Cataract Classification and Grading

Types of Cataracts

Nuclear cataracts are characterized by central opacification or discoloration of the lens, interfering with visual function, and are classified as either brunescent, opalescent, or both, typically progressing slowly and affecting distance vision more than near vision 1
Cortical cataracts can be central or peripheral, appearing as opaque spokes or oil droplets, with patients commonly complaining of glare symptoms, and when the entire cortex becomes white and opaque, it's referred to as a mature cortical cataract 1
Posterior subcapsular cataracts (PSC) are located just inside the posterior lens capsule, causing substantial visual impairment when involving the axial region, with patients often experiencing glare and poor vision in bright light, and near vision typically more affected than distance due to miosis with near accommodation, and are more common in younger patients and tend to progress more quickly than other types 1, 2
Less common types of cataracts include anterior subcapsular, anterior polar, and posterior polar cataracts 1

The American Academy of Ophthalmology recommends that cataract grading serves several important clinical purposes, including disease progression monitoring, with PSCs typically progressing more quickly than nuclear and cortical cataracts 1
Cataract grading allows for tracking cataract progression over time, with different types of cataracts affecting vision differently, such as nuclear cataracts primarily affecting distance vision 1
The American Academy of Ophthalmology notes that PSCs cause glare and poor vision in bright light, affecting near vision more 1
Cortical cataracts commonly cause glare symptoms, according to the American Academy of Ophthalmology 1

Glare testing is particularly useful for cortical and posterior subcapsular cataracts, which significantly impact vision in bright light conditions, as recommended by the American Academy of Ophthalmology 3, 4
Contrast sensitivity testing may reveal functional vision loss not detected by standard visual acuity testing, according to the American Academy of Ophthalmology 3, 4
Wavefront imaging can detect visual aberrations caused by even mild cataracts, as noted by the American Academy of Ophthalmology 4

The Lens Opacities Classification System (LOCS) is a standardized photographic reference system that grades cataracts by type and severity, with LOCS III being the most widely used version, employing decimal scoring for nuclear opalescence, nuclear color, cortical, and posterior subcapsular opacities, as recommended by the American Academy of Ophthalmology 5

Nuclear cataracts involve central lens opacification or discoloration, classified as brunescent or opalescent, and are graded by LOCS on two scales: nuclear opalescence (NO) and nuclear color (NC), with characteristics and progression rates that inform treatment decisions, according to the American Academy of Ophthalmology 6
Cortical opacities appear as spoke-like or oil droplet patterns and are associated with glare symptoms, with progression rates and characteristics that guide clinical management, as noted by the American Academy of Ophthalmology 6
Posterior Subcapsular Cataracts (PSC) are located just inside the posterior lens capsule, causing substantial visual impairment, particularly in bright light, and progress more rapidly than other types, with annual progression rates that influence treatment planning, as reported by the American Academy of Ophthalmology 6

The American Academy of Ophthalmology emphasizes that surgery should be performed when it will enhance patient function and when the informed patient elects this option, with timing mutually agreeable between patient and surgeon, considering factors beyond LOCS grading, such as functional impairment and patient preference 5
Preoperative LOCS III grading directly predicts phacoemulsification parameters, allowing surgeons to create customized operative plans, and is a critical factor in determining surgical candidacy, as recommended by the American Academy of Ophthalmology 5
Surgery may be indicated even with less severe LOCS grades when needed for improved visualization and management of coexisting ocular disease, such as glaucoma, macular degeneration, or diabetic retinopathy, as noted by the American Academy of Ophthalmology 5