What is defined as an area of partial or complete loss of vision surrounded by a field of normal vision?

A scotoma is indeed defined as an area of partial or complete loss of vision that is surrounded by a field of normal vision. This phenomenon can occur in various eye conditions, and its location and size can vary depending on the underlying cause. Scotomas can result from retinal damage, neurological issues, or other ocular diseases. Patients may not be aware of the scotoma until it is identified through visual field testing, as the rest of their visual field remains intact.

Astigmatism, on the other hand, refers to a refractive error caused by the irregular shape of the cornea or lens, leading to blurred vision. Diplopia is the medical term for double vision, which can happen when the eyes are not properly aligned. Nystagmus is characterized by involuntary eye movements that can affect a person's ability to focus. Each of these conditions relates to different aspects of vision and ocular health, distinguishing them from the specific definition of a scotoma.