Accuracy of the Majority Voting Method with Multiple IOL Power Formulae.

Purpose: This study aimed to evaluate the efficacy of a majority decision algorithm that integrates intraoperative aberrometry (IA) and two intraocular lens (IOL) frequency formulas. The primary objective was to compare the accuracy of three formulas (IA; Sanders, Retzlaff, and Kraff/Theoretical (SRK/T); and Barrett Universal II (BUII)), in achieving emmetropia in eyes implanted with TFNT lenses (Alcon). Patients and Methods: A total of 145 eyes of 145 patients were included in the evaluation. Preoperative data were obtained from IOLMaster 700, while intraoperative data were collected from ORA SYSTEMTM. Visual acuity ≥0.8 at the 3-month post-surgery mark was confirmed. We assessed refractive prediction error (RPE), which is the difference between predicted refraction (PR) and postoperative subjective refraction. This evaluation aimed to identify the optimal IOL power with the implemented algorithm. Results: Among the 145 eyes evaluated, 55.9%, 78.7%, and 97.2% achieved postoperative subjective refraction within ±0.13 Diopters (D), ±0.25 D, and ±0.50 D, respectively. The percentages of eyes within ±0.25 D of PR varied by formula type, with values of 57%, 57%, and 54% for IA, BUII, and SRK/T, respectively. For eyes with short to medium axial length (AL<26.00 mm), the percentages within ±0.25 D of RPE were 52%, 58%, and 58% for IA, SRK/T, and BUII, respectively. In contrast, for eyes with long axial length (≥26.00 mm) the percentages were 68%, 52%, and 45% for IA, BUII, and SRK/T, respectively. Conclusion: The proposed majority decision algorithm incorporating IA and two IOL frequency formulas was effective in reducing postoperative refractive error. IA was particularly beneficial for eyes with long axial length. These findings suggest the algorithm has potential to optimize IOL power selection to improve quality of life of patients and clinical practice outcomes.

Accuracy of new intraocular lens power calculation formula for short and long eyes using segmental refractive indices.

PURPOSE: To evaluate the accuracy of a new intraocular lens power calculation formula using segmental refractive index-based axial length (AL). SETTING: Chukyo Eye Clinic, Nagoya, Japan. DESIGN: Retrospective observational study. METHODS: This study included patients undergoing preoperative examination for cataract surgery with the new Barrett True AL (BTAL) and Emmetropia Verifying Optical (EVO) formulas using segmental refractive index, and conventional Barrett Universal II (BU II) formula using equivalent refractive index. The predicted refractive error of each formula was compared with the postoperative subjective spherical equivalent. RESULTS: The mean prediction error (MPE) in the short AL group (≤ 22 mm; 44 eyes) was 0.32 ± 0.40 D for BU II, 0.22 ± 0.37 D for BTAL, and 0.10 ± 0.37 D for EVO (P < 0.0001). MPE in the long AL group (≥ 26 mm; 92 eyes) was 0.01 ± 0.32 D for BU II, 0.04 ± 0.32 D for BTAL, and 0.09 ± 0.32 D for EVO (P < 0.0001). In patients with an AL ≥ 28 mm, BU II showed a myopic trend in 57.1% of cases, while BTAL and EVO showed a hyperopic trend in 71.4%. The MPE for patients with an AL ≥ 28 mm was -0.16 ± 0.34 D for BU II, 0.18 ± 0.33 D for BTAL, and 0.16 ± 0.32 D for EVO (P < 0.0001). CONCLUSIONS: The new EVO and BTAL formulas showed higher accuracy than BU II in short eyes, whereas there was no difference in long eyes.

Refractive prediction error in cataract surgery using an optical biometer equipped with anterior segment OCT.

PURPOSE: To evaluate refractive error after cataract surgery using an optical biometer equipped with anterior segment optical coherence tomography (AS-OCT). SETTING: Chukyo Eye Clinic, Nagoya, Japan. DESIGN: Retrospective observational design. METHODS: In total, 150 patients with cataract (150 eyes, mean age 73.4 ± 8.2 years, men 76, women 74), who underwent measurement of parameters with the AS-OCT scanners ANTERION (AS-OCTB) and IOLMaster 700 (OCTB) before cataract surgery, were enrolled in the study. Refractive prediction error was compared between the 2 devices using the SRK/T, Haigis, and Barrett Universal II (UII) formulas for intraocular lens (IOL) power calculation. RESULTS: There were significant differences between AS-OCTB and OCTB in axial length, mean corneal refractive power, anterior chamber depth, lens thickness, and corneal diameter (n = 150). In the SRK/T formula, the arithmetic means of refractive prediction errors for AS-OCTB and OCTB were -0.06 ± 0.46 diopters (D) and 0.02 ± 0.42 D, respectively. In the Haigis formula, the arithmetic means of refractive prediction errors for AS-OCTB and OCTB were -0.23 ± 0.40 D and -0.08 ± 0.35 D, respectively. In the Barrett UII formula, the arithmetic means of refractive prediction errors for AS-OCTB and OCTB were -0.02 ± 0.38 D and 0.11 ± 0.36 D, respectively. AS-OCTB showed significantly larger refractive prediction error toward myopia than OCTB in all 3 formulas (P < .0001). CONCLUSIONS: The refractive prediction error using AS-OCTB showed a small difference from that using OCTB. While clinically comparable, the 2 methods could drive meaningful differences in IOL selection.

