt injury can cause stellate lenticular opacities in the cortex and capsule. Such insult can lead to lens epithelium dysfunction, resulting in a significant edematous response to the superficial cortical lens. Vacuole pockets can then become trapped permanently within the lamellar zone, becoming integrated within the lenticular fibers while new layers are elaborated over the lesion. Alternatively, blunt trauma can also cause cataract formation within all the lenticular layers, leading to a diffuse fibrous metaplasia (<a class="figpopup" href="/books/NBK476171/figure/lens_cataract.F20/?report=objectonly" target="object" rid-figpopup="figlenscataractF20" rid-ob="figoblenscataractF20">Figure 20</a>). Other forms of trauma that can lead to cataract formation include exposure to radiation, infrared, extreme heat and electrical injury.</p><div class="iconblock whole_rhythm clearfix ten_col fig" id="figlenscataractF20" co-legend-rid="figlgndlenscataractF20"><a href="/books/NBK476171/figure/lens_cataract.F20/?report=objectonly" target="object" title="Figure 20. " class="img_link icnblk_img figpopup" rid-figpopup="figlenscataractF20" rid-ob="figoblenscataractF20"><img class="small-thumb" src="/books/NBK476171/bin/lens_cataract-Image024.gif" src-large="/books/NBK476171/bin/lens_cataract-Image024.jpg" alt="Figure 20. . Traumatic cataract." /></a><div class="icnblk_cntnt" id="figlgndlenscataractF20"><h4 id="lens_cataract.F20"><a href="/books/NBK476171/figure/lens_cataract.F20/?report=objectonly" target="object" rid-ob="figoblenscataractF20">Figure 20. </a></h4><p class="float-caption no_bottom_margin">Traumatic cataract. Extensive anterior fibrous metaplasia (arrows) displaying prominent collagen staining (blue) in a traumatic cataract (Trichrome stain, X20). </p></div></div></div><div id="lens_cataract.Druginduced_cataract"><h3>Drug-induced cataract</h3><p>Several pharmacological agents have been shown to cause cataract formation. Long term corticosteroid therapy and anabolic steroid use are among the most common agents associated with cataract formation, particularly posterior subcapsular cataract (<a class="bk_pop" href="#lens_cataract.REF.11">11</a>). The incidence and severity of PSC is directly related to the dose and duration of use (<a class="bk_pop" href="#lens_cataract.REF.12">12</a>). Interestingly, steroid therapy has become a frequent treatment option in the management of retinal pathologies, and in turn increases the rates of cataract formation. There does not appear to be any distinction between PSC induced by steroid use or a pure age-related PSC (<a class="bk_pop" href="#lens_cataract.REF.13">13</a>). Phenothiazine is another therapeutic agent that can cause lenticular opacities. Psychotropic agents, particularly phenothiazine, induce deposition of pigmented material into the anterior lens epithelium in a very distinct axial configuration (<a class="bk_pop" href="#lens_cataract.REF.14">14</a>). Other pharmaceutical agents known to cause lenticular cataracts include miotics, and amiodarone (<a class="bk_pop" href="#lens_cataract.REF.15">15</a>).</p></div><div id="lens_cataract.Other_causes_of_cataract"><h3>Other causes of cataract</h3><p>While age-related changes remain the leading factor for cataract formation, specifically senile cataract, other contributory factors include smoking, systemic disease, excessive exposure to sunlight and the aforementioned pharmacological agents (<a class="bk_pop" href="#lens_cataract.REF.16" data-bk-pop-others="lens_cataract.REF.17 lens_cataract.REF.18 lens_cataract.REF.19">16-19</a>). Many systemic diseases can cause cataracts, such as, diabetes mellitus, hypocalcemia, myotonic dystrophy and Wilson’s disease (<a class="bk_pop" href="#lens_cataract.REF.19" data-bk-pop-others="lens_cataract.REF.20 lens_cataract.REF.21">19-21</a>); In diabetic patients, cortical and PSCs appear to occur earlier, particularly among patients with poor glycemic control. Hypocalcemia-induced cataracts usually initiate as small white dot opacities that can coalesce into larger flakes.</p><p>Smoking, sun exposure and systemic disease management are modifiable risk factors, so taking measures to change these factors can delay the onset and progression of cataract formation. Phytonutrients, such as xanthophyll carotenoids, lutein and zeaxanthin may play a potential role in limiting or neutralizing light induced oxidative changes within the lens (<a class="bk_pop" href="#lens_cataract.REF.22">22</a>). Currently, there are several ongoing studies evaluating other possible protective agents. Although there is no definitive measure to prevent cataract formation, cataract surgery remains an extremely safe and highly successful intervention.