Final answer:
Cynthia's condition, characterized by optic nerve damage due to fluid accumulation, is glaucoma. It can be treated with eye drops that reduce eye pressure. Unlike cataracts that cloud the lens of the eye, glaucoma specifically causes vision loss through optic nerve damage.
Step-by-step explanation:
The disease that has damaged Cynthia's optic nerves due to the accumulation of fluid in the eye is glaucoma. This condition is characterized by an increased pressure in the eye, which can damage the optic nerve and potentially lead to vision loss. However, glaucoma can often be treated with medications such as eye drops that reduce the eye's pressure. While cataracts are also associated with aging and can lead to blindness through the clouding of the lens, the condition described in the question is specifically associated with optic nerve damage due to fluid, which is indicative of glaucoma. It is important to protect the eyes from UV exposure with sunglasses to prevent cataracts, and different visual impairments such as presbyopia and age-related macular degeneration (AMD) require other treatments or cannot be cured currently.