Evaluation of Axial Length Measurement Using Enhanced Retina Visualization Mode of the Swept-Source Optical Coherence Tomography Biometer in Dense Cataract.

INTRODUCTION: It has been reported that even using the swept-source (SS) optical coherence biometer, it is challenging to measure the axial length (AL) in cases with advanced cataracts. The enhanced retina visualization (ERV) mode, which is equipped with OCTB1 (ARGOS), shifts the peak of measurement sensitivity to the retinal side so that the AL can be measured even if the light energy is attenuated. The aim of the present study was to evaluate the accuracy and efficacy of the ERV mode in measuring the AL of dense cataracts. METHODS: This was a single-center retrospective observational case series conducted in Japan. We included 213 eyes of 213 consecutive patients with advanced cataracts who underwent preoperative evaluation. The AL was measured before and after surgery using two SS optical coherence tomography biometers (OCTB1 and OCTB2; IOLMaster 700). Cases in which OCTB1 the standard mode failed to measure AL, OCTB1 with the ERV mode was used instead. Primary outcome measures were the acquisition rate and the AL measurement accuracy using the ERV mode. The χ2 test, the Kruskal-Wallis test, and the Wilcoxon signed-rank test were used to compare the acquisition rate and differences between pre- and postoperative AL values, respectively. In the ERV subgroup, Bland-Altman plots were used to compare the pre- and postoperative AL values measured using OCTB1-ERV mode. A p-value of less than 5% was considered statistically significant. RESULTS: The AL acquisition rate was not significantly different between OCTB1 with the standard mode and OCTB2. The AL of 65 eyes (30.5%) could not be measured using OCTB1 with the standard mode. Conversely, the AL of 51 of these eyes (78.5%) was successfully measured using OCTB1 with the ERV mode. In these 51 eyes, a difference of ≤0.2 mm and of ≤0.1 mm between pre- and postoperative AL measurements was observed in 40 (78.4%) and 30 eyes (58.8%), respectively. The Bland-Altman plot found no systematic error between pre- and postoperative AL values measured using the ERV mode. CONCLUSION: In patients with dense cataracts, AL measurement using the standard mode of an SS-OCT biometer is challenging. Furthermore, the ERV mode could be promising for AL measurement in such cases.

Comparison of Clinical Outcomes Between Intracapsular Implantation and Intrascleral Fixation Using the Same Model of Intraocular Lens.

PURPOSE: To compare the clinical outcomes of intrascleral intraocular lens (IOL) fixation surgery with those of intracapsular IOL implantation in conventional cataract surgery. PATIENTS AND METHODS: Twenty-one eyes of 21 consecutive patients who underwent intrascleral IOL fixation (SF group) and 21 eyes of 21 patients who underwent IOL intracapsular implantation during cataract surgery (IN group) were retrospectively enrolled. For both groups, the same model of IOL was used in all cases. For all cases in the SF group, Yamane's double-needle technique was performed. RESULTS: The mean corrected visual acuity (logMAR) after surgery was significantly better in the IN than in the SF group (-0.063 ± 0.12 vs 0.05 ± 0.14; p = 0.0083). The mean anterior chamber depth after surgery was significantly smaller in the IN than in the SF group (4.65 ± 0.23 mm vs 4.98 ± 0.61 mm; p = 0.0231). The amounts of tilt and decentration were also significantly smaller in the IN group (5.21°± 1.47° and 0.22 ± 0.13 mm, respectively, vs 8.8° ± 3.9° and 0.52 ± 0.35 mm, respectively; p = 0.0003 and p = 0.0007). The mean absolute refractive prediction error was significantly smaller in the IN than in the SF group (0.22 ± 0.17 D vs 0.86 ± 0.59 D; p = 0.0002). CONCLUSION: The intrascleral IOL fixation surgery proved to be highly effective. However, its clinical outcomes were slightly inferior to those of IOL intracapsular implantation, and further improvement of this surgical technique may be needed.

