Which test is conducted for a patient who experiences metamorphopsia, indicating straight lines appear wavy?

The Amsler grid test is designed specifically to assess central visual field distortions, such as metamorphopsia, where straight lines appear wavy or distorted. This condition is often associated with macular degeneration or other retinal issues affecting the central vision. During the test, patients look at a grid of straight lines positioned at a distance, and any distortions observed can indicate changes in the health of the macula.

In contrast, the visual field test evaluates the entire field of vision, detecting peripheral vision loss rather than specific distortions of straight lines. The color vision test assesses the patient's ability to discern different colors but does not address the perception of line distortion. The contrast sensitivity test measures a patient's ability to distinguish objects from their background when there is a difference in luminance but is not focused on the visual distortions concerning straight lines.

Therefore, the Amsler grid is the most appropriate test for identifying metamorphopsia and its underlying causes, making it the correct choice in this scenario.