</p></div><div id="lens_cataract.Cataract_surgery"><h3>Cataract surgery</h3><p>Surgery for cataracts has undergone extensive evolution. Ancient knowledge viewed the cataratous eye as an imbalance of humors that needed displacement to recover vision. Using a needle, the surgeon would proceed to displace the abnormal humor until the crystalline lens dislocated. Modern cataract surgery has undergone significant changes and is now characterized by several steps: corneal incision, continuous curvilinear capsulorrhexis (CCC), hydrodissection, phacoemulsification, cortical aspiration, and intraocular lens (IOL) implantation.</p><p>Earlier surgical interventions to remove the entire cataractous lens required a 12-mm incision with subsequent suture closure. However, a small 2.4 to 2.8 mm wide clear corneal incision is enough to facilitate entry of the phaco handpiece while remaining sutureless for closure. The CCC technique was developed by Gimbel and Neuhann in the 1980s and truly revolutionized the phacoemulsification technique (<a class="bk_pop" href="#lens_cataract.REF.23">23</a>). CCC involves creating a tear in the anterior capsule then continuing the tear in a circular continuous fashion while minimizing shear forces exerted on the zonular fibers. After creation of the CCC, phacoemulsification is used to fragment and emulsify both the cortical and nuclear material. Originally pioneered by Kelman in 1967, phacoemulsification remains a vital part of cataract surgery (<a class="bk_pop" href="#lens_cataract.REF.24" data-bk-pop-others="lens_cataract.REF.25">24, 25</a>). The CCC opening is large enough to allow implantation of the entire optic and haptics of an intraocular lens (IOL) within the remnant lens capsular bag. The prior use of non-foldable polymethylmethacrylate lenses required a relatively large clear corneal incision for implantation. However, the development of the foldable silicone and acrylic IOLs allowed insertion through a small incision mostly less than 4.0 mm in length. Innovation is constantly improving these steps of cataract surgery, from novel IOLs with unique design to minimize the corneal incision, to use of the femtosecond laser to create an automated corneal incision, CCC and to fragment the nucleus prior to aspiration (<a class="bk_pop" href="#lens_cataract.REF.26" data-bk-pop-others="lens_cataract.REF.27">26, 27</a>).</p><p>Details of the types of intraocular lenses, that are presently being used in cataract surgery, are presented in the following chapter in Webvision by Jason Nguyen, and Liliana Werner.</p></div></div><div id="lens_cataract.About_the_authors"><h2 id="_lens_cataract_About_the_authors_">About the authors</h2><div id="lens_cataract."><h3>
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</h3><p>Joah F. Aliancy, MD, originally from Haiti, received his undergraduate degree from the University of South Florida in Chemistry with honors distinction and his medical degree from Florida State University. Presently he is an ocular pathology research fellow at the John A. Moran Eye Center. In a year, Dr. Aliancy will attend the Harkness Eye Institute at Columbia University for his Ophthalmology residency training. His research interests include novel intraocular lens technology, mechanisms to decrease capsular lens opacification, toxic anterior segment syndrome and nitric oxide as a treatment modality in glaucomatous disease. He has been honored with induction into both Alpha Omega Alpha and Gold Humanism Honor societies and recipient of the National Medical Association Rabb-Venable Award. Dr. Aliancy can be contacted at <a href="mailto:dev@null" data-email="ude.hatu@ycnaila.haoj" class="oemail">ude.hatu@ycnaila.haoj</a>.</p><p>
