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

Abstract

PurposeTo examine the impact of previous phototherapeutic keratectomy (PTK) on the outcome of subsequent penetrating keratoplasty (PK) in patients with stromal corneal dystrophies. DesignRetrospective, cross-sectional, clinical single-center study. MethodsPatient 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). ResultsRefractive 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). ConclusionPreceding PTK does not appear to impair the outcome of subsequent penetrating keratoplasty in stromal corneal dystrophy patients.