Compared with the preoperative state, conventional myopic excimer laser ablation characteristically induces which change in the eye's optical aberration profile?

• A Increase in negative spherical aberration
• B Increase in positive spherical aberration ✓
• C Decrease in positive spherical aberration
• D No change in any higher order aberration

Explanation

Conventional myopic ablation removes more tissue centrally and produces a flattened central cornea whose asphericity no longer matches the normal prolate shape. Peripheral rays then focus relatively in front, producing increased positive spherical aberration, which contributes to glare, haloes and reduced contrast sensitivity at night, particularly with large pupils and small optical zones. Hyperopic corrections tend toward the opposite shift. Wavefront-guided platforms were developed specifically to limit this induced aberration.

Reference: AAO Basic and Clinical Science Course, Section 13: Refractive Surgery, 2022-2023 ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.