PurposeTo demonstrate how higher-order corneal aberrations can cancel out, modify, or induce lower-order corneal astigmatism.Patients and methodsSix representative eyes are presented that show different scenarios in which higher-order aberrations interacting with corneal astigmatism can affect the manifest refraction. WaveLight® Contoura ablation maps showing the higher-order aberrations are shown, as are results of correction with full measured correction using the LYRA (Layer Yolked Reduction of Astigmatism) Protocol.ResultsHigher-order corneal aberrations such as trefoil, quadrafoil, and coma can create ovalization of the central cornea, which can interact with the ovalization caused by lower-order astigmatism to either induce, cancel out, or modify the manifest refraction. Contoura processing successfully determines the linkage of these interactions resulting in full astigmatism removal. Purely lenticular astigmatism appears to be rare, but a case is also demonstrated. The author theorizes that all aberrations require cerebral compensatory processing and can be removed, supported by the facts that full removal of aberrations and its linkage with lower-order astigmatism with the LYRA Protocol has not resulted in worse or unacceptable vision for any patients.ConclusionHigher-order aberrations interacting with lower-order astigmatism is the main reason for the differences between manifest refraction and Contoura measured astigmatism, and the linkage between these interactions can be successfully treated using Contoura and the LYRA Protocol. Lenticular astigmatism is relatively rare.

PurposeTo demonstrate how using the Wavelight Contoura measured astigmatism and axis eliminates corneal astigmatism and creates uniformly shaped corneas.Patients and methodsA retrospective analysis was conducted of the first 50 eyes to have bilateral full WaveLight® Contoura LASIK correction of measured astigmatism and axis (vs conventional manifest refraction), using the Layer Yolked Reduction of Astigmatism Protocol in all cases. All patients had astigmatism corrected, and had at least 1 week of follow-up. Accuracy to desired refractive goal was assessed by postoperative refraction, aberration reduction via calculation of polynomials, and postoperative visions were analyzed as a secondary goal.ResultsThe average difference of astigmatic power from manifest to measured was 0.5462D (with a range of 0–1.69D), and the average difference of axis was 14.94° (with a range of 0°–89°). Forty-seven of 50 eyes had a goal of plano, 3 had a monovision goal. Astigmatism was fully eliminated from all but 2 eyes, and 1 eye had regression with astigmatism. Of the eyes with plano as the goal, 80.85% were 20/15 or better, and 100% were 20/20 or better. Polynomial analysis postoperatively showed that at 6.5 mm, the average C3 was reduced by 86.5% and the average C5 by 85.14%.ConclusionsUsing WaveLight® Contoura measured astigmatism and axis removes higher order aberrations and allows for the creation of a more uniform cornea with accurate removal of astigmatism, and reduction of aberration polynomials. WaveLight® Contoura successfully links the refractive correction layer and aberration repair layer using the Layer Yolked Reduction of Astigmatism Protocol to demonstrate how aberration removal can affect refractive correction.

PurposeTo show how an incorrect manifest astigmatism axis can cause an abnormal induced astigmatism on a new axis.Patients and methodsFour eyes of three patients were treated primarily with WaveLight® EX500 wavefront optimized (WFO) treatments for astigmatism. All four eyes needed enhancements and were analyzed retrospectively via WaveLight® Contoura to determine the reason for the incorrect astigmatism treatment. Two of the eyes were retreated with topographic-guided ablation, and two were treated with WFO correction.ResultsThe eyes that had an incorrect manifest axis resulted in a new abnormal induced astigmatism on a wholly new axis. Treatment with topographic-guided ablation completely eliminated the newly induced astigmatism. Treatment with WFO of an abnormal induced astigmatism corrected the refraction but still left topographic evidence of the abnormal astigmatism behind. One eye was incorrectly treated for astigmatism due to coma affecting refraction when the patient was dilated. This eye had a normal induced astigmatism on a perpendicular axis and was corrected using WFO. The use of manifest refraction with WaveLight® Contoura topographic-guided ablation will lead to incorrect astigmatism correction when the manifest astigmatism and axis differ from the WaveLight® Contoura measured.ConclusionCorrection of an incorrect manifest refraction astigmatic axis does not simply create undercorrection of the astigmatism but induces an entirely new abnormal astigmatism on a different axis. Manifest refraction is less accurate and can lead to abnormal astigmatism when laser ablation is performed.

