What test would most likely be used to assess asymmetry in refractive error?

The cover test is designed to evaluate how the eyes work together and can indicate the presence of strabismus, which is a condition that may relate to asymmetry in refractive error. By covering one eye and then the other while observing for any movement of the uncovered eye, the test assesses how the eyes align with each other. If there is a significant difference in readability or alignment when one eye is covered, it suggests that the degree of refractive error may differ between the two eyes, indicating asymmetry.

In contrast, the refraction test measures the prescription needed for clear vision in each eye but does not directly assess how the two eyes interact or whether one eye has a significantly different refractive error than the other. The visual field test examines peripheral vision but does not provide insight into refractive errors at all. The color perception test identifies color deficiencies rather than refractive errors or asymmetries between the eyes.