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</p><p>Nick Mamalis is a Professor of Ophthalmology at the John A. Moran Eye Center of the University of Utah in Salt Lake City. He received his BA in Biochemistry from Harvard University and his MD from the University of Utah, School of Medicine. After a fellowship in Ophthalmic Pathology at the University of Utah he completed his residency in Ophthalmology at Loyola University Medical Center. He is currently the Director of Ophthalmic Pathology as well as the co-Director of the Intermountain Ocular Research Center at the University of Utah. He is the Editor of the <i>Journal of Cataract and Refractive Surgery</i> as well as a member of the Cataract Clinical Committee and the Executive Committee of the American Society of Cataract and Refractive Surgery (ASCRS). Dr. Mamalis is a former President of the Utah Ophthalmology Society. He was given the American Academy of Ophthalmology Honor Award in 1994, Senior Achievement Award in 2005, and a Life Achievement Honor in 2015. He was the recipient of the Brinkhorst Medal of Honor in 2013 by the ASCRS. He is known nationally and internationally, has published over 200 peer review journal articles and has written multiple textbooks and textbook chapters. Dr. Mamalis can be contacted at <a href="mailto:dev@null" data-email="ude.hatu.csh@silamam.kcin" class="oemail">ude.hatu.csh@silamam.kcin</a><u>.</u></p></div></div><div id="lens_cataract.References"><h2 id="_lens_cataract_References_">References</h2><dl class="temp-labeled-list"><dt>1.</dt><dd><div class="bk_ref" id="lens_cataract.REF.1">Foster A., Gilbert C., Rahi J. Epidemiology of cataract in childhood: a global perspective. <span><span class="ref-journal">Journal of Cataract & Refractive Surgery. </span>1997;<span class="ref-vol">23</span>:601–604.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9278811" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 9278811</span></a>]</div></dd><dt>2.</dt><dd><div class="bk_ref" id="lens_cataract.REF.2">Sheeladevi S., Lawrenson J., Fielder A., Suttle C. Global prevalence of childhood cataract: a systematic review. <span><span class="ref-journal">Eye. </span>2016</span> [<a href="/pmc/articles/PMC5023808/" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pmc">PMC free article<span class="bk_prnt">: PMC5023808</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/27518543" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 27518543</span></a>]</div></dd><dt>3.</dt><dd><div class="bk_ref" id="lens_cataract.REF.3">Birch E.E., Cheng C., Stager D.R., Weakley D.R. The critical period for surgical treatment of dense congenital bilateral cataracts. <span><span class="ref-journal">Journal of American Association for Pediatric Ophthalmology and Strabismus. </span>2009;<span class="ref-vol">13</span>(1):67–71.</span> [<a href="/pmc/articles/PMC3310432/" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pmc">PMC free article<span class="bk_prnt">: PMC3310432</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/19084444" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 19084444</span></a>]</div></dd><dt>4.</dt><dd><div class="bk_ref" id="lens_cataract.REF.4">Birch E.E., Stager D.R. The critical period for surgical treatment of dense congenital unilateral cataract. <span><span class="ref-journal">Investigative Ophthalmology & Visual Science. </span>1996;<span class="ref-vol">37</span>(8):1532–1538.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8675395" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 8675395</span></a>]</div></dd><dt>5.</dt><dd><div class="bk_ref" id="lens_cataract.REF.5">Holmes J.M., Clarke M.P. Amblyopia. <span><span class="ref-journal">The Lancet. </span>2006;<span class="ref-vol">367</span>(9519):1343–1351.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/16631913" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 16631913</span></a>]</div></dd><dt>6.</dt><dd><div class="bk_ref" id="lens_cataract.REF.6">Birch E.E., Stager D., Leffler J., Weakley D. Early treatment of congenital unilateral cataract minimizes unequal competition. <span><span class="ref-journal">Investigative Ophthalmology & Visual Science. </span>1998;<span class="ref-vol">39</span>(9):1560–1566.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9699545" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 9699545</span></a>]</div></dd><dt>7.</dt><dd><div class="bk_ref" id="lens_cataract.REF.7">Klein B.E., Klein R., Lee K.E., Gangnon R.E. Incidence of age-related cataract over a 15-year interval: the Beaver Dam Eye Study. <span><span class="ref-journal">Ophthalmology. </span>2008;<span class="ref-vol">115</span>(3):477–482.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/18171585" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 18171585</span></a>]</div></dd><dt>8.</dt><dd><div class="bk_ref" id="lens_cataract.REF.8">Seddon J., Fong D., West S.K., Valmadrid C.T. Epidemiology of risk factors for age-related cataract. <span><span class="ref-journal">Survey of Ophthalmology. </span>1995;<span class="ref-vol">39</span>(4):323–334.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/7725232" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 7725232</span></a>]</div></dd><dt>9.