Keratoconus Screening Using Values Derived From Auto-Keratometer Measurements: A Multicenter Study.

PURPOSE: Screening of early-stage keratoconus using auto-keratometer parameters. DESIGN: Evaluation of a screening approach. METHODS: At 5 major centers in Japan, we enrolled 123 eyes of 123 patients with Amsler-Krumeich classification stage 1 (<50 years of age [average 26.36 ± 8.68 years]; 84/39 male/female) and 205 eyes of 205 healthy subjects (average age 26.20 ± 7.34 years, 139/66 male/female). Participants were divided 2:1 into a prediction group and an application group. In the prediction group, multivariate logistic regression analysis was performed with keratoconus diagnosis as the dependent variable, and auto-keratometer parameters including average K, steep K, flat K, astigmatism, and astigmatic axis (no, with-the-rule, against-the-rule, and oblique) as independent variables. The diagnostic probability determined by regression analysis was defined as the keratometer keratoconus index. The cutoff value was determined from the receiver operating characteristic curve. This prediction equation was evaluated in the application group. Our primary outcome measure was the accuracy of the prediction equation for discriminating keratoconus from normal eyes. RESULTS: The selected explanatory variables were steep K (partial regression coefficient [ß] 1.284, odds ratio [OR] 3.610), flat K (ß -0.618, OR 0.539), and with-the-rule astigmatism (ß -3.163, OR 0.042). The area under the receiver operating characteristic curve of keratometer keratoconus index was 0.90, which was significantly better than individual parameters (P < .001). The sensitivity and specificity values in the application group were 85.0% and 86.7%, respectively. CONCLUSIONS: Although the sensitivity/specificity was not high, the new prediction equation using auto-keratometer-derived parameters enabled better discrimination of early-stage keratoconus than the isolated parameters.

Prediction of Best-Corrected Visual Acuity With Swept-Source Optical Coherence Tomography Parameters in Keratoconus.

PURPOSE: This study aimed to predict the best-corrected visual acuity (BCVA) based on swept-source optical coherence tomography (SS-OCT) parameters in eyes with keratoconus. METHODS: We retrospectively reviewed 135 eyes of 135 patients with keratoconus (mean age: 31.9 ± 12.4 years). The average keratometry value and BCVA (logarithm of the minimal angle of resolution [Snellen]) were 48.68 ± 5.44 diopter and 0.20 ± 0.36 (20/25), respectively. Eleven parameters were calculated using SS-OCT. Apart from the corneal height and elevation, all the other parameters were calculated from both anterior and posterior corneal OCT data. The patients were divided into 2 groups, 1 for creating the prediction equation (prediction group, 86 eyes) and another for verifying the equation (verification group, 49 eyes). In the former, individual correlations between the BCVA and SS-OCT parameters were analyzed. A stepwise multiple regression analysis was performed with the BCVA as a dependent variable and SS-OCT parameters as independent variables. After its creation, the accuracy of the prediction equation was verified in the verification group. RESULTS: All the parameters, except for age and total corneal cylinder, showed statistically significant correlations with BCVA (P < 0.0001). Using the stepwise multiple regression analysis, we selected 2 explanatory variables: root mean square of anterior corneal elevation (standardized regression coefficient: 1.221; P < 0.0001) and total coma aberration (standardized regression coefficient: -0.575; P = 0.001; adjusted R = 0.546). The prediction was correct in 84.6% of the eyes within ±1 line of Snellen BCVA. CONCLUSIONS: Using the equation we derived from SS-OCT parameters is a promising method to predict visual function in patients with keratoconus.

Prediction of Effective Lens Position Using Multiobjective Evolutionary Algorithm.

