A 62-year-old man reports that he can now read newspaper print without his distance glasses, though his distance vision has slowly worsened over three years. Slit lamp examination shows a dense amber-brown nucleus. The phenomenon responsible is:
- A Nuclear sclerosis increasing the refractive index of the lens, producing an acquired myopic shift ✓
- B Cortical spokes altering corneal astigmatism
- C Posterior capsule thickening acting as a pinhole
- D Zonular relaxation reducing accommodative demand
Correct answer: A. Nuclear sclerosis increasing the refractive index of the lens, producing an acquired myopic shift
Explanation
Progressive nuclear sclerosis raises the refractive index of the lens core, inducing an acquired myopia known as second sight, where the patient regains near reading ability while distance vision declines. The same process also reduces contrast and causes glare. Cortical cataracts do not produce a systematic myopic shift, posterior capsule changes are irrelevant in an unoperated eye, and zonular relaxation does not occur in simple ageing of the crystalline lens.
Reference: Parsons' Diseases of the Eye, 23rd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.