Impact of phototherapeutic keratectomy on the outcome of subsequent penetrating keratoplasty in patients with stromal corneal dystrophies

Abstract

Purpose: To examine the impact of previous phototherapeutic keratectomy (PTK) on the outcome of subsequent penetrating keratoplasty (PK) in patients with stromal corneal dystrophies.

Design: Retrospective, cross-sectional, clinical single-center study.

Patient population: Fifteen patients (21 eyes) age 39.9 +/- 11.4 years.

Inclusion criteria: Primary homologous PK performed in phakic patients with granular or macular dystrophy; no use of combined surgical procedures; defined graft size and technique. The study group comprised eight eyes of five patients, PK performed 3.7 +/- 2.3 years after PTK. The control group (no previous PTK) comprised 13 eyes of 10 patients. In both groups, 38% had granular and 62% had macular dystrophy. Intervention Procedures: Phototherapeutic keratectomy was performed using a 193 nm excimer laser. All PKs were also performed using this laser, with trephination using a metal mask. Subjective refractometry (trial lenses), standard keratometry (Zeiss ophthalmometer), and corneal topography (Tomey TMS-1) were performed preoperatively, 6 months after PK, and after first and second suture removal (1.1 +/- 0.2 years; 1.6 +/- 0.2 years).

Main outcome measures: Keratometric, topographic net astigmatism, and refractive cylinder; keratometric and topographic central power; best-corrected visual acuity (BCVA); surface regularity index (SRI), surface asymmetry index (SAI), potential visual acuity (PVA).

Results: Refractive power and astigmatism, BCVA, and PVA values did not differ significantly between the two groups at any time-point; SRI tended to be better in the study group after first suture removal (P =.05).

Conclusion: Preceding PTK does not appear to impair the outcome of subsequent penetrating keratoplasty in stromal corneal dystrophy patients.