Reviewed by Dr. Clement J. Cheng
The lens of the human eye is made mostly of water and protein. The protein is arranged to let light pass through and focus on the retina. Sometimes some of the protein clumps together and starts to cloud a small area of the lens. This is a cataract. Over time, the cataract may grow larger and cloud more of the lens, making it difficult to see.
Cataracts are painless. When a cataract is small, you may not notice any changes in your vision. Cataracts tend to grow slowly, so vision deteriorates gradually. Some people with a cataract find that their close-up vision suddenly improves, but this is temporary. Vision is likely to get worse again as the cataract grows.
Cataracts are the leading cause of blindness, despite the fact that surgery is available to reverse the damage in most cases. Most people do not consult doctors for cataract problems out of fear or ignorance; in the United States alone, 5,000 people per year go blind due to cataracts.
The different types of cataract are:
- Age-related cataract: This is the most common type of cataract.
- Congenital cataract: Some babies are born with cataracts or develop them in childhood, often in both eyes. These cataracts may not affect vision. If they do, they may need to be removed.
- Secondary cataract: Cataracts are more likely to develop in people who have certain other health problems, such as diabetes. Also, cataracts are sometimes linked to steroid use.
- Traumatic cataract: Cataracts can develop soon after an eye injury, or years later.
