Evaluation of long-term clinical outcomes after toric implantable collamer lens implantation.

PURPOSE: To evaluate the long-term (8-10 years) outcomes of toric implantable collamer lens (TICL) surgery. SETTING: Nagoya Eye Clinic, Nagoya, Aichi, Japan. DESIGN: Retrospective observational study. METHODS: Patients who underwent TICL surgery from 2005 to 2009 to correct myopia and myopic astigmatism were enrolled. The safety, efficacy, predictability, astigmatism correction efficacy, and complications were evaluated using preoperative, 1-year postoperative, and final examination data. RESULTS: 133 eyes of 77 patients were included. At the final visit, the mean uncorrected and corrected visual acuities were -0.01 ± 0.2 and -0.17 ± 0.05, respectively. The mean safety and efficacy indices were 0.91 ± 0.26 and 0.68 ± 0.21, respectively. The manifest astigmatism was -0.45 ± 0.43 diopters (D). The mean corneal astigmatism change from 1 year postoperatively to the final visit was 0.40 ± 0.26 D. Of the 38 eyes with a change in corneal astigmatism ≥0.5 D, 30 eyes (78.9%) changed to against-the-rule (ATR) astigmatism, 1 (2.6%) changed to oblique astigmatism, and 7 (18.4%) changed to with-the-rule (WTR) astigmatism. The mean manifest astigmatism change from 1 year postoperatively to the final visit was 0.43 ± 0.52 D. Of the 60 eyes with a change in manifest astigmatism ≥0.5 D, 25 (41.7%) changed to ATR astigmatism, 18 (30.0%) changed to oblique astigmatism, and 17 (28.3%) changed to WTR astigmatism. During follow-up, 8 (6.0%) of 133 eyes developed anterior subcapsular cataracts, among which 4 (3.0%) underwent TICL removal and phacoemulsification and aspiration. No vision-threatening complications occurred. CONCLUSIONS: TICL surgery showed good long-term astigmatism-correcting effects, although the long-term uncorrected visual acuity decreased. The procedure was effective in correcting myopia and astigmatism.

Flexural and Cell Adhesion Characteristic of Phakic Implantable Lenses.

Background and Objectives: In this study, we aimed to compare the physical properties of hole-implantable collamer lenses (H-ICLs) and implantable phakic contact lenses (IPCLs) and investigate their flexural and cell adhesion characteristics. Materials and Methods: Transverse compression load to achieve lens flexion and static Young's modulus were measured in H-ICLs and IPCLs using designated equipment. Load was measured both with and without restraining the optic section of the lenses. Adhesion of iHLEC-NY2 cells to the lens surfaces was examined using phase-contrast microscopy, and cell proliferation activity was evaluated using WST-8 assay. Results: The H-ICL showed a greater tendency for transverse compression load compared to IPCL, while the IPCL showed a higher Young's modulus with respect to the force exerted on the center of the anterior surface of the optic section. The joint between the optic section and haptic support in the IPCL was found to mitigate the effects of transverse compression load. Both lens types showed minimal cell adhesion. Conclusions: Our findings indicate that H-ICLs and IPCLs exhibit distinct physical properties and adhesive characteristics. The IPCL demonstrated higher Young's modulus and unique structural features, while the H-ICL required greater transverse compression load to achieve the flexion required to tuck the haptic supports into place behind the iris to fix the lens. The observed cell non-adhesive properties for both lens types are promising in terms of reducing complications related to cell adhesion. However, further investigation and long-term observation of IPCL are warranted to assess its stability and potential impact on the iris. These findings contribute to a better understanding of the performance and potential applications of H-ICLs and IPCLs in ophthalmology.

Age-related changes of color visual acuity in normal eyes.

