COMT Practice Exam 2026 – Complete Resource for Exam Prep

The appropriate time to stop increasing the amount of prism during the prism and alternate cover test is when a reversal in movement direction is observed. This reversal indicates that you have reached the point at which the visual system can no longer compensate for the strabismus. When the direction of eye movement changes from converging to diverging (or vice versa), it signifies the breaking point of fusion and helps determine the amount of deviation or heterotropia that is present. This is crucial for an accurate assessment of the eye alignment and for planning any potential treatment options.

While assessing patient comfort, fatigue, or a standard amount of prism are considerations during testing, they do not provide the same diagnostic information as observing the reversal. The critical aspect is to determine the precise moment of visual system failure, which is effectively indicated by the reversal in eye movement direction. Conducting the test with this knowledge ensures a more accurate understanding of the patient’s strabismus and helps to tailor any necessary interventions.