The following conditions are major causes of adult sight loss in the UK, according to RNIB:

Glaucoma

The most common type of glaucoma is primary open angle glaucoma (POAG). This is a chronic condition that develops slowly over time and gradually reduces peripheral vision. POAG is more common in older people and those who are very short-sighted. Acute angle closure glaucoma is caused by a sudden blockage to the flow of fluid in the eye, causing a build up of pressure that can damage the optic nerve. This is a painful condition and should be treated urgently to prevent sight loss.

Cataracts

These are cloudy patches in the lens that make vision blurred or misty. They can develop in one or both eyes and affect older men and women equally. In the UK, it is estimated that more than half of all people over 65 have some degree of cataract development.

Age-related macular degeneration 

Age-related macular degeneration (AMD) occurs when the macula is unable to function correctly, leading to a gradual loss of central vision. Peripheral or side vision is unaffected. AMD mainly affects people over the age of 50 and is more common in women. Smoking is a known risk factor.

Diabetic retinopathy

Diabetic retinopathy is a complication of diabetes where the blood vessels of the retina become damaged. Initially, it only mildly affects vision, but in severe cases it can cause blindness. Diabetic retinopathy can affect anyone with type 1 or type 2 diabetes. The longer a person has had diabetes, and the less controlled their blood sugar is, the more likely they are to develop the condition.