Which of the following is NOT measured under monocular conditions?

• A. Angle lambda
• B. Angle kappa
• C. Hirschberg
• D. Angle alpha

Answer: (C)

The idea being tested is understanding which ocular alignment measures can be obtained from a single eye and which require evaluating both eyes together.

Angle lambda and angle kappa describe the relationship between the eye’s visual axis and its optical or pupillary axes. These can be inferred from the position of the corneal light reflex relative to the pupil center in a single eye, or from imaging that focuses on one eye at a time, so monocular assessment is applicable.

Angle alpha is an anatomical optical-axis angle of an eye, which is a property that can be assessed or estimated for one eye without needing the fellow eye.

Hirschberg, on the other hand, is a binocular alignment test. It relies on observing and comparing the corneal light reflex positions in both eyes to estimate the deviation. When one eye is covered, you lose the necessary side-by-side reflex information, so this measurement isn’t done under monocular conditions.

So, the test that is not measured monocularly is the Hirschberg assessment.