Laser in situ keratomileusis assisted by corneal topography

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Abstract
Purpose: To assess whether laser in situ keratomileusis (LASIK) assisted by corneal topography can successfully treat corneal irregularities or irregular astigmatism in patients with previous ocular surgery or ocular trauma. Setting: University Eye Hospital, Klinikum Mannheim, Mannheim, Germany. Methods: In a prospective clinical study, LASIK was performed in 23 eyes of 22 patients. Reasons for surgery were irregular astigmatism after penetrating keratoplasty or penetrating injury or corneal irregularity after previous excimer laser surgery. Excimer ablation was based on preoperative corneal topography data (Corneal Analysis System, EyeSys Technologies) using a proprietary algorithm (Topographic Assist LASIK, Chiron Vision). Follow-up was 6 months. Results: Mean preoperative uncorrected visual acuity (UCVA) was 20/80 and mean best spectacle-corrected visual acuity (BSCVA), 20/35. Uncorrected visual acuity improved in all but two cases. Postoperatively, mean UCVA increased to 20/50; mean BSCVA was unchanged. No eye lost two or more lines of BSCVA. Postoperative topography showed less corneal irregularity in 81.3% of eyes; full correction was achieved in 19.4%, Four eyes (19.4%) needed re-treatment for undercorrection and three eyes (14.3%) for regression. Conclusion: Preliminary results indicate that the concept of topographic-assisted LASIK is feasible. However, most eyes were undercorrected and had regression. One reason might be that corneal topography underestimated corneal irregularity, causing significant undercorrection.