The Hirschberg test, used to estimate the angle of strabismus in a non-cooperative child, relies on which principle?

• A Comparison of pupil diameter in both eyes to detect anisocoria
• B The Maddox rod test to detect suppression
• C Cover-uncover test to detect manifest deviation
• D Estimation of corneal light reflex displacement from the pupil center; each 1 mm displacement ≈ 7° (approximately 15 prism diopters) of deviation ✓

Explanation

The Hirschberg test evaluates corneal light reflexes from a pen torch. In a straight eye the reflex falls at the pupil center; displacement of the reflex in the deviating eye estimates the angle of strabismus. Each 1 mm of corneal light reflex displacement corresponds to approximately 7° or 15 prism diopters (PD) of deviation. The Krimsky test uses prisms to center the deviating eye's reflex and quantifies the angle more precisely. The cover test detects manifest versus latent deviation.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.