An adult with perfectly aligned eyes on cover test has a corneal light reflex that sits nasal to the centre of the pupil in each eye during fixation. This finding represents:
- A Positive angle kappa, mimicking exotropia ✓
- B Negative angle kappa, mimicking esotropia
- C Microtropia with identity
- D Convergence excess esophoria
Correct answer: A. Positive angle kappa, mimicking exotropia
Explanation
The angle kappa is the angle between the visual axis and the pupillary axis. When it is positive, the reflex falls nasal to the pupil centre, so the eye appears turned outward although cover testing confirms orthophoria. This apparent exotropia matters clinically because a surgeon who operates on the Hirschberg reading would produce a real overcorrection. B negative angle kappa places the reflex temporally and mimics esotropia.
Reference: Parsons' Diseases of the Eye, 23rd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.