Editing Cataract (section)

==Diagnosis==
===Classification===
[[File:Human eye cross-sectional view grayscale.png|thumb|Cross-sectional view, showing the position of the human lens]]
[[File:Fetal cataract.ogv|thumb|Ultrasound scan of a unilateral cataract seen in a fetus at twenty weeks of pregnancy]]

Cataracts may be partial or complete, stationary or progressive, hard or soft. Histologically, the main types of age-related cataracts are nuclear sclerosis, cortical, and posterior subcapsular.<ref>{{Citation |last1=Aliancy |first1=Joah F. |title=Crystalline Lens and Cataract |date=1995 |work=Webvision: The Organization of the Retina and Visual System |editor-last=Kolb |editor-first=Helga |url=http://www.ncbi.nlm.nih.gov/books/NBK476171/ |access-date=2023-04-24 |place=Salt Lake City, Utah |publisher=University of Utah Health Sciences Center |pmid=29356473 |last2=Mamalis |first2=Nick |editor2-last=Fernandez |editor2-first=Eduardo |editor3-last=Nelson |editor3-first=Ralph}}</ref>

{{visible anchor|Nuclear sclerosis}} is the most common type of cataract, and involves the central or 'nuclear' part of the lens. This eventually becomes hard, or 'sclerotic', due to condensation on the lens nucleus and the deposition of brown pigment within the lens. In its advanced stages, it is called a brunescent cataract. In early stages, an increase in sclerosis may cause an increase in refractive index of the lens.<ref name=Bollinger_2008/> This causes a myopic shift (lenticular shift) that decreases hyperopia and enables presbyopic patients to see at near without reading glasses. This is only temporary and is called second sight.<ref name="Academic Press">{{Citation |last1=Joo |first1=C. -K. |title=Posterior Subcapsular and Anterior Polar Cataract |date=2010-01-01 |encyclopedia=Encyclopedia of the Eye |pages=476–479 |editor-last=Dartt |editor-first=Darlene A. |url=https://www.sciencedirect.com/science/article/pii/B9780123742032000403 |access-date=2024-02-20 |place=Oxford |publisher=Academic Press |doi=10.1016/b978-0-12-374203-2.00040-3 |isbn=978-0-12-374203-2 |last2=Choi |first2=J. -C. |last3=Kwan |first3=H. -G. |last4=Kim |first4=H.|url-access=subscription }}</ref>

{{visible anchor|Cortical cataracts}} are due to the lens cortex (outer layer) becoming opaque. They occur when changes in the fluid contained in the periphery of the lens cause fissuring.{{how|date=May 2024}}  When these cataracts are viewed through an [[ophthalmoscope]], or other magnification system, the appearance is similar to white spokes of a wheel. Symptoms often include problems with glare and light scatter at night.<ref name=Bollinger_2008>{{cite journal | vauthors = Bollinger KE, Langston RH | title = What can patients expect from cataract surgery? | journal = Cleveland Clinic Journal of Medicine | volume = 75 | issue = 3 | pages = 193–96, 199–200 | date = March 2008 | pmid = 18383928 | doi = 10.3949/ccjm.75.3.193| doi-broken-date = 19 February 2025 | s2cid = 27022598 }}</ref>

{{visible anchor|Posterior subcapsular cataracts}} are cloudy at the back of the lens adjacent to the capsule (or bag) in which the lens sits. Because light becomes more focused toward the back of the lens, they can cause disproportionate symptoms for their size.<ref name="Academic Press"/>

An immature cataract has some transparent protein, but with a mature cataract, all the lens protein is opaque. In a hypermature or Morgagnian cataract, the lens proteins have become liquid. Congenital cataract, which may be detected in adulthood, has a different classification and includes lamellar, polar, and sutural cataracts.<ref name=spencer>{{cite journal | vauthors = Spencer RW, Andelman SY | title = Steroid cataracts. Posterior subcapsular cataract formation in rheumatoid arthritis patients on long term steroid therapy | journal = Archives of Ophthalmology | volume = 74 | pages = 38–41 | date = July 1965 | pmid = 14303339 | doi = 10.1001/archopht.1965.00970040040009 }}</ref><ref>{{cite journal | vauthors = Greiner JV, Chylack LT | title = Posterior subcapsular cataracts: histopathologic study of steroid-associated cataracts | journal = Archives of Ophthalmology | volume = 97 | issue = 1 | pages = 135–144 | date = January 1979 | pmid = 758890 | doi = 10.1001/archopht.1979.01020010069017 }}</ref>

Cataracts can be classified by using the lens opacities classification system LOCS III. In this system, cataracts are classified based on type as nuclear, cortical, or posterior. The cataracts are further classified based on severity on a scale from 1 to 5. The LOCS III system is highly reproducible.<ref name="Yanoff_412">{{cite book |title=Ophthalmology |vauthors=Yanoff M, Duker JS |publisher=Mosby |year=2008 |isbn=978-0-323-05751-6 |edition=3rd |location=Edinburgh, Scotland |page=412 |language=en-uk}}</ref>

{{Gallery
|title=Different types of cataracts
|width=200
|height=200
|align=center
|File:Posterior polar cataract.jpg|alt1=ppc|Posterior polar cataract of an 8-year-old boy in left eye
|File:Nuclear sclerosis.jpg|alt2=ns |Nuclear sclerosis cataract of a 70-year-old male
|File:Cortical Cataract.jpg|alt3=cc|Cortical cataract of a 60-year-old male
|File:Cortical cataract.jpg|alt4=cc|Retroillumination of cortical cataract
|File:Posterior Subcapsular Cataract.jpg|alt5=psc|Posterior subcapsular cataract of a 16-year-old girl with type 1 diabetes
|File:Intumescent cataract.jpg|alt6=ic|Intumescent cataract of a 55-year-old male
|File:Anterior subcapsular cataract.jpg|alt7=asc|Anterior subcapsular cataract having back shadow
|File:Posterior subcapsular cataract.jpg|alt8=psc|Posterior subcapsular cataract by retroillumination
|File:Nuclear sclerosis and posterior polar cataract.jpg|alt9=ns & ppc|Nuclear sclerosis and posterior polar cataract of a 60-year-old female
|File:Dense white mature cataract.jpg|alt10=dc |Dense white mature cataract of a 60-year-old male
|File:Cataracte Corticale.png|alt11=dc |Cortical cataract of a melanoderm male
}}