Journal of refractive surgery最新文献

Purpose: To compare corneal deflection characteristics during air-puff before and after keratorefractive procedures using a mathematical method.

Methods: The authors collected Corvis ST (Oculus Optikgeräte GmbH) corneal images from 86 eyes after photorefractive keratectomy (PRK), 93 eyes after laser in situ keratomileusis (LASIK), and 76 eyes after small incision lenticule extraction (SMILE). Using these images, corneal deflection was quantified and modal coefficients obtained over time through a decomposition method. The results were then compared among individual patients to identify differences before and after surgery.

Results: SMILE surgery increased corneal deflection by a quantifiable amount with less dependence on the depth of removed tissue, demonstrating up to 1.46 times (maximum) greater modal deflection changes compared with other surgeries. In contrast, in PRK and LASIK, corneal deflection was increased with greater ablation depth. Inter-patient variability was the largest in PRK, particularly in lower-order modes, which affected a large central area. Higher-order modes of the decomposition method in the central area demonstrated that SMILE and PRK exhibited similar patterns before air-puff, whereas SMILE and LASIK exhibited similar deflection patterns during air-puff. A significant difference between LASIK and SMILE was observed in transient deflection during the early air-puff phase and the ending phase.

Conclusions: This computational method could comprehensively analyze the overall corneal bending over time. The results suggest the use of LASIK and PRK for patients with low myopia and SMILE for patients with high myopia.

Purpose: To evaluate the long-term efficacy of accelerated corneal cross-linking (A-CXL) in halting the progression of recurrence of keratoconus in the graft.

Methods: This was a retrospective chart review of patients who underwent A-CXL for recurrence of keratoconus between January 2017 and December 2018. Results of eye evaluations performed up to 4 years after A-CXL included slit-lamp examination, corneal tomography and biomechanics, binocular corrected distance visual acuity (CDVA), and the manifest refraction equivalent sphere. The efficacy of A-CXL was assessed with reference to thinnest corneal thickness (TCT), mean anterior axial radius curvature in corneal periphery (ARC), and posterior axial radius curvature (PRC) tomography data indicating the stability of the ectasia.

Results: Data from 25 eyes were collected. Significant worsening in TCT, ARC, PCR, maximum keratometry, posterior eccentricity, and CDVA (P = .01) were found before A-CXL. At 4 years of follow-up, no changes in all tomographic parameters and significant improvement in CDVA (P = .02) and in corneal biomechanics (stiffness parameter A1, deformation amplitude ratio highest, inverse concave radius, and appla-nation 2 velocity; P = .01) were found. None of the included eyes developed postoperative complications or required re-grafting or refractive procedures.

Conclusions: A-CXL is a safe procedure that could play a role in preventing graft ectatic changes in patients with recurrence of keratoconus after keratoplasty, strengthening the graft and halting the natural progression of the ectasia, with positive effects in improving CDVA.

Purpose: To assess visual, refractive, and optical outcomes and patient-reported satisfaction following bilateral implantation of two trifocal intraocular lenses (IOLs) sharing the same optical architecture but differing in their photopic light distribution: Vivinex Gemetric and Vivinex Gemetric Plus (HOYA Surgical Optics).

Methods: This was an observational, prospective, consecutive, non-comparative case series. Fifty-four eyes of 27 patients underwent bilateral cataract surgery or refractive lens exchange. Each patient received the Gemetric IOL in the dominant eye and the Gemetric Plus in the non-dominant eye. Examinations included full refractive and visual assessment, defocus curves, mesopic contrast sensitivity, pyramidal aberrometry, and validated patient-reported outcome measures (Quality of Vision Questionnaire and Near Activity Visual Questionnaire), with follow-up at 1 day and 1, 3, and 6 months.

Results: The paired IOL combination provided a visual acuity of 0.15 logarithm of the minimum angle of resolution (logMAR) or better between defocus levels of +0.50 to -3.00 diopters (D). Maximum mean value of visual acuity was obtained at 0.00 D (-0.07 ± 0.05 logMAR) and a second peak was found at -3.00 D (0.07 ± 0.09 logMAR). It was 0.13 ± 0.10 logMAR at a defocus level of -1.50 D. Monocular corrected near visual acuity was significantly better for the Gemetric Plus IOL (P = .03). Better monocular distance visual function was obtained with the Gemetric IOL (P = .05). Contrast sensitivity remained within or above age-matched normative values. Ocular aberrations remained low and stable, with no significant differences between lens types. Ninety-six percent of patients reported no or minor difficulties in conducting prolonged near work.

Conclusions: The pairing strategy of the Vivinex Gemetric and Gemetric Plus trifocal IOLs delivers excellent visual acuity across all distances, preserves contrast sensitivity, and maintains a high level of optical quality and patient satisfaction.

Purpose: To investigate the biomechanical effects of photorefractive keratectomy (PRK), laser in situ keratomileusis (LASIK), and keratorefractive lenticule extraction (KLEx) on postoperative corneal biomechanics and visual outcomes using patient-specific finite element simulations.

Methods: A cohort of 30 patients (24 ± 4 years) undergoing PRK, LASIK, or KLEx was modeled using finite element simulations. Patient-specific preoperative topographies informed the creation of surgical models with ablation and lenticule profiles tailored to the correction needs of each patient based on the same theoretical ablation profile across the three refractive procedures. The parameters of the mechanical model were calibrated using experimental data from human corneal tissue.

Results: Simulations showed a consistent undercorrection of the refractive targets for all procedures, which increased with higher spherical corrections. PRK showed the lowest undercorrection, followed by LASIK and KLEx. Procedure-specific correction factors were calculated to compensate for the biomechanical response and achieve the correction required for the patient: the spherical component should be multiplied by 1.40 for PRK, 1.57 for LASIK, and 1.71 for KLEx. Stress analysis revealed that PRK maintained a uniform anterior stress distribution (28% increase from preoperatively), whereas LASIK (53% increase from preoperatively) and KLEx (44% increase from preoperatively) concentrated stress in the posterior stroma.

