Journal of refractive surgery最新文献

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.

Purpose: To evaluate the repeatability of the ABC parameters of the ABCD progression display system, initially developed on the Pentacam HR tomography system (Oculus Optikgeräte GmbH), varying zonal averaging diameters, on two non-native devices.

Methods: Patients with keratoconus underwent three consecutive scans using a dual Scheimpflug/Placido analyzer and an optical coherence tomography (OCT)/Placido platform. Repeatability was assessed for the ABC parameters thinnest pachymetry (C), anterior (A) and posterior (B) keratometry derived as zonal averages centered on the thinnest point, both axial and local anterior radius of curvature (A), posterior radius of curvature (B), and thinnest pachymetry (C). Zonal averaging diameters ranging from 1 to 8 mm were evaluated. Repeatability was assessed by within-subject standard deviation, repeatability limits (r), and coefficient of variation (CoV).

Results: Fifty-four and 77 eyes in the dual Scheimpflug and OCT groups, respectively, were evaluated. For zonal averaging diameters of 1, 2, 3, 4, 5, 6, 7, and 8 mm, the anterior axial curvatures for the dual Scheimpflug/Placido system demonstrated repeatability limits of 1.47, 1.07, 0.80, 0.64, 0.49, 0.40, 0.40, and 0.44 diopters (D), respectively, whereas the posterior axial curvature values were 0.49, 0.25, 0.16, 0.16, 0.17, 0.19, 0.20, and 0.23 D, respectively. For the OCT/Placido group, the 1 to 8 anterior axial curvature values were 1.18, 0.96, 0.65, 0.56, 0.50, 0.45, 0.41, and 0.38 D, respectively, whereas the posterior values were 0.64, 0.48, 0.27, 0.19, 0.16, 0.14, 0.12, and 0.11 D, respectively. Axial curvature measurements were slightly more repeatable than local measurements with the dual Scheimpflug device. For diameters of 3 mm or greater, both technologies demonstrated comparable repeatability for posterior curvatures. Repeatability was better in eyes with maximum curvature (Kmax) values of 50.00 D or less than with Kmax values of greater than 50.00 D. In eyes with Kmax values of 50.00 D or less, anterior axial keratometric zonal averaging centered on the thinnest point showed clinically acceptable repeatability at 1 mm for both the dual Scheimpflug (r = 0.74) and OCT (r = 1.06) groups, and at 3 mm in eyes with Kmax values of greater than 50.00 D for both the dual Scheimpflug (r = 1.01) and OCT (r = 0.72) groups.

Conclusions: Anterior axial keratometric zonal averaging centered on the thinnest corneal pachymetry demonstrates clinically acceptable repeatability at an optimal diameter of 2 mm overall and at 3 mm in eyes with Kmax values of greater than 50.00 D for both devices. A comparable study would help determine whether the established Pentacam's ABCD 3-mm diameter is indeed optimal when using this technology.

Purpose: To develop and validate an automated lens cortex and nuclear opacity quantification method based on swept-source anterior segment optical coherence tomography (AS-OCT).

Methods: This cross-sectional study included 504 cataract surgery candidates. Lens images were captured using swept-source AS-OCT (CASIA-2; Tomey Corporation). Based on nnUNet framework, two artificial intelligence (AI) segmentation models were independently trained to quantify opacity in the lens cortex and nucleus. Data from 275 and 229 individuals were used for lens nucleus model training and external testing, respectively. The corresponding numbers for lens cortex model were 100 and 38. Five-fold cross-validation was employed for model selection. The performance of the auto-segmentation, as well as the mean pixel intensity values within the area of interest, were evaluated against the human-generated labels.

Results: The AI models demonstrated good segmentation accuracy for the lens cortex and nucleus (mean intersection over union [MIoU] = 0.959, 95% CI: 0.957 to 0.961 for cortex; MioU = 0.928, 95% CI: 0.925 to 0.931 for nucleus), and high agreement in the opacity quantification (intraclass correlation coefficient [ICC] = 0.9933, 95% CI: 0.9872 to 0.9965 for the cortex; ICC = 0.9939, 95% CI: 0.9921 to 0.9953 for the nucleus), compared to manual measurements by ophthalmologists.

Conclusions: The AI model is capable of accurately and objectively quantifying the opacity of both the lens cortex and nucleus based on swept-source AS-OCT images, thereby offering a method that is more precise, objective, and rapid for quantification in both clinical practice and research settings.

Purpose: To report visual and refractive outcomes after treatment with PRESBYOND Laser Blended Vision (Carl Zeiss Meditec AG) using non-linear aspheric profiles combined with micro-anisometropia laser in situ keratomileusis (LASIK) for the correction of myopic and hyperopic presbyopia.

Methods: This was a retrospective analysis of patients treated binocularly with PRESBYOND Laser Blended Vision using the MEL-90 excimer laser and VisuMax femtosecond laser (Carl Zeiss Meditec AG), and with at least 3-month postoperative data. Dominant eyes were targeted for plano and non-dominant eyes were targeted for myopia between -0.50 and -1.50 diopters (D). Manifest refraction, monocular and binocular uncorrected distance visual acuity (UDVA), monocular corrected distance visual acuity (CDVA), and binocular uncorrected near visual acuity were measured.

Results: The study included 232 eyes of 116 patients (170 hyperopic eyes and 62 myopic eyes). In the hyperopic group, mean spherical equivalent (SEQ) was reduced from +1.49 ± 0.67 D preoperatively to -0.06 ± 0.39 D postoperatively in dominant eyes, and to -1.29 ± 0.57 D in non-dominant eyes, with 96.5% of eyes within ±1.00 D of target. Binocularly, mean UDVA was -0.06 ± 0.08 logarithm of the minimum angle of resolution (logMAR) with 90.5% of patients 20/20 or better at distance and 98.8% reading N8 or better. In the myopic group, mean SEQ was reduced from -4.52 ± 2.28 D preoperatively to +0.12 ± 0.49 D postoperatively in dominant eyes and to -1.04 ± 0.54 D in non-dominant eyes, with 96.8% of eyes within ±1.00 D of target. Binocularly, mean UDVA was -0.07 ± 0.09 logMAR with 87.1% of patients 20/20 or better at distance and 87.1% reading N8 or better.

Conclusions: PRESBYOND Laser Blended Vision was a safe and effective procedure for the treatment of myopic and hyperopic presbyopia.