Intraocular Lens Power Calculation Research Articles

Advanced Artificial-Intelligence-Based Jiang Formula for Intraocular Lens Power in Congenital Ectopia Lentis.

The purpose of this study was to develop an artificial intelligence (AI)-based intraocular lens (IOLs) power calculation formula for improving the accuracy of IOLs power calculations in patients with congenital ectopia lentis (CEL). A total of 651 eyes with CEL that underwent IOLs implantation surgery were included in this study. An AI-based ensemble formula-the Jiang Formula, was developed using a training dataset of 520 eyes and evaluated on a testing dataset of 131 eyes. A five-fold cross-validation and a two-layer ensemble learning model were constructed. The formula was then tested in a test set and compared against five current classic formulas. The cohort included young patients (mean age = 14.38 ± 13.35 years). The Jiang Formula showed the lowest prediction error (PE; = 0.08 ± 1.01 diopters [D]), absolute error (AE; = 0.77 ± 0.65 D), median absolute error (MedAE; = 0.66 D), and root mean square error (RMSE; = 1.02 D) among six formulas (P < 0.001). Moreover, 68.00% of the eyes in the test set had AE within 1.0 D in the Jiang Formula. AI-integrated two-layer ensemble learning model demonstrates promising applications in IOLs power calculations for patients with CEL, not only providing higher predictive accuracy than current classic formulas but also accommodating extreme values and variations in surgical techniques. The Jiang Formula, an AI-integrated two-layer ensemble learning model, enhances IOLs power calculation accuracy in patients with CEL, ultimately improving surgical outcomes and supporting more effective, personalized treatment in this unique patient group.

The role of the epithelium in intraocular lens and corneal power calculation.

To investigate the influence of the corneal epithelium on corneal power, particularly in special cases such as post-refractive surgery and keratoconus. A retrospective observational study. Measurement data were obtained from a high-resolution anterior segment analyser (CSO MS-39). Corneal curvature and power data, as well as surface height data, were organised in a cylindrical coordinate system. Calculations considered one, two and three refractive surfaces, examining the role of epithelial thickness and stromal curvature. The effect of the epithelium on corneal power was minimal (<0.1 D) in normal corneas, but it was considerable in keratoconus and post-refractive surgery cases, with differences up to 0.9 D. The effect decreased for larger measurement zones. Incorporating epithelial thickness and stromal curvature into corneal power calculations is a crucial next step in accurate corneal power and intraocular lens calculation in eyes with previous refractive surgery or keratoconus. This study highlights the need for advanced diagnostic and calculation methods in complex cases.

Outcomes of Zero Power Intraocular Lenses: Insights into the Keratometric Index and Axial Length.

We analyzed intraocular lens (IOL) power calculation in a series of patients with a zero diopter power implant. The idea was to bypass the Estimated Lens Plane (ELP), an important variable in normal IOL calculation. Large multi-center group practice. Retrospective, observational study. A consecutive series of patients undergoing cataract surgery after optical biometry and implantation of a zero (0.0 D) power IOL were studied. Complete biometry was performed with an optical low coherence optical biometer. The predicted refraction was calculated with and without recalibrating the axial length (AL) using a Sum-Of-Segments (SOS) approach with the Hoffer Q, Holladay 1, SRK/T, Haigis, Barrett Universal II, and Olsen formulas. A ray tracing model to back-calculate the corneal power from the observed postoperative refraction and AL was also included. In 52 eyes of 52 patients, mean prediction errors for the Hoffer Q, Holladay 1, SRK/T, Haigis, Barrett Universal II, and the Olsen formulas were +1.48, +1.15, +0.91, +0.65, +0.15 and +0.11 D respectively using standard AL and after SOS correction of the AL the mean errors changed to +1.08, +0.75, +0.52, +0.26, -0.25, and -0.27 D respectively. The mean back-calculated corneal power was 1.25 D lower than the mean keratometer reading using the standard keratometric index of 1.3375 and corresponded to an effective index of 1.328. The hyperopic error commonly seen in highly myopic eyes with classical thin-lens formulas is only partly corrected by SOS recalibration of the AL. We suggest the source of the residual error is an incorrect keratometric index.

