Which diagnostic test would be anticipated for a patient reporting gradual peripheral vision loss?

For a patient experiencing gradual peripheral vision loss, tonometry is the most relevant diagnostic test as it measures intraocular pressure (IOP). Elevated IOP can be a significant indicator of glaucoma, a condition often associated with peripheral vision loss.

Gradual peripheral vision loss can signal the early stages of glaucoma, where the optic nerve is damaged, typically due to high IOP. By assessing the IOP, healthcare providers can determine if the patient is at risk for glaucoma, guiding further management and treatment options.

Other diagnostic tests mentioned have their specific purposes but do not directly address the concern of peripheral vision loss. Gonioscopy evaluates the angle of the anterior chamber in the eye and is primarily used to determine the type of glaucoma present, but it does not measure vision loss directly. Glare testing assesses how well a person can see under bright light conditions, which does not correlate directly with peripheral vision issues. The Amsler grid test checks for central vision distortions specifically related to macular problems but is not suitable for evaluating peripheral vision loss. Thus, tonometry is the most appropriate initial test in this scenario.