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Custom-contoured ablation pattern method for the treatment of decentered laser ablations
1Department of Ophthalmology, Stanford University Medical Center, 900 Blake Wilbur Drive, Stanford, CA 94304, USA.
Purpose:
To evaluate the custom-contoured ablation pattern (C-CAP) method as a tool for providing customized laser ablations for decentered ablations based on corneal topography data.
Setting:
Department of Ophthalmology, Stanford University, Stanford, California, USA.
Methods:
In a prospective noncomparative interventional case series, 8 eyes from 7 post-laser in situ keratomileusis (LASIK) patients and 1 post-photorefractive keratectomy (PRK) patient with symptomatic laser decentration were treated with the C-CAP method. The Zeiss Humphrey topography system was used to identify and analyze decentered ablations. The computer software allowed the surgeon to preoperatively model the effect of various ablation schemes on the preoperative topography until a scheme that alleviated the decentration was identified. The planned ablation parameters, which included size, depth, and location of the ablation, were programmed into the Visx S4 excimer laser before treatment.
Results:
The mean follow-up after C-CAP ablation was 4.2 months (range 1.8 to 6.3 months). At the last postoperative examination, no eye lost a line of best spectacle-corrected visual acuity (BSCVA). The uncorrected visual acuity (UCVA) improved by 3 lines in 1 eye (12.5%), by 2 lines in 1 eye (12.5%), and by 1 line in 3 eyes (37.5%); it remained unchanged in 2 eyes (25.0%) and decreased by 1 line in 1 eye (12.5%). The BSCVA improved by 3 lines in 1 eye (12.5%), by 2 lines in 2 eyes (25.0%), and by 1 line in 3 eyes (37.5%); it remained unchanged in 2 eyes (25.0%). In all eyes, including those without improvement in UCVA or BSCVA, a significant improvement in centration and subjective complaints was achieved. The pre-C-CAP and post-C-CAP root-mean-square (RMS) wavefront data were available in 5 of 8 eyes. The total and higher-order RMS aberrations decreased by 41.7% (P =.0027) and 45.5% (P =.039), respectively, after C-CAP treatment.
Conclusions:
Early U.S. results show the topography-driven C-CAP method is an effective tool to address untreatable postsurgical decentration. This method is presented as a technique to enhance the overall quality of vision, reduce patient-perceived visual aberrations, regularize the corneal surface, and maximize BSCVA.