Opacification of the lens or its capsules sufficient to interfere with the vision of the eye is called cataract. In Ayurveda it is called timira. Cataracts are the common cause of vision loos in people over age of 40. There are three types of cataracts.
1) Subcapsular cataract, 2) Nuclear cataract, 3) Cortical cataract.
A nuclear cataract forms deep in the central zone of the lens. This is normally associated with aging. A cortical cataract is characterized by white wedge like opacities that starts in the periphery of the lens and work their way to the center in a spoke like fashion. This is occurs in the lens cortex, which is the part of the lens that surrounds the central nucleus.
A subcapsular cataract occurs at the back of the lens. People with diabetes or those taking high dose of steroid have a great risk of developing a subcapsular cataract
The lens is mostly made of water and protein. The protein is arranged in a precise way that keeps the lens clean and lets light pass through it. But as we age some of the protein may clump together and start to cloud a small area of the lens. This is a cataract and over time it may grow larger and cloud more of the lens, making it harder to see.
Amalaki, daruhaldi, baheda, lodhra, shatavari and guduchi are useful herbs in cataract. Saptamrit lauh, maha triphala ghrita also useful in this condition.