Visual Acuity Testing in Adults

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Article initiated by:
Karine Duarte Bojikian
All contributors:
Zahraa Alomar, Karine Duarte Bojikian
Assigned editor:
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Introduction

Visual acuity (VA) is a fundamental measure of visual function that assesses the eye’s ability to distinguish fine details and shape of objects in the direct line of vision. It serves as a cornerstone of the ophthalmic exam informing diagnosis and treatment decisions. All adults, regardless of risk factors, must undergo a comprehensive medical eye evaluation with increasing frequency as patients age, aimed at preventing or minimizing vision through early detection of ocular diseases, visual dysfunction, and underlying systemic conditions. Visual acuity may also be performed periodically to monitor disease processes and progression in patients with a known eye condition1,2.

Conceptual Framework

Minimum Angle of Resolution

Visual acuity is defined as the reciprocal of the minimum angle of resolution (MAR) expressed in minutes of arc. The minimum angle of resolution is the smallest angle of separation at which two points can be distinguished as separate, best represented by the letter E on the Snellen chart. For an ideal human eye, under optimal conditions, the MAR is approximately 1 minute of arc.