Which procedure is essential for assessing how well a patient can see at various distances?

The procedure that is essential for assessing how well a patient can see at various distances is refraction. This test measures how light rays are bent as they enter the eye in order to provide a precise prescription for corrective lenses. During a refraction test, the patient looks through a series of lenses while the ophthalmic technician evaluates which lenses provide the clearest vision at different distances. This is crucial for diagnosing refractive errors such as nearsightedness, farsightedness, and astigmatism, which directly impact how well a patient can see at different ranges.

In contrast, a fundus examination is primarily concerned with the health of the retina and optic nerve, visual field tests focus on peripheral vision, and tonometry measures intraocular pressure but does not assess visual acuity or clarity. Understanding the specific roles of these tests helps clarify why refraction stands out in assessing visual acuity at varying distances.