Glaucoma primarily affects which ocular structure?

Glaucoma primarily affects the optic nerve, which is crucial for transmitting visual information from the eye to the brain. This condition is characterized by increased intraocular pressure, which can damage the optic nerve fibers. Over time, this damage leads to peripheral vision loss and, if untreated, can result in total vision loss. The primary pathophysiological process in glaucoma involves ischemia and degeneration of the optic nerve head due to elevated pressure.

While the cornea, lens, and retina are important structures of the eye, they are not the primary targets of glaucoma. The cornea serves as the outer protective layer, the lens is responsible for focusing light, and the retina is where light is converted into neural signals. However, in the context of glaucoma, the direct impact is on the optic nerve, making it the correct answer.