Definition, Causes and the Lens
A cataract is a cloudy formation in the lens of the eye. It causes blockage of light to the eye, which results in scattered images and eventually causes loss of vision. The exact cause of cataracts is not completely known although age appears to weigh heavily on their development. Eye lenses tend to change with age thus leading the way for cataract growth. Issues behind lens change include exposure to ultraviolet light and cigarette smoking. Some individuals are born with cataracts or grow them early in life. These are often tied to German Measles or physical abnormalities. Additional causes can be found in injuries or trauma to the eyes.
The lens of the eye is the portion that sits behind the colored part of the eye (the iris). Its purpose is to focus the light that enters the eye through the cornea and the pupil. Once focused, the light becomes images to the retina. It is the clarity of the lens that gives sharp images to the retina.
Nuclear Cataracts
There are three types of cataracts. There is the nuclear, the subcapsular and the cortical. The first type, the nuclear, grows in the center of the eye's lens. It warps the way light enters the eye and increases nearsightedness. There is a possibility that nuclear cataracts can cause a slight improvement in vision until the lens continues to suffer as the cataract grows. The formation becomes thicker and more cloudy causing issues with seeing in dark rooms and night driving. Nuclear cataracts go from a yellow cloudiness to a blue shade to a purple.
Subcapsular Cataracts
The second type of cataract, a subcapsular, begins as a small, somewhat-clear spot under the lens. It starts at the rear and directly in the way of light heading to the retina. Subcapsular cataracts cause noticeable issues with reading, bothers the eye when in presence of extreme light and creates the optical effect of "halos," auras of light around sources of illumination (e.g., flashlights, streetlights, light bulbs).
Cortical Cataracts
Finally, cortical cataracts start as white, triangular growths on the lens' edge. As corticals grow, they reach toward the center of the lens and block light going to the middle. Cortical cataract sufferers struggle with light glare.
Eye Growth
Cataracts can grow in one eye or both. They can develop in different stages but tend to grow proportionately in both of the eyes.
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