Editing Cataract (section)

{{Short description|Clouding of the lens inside the eye, causing poor vision}}
{{Other uses}}
{{cs1 config|name-list-style=vanc|display-authors=6}}
{{Infobox medical condition (new)
| name            = Cataract
| image           = Cataract in human eye.png
| caption         = Magnified view of a cataract seen on [[eye examination|examination]] with a [[slit lamp]]
| field           = [[Ophthalmology]], [[Optometry]]
| symptoms        = Faded colors, blurry vision, halos around light, trouble with bright lights, trouble seeing at night<ref name=NIH2009/>
| complications   = [[Falling (accident)|Falling]], [[Depression (mood)|depression]], [[blindness]]<ref name=Gim2011/><ref name=WHO2014/>
| onset           = Gradual<ref name=NIH2009/>
| duration        =
| causes          = [[senescence|Aging]], [[Trauma (medicine)|trauma]], [[radiation exposure]], following eye surgery, genetic<ref name=NIH2009/><ref name=WHOPri/><ref>{{cite journal | vauthors = Chan WH, Biswas S, Ashworth JL, Lloyd IC | title = Congenital and infantile cataract: aetiology and management | journal = European Journal of Pediatrics | volume = 171 | issue = 4 | pages = 625–630 | date = April 2012 | pmid = 22383071 | doi = 10.1007/s00431-012-1700-1 | s2cid = 195680440 }}</ref>
| risks           = [[diabetes mellitus|Diabetes]], [[smoking tobacco]], prolonged exposure to [[sunlight]], alcohol<ref name=NIH2009/>
| diagnosis       = [[Eye examination]]<ref name=NIH2009/>
| differential    =
| prevention      = [[Sunglasses]], proper diet, not smoking<ref name=NIH2009/>
| treatment       = [[Glasses]], [[cataract surgery]]<ref name=NIH2009/>
| medication      =
| prognosis       =
| frequency       = 60 million (2015)<ref name=GBD2015Pre>{{cite journal | title = Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the Global Burden of Disease Study 2015 | journal = Lancet | volume = 388 | issue = 10053 | pages = 1545–1602 | date = October 2016 | pmid = 27733282 | pmc = 5055577 | doi = 10.1016/S0140-6736(16)31678-6 | last1 = Vos | first1 = Theo | last2 = Allen | first2 = Christine | last3 = Arora | first3 = Megha | last4 = Barber | first4 = Ryan M. | last5 = Bhutta | first5 = Zulfiqar A. | last6 = Brown | first6 = Alexandria | last7 = Carter | first7 = Austin | last8 = Casey | first8 = Daniel C. | last9 = Charlson | first9 = Fiona J. | last10 = Chen | first10 = Alan Z. | last11 = Coggeshall | first11 = Megan | last12 = Cornaby | first12 = Leslie | last13 = Dandona | first13 = Lalit | last14 = Dicker | first14 = Daniel J. | last15 = Dilegge | first15 = Tina | last16 = Erskine | first16 = Holly E. | last17 = Ferrari | first17 = Alize J. | last18 = Fitzmaurice | first18 = Christina | last19 = Fleming | first19 = Tom | last20 = Forouzanfar | first20 = Mohammad H. | last21 = Fullman | first21 = Nancy | last22 = Gething | first22 = Peter W. | last23 = Goldberg | first23 = Ellen M. | last24 = Graetz | first24 = Nicholas | last25 = Haagsma | first25 = Juanita A. | last26 = Hay | first26 = Simon I. | last27 = Johnson | first27 = Catherine O. | last28 = Kassebaum | first28 = Nicholas J. | last29 = Kawashima | first29 = Toana | last30 = Kemmer | first30 = Laura }}</ref>
| deaths          =
}}

