Learn
Eye conditions in plain language
A short guide to the conditions behind much vision loss: what each one is, how it can affect sight and why a regular eye exam matters.
This page is for general understanding. It is not medical advice. Only an eye care professional can tell you what is happening in your eyes. Conditions affect people differently, and the descriptions below say what can happen, not what will.
Age-related macular degeneration (AMD)
The macula is the small center of the retina that gives sharp, detailed sight. In AMD it wears down, so the middle of what you look at can blur, warp or fade while side vision stays. It is more common as people age. There are dry and wet forms, and some treatments exist for the wet form.
Amblyopia (lazy eye)
Reduced sight in one eye that happens when the brain and the eye do not develop together in early childhood. It is found with an eye exam and is treated best when caught early.
Cataract
The lens inside the eye gets cloudy, like looking through a foggy window. Colors fade and lights glare. Surgery to replace the clouded lens is common.
Cerebral visual impairment (CVI)
Vision loss caused by how the brain processes what the eyes send, not by damage to the eye itself. Sight can change from day to day and may be worse with clutter or movement.
Color vision deficiency (color blindness)
Trouble telling some colors apart, most often reds from greens. It is usually inherited and affects men more often than women. Most people see some color; seeing none at all is rare.
Diabetic retinopathy
High blood sugar over time can damage the tiny blood vessels in the retina. There may be no warning signs at first, which is why people with diabetes are advised to have regular dilated eye exams.
Glaucoma
Damage to the optic nerve, often linked to pressure inside the eye. It often starts with the loss of side vision and may cause no pain or early symptoms. Lost sight cannot be restored, but treatment can slow further loss, so regular exams matter.
Optic nerve conditions
The optic nerve carries the picture from the eye to the brain. Inflammation, injury, pressure or disease affecting it can blur sight, dim colors or leave blank areas. A doctor needs to find the cause.
Retinal detachment
The retina pulls away from the back of the eye. Warning signs include a sudden shower of floaters, flashes of light, or a curtain or shadow over part of your sight. This is an emergency: get care right away.
Retinitis pigmentosa (RP)
A group of inherited conditions in which the retina slowly loses cells. Night vision and side vision often go first, which can feel like looking through a tube. How fast it changes is different for each person.
Stargardt disease
An inherited condition of the macula that often begins in childhood or young adulthood. Central sight blurs and blind spots form in the middle, while side vision usually remains.
Usher syndrome
An inherited condition that affects both hearing and vision. The vision part is a form of retinitis pigmentosa. People may use a mix of tools for hearing and for sight, including touch.
Keep learning
The National Eye Institute has a plain-language page for each of these conditions and many more. If a word here is new, the glossary explains it. For research news, see our page on research and clinical trials.