A 30-year-old undergoes traumatic removal of the left lens, leaving unilateral aphakia corrected with a spectacle lens of about +10.00 D. Compared with contact lens correction, the approximate retinal image magnification produced by the spectacle lens is:
- A About 5%
- B About 30% ✓
- C About 10%
- D No magnification difference exists between the two corrections
Correct answer: B. About 30%
Explanation
A high plus spectacle lens sits well in front of the eye, far from the eye's entrance pupil, producing marked angular magnification of roughly 25 to 30% in aphakia. This large interocular image size difference causes intolerable aniseikonia in unilateral aphakia. A contact lens moves the correcting power onto the cornea, cutting magnification to roughly 7%, which is why contact lenses or intraocular lenses are preferred for unilateral aphakia. The 30% figure is the standard textbook value for spectacles.
Reference: Khurana Comprehensive Ophthalmology, 7th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.