Eye diseases you need to know for USABO 👁️👄👁️

This article will be kind of like a list. It’s just a short summary of important points.

To get you oriented, here is a labeled image of the human eye:

Glaucoma is when there is so much fluid in the vitreous chamber that it puts pressure on the optic nerve. Look at the image above to see why this makes sense: the vitreous chamber is directly in contact with structures surrounding the optic nerve, so it makes total sense that pressing outwards from the vitreous chamber would cause physical damage to the optic nerve. People start to develop blind spots in their vision.

Cataracts are mainly caused by smoking and diabetes, and occur when the lens is cloudy. Smoking causes oxidative stress which damages lens proteins and causes cataracts. Smoking also can cause heavy metal deposits in the lens, which promotes further clouding. Advanced diabetes produces advanced glycation end products, or AGEs (too much sugar in the blood causes everything to get sugar groups added on it which is harmful), which accumulate in the lens and contribute to clouding.

Astigmatism is where the cornea, or outer layer of the eye, is bumpy or irregularly curved. The causes are mostly unknown, unless it was physical trauma that damaged the cornea.

Presbyopia is a natural condition that nearly everyone struggles with as they age. The lens, which adjusts light to focus the image in the eye, becomes less flexible with age due to getting thicker.

Myopia, or nearsightedness (only being able to see near things), is where the eyeball is too long, so the image that the optic nerve receives is not optimal as it separates again (optical input is analyzed after the optimal point). Hyperopia, or farsightedness (only being able to see far things), is where the eyeball is too short, so the image that the optic nerve receives is not optimal as it never reaches the optimal point due to the eyeball being too short (optical input is analyzed before the optimal point).

Myopia is corrected with a concave lens, while hyperopia is corrected with a convex lens.