Certified Ophthalmic Medical Technologist (COMT) Practice Exam

Which test is used to estimate the size of a tropia based on corneal reflex placement?

1. Cover test

2. Krimsky method

3. Hirschberg's estimation

4. Prism alternate cover test

The correct answer is: Hirschberg's estimation

The test used to estimate the size of a tropia based on corneal reflex placement is the Hirschberg's estimation. This method involves assessing the position of the corneal light reflex when the patient is fixating on a light source. By observing where the light reflex falls on the cornea, an examiner can determine the presence and magnitude of misalignment in eye position, which is indicative of the degree of strabismus, or tropia. The light reflex should ideally be centered in the cornea for a properly aligned eye. If one corneal reflex is displaced relative to the center of the pupil, it suggests that one eye is misaligned. The amount of displacement can be quantified, giving an estimate of the angle of deviation. This makes Hirschberg's estimation a useful tool in clinical settings for quickly assessing strabismus in both children and adults. In comparison, the cover test is generally used for both tropia and phoria detection, but it does not provide a direct measurement of the angle of deviation based on corneal reflexes. The Krimsky method is a more specific evaluation that also uses prisms to refine the measurement of tropia, while the prism alternate cover test primarily assesses the presence of tropia and measures its size indirectly