PURPOSE: The purpose of this study was to evaluate the prediction accuracy of effective lens position (ELP) after cataract surgery using a multiobjective evolutionary algorithm (MOEA). METHODS: Ninety-six eyes of 96 consecutive patients (aged 73.9 ± 8.6 years) who underwent cataract surgery were retrospectively studied; the eyes were randomly distributed to a prediction group (55 eyes) and a verification group (41 eyes). The procedure was repeated randomly 30 times to create 30 data sets for both groups. In the prediction group, based on the parameters of preoperative optical coherence tomography (OCT), biometry, and anterior segment (AS)-OCT, the prediction equation of ELP was created using MOEA and stepwise multiple regression analysis (SMR). Subsequently, the prediction accuracy of ELPs was evaluated and compared with conventional formulas, including SRK/T and the Haigis formula. RESULTS: The rate of mean absolute prediction error of 0.3 mm or higher was significantly lower in MOEA (mean 4.9% ± 3.2%, maximum 9.8%) than SMR (mean 7.3% ± 4.8%, maximum 24.4%) (P = 0.0323). The median of the correlation coefficient (R 2 = 0.771) between the MOEA predicted and measured ELP was higher than the SRK/T (R 2 = 0.412) and Haigis (R 2 = 0.438) formulas. CONCLUSIONS: The study demonstrated that ELP prediction by MOEA was more accurate and was a method of less fluctuation than that of SMR and conventional formulas. TRANSLATIONAL RELEVANCE: MOEA is a promising method for solving clinical problems such as prediction of ocular biometry values by simultaneously optimizing several conditions for subjects affected by various complex factors.

Clinical Evaluation of a New Swept-Source Optical Coherence Biometer That Uses Individual Refractive Indices to Measure Axial Length in Cataract Patients.

BACKGROUNDS: Although the OCT biometer using individual refractive index is available, comparisons of measurement value and intraocular lens (IOL) power calculation error with other SS-OCT biometers are not known. OBJECTIVES: To compare the new SS-OCT biometer ARGOS (OCTB1), which uses individual refractive indices to measure axial length, with the IOLMaster 700 (OCTB2) and OA-2000 (OLCR), which use equivalent refractive index. METHOD: Six hundred and twenty-two eyes of 622 patients who had been diagnosed with cataract were enrolled in the study. Among the 158 eyes that had undergone cataract surgery, the postoperative refractive error was evaluated using the Haigis formula. RESULTS: The axial length measured by the OCTB1 showed a proportional bias in comparison with the other two biometers and a fixed bias in eyes with an axial length ≥26 mm. No significant difference was found in the median absolute refractive prediction error (p = 0.3278). However, in eyes with an axial length ≥26 mm, the OCTB1 showed myopic error compared with the other two biometers (p < 0.0001). CONCLUSIONS: In eyes with long axial length, when the conventional IOL calculation was optimized with the equivalent refractive index-based instrument, we need to consider that IOL calculation using OCTB1 tends to cause slightly myopic refractive prediction error.

Impact of the anterior-posterior corneal radius ratio on intraocular lens power calculation errors.

PURPOSE: To evaluate the distribution of the anterior-posterior corneal radius ratio (AP ratio; anterior corneal radius/posterior corneal radius) in patients before cataract surgery, and investigate which parameters can affect this ratio. We also investigated the impact of the AP ratio on the intraocular lens (IOL) power calculation error in cataract surgery. METHOD: A total of 501 eyes of 501 consecutive patients who had no history of corneal diseases and had undergone cataract surgery were enrolled in this study. The patients' AP ratio was measured before surgery using anterior segment optical coherence tomography; using these data, we evaluated the correlation between the AP ratio and various parameters that can affect the corneal radius. For subgroup analyses, we investigated the correlation between the AP ratio and IOL power calculation error in 181 eyes of 181 patients. Stepwise multiple regression analysis was performed with the IOL power calculation errors of the SRK/T, Haigis, Holladay 1, and Hoffer Q formulas as the dependent variables and various parameters that can affect the postoperative IOL power calculation error as the independent variables. RESULTS: The mean AP ratio was 1.19±0.02, and it weakly correlated with corneal thickness, horizontal corneal diameter, and posterior corneal radius. The correlations between the AP ratio and IOL power calculation errors in the 4 calculation formulas were not statistically significant. Stepwise multiple regression analysis could not detect any significant parameters affecting this ratio. CONCLUSION: The AP ratio has no major influence on IOL power calculation error in patients with any history of corneal disease.

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.

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.

Intraocular lens power calculation in cases with posterior keratoconus.

