A cataract is a condition where the lens of the eye loses its clarity, becomes clouded and affects vision. Clouding causes the lens to become yellowish-brown in color.
Lens is a transparent structure that lies behind the iris and the pupil and works like the lens of a camera. It helps focus light on the retina (light sensitive tissue at the back of the eye) to form an image. In normal condition since the lens is clear, you see a sharp image of the objects around you. In cataract, since the lens is not clear, the images you see are blurred. Most cataracts occur in older people and are age related. Cataract can affect one or both eye but it cannot spread from one eye to another.
Types of Cataract
Apart from age related cataracts, which begin forming when you are in your 40s or 50s and mature by the time you are in your 60s, other types of cataracts are:
The lens is made of water and protein, with the proteins arranged in such a way that the lens remains clear and allows light to pass through it. As you age, the proteins lose their precise arrangement, clump together and form a small cloudy area on the lens. This reduces the amount of light passing through the lens and affects the sharpness of the image formed. With time the cloudy area enlarges and affects the vision. However the growth of an age-related cataract is slow and may take years and the vision slowly turns dull. Finer detailing as in reading is the last to go. The vision becomes tainted with brown color and you may lose your sense of colors.
Smoking and diabetes can also affect the quality of lens and so also repeated use of steroid eye drops.
Prolonged exposure to UV radiation can also cause cataracts (in people who work outdoors and are exposed to direct sunlight.
The most common symptoms of a cataract are:
- Cloudy or blurred vision
- Colors look faded
- The lamps, headlights etc appear too bright or glare
- Halo appears around lights
- Frequently changing eyeglasses or contact lenses as ‘power’ changes
- Poor night vision
- Double vision or diplopia
- Multiple images (in large cataracts)
To diagnose whether you have cataract or not, your doctor will conduct a comprehensive eye examination which includes: