What is the term for loss of vision without any apparent disease of the eye?

The term that refers to loss of vision without any apparent disease of the eye is amblyopia. Amblyopia is a condition often described as "lazy eye," where one eye does not achieve normal visual acuity, typically due to a lack of visual stimulation during early childhood. This condition can occur even when there is no detectable structural or pathological issue in the eye itself, meaning that traditional eye examinations may not reveal the underlying problem that leads to the impaired vision.

In contrast, the other terms refer to identifiable eye conditions. Cataract refers to a clouding of the lens that affects vision, while glaucoma is characterized by increased intraocular pressure and damage to the optic nerve, often resulting in vision loss. Retinopathy refers to damage to the retina, often seen in conditions such as diabetes. Therefore, amblyopia is unique in that it describes vision loss linked primarily to the brain's inability to process visual signals rather than any discernible eye disease.