Wavefront-Guided versus Standard LASIK Enhancement for Residual Refractive Errors
Received 4 January 2005; accepted 3 October 2005. published online 28 December 2005.
Objective
To assess efficacy, safety, predictability, stability, and changes in higher-order aberrations (HOAs) and contrast sensitivity (CS) after wavefront-guided and standard LASIK enhancement for the correction of residual refractive errors.
Twenty eyes of 20 consecutive patients (spherical equivalent [SE], −2.01±1.36 diopters [D]) treated with wavefront-guided Zyoptix Ablation Refinement software (ZAR) LASIK and 20 eyes of 20 consecutive patients (SE, −1.81±1.21 D) treated with standard Planoscan LASIK, both for residual refractive error enhancement.
Main Outcome Measures
Efficacy, safety, predictability, stability, HOAs, and CS were evaluated before and after enhancement at 6 months’ follow-up.
Methods
Uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), manifest refraction, CS by means of the Functional Acuity Contrast Test, and HOAs by means of Zywave aberrometry were evaluated preoperatively and 6 months after retreatment.
Results
At 6 months postoperatively, UCVA was 20/25 or better in 100% of the eyes. Efficacy indexes were 1.09 for ZAR patients and 0.95 for Planoscan patients. No eyes lost ≥1 line of BCVA; in the ZAR group, 2 eyes gained 1 line and 6 eyes gained ≥2 lines; in the Planoscan group, 3 eyes gained 1 line. The ZAR group showed a percentage of eyes (94.4%) within the 0.5-D range in SE higher than that shown by the Planoscan group (88.8%). After 6 months, the HOA root mean square (RMS) increased on average by a factor of 1.44 for the Planoscan group (P = 0.003). No change or reduction in HOA RMS was found in the ZAR group (factor of 0.96; P>0.01). Contrast sensitivity was reduced in the Planoscan group only at the highest spatial frequency (18 cycles per degree; P<0.01). There was a significant reduction of CS as a function of HOA increase for the Planoscan group (P<0.0001). No changes were observed for the ZAR group at any spatial frequency (1.5–18 cycles per degree; P>0.01).
Conclusions
Wavefront-guided LASIK using the ZAR algorithm is an effective and safe procedure for treatment of residual refractive errors. Wavefront-guided LASIK does not increase HOAs and does not modify CS compared with preoperative values. Wavefront-guided LASIK seems to be better than standard LASIK for retreatments.
1Research, Development and Innovation Department, VISSUM Ophthalmologic Institute of Alicante, Alicante, Spain
2School of Medicine, University Miguel Hernández, Elche, Spain
Correspondence to Jorge L. Alió, MD, PhD, VISSUM, Instituto Oftalmológico de Alicante, Avda. Denia s/n, 03016 Alicante, Spain.
Manuscript no. 2005-5.
This work was supported in part by a grant from the Spanish Ministry of Health, Instituto de Salud Carlos III, Red Tematica de Investigación Cooperativa en Oftalmología (reference no.: C 03/13) Subproyecto Cirugía Refractiva y Calidad Visual, Madrid, Spain.
The authors have no financial interest in any of the issues discussed in the article and have no proprietary interest in the development or marketing of the products or medical equipment used in the study.
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