Abstract
BackgroundSeveral planning algorithms have been developed for topography-guided custom ablation treatment (T-CAT), but each has its own deficiencies. The purpose of this study is to demonstrate the potential of a novel mutual comparative analysis (MCA) informed by manifest refraction and corneal topographic data and the patient’s subjective perception in correcting ametropia.MethodsThis retrospective review included patients with significant preoperative differences in the power or axis of astigmatism according to the manifest refraction and corneal topographic data (power > 0.75 D and/or axis > 10°). T-CAT planning was designed using MCA. Follow-ups were conducted for at least 6 months.ResultsSeventy-nine patients (121 eyes) were included. The mean preoperative deviation in the astigmatic power and axis were 0.72 ± 0.43 D and 20.18 ± 23.68°, respectively. The average oculus residual astigmatism (ORA) was 0.81 ± 0.32 D (range: 0.08–1.66 D). Six months postoperatively, the mean spherical equivalent refraction was 0.04 ± 0.42 D, and the mean cylinder was − 0.27 ± 0.24 D. The mean efficacy and safety indices were 1.10 and 1.15, respectively. The uncorrected distance visual acuity in 92% of the eyes was the same or better than the corrected distance visual acuity. The angle of error was ±5° in 61% of eyes and ± 15° in 84% of eyes. Residual astigmatism was ≤0.5 D in 91% of eyes. Optical quality and photopic contrast sensitivity did not change significantly (p > 0.05), and the scotopic contrast sensitivity decreased at 3, 6, and 12 cpd (p < 0.05). The vertical coma and horizontal coma of the anterior corneal surface significantly decreased postoperatively but increased during follow-up.ConclusionsThe MCA demonstrated safety, efficacy, accuracy, predictability, and stability and can be used as a complementary and feasible method for T-CAT.
Highlights
Several planning algorithms have been developed for topography-guided custom ablation treatment (T-CAT), but each has its own deficiencies
The Food and Drug Administration (FDA) algorithm uses manifest refraction as the correction amount during the operation, while a modified FDA algorithm determines the astigmatic axis of the correction based on corneal topographic data
The topographymodified refraction (TMR) [7] and Layer Yolked Reduction of Astigmatism (LYRA) protocols [8] have been reported using astigmatic data measured by corneal topography as the correction amount of astigmatism
Summary
Several planning algorithms have been developed for topography-guided custom ablation treatment (T-CAT), but each has its own deficiencies. Developed over the course of two decades, topographyguided custom ablation treatment (T-CAT) [1, 2] was initially used for the retreatment of irregular corneas after corneal refractive surgery [3, 4] and the treatment of keratectasia with collagen cross-linking [5]. Asymmetric astigmatism, or astigmatism in the eye, the power and axis of the astigmatism are sometimes different between manifest refraction and topographic data. The LYRA protocol is applied when the manifest refraction and topographic data differ largely in terms of the power and axis of the astigmatism
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