</dt><dd><div class="bk_ref" id="lens_cataract.REF.9">Streeten B.W., Eshaghian J. Human posterior subcapsular cataract: a gross and flat preparation study. <span><span class="ref-journal">Archives of Ophthalmology. </span>1978;<span class="ref-vol">96</span>(9):1653–1658.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/687210" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 687210</span></a>]</div></dd><dt>10.</dt><dd><div class="bk_ref" id="lens_cataract.REF.10">Font R.L., Brownstein S. A light and electron microscopic study of anterior subcapsular cataracts. <span><span class="ref-journal">American Journal of Ophthalmology. </span>1974;<span class="ref-vol">78</span>(6):972–984.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/4140696" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 4140696</span></a>]</div></dd><dt>11.</dt><dd><div class="bk_ref" id="lens_cataract.REF.11">Urban R.C., Cotlier E. Corticosteroid-induced cataracts. <span><span class="ref-journal">Survey of Ophthalmology. </span>1986;<span class="ref-vol">31</span>(2):102–110.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/3541262" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 3541262</span></a>]</div></dd><dt>12.</dt><dd><div class="bk_ref" id="lens_cataract.REF.12">McGraw B.F., Rollins C.L. Topical-Corticosteroid-Induced Cataracts. <span><span class="ref-journal">Drug Intelligence & Clinical Pharmacy. </span>1979;<span class="ref-vol">13</span>(9):537–538.</span></div></dd><dt>13.</dt><dd><div class="bk_ref" id="lens_cataract.REF.13">Havre D.C. Cataracts in children on long-term corticosteroid therapy. <span><span class="ref-journal">Archives of Ophthalmology. </span>1965;<span class="ref-vol">73</span>(6):818–821.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/14302515" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 14302515</span></a>]</div></dd><dt>14.</dt><dd><div class="bk_ref" id="lens_cataract.REF.14">Isaac N.E., Walker A.M., Jick H., Gorman M. Exposure to phenothiazine drugs and risk of cataract. <span><span class="ref-journal">Archives of Ophthalmology. </span>1991;<span class="ref-vol">109</span>(2):256–260.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1671548" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 1671548</span></a>]</div></dd><dt>15.</dt><dd><div class="bk_ref" id="lens_cataract.REF.15">Abraham S., Teller J. Influence of various miotics on cataract formation. <span><span class="ref-journal">The British Journal of Ophthalmology. </span>1969;<span class="ref-vol">53</span>(12):833.</span> [<a href="/pmc/articles/PMC506768/" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pmc">PMC free article<span class="bk_prnt">: PMC506768</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/5386373" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 5386373</span></a>]</div></dd><dt>16.</dt><dd><div class="bk_ref" id="lens_cataract.REF.16">West S., Munoz B., Emmett E.A., Taylor H.R. Cigarette smoking and risk of nuclear cataracts. <span><span class="ref-journal">Archives of Ophthalmology. </span>1989;<span class="ref-vol">107</span>(8):1166–1169.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2757547" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 2757547</span></a>]</div></dd><dt>17.</dt><dd><div class="bk_ref" id="lens_cataract.REF.17">Christen W.G., Manson J.E., Seddon J.M., Glynn R.J., Buring J.E., Rosner B., Hennekens C.H. A prospective study of cigarette smoking and risk of cataract in men. <span><span class="ref-journal">Jama. </span>1992;<span class="ref-vol">268</span>(8):989–993.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1501324" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 1501324</span></a>]</div></dd><dt>18.</dt><dd><div class="bk_ref" id="lens_cataract.REF.18">Hankinson S.E., Willett W.C., Colditz G.A., Seddon J.M., Rosner B., Speizer F.E., Stampfer M.J. A prospective study of cigarette smoking and risk of cataract surgery in women. <span><span class="ref-journal">Jama. </span>1992;<span class="ref-vol">268</span>(8):994–998.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/1501325" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 1501325</span></a>]</div></dd><dt>19.</dt><dd><div class="bk_ref" id="lens_cataract.REF.19">Delcourt C., Carrière I., Ponton-Sanchez A., Lacroux A., Covacho M.-J., Papoz L. Light exposure and the risk of cortical, nuclear, and posterior subcapsular cataracts: the Pathologies Oculaires Liees a l'Age (POLA) study. <span><span class="ref-journal">Archives of Ophthalmology. </span>2000;<span class="ref-vol">118</span>(3):385–392.