Accuracy of keratoconus-specific formulae compared to standard formulae for intraocular lens power calculation in patients with keratoconus.

To compare the accuracy of keratoconus-specific formulae for nontoric and toric intraocular lenses in eyes with keratoconus undergoing cataract surgery. Consecutive retrospective case series. Patients with keratoconus who underwent cataract surgery. A retrospective chart review was conducted on cataract surgeries performed by the Cornea Service in the Department of Ophthalmology and Visual Sciences of the University of British Columbia from 2000 to 2023. The Kane keratoconus, Kane, Barrett Universal 2, Barrett True K, SRK II, SRK/T, Hoffer Q, Holladay I, EVO, Hill RBF and Hoffer QST, and Pearl DGS formulae were calculated. The postoperative mean absolute error (MAE) and mean prediction error (MPE) were calculated for each formula. A total of 133 eyes from 88 patients were eligible for inclusion in the study, 113 from 74 patients received nontoric IOLs, and 20 from 14 patients received toric IOLs. Pearl DGS had the most myopic MPE of -0.51 ± 1.04, which was statistically significant (p < 0.001) compared to all other formulae. There were no statistically significant differences in the MPE and MAE of the Kane keratoconus, Kane, Barrett Universal 2, Barrett True K keratoconus-specific formula, SRK II, SRK/T, Hoffer Q, Holladay I, EVO, Hill RBF and Hoffer QST formulae (p > 0.05). There was no difference in IOL power estimation accuracy with keratoconus-specific formulae compared to conventional formulae for cataract surgery in KC patients. The IOL power estimation in KC remains significantly less accurate compared with non-KC patients.

Intraocular lens power calculation in cataract patients with keratoconus: Bayesian network meta-analysis.

To compare the accuracy of intraocular lens (IOL) power calculation formulas in cataract patients with keratoconus (KC). This study followed the Preferred Reporting Items for Systematic Reviews and Meta-analysis statementand and was registered on PROSPERO (CRD42024568997). Pubmed, Web of Science, Cochrane Library, and EMBASE were searched for retrospective and prospective clinical studies published until October 2024. The outcome measurement was the percentage of eyes with a predicted error (PE) within ± 0.50 or ± 1.00 diopter (D). The study have nine retrospective clinical trials, involving a total of 637 eyes and 18 calculation formulas. According to the ranking based on the surface under the cumulative ranking curve by Bayesian method, the top three formulas were Barrett True-K formula for keratoconus predicted posterior corneal astigmatism (Barrett KC P-PCA), EVO2.0, and Barrett True-K formula for keratoconus measured posterior corneal astigmatism (Barrett KC M-PCA) on the percentage of PE within ± 0.50 D, and the comparison between the three formulas and Barrett Universal II formula has statistical significance. In the range of ± 1.00D, the top three formulas were Barrett KC P-PCA, Barrett KC M-PCA and Kane for keratoconus formula, and the difference was significant. Thereforewe recommend using the Barrett KC P-PCA formula and the Barrett KC M-PCA formula for calculating IOL power in cataract patients with KC. This study revealed that the KC-specific IOL formulas, notably the Barrett KC P-PCA and Barrett KC M-PCA formulas, demonstrated superior accuracy. In clinical practice, when managing patients with different degrees of KC, surgeons should take into account the individual characteristics of each patient and adopt multiple formulas to improve the accuracy of refractive prediction.

