Topography-guided ablation for treatment of patients with irregular astigmatism

PURPOSE: To evaluate the customized aspheric treatment zone (CATz) topography-guided ablation for the correction of irregular astigmatism induced by initial corneal refractive surgery or corneal injury. METHODS: CATz ablation was performed on 32 eyes of 28 patients. Each procedure was performed by photorefractive keratectomy (PRK) or LASIK using a NIDEK EC-5000 excimer laser, the eyes had decentered ablations, small optical zones, decreased best spectacle-corrected visual acuity (BSCVA), and asymmetrical astigmatism. Subjective symptoms, uneorrectied visual acuity (UCVA), BSCVA, refraction, corneal topography, and higher order aberrations were measured. Mean follow-up was 161.9±129.9 days (range: 90 to 492 days). RESULTS: Data obtained at final postoperative follow-up show that UCVA and BSCVA inereased by ≥2 lines after CATz ablation in 17 and 11 eyes and decreased in 4 and 2 eyes, respectively. Higher order aberrations were decreased in 16 eyes and increased in 1 eye. Topographical maps were improved with decreased surface regularity index (20 eyes) and surface asymmetry index (22 eyes). Seven eyes retired further enhancement for residual refractive errors, Thirteen patients (15 eyes) claimed they were satisfied with the outcome, 6 patients (7 eyes) stated that the outcome was lower than expected, and 4 patients (4 eyes) stated they were dissatisfied. CONCLUSIONS: CATz topographic ablation effectively improves the quality of vision and symptoms in the majority of patients with irregular corneal astigmatism from previous excimer laser refractive surgery. However, residual or induced refractive errors may need to be corrected with a second operation after CATz.