Corneal disease is a group of conditions that affect your cornea (the clear window at the front of your eye).

Vascular disease includes any condition that affects your circulatory system, or system of blood vessels. This ranges from diseases of your arteries, veins and lymph vessels to blood disorders that affect circulation.

Refractive errors are a common eye condition that occurs when the eye's shape prevents light from focusing directly on the back of the eye

Degenerative disease is the result of a continuous process based on degenerative cell changes, affecting tissues or organs, which will increasingly deteriorate over time

It occurs when inflammatory cells travel to the place of an injury or foreign body like bacteria. If inflammatory cells stay too long, it may lead to chronic inflammation. Chronic inflammation is a symptom of other health conditions, such as rheumatoid arthritis.