Refractive and visual outcomes of traumatic cataract surgery: a ten-year perspective

Background: Traumatic cataract is a major consequence of penetrating and blunt ocular injuries, often requiring surgical intervention. We evaluated the visual and refractive outcomes of traumatic cataract surgery and intraocular lens (IOL) implantation in adults who sustained open- or closed-globe injuries. Methods: Patients who underwent cataract surgery and IOL implantation due to closed or open eye injuries were included in this descriptive-analytical, retrospective, case-series study. Eligible patients were scheduled for re-evaluation and a complete ocular re-examination, and individuals who returned and had a follow-up of at least 6 months were ultimately recruited. Because the accuracy of IOL power calculation was a primary outcome, patients who were left aphakic were excluded. Medical records were also reviewed to document baseline data, surgical details, and complications. Results: We included 72 eyes of 72 patients with a mean (standard deviation [SD]) age of 39.5 (13.6) years and a male-to-female ratio of approximately 6:1. Forty-one (56.9%) eyes sustained open-globe injuries and 31 (43.1%) closed-globe injuries. The mean (SD) initial best-corrected distance visual acuity (BCDVA) was 1.1 (0.6) logarithm of the minimum angle of resolution (logMAR) and improved significantly to 0.3 (0.3) logMAR at the final visit (P &lt; 0.001). A final BCDVA better than 20/40 was detected in 43 (59.7%), 23 (74.2%), and 20 (48.8%) eyes in the entire series, eyes sustaining closed-globe injuries, and those with open-globe injuries, respectively. The absolute prediction error was 1.0 diopter or less in 42 (58.3%) eyes in the entire series. A mean absolute prediction error of 1.0 D or less was more frequent in closed-globe than in open-globe injuries (n = 22 [71.0%] vs. n = 20 [48.8%], respectively). The mean absolute prediction error differed significantly between groups (P &lt; 0.05). Eyes that sustained open-globe injury were less likely to obtain a BCDVA better than 20/40 (odds ratio, 0.33; 95% confidence interval, 0.12 – 0.91; P &lt; 0.05). Conclusions: Visual acuity significantly improved after traumatic cataract extraction with IOL implantation. Most cases achieved satisfactory visual and refractive outcomes. Eyes with open-globe injuries might have less favorable visual prognosis. These initial findings must be confirmed through large-scale, multi-center longitudinal studies.

Accuracy of Intraocular Lens Power Calculation Based on Distance from Haptic to Principal Object Plane.

To investigate the impact of the distance from the most-anterior surface of the optic to the principal object plane (POP) and from the foremost haptic to the principal object plane (H-POP) on the intraocular lens (IOL) power calculation. A tertiary hospital. Optical simulation and retrospective cross-sectional study. The optical simulation study plotted changes in the POP and H-POP as a function of IOL power using ICB00 IOL configuration data. The clinical study included 102 eyes of 102 patients implanted with ICB00 IOL to examine the correlation between changes in both the POP and the H-POP, and the prediction error calculated using the Barrett Universal II formula with varying IOL power. The ICB00 IOL showed minor fluctuations in the POP (0.21 mm to 0.30 mm) with changing IOL power. The H-POP increased stepwise from 5.0 D, peaking at 0.60 mm at 16.0 D, then decreased to a minimum of 0.14 mm at 34.0 D. The prediction error graph primarily mirrored the pattern of changes in the H-POP rather than the POP with varying IOL power. Linear regression showed a significant myopic shift in prediction error as IOL power increased beyond 16.0 D (Y = -0.069X+1.420, R2=0.178, p<0.001). For the ICB00 IOL, the H-POP has more impact on IOL power calculation than the POP itself. For more accurate IOL power calculations, it is essential for all IOL manufacturers to provide comprehensive information on both optic and haptic geometries, which will enable the precise calculation of H-POP.

Refractive accuracy of the new Barrett formula using segmented axial length compared with that of the traditional Barrett Universal II formula.