<!-- Definition and symptoms -->
A '''cataract''' is a cloudy area in the [[lens (anatomy)|lens]] of the [[eye]] that leads to a [[visual impairment|decrease in vision]] of the eye.<ref name="NIH2009" /><ref name=":0" /> Cataracts often develop slowly and can affect one or both eyes.<ref name="NIH2009" /> Symptoms may include faded colours, blurry or [[double vision]], halos around light, trouble with bright lights, and [[Nyctalopia|difficulty seeing at night]].<ref name="NIH2009">{{cite web |date=September 2009 |title=Facts About Cataract |url=http://www.nei.nih.gov/health/cataract/cataract_facts |url-status=live |archive-url=https://web.archive.org/web/20150524095805/https://www.nei.nih.gov/health/cataract/cataract_facts |archive-date=24 May 2015 |access-date=24 May 2015}}</ref> This may result in trouble driving, reading, or recognizing faces.<ref name="Allen-2006">{{cite journal | vauthors = Allen D, Vasavada A | title = Cataract and surgery for cataract | journal = BMJ | volume = 333 | issue = 7559 | pages = 128–132 | date = July 2006 | pmid = 16840470 | pmc = 1502210 | doi = 10.1136/bmj.333.7559.128 }}</ref> Poor vision caused by cataracts may also result in an increased risk of [[Falling (accident)|falling]] and [[Depression (mood)|depression]].<ref name=Gim2011>{{cite journal | vauthors = Gimbel HV, Dardzhikova AA | title = Consequences of waiting for cataract surgery | journal = Current Opinion in Ophthalmology | volume = 22 | issue = 1 | pages = 28–30 | date = January 2011 | pmid = 21076306 | doi = 10.1097/icu.0b013e328341425d | s2cid = 205670956 }}</ref> Cataracts cause 51% of all cases of [[blindness]] and 33% of [[visual impairment]] worldwide.<ref name=WHO2014>{{cite web|title=Visual impairment and blindness Fact Sheet N°282|url=https://www.who.int/mediacentre/factsheets/fs282/en/|access-date=23 May 2015|date=August 2014|url-status=live|archive-url=https://web.archive.org/web/20150512062236/http://www.who.int/mediacentre/factsheets/fs282/en/|archive-date=12 May 2015}}</ref><ref name=WHO2012Data>{{cite book|title=Global Data on Visual Impairments 2010|date=2012|publisher=WHO|page=6|url=https://www.who.int/blindness/GLOBALDATAFINALforweb.pdf?ua=1|url-status=live|archive-url=https://web.archive.org/web/20150331221058/http://www.who.int/blindness/GLOBALDATAFINALforweb.pdf?ua=1|archive-date=2015-03-31}}</ref>

<!-- Cause, mechanisms and diagnosis -->
Cataracts are most commonly due to [[senescence|aging]] but may also occur due to [[Trauma (medicine)|trauma]] or radiation exposure, be [[congenital cataract|present from birth]], or occur following eye surgery for other problems.<ref name=NIH2009/><ref name=WHOPri>{{cite web|title=Priority eye diseases|url=https://www.who.int/blindness/causes/priority/en/index1.html|access-date=24 May 2015|url-status=dead|archive-url=https://web.archive.org/web/20150524095804/http://www.who.int/blindness/causes/priority/en/index1.html|archive-date=24 May 2015}}</ref> Risk factors include [[diabetes mellitus|diabetes]], longstanding use of [[corticosteroid]] medication, [[smoking tobacco]], prolonged exposure to [[sunlight]], and [[Alcohol (drug)|alcohol]].<ref name=NIH2009/> In addition to these, poor nutrition, obesity, chronic kidney disease, and autoimmune diseases have been recognized in various studies as contributing to the development of cataracts.<ref>{{Cite journal |last1=Ang |first1=Michael J. |last2=Afshari |first2=Natalie A. |date=2021 |title=Cataract and systemic disease: A review |url=https://onlinelibrary.wiley.com/doi/10.1111/ceo.13892 |journal=Clinical & Experimental Ophthalmology |language=en |volume=49 |issue=2 |pages=118–127 |doi=10.1111/ceo.13892 |pmid=33426783 |issn=1442-9071|url-access=subscription }}</ref> Cataract formation is primarily driven by oxidative stress, which damages lens proteins, leading to their aggregation and the accumulation of clumps of protein or yellow-brown pigment in the lens. This reduces the transmission of light to the retina at the back of the eye, impairing vision. Additionally, alterations in the lens’s metabolic processes, including imbalances in calcium and other ions, contribute to cataract development.<ref>{{Cite journal |last=Spector |first=Abraham |date=1995 |title=Oxidative stress-induced cataract: mechanism of action |journal=The FASEB Journal |language=en |volume=9 |issue=12 |pages=1173–1182 |doi=10.1096/fasebj.9.12.7672510 |doi-access=free |pmid=7672510 |issn=1530-6860}}</ref><ref name=NIH2009/> Diagnosis is typically through an [[eye examination]],<ref name=NIH2009/> with ophthalmoscopy and slit-lamp examination being the most effective methods. During ophthalmoscopy, the pupil is dilated, and the red reflex is examined for any opacities in the lens. Slit-lamp examination provides further details on the characteristics, location, and extent of the cataract.<ref>{{Cite web |title=Cataract - Eye Disorders |url=https://www.msdmanuals.com/professional/eye-disorders/cataract/cataract |access-date=2025-02-19 |website=MSD Manual Professional Edition |language=en}}</ref>