Purpose: To identify the laser programming strategy that will achieve optimal refractive outcomes of LASIK with a topography-guided laser for eyes with a disparity between cylinder measured by manifest refraction and cylinder measured by topography. Setting: Six surgeons at 5 clinical sites in the USA. Design: Retrospective data review. Methods: Preoperative, treatment, and postoperative data on 52 eyes that underwent topographyguided LASIK with the WaveLight EX500 Contoura ® Vision excimer laser ablation profile in which the vectors representing the preoperative refractive cylinder and the cylinder measured by the WaveLight ® Topolyzer™ VARIO Diagnostic Device (Vario cylinder) differed by >/= 0.50D and/or >/= 10 degrees of orientation were analyzed retrospectively. Data were contributed by six surgeons using the laser at 5 different clinical sites. Vector analysis of postoperative cylindrical refractive error and the actual laser programming strategy was used to calculate the cylindrical correction that would, theoretically, have completely eliminated postoperative refractive cylinder. This was compared to expected results using the preoperative manifest cylinder, the topographic cylinder, and the Phorcides Analytic Engine (Phorcides LLC, North Oaks MN; Phorcides). For analysis, subjects were stratified on the basis of the vector difference between Manifest and Topo cylinder (High, >0.75 D; and Low, ≤0.75 D). Results: The poorest calculated theoretical outcomes were obtained with the manifest refraction (centroid: −0.43, 0.22; mean calculated error vector: 0.56 ± 0.42 D; p=ns). Better outcomes were obtained with the topographically measured refraction (centroid: 0.37, 0.02; mean calculated error vector: 0.47 ± 0.33 D; p=ns). The best outcomes were obtained with Phorcides (centroid: −0.15, 0.06; mean calculated error vector: 0.39 ± 0.28 D; p=ns). The mean error vector magnitude in the Phorcides Low group was significantly lower than for the Manifest and Topo Low groups (0.26 D vs 0.48 D and 0.33 D; p<0.01). The mean error magnitude in the Phorcides High group was nearly 0.25 D lower than for the Manifest High group (0.48 D vs 0.70 D; p<0.01), but was the same as for the Topo High group (0.48 D vs 0.48 D). Conclusion: Our study suggests that using the topographically measured cylinder or the cylinder selected by Phorcides will produce more desirable refractive outcomes than entry of the preoperative refractive cylinder as the basis for correction of myopia and myopic astigmatism with the WaveLight Contoura Vision excimer laser.

PurposeTo evaluate the efficacy of treating patients with +3.00 diopters (D) to +6.00 D of hyperopia via laser-assisted in situ keratomileusis (LASIK) with the WaveLight Allegretto 400 and EX500 excimer laser systems.SettingPrivate clinical ophthalmology practice.Patients and methodsThis was a retrospective study of patients undergoing LASIK treatments of +3.00 to +6.00 D on two different WaveLight laser systems: 163 eyes on the 400 (Hertz) Hz system and 54 eyes on the 500 Hz system. The duration of follow-up was 6 months postoperation. Data were evaluated for uncorrected distance visual acuity, corrected distance visual acuity (CDVA), spherical equivalents (SEQs), and changes in these parameters (eg, loss of vision, regression over time).ResultsTreatment with both lasers was safe and effective, with loss of one line of CDVA in four of 162 eyes using the 400 Hz laser system, and none of the 54 eyes with the 500 Hz laser system. Overall, regression ≥0.75 D from goal at 6 months was observed in 11.7% (19/163) of eyes in the 400 Hz laser group and 9.26% (5/54) of eyes in the 500 Hz laser group (regression ≥0.50 D =77.9% [127/163] and 77.8% [42/54], respectively). The mean SEQ regressions for all eyes with moderate hyperopia were 0.10 and 0.18 D for those with high hyperopia.ConclusionsBoth the 400 and 500 Hz excimer laser systems were safe and effective for the LASIK treatment of moderate-to-high hyperopia. The overall rate of regression was low and the amount of regression was relatively small with both systems.