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10721962" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 10721962</span></a>]</div></dd><dt>20.</dt><dd><div class="bk_ref" id="lens_cataract.REF.20">Khurana, A., <em>Diseases of the lens</em>, in <em>Comprehensive Ophthalmology</em>. 2015, JP Medical Ltd: London. p. 179-218.</div></dd><dt>21.</dt><dd><div class="bk_ref" id="lens_cataract.REF.21">Gupta V.B., Rajagopala M., Ravishankar B. Etiopathogenesis of cataract: an appraisal. <span><span class="ref-journal">Indian Journal of Ophthalmology. </span>2014;<span class="ref-vol">62</span>(2):103.</span> [<a href="/pmc/articles/PMC4005220/" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pmc">PMC free article<span class="bk_prnt">: PMC4005220</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/24618482" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 24618482</span></a>]</div></dd><dt>22.</dt><dd><div class="bk_ref" id="lens_cataract.REF.22">Liu X.-H., Yu R.-B., Liu R., Hao Z.-X., Han C.-C., Zhu Z.-H., Ma L. Association between lutein and zeaxanthin status and the risk of cataract: a meta-analysis. <span><span class="ref-journal">Nutrients. </span>2014;<span class="ref-vol">6</span>(1):452–465.</span> [<a href="/pmc/articles/PMC3916871/" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pmc">PMC free article<span class="bk_prnt">: PMC3916871</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/24451312" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 24451312</span></a>]</div></dd><dt>23.</dt><dd><div class="bk_ref" id="lens_cataract.REF.23">Gimbel H.V., Neuhann T. Continuous curvilinear capsulorhexis. <span><span class="ref-journal">Journal of Cataract & Refractive Surgery. </span>1991;<span class="ref-vol">17</span>(1):110–111.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/2005552" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 2005552</span></a>]</div></dd><dt>24.</dt><dd><div class="bk_ref" id="lens_cataract.REF.24">Kelman C.D. Phacoemulsification in the anterior chamber. <span><span class="ref-journal">Ophthalmology. </span>1979;<span class="ref-vol">86</span>(11):1980–1982.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/552621" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 552621</span></a>]</div></dd><dt>25.</dt><dd><div class="bk_ref" id="lens_cataract.REF.25">Kelman C.D. The history and development of phacoemulsification. <span><span class="ref-journal">International Ophthalmology Clinics. </span>1994;<span class="ref-vol">34</span>(2):1–12.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/8071012" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 8071012</span></a>]</div></dd><dt>26.</dt><dd><div class="bk_ref" id="lens_cataract.REF.26">Nagy Z., Takacs A., Filkorn T., Sarayba M. Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery. <span><span class="ref-journal">Journal of Refractive Surgery. </span>2009;<span class="ref-vol">25</span>(12)</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/20000286" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 20000286</span></a>]</div></dd><dt>27.</dt><dd><div class="bk_ref" id="lens_cataract.REF.27">Roberts T.V., Lawless M., Bali S.J., Hodge C., Sutton G. Surgical outcomes and safety of femtosecond laser cataract surgery: a prospective study of 1500 consecutive cases. <span><span class="ref-journal">Ophthalmology. </span>2013;<span class="ref-vol">120</span>(2):227–233.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/23218822" ref="pagearea=cite-ref&targetsite=entrez&targetcat=link&targettype=pubmed">PubMed<span class="bk_prnt">: 23218822</span></a>]</div></dd></dl></div><div><dl class="temp-labeled-list small"><dt>*</dt><dd><div id="lens_cataract.Tc.an1"><p class="no_top_margin">