To compare the refractive accuracy of the Barrett True axial length (BTAL) formula, newly integrated into ARGOS, with that of the Barrett Universal II (BUII) formula calculated using axial length (AL) from IOL Master 700. Private clinics in Kanagawa, Japan. Retrospective observational study. We assessed eyes of patients who underwent cataract surgery with SY60WF IOL implantation, using ARGOS and IOL Master 700. The predicted refraction for BTAL was back-calculated. Refractive prediction errors (RPEs) for BTAL, BUII with ARGOS (segmented BUII), and BUII with IOL Master 700 (composite BUII) were compared. We primarily aimed to demonstrate the non-inferiority of BTAL to composite BUII in absolute RPE. We included 209 eyes from 209 patients. BTAL met the non-inferiority criteria, as the upper confidence interval (CI) boundary was below the non-inferiority margin of 0.10 diopters (D) for the difference in absolute RPE (-0.03 D; 95% CI: -0.06 to 0.01). In short eyes (AL ≤ 22.5 mm), the median absolute RPEs for BTAL, segmented BUII, and composite BUII were 0.25, 0.18, and 0.37 D, respectively, with significant differences between BTAL and composite BUII (p = 0.028) and segmented BUII and composite BUII (p = 0.018). In long eyes (AL > 26 mm), the median absolute RPEs were 0.21, 0.20, and 0.28 D for BTAL, segmented BUII, and composite BUII, respectively. BTAL was non-inferior to composite BUII in absolute RPE. BTAL is an accurate and useful intraocular lens power calculation formula, even in eyes with short and long AL.

Prediction of Seven Artificial Intelligence-Based Intraocular Lens Power Calculation Formulas in Medium-Long Caucasian Eyes.

Purpose: To compare the accuracy of seven artificial intelligence (AI)-based intraocular lens (IOL) power calculation formulas in medium-long Caucasian eyes regarding the root-mean-square absolute error (RMSAE), the median absolute error (MedAE) and the percentage of eyes with a prediction error (PE) within ±0.5 D. Methods: Data on Caucasian patients who underwent uneventful phacoemulsification between May 2018 and September 2023 in MW-Med Eye Center, Krakow, Poland and Kyiv Clinical Ophthalmology Hospital Eye Microsurgery Center, Kyiv, Ukraine were reviewed. Inclusion criteria, i.e., complete biometric and refractive data, were applied. Exclusion criteria were as follows: intraoperative or postoperative complications, previous eye surgery or corneal diseases, postoperative BCVA less than 0.8, and corneal astigmatism greater than 2.0 D. Prior to phacoemulsification, IOL power was computed using SRK/T, Holladay1, Haigis, Holladay 2, and Hoffer Q. The refraction was measured three months after cataract surgery. Post-surgery intraocular lens calculations for Hill-RBF 3.0, Kane, PEARL-DGS, Ladas Super Formula AI (LSF AI), Hoffer QST, Karmona, and Nallasamy were performed. RMSAE, MedAE, and the percentage of eyes with a PE within ±0.25 D, ±0.50 D, ±0.75 D, and ±1.00 were counted. Results: Two hundred fourteen eyes with axial lengths ranging from 24.50 mm to 25.97 mm were tested. The Hill-RBF 3.0 formula yielded the lowest RMSAE (0.368), just before Pearl-DGS (0.374) and Hoffer QST (0.378). The lowest MedAE was achieved by Hill-RBF 3.0 (0.200), the second-lowest by LSF AI (0.210), and the third-lowest by Kane (0.228). The highest percentage of eyes with a PE within ±0.50 D was obtained by Hill-RBF 3.0, LSF AI, and Pearl-DGS (86.45%, 85.51%, and 85.05%, respectively). Conclusions: The Hill-RBF 3.0 formula provided highly accurate outcomes in medium-long eyes. All studied AI-based formulas yielded good results in IOL power calculation.

Distribution and associated factors of keratometry and corneal astigmatism in general elderly population

