Approximately how many eye disease have been identified?

Many: The major ones are cataracts, glaucoma and diabetic eye changes. But many systemic diseases have eye manifestations. The eyes can be traumatized, infected and inflicted with allergic problems. Disease can affect the nerves to the eyes and the muscles of the eyes. Auxiliary components of the eye can be affected like tear flow, lid function and of course cancer can originate or travel to the eye