Conclusions: Although the same volume of tissue was removed in all procedures, corneal biomechanics influence refractive surgery outcomes, with PRK offering advantages in terms of reduced undercorrection and more favorable stress distribution. PRK's conservative approach offers a greater biomechanical safety margin, making it the recommended option for suspiciously weak corneas.

Purpose: To assess visual and refractive outcomes of 1,500 eyes that underwent small incision lenticule extraction (SMILE) with the VisuMax 800 femtosecond laser (Carl Zeiss Meditec AG).

Methods: This retrospective study includes 1,500 eyes of 770 patients younger than 45 years with corrected distance visual acuity (CDVA) of 20/20 or better who were treated with SMILE using the VisuMax 800. The surgery was performed by an experienced surgeon using a standard technique and 3-month follow up data were analyzed.

Results: A total of 1,500 eyes of patients with a mean age of 27.25 ± 4.746 years (39.5% men and 60.52% women) were included in this study. At 3 months, 98% of eyes had uncorrected distance visual acuity (UDVA) of 20/20 or better with an efficacy index of 1.011. Mean preoperative spherical equivalent (SE) was -4.170 ± 1.860 and -0.025 ± 0.120 diopters (D) at 3 months (P < .001). A total of 18.4% gained one line of CDVA and 9.2% lost one line with a safety index of 1.085. Postoperative SE was within ±0.50 and ±1.00 D in 99% and 100% of eyes, respectively. A total of 98.4% and 100% of eyes showed astigmatism of 0.50 and 1.00 D or less, respectively. No eyes lost two or more lines of CDVA. At 3 months, the Objective Scatter Index score was 0.844 ± 0.486, which was close to preoperative values (0.733 ± 0.871), with a mean change of 0.11. Subgroup analysis was done based on grade of myopia and age.

Conclusion: The VisuMax 800, with centration guidance (CentraLign) and cyclotorsion adjustment features (OcuLign), showed safe and effective outcomes for the treatment of myopia and myopic astigmatism in a large cohort of 1,500 eyes.

Purpose: To determine the repeatability of the Pentacam HR (Oculus Optikgeräte GmbH) and IOLMaster 700 (Carl Zeiss Meditec AG) in patients with keratoconus and intracorneal ring segments (ICRS) implantation.

Methods: The setting of this cross-sectional and observational study was the Fundación de Oftalmología Médica de la Comunitat Valenciana, Valencia, Spain. Eyes were scanned three consecutive times on each device. Repeatability was assessed using within-subject standard deviation (Sw), within-subject coefficient of variation (CVw), repeatability index (R), and intraclass correlation coefficient (ICC). Agreement between devices was evaluated with Bland-Altman plots and 95% limits of agreement (LoA). The sample was divided into two (lower and higher keratometry groups) to evaluate differences according to the severity of keratoconus.

Results: The study comprised 131 eyes of 100 patients. The repeatability of all parameters for both devices was excellent (ICC > 0.9 and low Sw), Bland-Altman analysis revealed wide 95% LoA, indicating clinically relevant differences between devices. A slight decrease in repeatability was observed in the higher keratometry group for flat keratometry in the IOLMaster 700 (ICC = 0.894) and ACD in the Pentacam HR (ICC = 0.895). Keratometry Sw and R values in both devices were slightly higher in the higher keratometry group.

Conclusions: The Pentacam HR and IOLMaster 700 showed high repeatability in patients with ICRS. However, the wide 95% LoA indicate poor agreement between devices and hence they cannot be used interchangeably in clinical practice. A slight decrease in repeatability could be expected in eyes with higher keratometry.

Purpose: To investigate the effect of posterior corneal astigmatism measured with different biometers on toric intraocular lens (IOL) power calculation.

Methods: This prospective case series study was conducted at Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China. Patients undergoing measurements by the IOLMaster 700 (Carl Zeiss Meditec AG), CASIA2 (Tomey Corporation), and Pentacam AXL (Oculus Optikgeräte GmbH), uneventful cataract surgery, and toric intraocular lens (IOL) implantation were included. The prediction accuracy of the Barrett toric calculator with predicted and measured posterior corneal astigmatism (Barrett-PPCA and Barrett-MPCA, respectively) was evaluated.

Results: A total of 94 patients (94 eyes) were included. Both Barrett-PPCA and Barrett-MPCA with the IOLMaster 700 showed lower median absolute prediction errors (MedAEs) than with the CASIA2 (0.38 to 0.39 vs 0.63 to 0.67 D, both P < .001) and Pentacam AXL (0.38 to 0.39 vs 0.50 to 0.54 D, both P < .05). Similarly, Barrett-PPCA with the Pentacam AXL showed a lower MedAE than with the CASIA2 (0.50 vs 0.63 D, P = .026). There was no significant difference in MedAEs between Barrett-PPCA and Barrett-MPCA for the IOLMaster 700 (0.39 vs 0.38 D, P = .438). Barrett-PPCA showed lower MedAEs than Barrett-MPCA for the CASIA2 (0.63 vs 0.67 D, P = .006) and Pentacam AXL (0.50 vs 0.54 D, P < .001).

Conclusions: The IOLMaster 700 exhibited the highest prediction accuracy for toric IOL compared to the CASIA2 and Pentacam AXL. When compared with Barrett-MPCA, Barrett-PPCA yielded comparable prediction accuracy for the IOLMaster 700 and improved accuracy for the CASIA2 and Pentacam AXL.