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<div xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Views</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="PDF_download" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="/books/NBK476171/?report=reader">PubReader</a></li><li><a href="/books/NBK476171/?report=printable">Print View</a></li><li><a data-jig="ncbidialog" href="#_ncbi_dlg_citbx_NBK476171" data-jigconfig="width:400,modal:true">Cite this Page</a><div id="_ncbi_dlg_citbx_NBK476171" style="display:none" title="Cite this Page"><div class="bk_tt">Aliancy JF, Mamalis N. Crystalline Lens and Cataract. 2017 Aug 15. In: Kolb H, Fernandez E, Jones B, et al., editors. Webvision: The Organization of the Retina and Visual System [Internet]. 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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">StatPearls. 2025 Jan</em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/32644679" ref="ordinalpos=1&linkpos=2&log$=relatedarticles&logdbfrom=pubmed">Cataract Surgery.</a><span class="source">[StatPearls. 2025]</span><div class="brieflinkpop offscreen_noflow">Cataract Surgery.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Moshirfar M, Milner D, Patel BC. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">StatPearls. 2025 Jan</em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/29437325" ref="ordinalpos=1&linkpos=3&log$=relatedreviews&logdbfrom=pubmed"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Intraocular Lenses for Cataract Surgery.</a><span class="source">[Webvision: The Organization of...]</span><div class="brieflinkpop offscreen_noflow"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Intraocular Lenses for Cataract Surgery.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Nguyen J, Werner L. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Webvision: The Organization of the Retina and Visual System. 1995</em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/36508527" ref="ordinalpos=1&linkpos=4&log$=relatedarticles&logdbfrom=pubmed">Jackson Cross Cylinder.</a><span 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2013]</span><div class="brieflinkpop offscreen_noflow"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Manual small incision cataract surgery (MSICS) with posterior chamber intraocular lens versus phacoemulsification with posterior chamber intraocular lens for age-related cataract.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Riaz Y, de Silva SR, Evans JR. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Cochrane Database Syst Rev. 2013 Oct 10; 2013(10):CD008813. Epub 2013 Oct 10.</em></div></div></li></ul><a class="seemore" href="/sites/entrez?db=pubmed&cmd=link&linkname=pubmed_pubmed_reviews&uid=29356473" ref="ordinalpos=1&log$=relatedreviews_seeall&logdbfrom=pubmed">See reviews...</a><a class="seemore" href="/sites/entrez?db=pubmed&cmd=link&linkname=pubmed_pubmed&uid=29356473" ref="ordinalpos=1&log$=relatedarticles_seeall&logdbfrom=pubmed">See all...</a></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Recent Activity</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="recent_activity" id="Shutter"></a></div><div class="portlet_content"><div xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" id="HTDisplay" class=""><div class="action"><a href="javascript:historyDisplayState('ClearHT')">Clear</a><a href="javascript:historyDisplayState('HTOff')" class="HTOn">Turn Off</a><a href="javascript:historyDisplayState('HTOn')" class="HTOff">Turn On</a></div><ul id="activity"><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&linkpos=1" href="/portal/utils/pageresolver.fcgi?recordid=67c9a788b15b832ebc7ac7b0">Crystalline Lens and Cataract - Webvision</a><div class="ralinkpop offscreen_noflow">Crystalline Lens and Cataract - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&linkpos=2" href="/portal/utils/pageresolver.fcgi?recordid=67c9a787f4a390645ea5cdb9">Part XVI: Anterior Segment - Webvision</a><div class="ralinkpop offscreen_noflow">Part XVI: Anterior Segment - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&linkpos=3" href="/portal/utils/pageresolver.fcgi?recordid=67c9a78684f3725e59a85b82">Retinal Prostheses - Webvision</a><div class="ralinkpop offscreen_noflow">Retinal Prostheses - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&linkpos=4" href="/portal/utils/pageresolver.fcgi?recordid=67c9a784b15b832ebc7a9e26">Part XV: Visual Prostheses - Webvision</a><div class="ralinkpop offscreen_noflow">Part XV: Visual Prostheses - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&linkpos=5" href="/portal/utils/pageresolver.fcgi?recordid=67c9a784a68b6b5afce04250">Introduction to Visual Prostheses - Webvision</a><div class="ralinkpop offscreen_noflow">Introduction to Visual Prostheses - Webvision<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li></ul><p class="HTOn">Your browsing activity is empty.</p><p class="HTOff">Activity recording is turned off.</p><p id="turnOn" class="HTOff"><a href="javascript:historyDisplayState('HTOn')">Turn recording back on</a></p><a class="seemore" href="/sites/myncbi/recentactivity">See more...</a></div></div></div>
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