PURPOSE: To evaluate the age-related change in color visual acuity (CVA) in normal eyes. METHODS: In total, 162 normal eyes (162 subjects, women: 52, men: 110, age range: 15-68 years) with best-corrected visual acuity (BCVA) ≥20/13 were enrolled. Fifteen colors from the New Color Test (chroma 6) were applied to Landolt "C" rings, white point D65 was applied as background, and a luminance of 30 cd/m2 was set for both the rings and the background. These rings were used to measure the chromatic spatial discrimination acuity as the CVA value, while changing the stimulus size. Correlations of the CVA value of each color and age were evaluated. Mean CVA values of all 15 colors (logarithm of the minimum angle of resolution) were compared between age groups in 10-year increments. RESULTS: Nine CVA values (red, yellow-red, red-yellow, green, blue-green, green-blue, purple, red-purple, and purple-red) were negatively correlated with age (all p<0.05); the remaining six (yellow, green-yellow, yellow-green, blue, purple-blue, and blue-purple), as well as BCVA were not. The age groups with the best to worst mean CVA values of 15 colors were as follows: 20-29 (mean ± standard deviation, 0.303 ± 0.113), 30-39 (0.324 ± 0.096), 10-19 (0.333 ± 0.022), 50-59 (0.335 ± 0.078), 40-49 (0.339 ± 0.096), and 60-69 (0.379 ± 0.125) years. There were statistically significant differences between mean CVA values of the following groups: 20-29 and 40-49 years; 20-29 and 60-69 years; 30-39 and 60-69 years (all p<0.01). CONCLUSIONS: The CVA values related to the medium/long-wavelength-sensitive cones were more susceptible to aging than those related to the short-wavelength-sensitive cones. This differed from previous reports, and may be related to the difference in the range of foveal cone function evaluated with each examination.

Control-matched comparison of refractive and visual outcomes between small incision lenticule extraction and femtosecond laser-assisted LASIK.

PURPOSE: This retrospective case-matched study aimed to compare visual and refractive outcomes between small incision lenticule extraction (SMILE) and LASIK. PATIENTS AND METHODS: Patients who underwent SMILE (34 eyes of 23 patients) or LASIK (34 eyes of 24 patients) were enrolled and matched according to preoperative manifest refractive spherical equivalents. The mean preoperative manifest refractive spherical equivalent was -4.69±0.6 and -4.67±0.64 D in the SMILE and LASIK groups, respectively. The safety, efficacy, and predictability were compared 3 months after surgery. Changes in corneal refractive power from the center to peripheral points and their maintenance ratios were analyzed and compared between the two groups. RESULTS: In the SMILE and LASIK groups, 82.4% and 85.3% of patients, respectively, achieved 20/13 or better uncorrected distance visual acuity (p=1.00). There were no eyes that lost two or more lines of corrected distance visual acuity in either group. The maintenance ratios of corneal refractive power changes at the peripheral points in the SMILE group were significantly higher than those in the LASIK group (p<0.05). CONCLUSION: Both groups achieved similar high efficacy and safety. SMILE surgery resulted in higher refractive power correction in the peripheral cornea than LASIK surgery.

New surgical approach for intrascleral fixation using an intraocular lens with hook-shaped haptics.

We report a new surgical technique of intrascleral posterior chamber intraocular lens (PC IOL) fixation using a newly developed hook-shaped haptic IOL (NX-70CH) and a 25-gauge loop-shaped haptic manipulator. Previous techniques of intrascleral PC IOL fixation had 2 major technical challenges; that is, externalization of the haptic and fixation of the haptic into the scleral tunnel. The new IOL and manipulator can facilitate externalization and secure fixation of the IOL haptic and can be used for suture fixation or implantation in the capsular bag in cases with presumed subluxated lens.

Clinical and ex vivo laboratory comparison of the self-sealing properties and dimensional stability between the femtosecond laser and manual clear corneal incisions.