Purpose: To determine the distribution and associated factors of keratometry and corneal astigmatism in people aged 60 years and above.Methods: In this cross‐sectional study, 160 clusters were randomly selected from Tehran city (Iran) using the multi‐stage cluster sampling method. All participants underwent optometric examinations including testing uncorrected and best‐corrected distance visual acuity, non‐cycloplegic autorefraction, and subjective refraction. Pentacam imaging for all participants was carried out using Pentacam AXL. Keratometry and corneal astigmatism were reported based on Pentacam's data.Results: 4244 eyes from 2268 individuals were analyzed. The average, standard deviation and 95% confidence interval of flat keratometry, steep keratometry, mean keratometry, and corneal astigmatism were 44.02±1.58 diopters (95% confidence interval: 43.94 to 44.1), 44.86±1.67 diopters (95% confidence interval: 44.78 to 44.94), 44.44±1.58 diopters (95% confidence interval: 44.36 to 44.52), and 0.84±0.74 diopters (95% confidence interval: 0.81 to 0.87), respectively. According to the multiple generalized estimating equation model, the mean keratometry was significantly higher in males, in myopes, and in those with higher systolic blood pressure. Moreover, the mean keratometry was inversely related to the axial length, height, anterior chamber depth, corneal diameter, and central corneal thickness. The prevalence of various types of corneal astigmatism &gt; 0.50 diopters was as follows; with‐the‐rule: 32.5%, against‐the rule: 18.2%, and oblique: 10.0 %.Conclusions: The present study investigated the normal distribution of keratometry and corneal astigmatism in elderly, and results can be used in clinical matters, especially in intraocular lens power calculation. Sex and some biometric components such as anterior chamber depth, corneal diameter, and central corneal thickness are significantly related to keratometry.

The influence of anterior chamber depth on the calculation of piggyback intraocular lenses.

Demonstrate the variability of the spherical and toric ratios between the refraction at the intraocular lens (IOL) plane and the refraction at the spectacle plane when the sphere and the cylinder power of toric piggyback IOLs are calculated. Also, a comparison of the results of piggyback power calculation with variable ratios, to the power calculation performed by a major manufacturer online calculator using a fixed ratio. Experimental study with theoretical eye models. Private practice, Buenos Aires Argentina. Schematic eyes with different values of pseudophakic anterior chamber depth (ACD), refractive cylinder and sphere were used to calculate the exact toric and spherical power of the IOL needed to achieve emmetropia. The toric ratio could range between 0.88 and 1.6, while the spherical ratio between 1.01 and 1.61. Therefore, using fixed ratios can lead to errors in IOL power calculation up to 1 diopter. The most likely errors are undercorrection in eyes with deep ACD and low amounts of sphere and astigmatism and overcorrections in eyes with shallow ACD and high preoperative sphere and/or cylinder. Manufacturers that calculate the power of piggyback IOLs with a fixed ratio of toricity and sphere should develop calculators that change this ratio according to the preoperatively measured variables. An excel file with the calculator used is provided.

The importance of adequate preparation of the ocular surface before biometry in reducing refractive errors in patients undergoing cataract surgery

Aims/Purpose: To evaluate the impact of dry eye disease (DED) on refractive errors in patients after cataract surgery.Methods: Fifty patients undergoing cataract surgery were studied. Two study groups and a control group were distinguished. The first study group (group A, n = 22, 44%) were patients with preoperatively diagnosed DED who received appropriate treatment (eyelid margin hygiene and moisturizing the ocular surface). The second study group (group B, n = 14, 28%) were patients in whom such treatment was also implemented, despite the lack of a diagnosis of DED. The remaining patients (n = 14, 28%) were the control group (Group C). Biometric measurements with calculation of intraocular lens (IOL) power were performed twice in all of them (before and after treatment of DED). Refraction and refractive errors were evaluated one month after surgery.Results: Significant improvement in best corrected visual acuity (BCVA) was obtained in all groups after surgical treatment. In both study groups, a significant reduction in the mean absolute error (MAE) after the treatment was achieved – in study group A, the MAE was 0.37 ± 0.30 D vs 0.24 ± 0.33 D, p = 0.003. In study group B, MAE was 0.29 ± 0.26 D vs 0.23 ± 0.23 D, p = 0.017. The control group showed no difference in MAE (0.27 ± 0.18D vs 0.33 ± 0.21 D, p = 0.322). In study group A, there was a significant reduction in the percentage of MAE in the ± 0.25 D range (36.36% vs 77.27%, p = 0.016). The results are comparable with previous publications.Conclusions: Diagnosis and treatment of dry eye syndrome before cataract surgery is an important factor in reducing refractive errors after surgery. The use of lubricating drops and eyelid margin hygiene before biometry can be considered for all patients undergoing cataract surgery.

