Topography-driven excimer laser for the retreatment of decentralized myopic photorefractive keratectomy1
Presented in part at the annual meeting of the Association for Research in Vision and Ophthalmology (ARVO), Fort Lauderdale, Florida, May 2000.
Received 1 December 2000; accepted 17 April 2001.
Abstract
Objective
This study evaluated the efficacy, predictability, stability, and safety of a software program (Corneal Interactive Programmed Topographic Ablation, CIPTA, LIGI, Taranto, Italy), which, by transferring programmed ablation from the corneal topograph to a flying-spot excimer laser, provides customized laser ablation for correction of postmyopic photorefractive keratectomy (PRK) decentrations.
Design
Noncomparative consecutive case series.
Participants
Thirty-two eyes of 32 subjects with a mean age of 35 years (range, 19–49; standard deviation [SD], 7.9) had CIPTA-guided PRK at the Clinica Oculistica of Bari University (Italy). All the subjects had irregular astigmatism after postmyopic PRK because of clinically significant, decentered treatments of more than 1 mm.
Operation
Individual topographies were acquired by a corneal topograph (Orbscan II, Orbtek, Inc., Salt Lake City, UT). These, together with refractive data, were processed to obtain a customized altimetric ablation profile that was transferred to a flying-spot laser (Laserscan 2000, Lasersight, Orlando, FL).
Main outcome measures
The topographic study of centration and data on uncorrected (UCVA) and best-corrected (BCVA) visual acuity, predictability, and stability of refraction, and any complications, were analyzed.
Results
Mean follow-up was 10.3 months (range, 4–18 months; SD, 5.8). At the last postoperative examination, 29 eyes (90.6%) had a UCVA superior to 20/40. Nineteen eyes (59.4%) had a UCVA of 20/20. Twenty-two eyes (68.75%) were within 0.50 diopters (D) of attempted correction in the spherical equivalent and 28 eyes (87.5%) were within 1 D. The index of success of astigmatic correction was 0.15. No eye lost Snellen lines of BCVA, whereas 18 eyes (56.25%) gained Snellen lines. Postoperative topographies revealed well-centered treatments.
Conclusions
The combination of topographic data with computer controlled flying-spot excimer laser ablation is a suitable solution for correcting irregular astigmatism after postmyopic PRK decentrations.
Manuscript no. 200842.
aClinica Oculistica, Department of Otorhinolaryngology and Ophthalmology, University of Bari, Bari, Italy
Reprint requests to Prof. Carlo Sborgia, MD, Department of Ophthalmology and Otorhinolaryngology, University of Bari, Piazza Giulio Cesare, 11 Bari, Italy
1 The authors have no proprietary interest in any of the materials used in this study
ABSTRACT