<!-- Prevention and treatment -->
Wearing [[sunglasses]] with UV protection and a wide brimmed hat, eating leafy vegetables and fruits, and avoiding smoking may reduce the risk of developing cataracts, or slow the process.<ref name=NIH2009/><ref name="NIH News in Health 2017 on cataract">{{cite web | title=Recognizing Cataracts | website=NIH News in Health | date=2017-05-30 | url=https://newsinhealth.nih.gov/2013/08/recognizing-cataracts | access-date=2020-02-02 | quote=Try wearing sunglasses or a hat with a brim. Researchers also believe that good nutrition can help reduce the risk of age-related cataract. They recommend eating plenty of green leafy vegetables, fruits, nuts and other healthy foods.}}</ref> Early on, the symptoms may be improved with [[glasses]].<ref name=NIH2009/> If this does not help, [[cataract surgery|surgery to remove the cloudy lens and replace it with an artificial lens]] is the only effective treatment.<ref name=NIH2009/> Cataract surgery is not readily available in many countries, and surgery is needed only if the cataracts are causing problems and generally results in an improved [[quality of life]].<ref name=NIH2009/><ref>{{cite journal | vauthors = Lamoureux EL, Fenwick E, Pesudovs K, Tan D | title = The impact of cataract surgery on quality of life | journal = Current Opinion in Ophthalmology | volume = 22 | issue = 1 | pages = 19–27 | date = January 2011 | pmid = 21088580 | doi = 10.1097/icu.0b013e3283414284 | s2cid = 22760161 }}</ref><ref name=WHOPri/><ref name=Rao2011/>

<!-- Epidemiology -->
About 20 million people worldwide are blind due to cataracts.<ref name=WHOPri/> It is the cause of approximately 5% of blindness in the United States and nearly 60% of blindness in parts of Africa and South America.<ref name=Rao2011>{{cite journal | vauthors = Rao GN, Khanna R, Payal A | title = The global burden of cataract | journal = Current Opinion in Ophthalmology | volume = 22 | issue = 1 | pages = 4–9 | date = January 2011 | pmid = 21107260 | doi = 10.1097/icu.0b013e3283414fc8 | s2cid = 205670997 }}</ref> Blindness from cataracts occurs in about 10 to 40 per 100,000 children in the [[Developing country|developing world]], and 1 to 4 per 100,000 children in the [[developed world]].<ref name=":0">{{cite book |last1=Wilson Jr. |first1=M. Edward |url=https://books.google.com/books?id=gLJZDD2igCMC&pg=PA20 |title=Pediatric cataract surgery techniques, complications, and management |last2=Trivedi |first2=Rupal H. |last3=Pandey |first3=Suresh K. |date=2005 |publisher=Lippincott Williams & Wilkins |isbn=978-0-7817-4307-5 |location=Philadelphia, Pennsylvania |page=20 |language=en |archive-url=https://web.archive.org/web/20150524134557/https://books.google.ca/books?id=gLJZDD2igCMC&pg=PA20 |archive-date=2015-05-24 |url-status=live}}</ref> Cataracts become more common [[Ageing|with age]].<ref name=NIH2009/> In the United States, cataracts occur in 68% of those over the age of 80 years.<ref name = NEI2019>{{Cite web|url=https://www.nei.nih.gov/learn-about-eye-health/resources-for-health-educators/eye-health-data-and-statistics/cataract-data-and-statistics|title=Cataract Data and Statistics |publisher=National Eye Institute|access-date=2019-11-18}}</ref> Additionally they are more common in women, and less common in Hispanic and Black people.<ref name = NEI2019/>