The importance of adequate preparation of the ocular surface before biometry in reducing refractive errors in patients undergoing cataract surgery

Aims/Purpose: To evaluate the impact of dry eye disease (DED) on refractive errors in patients after cataract surgery.Methods: Fifty patients undergoing cataract surgery were studied. Two study groups and a control group were distinguished. The first study group (group A, n = 22, 44%) were patients with preoperatively diagnosed DED who received appropriate treatment (eyelid margin hygiene and moisturizing the ocular surface). The second study group (group B, n = 14, 28%) were patients in whom such treatment was also implemented, despite the lack of a diagnosis of DED. The remaining patients (n = 14, 28%) were the control group (Group C). Biometric measurements with calculation of intraocular lens (IOL) power were performed twice in all of them (before and after treatment of DED). Refraction and refractive errors were evaluated one month after surgery.Results: Significant improvement in best corrected visual acuity (BCVA) was obtained in all groups after surgical treatment. In both study groups, a significant reduction in the mean absolute error (MAE) after the treatment was achieved – in study group A, the MAE was 0.37 ± 0.30 D vs 0.24 ± 0.33 D, p = 0.003. In study group B, MAE was 0.29 ± 0.26 D vs 0.23 ± 0.23 D, p = 0.017. The control group showed no difference in MAE (0.27 ± 0.18D vs 0.33 ± 0.21 D, p = 0.322). In study group A, there was a significant reduction in the percentage of MAE in the ± 0.25 D range (36.36% vs 77.27%, p = 0.016). The results are comparable with previous publications.Conclusions: Diagnosis and treatment of dry eye syndrome before cataract surgery is an important factor in reducing refractive errors after surgery. The use of lubricating drops and eyelid margin hygiene before biometry can be considered for all patients undergoing cataract surgery.

Cataract surgery in corneal ectatic disorders

This case series highlights challenges during intraocular lens (IOL) power calculation and cataract surgery in various corneal ectatic disorders. Approaching cataract surgery in these patients requires careful assessment of corneal stability, keratometric values, IOL selection, and surgical techniques to increase the likelihood of a successful outcome. Here, we report three scenarios of corneal ectasias who had satisfactory visual outcomes after cataract surgery with IOL implantation.

Challenges and outcomes of cataract surgery after vitrectomy.

This review examines the challenges and outcomes of cataract surgery after pars plana vitrectomy (PPV), focusing on surgical techniques, timing, and complication management. Cataract formation remains the primary complication post-PPV, affecting approximately 80-100% of patients within two years. Nuclear sclerotic cataracts are most common, occurring in 60-100% of patients over 50, followed by posterior subcapsular cataracts (4-34%), which primarily affect younger and diabetic patients. PPV disrupts the normal oxygen gradient in the vitreous, resulting in a more uniform oxygen distribution and accelerating cataract formation.Post-PPV eyes present unique surgical challenges due to anatomical alterations, including zonular instability and capsular changes characterized by increased fragility, the potential for tears, and altered elasticity. Newer intraocular lens power calculations show promise, but unexpected refractive outcomes may occur. The choice between combined phacovitrectomy and sequential surgeries remains debated, with patient-specific factors guiding the approach. Visual outcomes vary depending on preexisting vitreoretinal pathologies and baseline vision before PPV. Further randomized controlled trials are needed to establish treatment guidelines and improve predictive models. Post-PPV cataract surgery presents unique challenges, including anatomical alterations and an increased risk of capsular complications. These necessitate careful consideration of the surgical approach and highlight the need for further research to optimize outcomes and establish treatment guidelines.

Effect of Posterior Corneal Surgically Induced Astigmatism on Toric Intraocular Lens Power Calculations.

