A cataract refers to the clouding of the eye’s natural lens, which is normally clear. This common, age-related eye condition leads to vision impairment. The lens, positioned behind the iris, focuses light onto the retina to produce sharp images. When the lens becomes cloudy, light cannot pass through efficiently, causing blurry or dim vision.
Understanding Cataract Occurrence
Cataracts can develop in one eye or in both eyes, a condition known as bilateral cataracts. While it is common for cataracts to occur in both eyes, they often do not develop at the same rate or to the same degree. This means a person might experience more significant vision impairment in one eye compared to the other.
It is also possible for a single eye to have more than one type of cataract simultaneously. For instance, an individual might have both a nuclear cataract and a posterior subcapsular cataract in the same eye, as different parts of the lens can be affected by various forms of opacification.
Diverse Types of Cataracts
Cataracts are classified based on where they form within the eye’s lens, each presenting with distinct characteristics. Nuclear cataracts affect the center of the lens, known as the nucleus. This type of cataract often causes the lens to gradually yellow or brown and harden, which can lead to blurry vision and glare.
Cortical cataracts begin as wedge-shaped opacities or streaks on the outer edge of the lens, in the cortex, and spread inwards like spokes on a wheel. These cataracts can cause light to scatter as it enters the eye, leading to hazy vision and increased sensitivity to light.
Posterior subcapsular cataracts form at the back of the lens, just beneath the lens capsule. This type of cataract can progress relatively quickly and significantly impact vision, especially affecting reading ability and causing glare or halos around lights, particularly in bright conditions. Less common types include congenital cataracts, present at birth or developing in childhood, and traumatic cataracts, which result from an eye injury.
Cataract Development and Symptoms
Cataracts form when proteins within the eye’s lens break down and clump together, causing the lens to become cloudy. This process often occurs naturally with aging, as the lens becomes less flexible and thicker over time. While age is the primary factor, other elements such as diabetes, eye injury, certain medications like steroids, and excessive sun exposure can contribute to their development.
Symptoms include cloudy, blurry, or dim vision, and increasing difficulty seeing clearly at night. Increased sensitivity to light and glare, halos around bright lights, or faded/yellowish colors are common visual disturbances. Frequent changes in eyeglass or contact lens prescriptions can also indicate cataract progression.
Diagnosis and Treatment Options
An eye care professional diagnoses cataracts through a comprehensive eye examination. This typically involves a visual acuity test to assess vision, and a dilated eye exam, where eye drops are used to widen the pupil, allowing for a detailed inspection of the lens and other parts of the eye. A slit-lamp examination may also be performed, which provides a magnified, three-dimensional view of the eye’s structures.
When cataracts begin to significantly impair daily activities and vision, surgical removal is the most effective treatment. During cataract surgery, the clouded natural lens is removed and replaced with a clear, artificial intraocular lens (IOL). The procedure is generally performed on an outpatient basis and is known for its high success rate.