Retinoscopy is performed with a plane mirror at a working distance of 67 cm. Neutralization of the right eye is achieved with a +3.00 DS trial lens in the frame. Taking the working distance into account, the patient's actual refractive error is:

• A +4.50 DS
• B +3.00 DS
• C +1.50 DS ✓
• D -1.50 DS

Explanation

The trial lens neutralizes the eye only for the observer's working distance, so the reciprocal of that distance must be subtracted. At 67 cm the working distance allowance is 100/67, approximately 1.50 D. The true refraction is +3.00 minus 1.50, giving +1.50 DS of hypermetropia. Forgetting this step and reporting +3.00 DS is the classic error, and the allowance is always subtracted for hypermetropic findings such as this one.

Reference: Khurana Comprehensive Ophthalmology, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.