An anopsia, or anopia, (from Ancient Greek ἀν- (an-) 'without' and ὄψις (opsis) 'sight') is a defect in the visual field. If the defect is only partial, then the portion of the field with the defect can be used to isolate the underlying cause. It is particularly used to describe the lack of sight in one eye.

Types of partial anopsia include: