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Purpose: To compare variance of manifest refraction (MR) measurement and variance of refractive outcomes after keratorefractive lenticule extraction (KLEx) in the same cohort. Methods: This was a retrospective study of consecutive patients attending at least three preoperative refractions before undergoing KLEx. All manifest refractions were performed according to a standard protocol. Additionally, automated refraction, spectacles prescription, wavefront refraction, and tomography/topography were also considered when determining the treatment refraction. Variance of postoperative outcomes was compared to variance of MR measurement. Results: The difference in MR of 153 eyes between the first and last preoperative visit showed a mean pairwise absolute difference of 0.22 ± 0.22 diopters (D) (range: 0.00 to 1.25 D) in spherical equivalent (SE). The 95% limit of agreement (LoA) was within 0.73 D for sphere, 0.60 D for cylinder, and 0.61 D for SE. Standard deviation (SD) for corrected distance visual acuity (CDVA) was 0.06 logarithm of the minimum angle of resolution (logMAR) and the 95% LoA was within 1.3 Snellen lines. The differences between reproducibility of the two last preoperative MR and the variance of postoperative outcomes after KLEx (ie, the isolated repeatability of corneal lenticule extraction) was SD of 0.13 D for sphere, cylinder, and SE, and 11 degrees in axis, respectively. Conclusions: Predictability of KLEx was equal to variance of refraction measurement. Isolated repeatability of the laser treatment was better than the reproducibility of MR. Thus, the authors have shown for the first time that precision of KLEx has reached such a level today that further improvement is limited by MR measurements. [J Refract Surg. 2024;40(11):e814–e823.] [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the impact of refractive couplings in myopia and myopic astigmatism with two different keratorefractive lenticule extraction (KLEx) systems. Methods: This was a retrospective evaluation of refractive outcomes with two different lasers studying 2,841 eyes undergoing small incision lenticule extraction (SMILE) (VisuMax 500; Carl Zeiss Meditec) and 2,528 eyes undergoing SmartSight (ATOS; SCHWIND eye-tech-solutions GmbH). Coupling effects (derived from the ratio between partial slopes) were determined for sphere and cylinder and for spherical equivalent, cardinal, and oblique astigmatism separately. Results: Statistically significant coupling effects were observed for both the VisuMax and ATOS systems, as indicated by P values less than.05. For the VisuMax, a coupling effect of 8% of cylinder into sphere and a 2% coupling of sphere into cylinder was found. For the ATOS, the coupling effect of sphere into cylinder was 1%. A 3% coupling effect of oblique astigmatism into cardinal astigmatism in the VisuMax, and conversely, a 0.1% coupling effect of defocus into oblique astigmatism in the ATOS were found. In cases with no astigmatism plan, sphere had a 2% effect on induced astigmatism in the VisuMax and 0.6% in the ATOS. In high astigmatism plans, sphere had a significant 16% impact on cylinder in the VisuMax. Additionally, the effect of defocus on cardinal astigmatism was 6% in the VisuMax and 0.8% on oblique astigmatism in the ATOS. Conclusions: Despite the P values less than.05 indicating statistical significance, the observed coupling effects were consistently low, with magnitudes below 10%, even for astigmatism exceeding 2.50 diopters. These couplings may be partly attributed to cross-effects of torsional eye movements. Coupling values for KLEx were markedly lower than those reported for non-aspheric excimer laser ablations. The results suggest that surgical results may be refined further by optimizing nomograms to mitigate coupling effects. [J Refract Surg. 2024;40(10):e706–e715.] [ABSTRACT FROM AUTHOR]

Purpose: To compare clinical outcomes and rotational stability of the toric implantable Collamer lens (TICL) and toric implantable phakic contact lens (TIPCL). Methods: Charts were reviewed from January 2011 to January 2023 to identify all TICLs and TIPCLs implanted by a single surgeon. Implant size was generally chosen according to the manufacturer's recommendation, but 15 TIPCLs 0.25 mm larger than recommended to increase vaulting were included. Results: Eighty-four TICLs and 98 TIPCLs were identified and yielded excellent refractive and visual results in eyes with high myopic astigmatism at the last follow-up visit. No case of acute glaucoma or cataract induction was observed. In total, 15 (8.2%) rotated lenses were recorded; 2 (2.4%) TICLs and 13 (13.3%) TIPCLs (P =.013). Eyes in both groups were similar in preoperative spherical equivalent, cylinder, white-to-white distance, anterior chamber depth (ACD), anterior chamber angle, and mean follow-up times (P =.925,.673,.822,.794,.358, and.873, respectively). Average TICL size was larger than TIPCL size (P <.001). Rotation of the lenses was positively correlated with cylinder and negatively correlated with ACD but not with vaulting (P =.001, r = 0.253; P =.011, r = −0.193; P =.488, r = −0.057; respectively). Vaulting was positively correlated with preoperative ACD (P ≤.001, r =.329). In eyes with a rotated TIPCL, preoperative cylinder was higher and ACD was shallower than in eyes with a stable TIPCL (P =.001 and.007, respectively). Increasing the implant size had no significant effect on rotation rate (P =.685). Conclusions: Although both implants were safe and effective in highly myopic eyes, TICL rotated less frequently than TIPCL and required fewer secondary interventions. Rotation was correlated with preoperative cylinder and ACD but not lens vaulting. [J Refract Surg. 2023;39(7):463–472.] [ABSTRACT FROM AUTHOR]

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