PRK and LASIK reduces retinal image quality

Performing photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) reduces the retinal image quality in myopic patients, declared a paper in the Journal of Cataract and Refractive Surgery.

The comparative case series, headed by Dr Meritxell Vilaseca, Universitat Politècnica de Catalunya, Terrassa, Barcelona Institute of Ocular Microsurgery, Barcelona, Spain, assessed 34 myopic eyes that underwent PRK and 55 myopic eyes that underwent LASIK.

Preoperatively and 3 months after PRK or LASIK optical quality was assessed with a clinical double-pass system. The team calculated the modulation transfer function (MTF), retinal image quality parameters (MTF cut-off frequency, Strehl ratio), and intraocular scattering [objective scatter index (OSI)].

PRK and LASIK demonstrated a statistically significant reduction on retinal image quality. However, there were no differences in reduction between the two techniques.

In the PRK group the MTF decreased by a factor of 1.50 and in the LASIK group it decreased by 1.32. The Strehl ratio was decreased by 1.10 and 1.07 for the PRK and LASIK group, respectively.

PRK and LASIK caused an increase in the objective scatter index by factors of 1.48 and 1.57, respectively. The preoperative refraction and the OSI were strongly linked.