When the Amsler Grid is viewed correctly, each square subtends an angle of how many degrees?

The Amsler Grid is a tool used primarily to assess central visual field function and is particularly beneficial for detecting macular degeneration. Each square on the grid is designed to subtend an angle of one degree at the eye. This means that when a person views the grid at the recommended distance (typically 30 cm), they are able to effectively gauge any distortions or changes in their central vision.

In practical terms, since one degree of visual angle corresponds to a small portion of what the eye can see, each square being one degree ensures that any visual anomalies can be detected accurately. This design choice is crucial in helping clinicians evaluate the patient's vision, as it allows for a detailed assessment of any central vision changes. By focusing on just this one degree per square, it facilitates not only patient self-checks but also provides valuable data for eye care professionals monitoring the patient's visual health.