PURPOSE: To compare the self-sealing features and dimensional stability between the femtosecond laser (FL) and manual knife corneal incision. METHODS: For the clinical study, 29 consecutive eyes from 29 patients and 28 eyes from 28 patients who underwent cataract surgery with FL corneal incision and manual knife incision, respectively, were enrolled. Immediately after cataract surgery, the self-sealing features of the corneal incisions were evaluated. Scanning electron microscopy (SEM) images were obtained. For the experimental study, clear corneal incisions with a knife or FL with different energy settings (3, 6 and 9 µJ) were created in fresh porcine eyes, followed by a stress test. The incision width was measured before and after the stress test. RESULTS: In the clinical study, the knife group had a higher self-sealing score (0.60 ± 0.49 points) than the FL group (0.17 ± 0.38 points). In the experimental study, the deformation rate in the knife incision (5.04 ± 1.93) was significantly lower than that in the FL with any energy. The deformation rate in the 9 µJ (12.98 ± 2.76) was significantly higher than in the 3 µJ (8.54 ± 2.38) and 6 µJ (8.82 ± 2.85) FL energies. Scanning electron microscopy (SEM) images revealed that the corneal stromal surface of the knife incision was smoother than that of the FL. Higher energy FL showed more irregular surfaces. CONCLUSION: Higher FL energy tended to widen a clear corneal incision when mechanical stress was applied. The histological differences at the inner tunnel surface may cause differences in wound stability of the corneal incision.

Effect of Background Luminance Level on the Assessment of Color Visual Acuity Using Colored Landolt Rings in Young Healthy Subjects.

PURPOSE: To evaluate the color visual acuity (CVA) of young healthy subjects using colored Landolt rings and the effect of background luminance level on the CVA. MATERIALS AND METHODS: We measured the CVA of 20 young healthy subjects (age: 23.8 ± 3.8 years) with different colors using a computer and a liquid crystal display, with 15 Landolt ring colors (30 cd/m2) with a background luminance of 30 cd/m2, and then 100 cd/m2. We then used different background luminance levels (15-50 cd/m2) using four Landolt ring colors (red, green-yellow, green, and blue-green) to evaluate the effect of the background luminance level on CVA. RESULTS: The CVA significantly differed among the colors with a background luminance of 30 cd/m2 (p < 0.0001). Green-yellow and blue-purple had poor CVA (high LogMAR value; 0.808 ± 0.107 and 0.633 ± 0.150, respectively) with a background luminance of 30 cd/m2 (same luminance as the Landolt rings). There were no significant differences in the CVAs among the colors with a background luminance of 100 cd/m2 (p = 0.5999). There were no significant difference in the CVA between background luminance 30 cd/m2 and other luminance level ranging from 28 to 32 cd/m2 for colors of red, green-yellow, green, and blue-green. CONCLUSIONS: The results reveal that the background luminance of Landolt rings affects the CVA. Distinctive CVAs for each color are measured by equalizing the luminance between the Landolt ring and the background. We consider that the poor CVAs of these colors reflect the visual function of S-cone, because GY and BP are included in the confusion locus of tritan axis on the chromaticity diagram. We believe that CVA assessment may be useful for individuals who have known or suspected ocular dysfunction or color vision deficiencies.

Comparison of Maximum Stretch Forces between Femtosecond Laser-Assisted Capsulotomy and Continuous Curvilinear Capsulorhexis.

The current study reports comparing the postoperative mechanical properties of the anterior capsule between femtosecond laser capsulotomy (FLC) and continuous curvilinear capsulorhexis (CCC) of variable size and shape in porcine eyes. All CCCs were created using capsule forceps. Irregular or eccentric CCCs were also created to simulate real cataract surgery. For FLC, capsulotomies 5.3 mm in diameter were created using the LenSx® (Alcon) platform. Fresh porcine eyes were used in all experiments. The edges of the capsule openings were pulled at a constant speed using two L-shaped jigs. Stretch force and distance were recorded over time, and the maximum values in this regard were defined as those that were recorded when the capsule broke. There was no difference in maximum stretch force between CCC and FLC. There were no differences in circularity between FLC and same-sized CCC. However, same-sized CCC did show significantly higher maximum stretch forces than FLC. Teardrop-shaped CCC showed lower maximum stretch forces than same-sized CCC and FLC. Heart-shaped CCC showed lower maximum stretch forces than same-sized CCC. Conclusively, while capsule edge strength after CCC varied depending on size or irregularities, FLC had the advantage of stable maximum stretch forces.