PURPOSE: To compare the calculation errors of intraocular lens (IOL) power in patients with posterior keratoconus and to determine which corneal refractive power is suitable for these calculations. SETTING: Chukyo Hospital, Nagoya, Japan. DESIGN: Retrospective case series. METHODS: This retrospective chart review was performed to identify eyes diagnosed with posterior keratoconus using anterior segment optical coherence tomography (AS-OCT). The keratometry (K) values were measured using an autokeratometer and partial coherence interferometry (PCI) (IOLMaster). The AS-OCT measured the total refractive corneal power and the anterior to posterior corneal curvature (A/P) ratio. Predicted refractive errors were calculated from K values based on the postoperative subjective refractive errors. RESULTS: The chart review of 4621 eyes found that 4 eyes of 4 patients (mean age 74.8 years ± 13.0 [SD]) were diagnosed with posterior keratoconus. The total refractive corneal power values were the smallest among all of the corneal refractive powers in all 4 eyes. The preoperative A/P ratio was 1.45 (Case 1), 1.26 (Case 2), 1.25 (Case 3), and 1.44 (Case 4). When the PCI measured K values were applied for the IOL power calculations, all of the eyes became hyperopic with postoperative refractive errors of +1.51 diopters (D) (Case 1), +0.34 D (Case 2), +0.97 D (Case 3), and +1.08 D (Case 4). When the total refractive corneal power values were applied, the errors were +0.10 D (Case 1), -0.18 D (Case 2), -0.61 D (Case 3), and -0.65 D (Case 4). CONCLUSION: The real corneal power values that take both the anterior and posterior corneal curvatures into consideration should be applied for IOL power calculations in cases with posterior keratoconus. FINANCIAL DISCLOSURE: No author has a financial or proprietary interest in any material or method mentioned.

Astigmatism correction: Laser in situ keratomileusis versus posterior chamber collagen copolymer toric phakic intraocular lens implantation.

PURPOSE: To compare the stability and predictability of astigmatism correction between toric phakic intraocular lens (pIOL) implantation and laser in situ keratomileusis (LASIK). SETTING: Nagoya Eye Clinic, Nagoya, Japan. DESIGN: Comparative case series. METHODS: Consecutive patients who had Implantable Collamer Lens pIOL implantation or LASIK were divided into 3 subgroups according to the amount of refractive cylinder correction (low, 0.00 to 1.25 diopters [D]; moderate, 1.50 to 2.75 D; high, ≥ 3.00 D). Manifest refraction was measured preoperatively and 1, 3, 6, and 12 months postoperatively. Based on these data, the predictability and stability of the refractive cylinder correction, error of the refractive cylinder correction, and error of the refractive cylinder correction axis were evaluated. RESULTS: The study comprised 338 eyes (196 patients) in the toric pIOL group and 351 eyes (202 patients) in the LASIK group. In the moderate cylinder subgroup, more eyes were corrected within ± 0.50 D of the postoperative refractive cylinder in the LASIK group (132 eyes [91%]) than in the toric pIOL group (111 eyes [79%]). In the high refractive cylinder subgroup, the error of the refractive cylinder correction in the LASIK group was significantly higher than in the toric pIOL group (P=.032). The postoperative manifest refractive cylinder did not change in either group during the follow-up period. CONCLUSIONS: The stability of the refractive cylinder after toric pIOL implantation was as high as after LASIK. Although predictability in the LASIK group was higher than in the toric pIOL group in eyes with moderate refractive cylinder, the toric pIOL group had higher predictability than the LASIK group in eyes with high refractive cylinder.

Evaluation of axial length measurement of the eye using partial coherence interferometry and ultrasound in cases of macular disease.

PURPOSE: The present study evaluated the accuracy of using partial coherence interferometry (PCI) and ultrasound (US) to measure axial length in eyes with macular disease, the nature of the double peak (DP) in PCI measurements, and the applicability of intraocular lens (IOL) power calculation. DESIGN: Retrospective noncomparative case series. PARTICIPANTS: We studied 132 eyes with macular edema, epiretinal membrane, and macular hole in 132 patients who underwent combined cataract and vitrectomy surgery. METHODS: Axial length was measured using PCI and US. If a DP was observed in the PCI measurement, the posterior peak was used for the IOL calculation. The central retinal thickness (CRT) was measured using optical coherence tomography. MAIN OUTCOME MEASURES: Measurements were made of the frequency of DP observation in PCI measurement and the postoperative refractive errors when either PCI or US measurements were applied. RESULTS: A DP was observed in 25 (18.7%) of 132 eyes in the axial length measurement using PCI. There was a significant correlation between the interpeak distance and the CRT (P<0.001, r(2)=0.3869). The 6-month postoperative refractive errors in the DP and single peak (SP) groups were predicted correctly within +/-0.5 diopters in 56.0% (DP) and 61.7% (SP) of the cases and within +/-1.0 diopters in 92.0% (DP) and 92.2% (SP) of the cases. The accuracy of the axial length measurement was similar between PCI and US. CONCLUSIONS: Our results suggest that the longer axial length of the DP observed in PCI represents retinal pigment epithelium. If a DP was observed in PCI measurement, application of the longer peak for the IOL calculation resulted in a refractive error similar to that in the SP group.