Which device tests a rotatable arc of about 180 to 200 degrees?

Which device tests a rotatable arc of about 180 to 200 degrees?

• A. Tangent Screen
• B. Automated Perimeter
• C. Amsler Grid
• D. Arc Perimeter

Answer: (D)

Testing a rotatable arc of about 180 to 200 degrees is about mapping the peripheral visual field along a curved path around the eye. An arc perimeter uses a semicircular, curved arc—typically about 180 degrees, sometimes up to 200—where stimuli are presented along that arc. The arc can be rotated so you can align it with different meridians and directions around the eye, allowing a full, map-like assessment of peripheral vision. This setup is distinct from a tangent screen, which uses a flat plane and a fixed testing path, and from an automated perimeter, which tests on a curved surface but not specifically by rotating a single arc around the eye. The Amsler grid tests central vision on a grid and does not assess a wide, rotating arc. So the device that fits the description of a rotatable arc covering roughly half the field is the arc perimeter.

Testing a rotatable arc of about 180 to 200 degrees is about mapping the peripheral visual field along a curved path around the eye. An arc perimeter uses a semicircular, curved arc—typically about 180 degrees, sometimes up to 200—where stimuli are presented along that arc. The arc can be rotated so you can align it with different meridians and directions around the eye, allowing a full, map-like assessment of peripheral vision.

This setup is distinct from a tangent screen, which uses a flat plane and a fixed testing path, and from an automated perimeter, which tests on a curved surface but not specifically by rotating a single arc around the eye. The Amsler grid tests central vision on a grid and does not assess a wide, rotating arc.

So the device that fits the description of a rotatable arc covering roughly half the field is the arc perimeter.