Factors affecting rotation of a posterior chamber collagen copolymer toric phakic intraocular lens.

PURPOSE: To evaluate the correlation between postoperative rotation of the toric Implantable Collamer Lens phakic intraocular lens (pIOL) and associated factors. SETTING: Nagoya Eye Clinic, Nagoya, Japan. DESIGN: Case series. METHODS: The toric pIOL axis was analyzed by calculating the ocular internal cylinder power and axis from the total refractive cylinder and corneal astigmatism using vector analysis (Jaffe and Clayman method). The correlation between the toric pIOL rotation over 6 months postoperatively and the associated factors (ie, age, preoperative manifest refractive sphere, preoperative manifest spherical equivalent, mean keratometric power, axial length, toric pIOL intraoperative fixation angle, postoperative toric pIOL vault [distance between toric pIOL and anterior surface of crystalline lens], toric pIOL spherical power) were evaluated. RESULTS: The mean age of the 34 patients (58 eyes) was 35.7 years ± 6.5 (SD). The mean rotation 6 months postoperatively was 4.82 ± 6.98 degrees (range 0.0 to 47.2 degrees). The intraoperative toric pIOL fixation angle and postoperative toric pIOL rotation were significantly correlated (Spearman rank correlation: P=.0096 and R(2) = 0.1140; multiple logistic regression analysis: P=.009). In the 1 eye with significant rotation (47.2 degrees), the toric pIOL was exchanged for a larger toric pIOL. CONCLUSIONS: A small toric pIOL rotation occurred during the 6-month follow-up. One cause of rotation could be the intraoperative fixation angle of the toric pIOL. A toric pIOL with a minimum intraoperative fixation angle should be used to prevent postoperative rotation.

Optimization of an implantable collamer lens sizing method using high-frequency ultrasound biomicroscopy.

PURPOSE: To develop and evaluate a new implantable collamer lens (ICL) sizing method that uses high-frequency ultrasound biomicroscopy (UBM). DESIGN: Interventional case series. METHODS: ICL were implanted in 47 eyes of 25 patients (8 male, 17 female, mean age 34.7±6.8 years). At 3 months after ICL surgery, the vault (distance between ICL and crystalline lens) was measured using anterior optical coherence tomography (OCT). Stepwise multiple regression analysis was performed in order to determine the optimal ICL size that will be expected to achieve a 0.5-mm vault, and the regression equation was calculated. Mean keratometric power, axial length, anterior chamber depth, sulcus-to-sulcus (STS) diameter, and distance between STS plane and crystalline lens were applied as candidates for explanatory variables. Subsequently, the equation was applied to a new group of patients (81 eyes of 43 patients, 20 male and 23 female, mean age 35.6±7.2 years) in order to decide the ICL size. Postoperative vault was evaluated at 3 months after surgery. Main outcome measures were mean postoperative vault and percentages of eyes that achieved moderate vault. RESULTS: The regression equation was determined using 3 explanatory variables: anterior chamber depth (ACD), STS diameter, and distance between STS plane and anterior crystalline lens surface (STSL). The mean vault error (postoperative vault-predicted vault) was -0.06±0.29 mm. Of the total number of eyes, 88.9% had a vault between 0.15 and 1.0 mm. None of the eyes had a low vault (<0.15 mm). Nine eyes (11.1%) had a high vault (>1.0 mm). CONCLUSION: A novel ICL sizing equation was developed and shown to be an effective method for calculation of the optimal ICL size in order to achieve an appropriate vault.