To determine whether accounting for posterior corneal surgically induced astigmatism (SIA) would improve toric intraocular lens power calculation prediction error. A total of 189 eyes of 148 patients undergoing routine cataract surgery were included in the study. Standard and posterior keratometry were measured pre- and postoperatively. Centroid SIA with standard keratometry and posterior keratometry were calculated separately. Prediction errors for postoperative refractive astigmatism at 4weeks postoperatively were compared for Barrett Toric with predicted posterior corneal astigmatism (PPCA); Barrett Toric with preoperative measured posterior corneal astigmatism (MPCA); Barrett Toric with postoperative MPCA, which accounts for posterior corneal SIA. There was a significant increase in PCA magnitude postoperatively (p < 0.001), although a change of >0.3D occurred in only 3% of eyes. There was a postoperative rotation in the steep meridian of >10° in 32% of eyes. The Barrett Toric formula with PPCA yielded a significantly smaller refractive astigmatism prediction error compared to when a postoperative MPCA value was used (p < 0.01). Postoperative MPCA had a lower proportion of eyes within 0.50, 0.75 and 1.00D of predicted refractive astigmatism than PPCA or preoperative MPCA, although this was not statistically significant. This study demonstrated postoperative changes in posterior corneal astigmatism magnitude and the orientation of the steep meridian. However, accounting for posterior keratometric SIA in the Barrett Toric formula does not improve refractive astigmatism prediction accuracy.

Evaluation of the Accuracy of IOL Calculation from the Standpoint of the Medical and Social Model of Health in Patients with Visually Intense Work and Bilateral Cataracts

Purpose: to compare the accuracy of IOL calculation from the standpoint of the social model of health (based on the study of “quality of life”, QOL) in patients with visually intense work (VIW) and bilateral cataract.Methods. We observed 108 patients with binocular cataract (216 eyes) aged 40 to 69 years (mean age 55.9 ± 1.4 years), everyday activities were characterized as VIW (at least 4 hours per day). All patients underwent (sequentially on both eyes) ultrasound phacoemulsification using the standard technique. All patients were operated on by the same surgeon (N.I. Ovechkin). To correct aphakia, a monofocal IOL “Flex HB Medicontur” (Switzerland) with a predicted emmetropic “target refraction” (TR) was implanted. All patients were divided into two groups: a group of patients (56 patients, 112 eyes) in which the IOL calculation was performed using the Kane formula (KF); a group of patients (52 patients, 104 eyes) in which the IOL calculation was performed using the Barrett Universal II formula (BU-II). The patients were examined 3 months after the second surgery based on a comparative study of refraction between the RC and the calculated one. The basic research method in relation to the target objectives of the work was a study of QOL using two questionnaires — Catquest-9SF and FEC22.Results. The data obtained indicate an insignificant, statistically insignificant trend towards improvement in traditional refraction indices and QOL according to the Catquest-9SF questionnaire when calculating IOL using the KF compared to BU-II. At the same time, these differences in relation to the assessment of QOL using the FEK-22 questionnaire are characterized by pronounced (by 2.3 %), statistically significant (p &lt; 0.05) differences.Conclusion. The use (based on the original FEK-22 questionnaire) of the “medical and social” health model in the context of assessing the effectiveness of IOL calculation in VIW patients indicates a higher accuracy of the Kane formula compared to the Barrett Universal II formula. The identified differences are due to the fact that calculations using the Kane formula are performed in a comprehensive manner based on basic eye parameters, theoretical optics, regression analysis and, most importantly, artificial intelligence.

Prediction and Estimation of Postoperative Refractive Error in Phacoemulsification: Using Ultrasound A-Scan and Intra Ocular Lens Master

Background: This study aims to predict and estimate the postoperative refractive outcome in participants undergoing phacoemulsification using IOL Master and A-scan biometry.Methods: A cross-sectional study was done where ninety eyes of 90 participants undergone phacoemulsification using SRK/T formula were included in longitudinal research. Each participant underwent axial length (AL) measurement by IOL Master and A-scan, and keratometry reading (k- reading) by manual TOPCON keratometer and automated keratometer on IOL master for IOL power calculation. All the pre-operative measurements between A-scan and IOL master and two keratometers were compared using paired-t tests. The four-week postoperative refractive error was estimated using univariate analysis and its prediction was compared with the ocular biometry parameters using quadratic regression.Results: Preoperative findings were higher for AL and ACD by IOL master and A-scan (0.27±0.14mm; p&lt;0.001, 0.14±0.31mm, p&lt;0.001) respectively. The AL and K-reading were found to be strong predictors of IOL power calculation (β = -1.07; p&lt;0.001, β = 0.75; p&lt;0.001), respectively. The AL, K-reading were found to be strong predictors for four-week postoperative refractive error (β = -1.563; p = 0.012, β = 1.052; p = 0.012) where postoperative error was found to be higher (F = 7.521, p&lt;0.001) in A-scan than IOL Master. For K-reading, the two keratometer’s and for AL by A-scan and IOL Master’s level of agreement (95% LoA) was comparable (-0.15 to 0.12mm and -0.01 to 0.54mm). Conclusions: IOL Master is more reliable for ocular biometry and minimizes postoperative refractive error.Keywords: Axial length; intraocular lens power; keratometry-reading; refractive error estimation; postoperative refractive error.

