Which test helps determine the extent of peripheral vision loss?

The visual field test is specifically designed to measure peripheral vision and identify any loss in this area. This test involves the patient looking straight ahead while indicating when they can see lights or objects in their peripheral vision. By mapping out these responses, the test can reveal areas of vision loss that may indicate various conditions affecting the retina or optic nerve, such as glaucoma, retinal detachment, or other neurological issues.

On the other hand, fundoscopy is primarily used to examine the interior surface of the eye, including the retina and optic disc, rather than assess peripheral vision. Tonometry measures intraocular pressure to check for glaucoma but doesn't provide information about the visual field. Refraction determines the correct prescription for lenses by assessing how light rays are focused on the retina, and it also does not address peripheral vision. Thus, the visual field test stands out as the appropriate method for evaluating peripheral vision loss.