Repeatability of the ciliary sulcus-to-sulcus diameter measurement using wide-scanning-field ultrasound biomicroscopy.

PURPOSE: To evaluate the interexaminer and intraexaminer variance in ciliary sulcus-to-sulcus (STS) diameter measurements using wide-scanning-field ultrasound biomicroscopy (UBM) (Vumax II). SETTING: Nagoya Eye Clinic, Nagoya, Japan. DESIGN: Evaluation of diagnostic test or technology. METHOD: Two examiners measured the STS diameter 10 times in each subject. Intraexaminer and interexaminer variances were calculated. To determine interexaminer variance at each UBM measurement step, the examiner was changed every 2 steps when the STS diameter was measured. The Bland-Altman plot test was used to analyze each step of measurement variance. RESULTS: Thirty eyes of 15 volunteers (9 men, 6 women; mean age 29.6 years ± 6.2 [SD]) were enrolled. The mean coefficient of variation was 0.62% ± 0.20% for intraexaminer measurements and 3.4% ± 2.4% for interexaminer measurements. There were statistically significant differences between the 2 examiners in the step of extracting images and determining and measuring the STS diameter (P=.02). The 95% confidence intervals in all steps were relatively high (recordings, -1.02 to 1.08 mm; extracting images and determining and measuring STS; -0.79 to 1.25 mm). CONCLUSION: Interexaminer variance in STS measurement should be considered if the STS diameter is used for selecting the size of posterior chamber phakic intraocular lenses.

Quantitative evaluation of night vision and correlation of refractive and topographical parameters with glare after orthokeratology.

PURPOSE: To evaluate night vision disturbance and investigate correlations between pre- and post-treatment parameters and glare scores in orthokeratology patients. METHODS: Twenty-eight right eyes of 28 patients were enrolled in this study. Corneal topography and a night vision test (NVT) to evaluate the extent of glare were performed after orthokeratology. From the corneal topography, two indices [surface regularity index (SRI) and surface asymmetry index (SAI)] were calculated. Fourier analysis was performed on the topographic data from the central 6 mm, and data were decomposed into asymmetric and higher order components for analysis. RESULTS: There was no correlation between the glare score and pre-treatment keratometric value, pre-treatment cylinder, post-treatment sphere, and post-treatment cylinder. However, there was a statistically significant correlation between pre-treatment sphere and glare score (Pearson correlation coefficient, r = -0.54, p < 0.01). SRI and SAI significantly correlated with glare score (SRI: r = 0.52, p < 0.01, SAI: r = 0.41, p < 0.05). Higher order and asymmetric components were also significantly correlated with glare score (asymmetry: r = 0.61, p < 0.01, higher order: r = 0.67, p < 0.001). CONCLUSIONS: The glare score was significantly correlated with corneal irregularity, and appeared to be a beneficial parameter for assessment of night vision performance in patients receiving orthokeratology.

Correction of residual refractive error in pseudophakic eyes with the use of a secondary piggyback toricImplantable Collamer Lens.

PURPOSE: To evaluate the feasibility of piggyback insertion with a toric Implantable Collamer Lens (ICL, STAAR Surgical). METHODS: This study investigated eight pseudophakic eyes of five patients who underwent piggyback insertion of a toric ICL to correct residual refractive error. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and manifest refractive sphere and astigmatism were measured before and 6 months after surgery. RESULTS: Pre- and 6-month postoperative logMAR UDVA were 0.759±0.430 and 0.201±0.458, respectively. All eyes were corrected within ±0.50 diopters (D) of intended spherical equivalent refraction. The manifest refractive astigmatism was within ±0.50 D in five (62.5%) eyes and ±1.00 D in seven (87.5%) eyes. No eyes lost more than one line of CDVA. Pupillary block occurred in one eye on postoperative day 1. CONCLUSIONS: Piggyback insertion of a toric ICL appears to be effective and predictable in correcting refractive error in pseudophakic eyes.