Evaluation of an artificial intelligence-based intraocular lens calculator: AI-based IOL-optimized formula.

To evaluate the ZEISS AI IOL Calculator (ZEISS AI) and compare its accuracy in refractive prediction to the Barrett Universal II (BUII) and Kane formulas. Cullen Eye Institute, Baylor College of Medicine, Houston, TX. Retrospective case series. The ZEISS AI IOL Calculator (ZEISS AI) is an artificial intelligence (AI) based IOL-optimized formula. The refractive prediction errors (PEs) were calculated in the entire dataset and subgroups of short eyes (axial length (AL) ≤ 22.5 mm) and long eyes (AL ≥ 25.0 mm). The standard deviation (SD), root-mean-square absolute error (RMSAE), mean absolute error (MAE), median absolute error (MedAE), and percentage of eyes within ±0.25 D, ±0.50 D, ±0.75 D, and ±1.00 D of PEs were calculated. Values with ZEISS AI were compared to those from Barrett Universal II (BUII) and Kane. Advanced statistical methods were applied using R. A dataset of 10,838 eyes was included. Compared to ZEISS AI, BUII produced significantly greater SDs, RMSAEs, and MAEs in the whole group and short eyes, and the Kane had greater SD, RMSAE, and MAE in short eyes (all adjusted P<0.05); the BUII had significantly lower percentages of eyes within ±0.50 D of PEs in the whole group (80.0% vs 81.2%) and in short eyes (71.3% vs. 76.1%), and the Kane had lower percentage of eyes within ±0.50 D of PEs in short eyes (71.9% vs. 76.1%) (all adjusted P<0.05). The ZEISS AI IOL Calculator had superior performance compared to the BUII and Kane formulas, especially in short eyes.

Improving the Accuracy of Lens Formulas for in-the-bag Intraocular Lens Implantation in Marfan Syndrome Patients with Ectopia Lentis.

To improve the accuracy of intraocular lens (IOL) power calculation formulas by modifying the effective lens position (ELP) equations for patients with Marfan Syndrome (MFS) and ectopia lentis (EL) undergoing in-the-bag IOL implantation. Eye and ENT Hospital of Fudan University. Retrospective cohort study. The formula-specific ELP was obtained from the SRK/T, T2, Holladay I, and HofferQ formulas. The back-calculated ELP was obtained based on the vergence formula using preoperative biometry, postoperative refraction, and the IOL power. The Generalized Linear Models or Gradient Boosting Machines were used to predict ELP or ELP error. A total of 255 patients (255 eyes) were assigned randomly into a training set and a validation set (7:3 ratio). Linear correlation identified axial length(AL), corneal height, and white-to-white as predictors for ELP and ELP error for patients with shorter AL (AL ≤ 24 mm). For those with longer AL (AL > 24 mm), AL and the central corneal radius were identified as the primary predictors. Incorporating these predictors into the modified ELP formula significantly improved the accuracy in the validation set, including SRK/T, T2, Haigis, Holladay I, and HofferQ formulas. The improvement was more pronounced in patients with shorter AL. Additionally, the GLM-modified formulas outperformed both the Barrett Universal II and Kane formulas. The accuracy across different ocular dimensions was comparable among the modified formulas, based on which an online calculator was developed. Using the more accurately predicted ELP can significantly improve the accuracy of existing formulas in patients with MFS.