What Are the 4 Types of Cataracts?
Cataracts are a clouding of the natural lens inside the eye that leads to blurry vision, glare, and difficulty with daily activities. They develop gradually and are most common with aging, but can also result from injury, medications, or medical conditions. The four primary types are nuclear sclerosis, cortical, posterior subcapsular, and congenital or developmental cataracts. Each type affects the lens differently and produces distinct visual complaints.
Nuclear Sclerosis Cataracts
Nuclear sclerosis affects the central zone of the lens called the nucleus. Over time, lens proteins compact and yellow, causing the center of the lens to harden and become less transparent. This change typically occurs with age and is the most common form of cataract.
Early symptoms often include a gradual decline in distance vision and increased nearsightedness. Some people notice that reading vision improves for a short time without glasses, a phenomenon sometimes called second sight. As the cataract progresses, overall clarity diminishes, colors appear muted, and glare from headlights or bright sunlight becomes more bothersome.
On examination, the nucleus looks yellow to brown, and the degree of discoloration correlates with the severity of visual impairment. Treatment is based on functional impact. When glasses can no longer provide adequate clarity, cataract surgery to remove the clouded lens and implant a clear artificial lens is recommended.
Cortical Cataracts
Cortical cataracts involve the outer layer of the lens known as the cortex. They often start as wedge-shaped or spoke-like opacities extending from the lens edge toward the center. These spokes scatter light as it enters the eye.
Patients commonly report glare and halos around lights, especially at night. Vision can fluctuate as the pupil size changes because wider pupils allow more light to pass through the affected cortical areas. Reading and contrast sensitivity may be impaired even when the eye chart acuity appears reasonable.
Cortical cataracts are associated with aging and can be influenced by factors such as diabetes, ultraviolet exposure, and electrolyte imbalances within the lens. Management focuses on controlling risk factors, improving lighting, and updating glasses until symptoms interfere with daily activities. Surgery is highly effective when visual function declines.
Posterior Subcapsular Cataracts
Posterior subcapsular cataracts form at the back of the lens just in front of the capsule. Because of their location along the visual axis, even small opacities can cause significant symptoms. These cataracts tend to progress faster than other types.
Patients often complain of difficulty reading, glare sensitivity, and trouble with bright lights. Vision may seem worse in daylight or when looking at oncoming headlights. Younger individuals can develop this type due to steroid use, diabetes, inflammation, or radiation exposure.
During an eye examination, a granular or plaque-like opacity is seen just beneath the posterior capsule. Since these cataracts impair vision early, surgery is frequently recommended sooner compared to other types. Outcomes after removal and lens implantation are generally excellent.
Congenital and Developmental Cataracts
Congenital or developmental cataracts are present at birth or arise during childhood. They may affect one or both eyes and vary in size, density, and location within the lens. Causes include genetic conditions, metabolic disorders, infections during pregnancy, and certain medications. Some cases are idiopathic with no identifiable cause.
In infants and children, even a partial lens opacity can disrupt normal visual development and lead to amblyopia if not addressed promptly. Signs include a white pupil reflex, misalignment of the eyes, nystagmus, or poor visual tracking. Early diagnosis by pediatric screening is critical.
Treatment depends on the severity and impact on vision. Small, non-progressive cataracts may be monitored, while visually significant cataracts often require early surgery. Postoperative care includes optical correction with glasses or contact lenses and amblyopia therapy to ensure proper visual development.
Diagnosis and Evaluation
A comprehensive eye examination confirms the presence and type of cataract. Visual acuity testing, glare testing, and slit-lamp evaluation characterize the opacity. The physician assesses how the cataract affects functional vision and screens for coexisting eye conditions such as macular degeneration, glaucoma, or diabetic retinopathy that may influence outcomes.
Imaging such as optical coherence tomography helps evaluate the retina when the lens opacity limits the view. Preoperative measurements determine the appropriate power of the intraocular lens implant for surgery.