[Reasonability of accounting for gender in intraocular lens power calculation]. / O tselesoobraznosti ucheta gendernoi prinadlezhnosti pri raschete opticheskoi sily intraokulyarnykh linz.

PURPOSE: The study assesses the influence of gender on the accuracy of intraocular lens (IOL) power calculation by formulas SRK/T, Barrett Universal II (BUII), Ladas super formula (LSF), Hill RBF (RBF) and Kane. MATERIAL AND METHODS: The study enrolled 214 patients (106 men and 108 women) who underwent cataract phacoemulsification (PE). Optical biometry was performed on IOL-Master 500. IOL power calculation was performed either adjusting for gender (formulas SRK/T, BUII, LSF) or without such adjustment (formulas RBF, Kane). Calculation error (CE) was assessed one month after PE by comparing the achieved (autorefractometer Topcon-8800) and target spherical equivalent of refraction. RESULTS: Significant differences were found in mean IOL CE with gender-unspecific formulas (SRK/T, BUII, LSF) and no differences in gender-specific calculators (RBF, Kane). The Kane formula demonstrated the lowest CE between men and women (-0.01±0.43 versus -0.09±0.41 D; p=0.158), while the SRK/T formula had the highest CE (0.02±0.46 versus -0.21±0.44 D, respectively; p<0.001). Presence of a significant correlation between CE and gender was found for all formulas except Kane (R2=0.005, p=0.158). CONCLUSION: Patient's gender has a significant impact on IOL calculation accuracy. Using gender-responsive formulas could help achieve better refractive results with PE. The present study showed Kane formula to have the least CE dependence from gender. However, the CE difference (less than 0.25 D) was lower than the value of division (0.5D) in modern IOL models.

A comparison of SRK/T formula with Hill RBF 2 and Barrett Universal II in the calculation of intraocular lens power.

OBJECTIVE: To compare the accuracy of SRK/T, Barrett Universal II and Hill radial basis activation function-2 formulas in intraocular lens power calculation using different axial lengths. METHODS: The retrospective study was conducted at the Lahore General Hospital, Lahore, Pakistan, and comprised data from June to December 2020 of patients who underwent phacoemulsification with non-toric, monofocal intraocular lens implantation. Data was sorted in 3 groups on the basis of axial length; group 1 22-25mm, group 2>25mm, and group 3 <22mm. Intraocular lens power was calculated using SRK/T with IOL Master, while online calculators were used for Barrett Universal II and Hill radial basis activation function-2 formulas. Data was analysed using SPSS 21. RESULTS: Of the 100 patients, 47(347%) were males and 53(53%) were females. There were 49(49%) diabetics, and 57(57%) were right eyes. There were 77(77%) patients with mean age 62.38±9.5 in group 1, 17(17%) patients with mean age 52.59±12.78 in group 2, and 6(6%) patients with mean age 61.33+7.61 years in group 3. Mean axial length in group 1 was 23.55±0.81mm with anterior chamber depth of 3.1± 0.37mm. In group 2, mean axial length was 27.54±2.8mm, with anterior chamber depth of 3.4±0.15mm. In group 3, mean axial length was 21.74mm, with anterior chamber depth of 3.14±0.44mm. Mean prediction error of SRK/T versus Barrett Universal II was 0.092±0.041D (p=0.078), SRK/T versus Hill radial basis activation function-2 was 0.066±0.037D (p=0.221) and Barrett Universal versus Hill radial basis activation function-2 was -0.025±0.019D (p=0.553). Mean prediction error of group 1 versus group 2 was -0.105±0.14D, group 2 versus group 3 was 0.046±0.216D and group 2 versus group 3 was 0.151±0.243D (p=1.0). In 74% eyes, absolute prediction error was within ±0.5D in group 1, 64% in group 2 and 50% in group 3 for all formulas. CONCLUSIONS: SRK/T formula was found to be as reliable as Barrett Universal II and Hill radial basis activation function-2 in terms of calculating intra ocular lens power for all axial lengths.

Could anatomical changes occurring with cataract surgery have a clinically significant effect on effective intraocular lens position?

PURPOSE: To assess if the calculation of the effective lens position (ELP) of two different monofocal intraocular lenses (IOLs) could be optimized by considering the potential anatomical changes occurring after cataract surgery. METHODS: Prospective, descriptive, single-center study involving 472 eyes of 280 subjects (mean age 73.5 years) undergoing cataract surgery that were divided into two groups according to the IOL implanted: group 1330 eyes with AcrySof IQ SN60WF (Alcon), and group 2142 eyes with Akreos MI60L (Bausch + Lomb). Refractive and biometric changes were evaluated during a period of 6-month follow-up with an optical biometer (considering potential measurement artifacts). Comparison of ELP estimated with the SRK-T formula (ELPSRK-T) and ELP calculated considering clinical real data was made (ELPAXL-corrected clinical). RESULTS: Besides significant changes in refraction (p ≤ 0.020), a significant increase in anterior chamber depth (ACD) (p < 0.001) and a significant reduction in the axial length (AXL) (p < 0.001) were detected at 1 month after surgery. Mean 1-month postoperative AXL change was - 0.08 ± 0.06 and - 0.10 ± 0.11 mm in groups 1 and 2, respectively (p = 0.001), with no significant changes afterward. Mean difference between ELPSRK-T and ELPAXL-corrected clinical was 0.17 ± 0.39 and - 0.23 ± 0.43 mm in groups 1 and 2, respectively (p < 0.001). A strong and statistically significant correlation of these differences with the prediction refractive error was found in both groups (group 1, r = - 0.723; group 2, r = - 0.819; p < 0.001). CONCLUSIONS: The estimation of ELP using the SRK-T formula for the two IOLs evaluated may be optimized considering biometric changes with surgery, helping to understand better some problems of refractive unpredictability.

Refractive outcomes and accuracy of IOL power calculation with the SRK/T formula for sutured, scleral-fixated Akreos AO60 intraocular lenses.

BACKGROUND: Scleral fixation of intraocular lenses has become a popular procedure for treating aphakia in the absence of capsular support. However, the lens formulas used to predict refractive outcomes were designed for in-the-bag lens placement. This study evaluates the accuracy of the SRK/T formula in predicting a target postoperative refraction when suturing a scleral-fixated intraocular lens (IOL) implant 3 mm posterior to the limbus. METHODS: This is a retrospective, case series including 20 eyes of 20 patients who underwent scleral fixation of Akreos AO60 IOLs (Bausch & Lomb, Rochester, NY) by a single surgeon at the OSU Wexner Medical Center. Preoperative measurements were performed with optical biometry, and IOL power was calculated with the SRK/T formula. Following surgery, the actual refractive spherical equivalent (SE) was performed and compared with the preoperative prediction. Prediction error (PE), defined as the deviation of actual postoperative SE refraction in diopters (D) from preoperative predicted SE refraction, was the primary outcome measure. RESULTS: The mean attempted (predicted) SE was - 1.12 D (± 0.87). Mean achieved SE was - 0.96 D (± 1.04). Mean PE (actual postoperative SE versus predicted preoperative SE) was 0.16 D (± 0.69). A total of 9 eyes (45%) were within ± 0.5 D of the predicted SE, 16 eyes (80%) were within ± 1.0 D, and all 20 eyes (100%) were within ± 1.5 D. CONCLUSION: IOL power calculation using the SRK/T formula with optical biometry demonstrates reliable postoperative refractive outcomes in patients undergoing scleral fixation of an IOL (Akreos AO60). Further studies are needed to refine the predictive value of the SRK/T and other formulas for application in scleral fixation of IOLs.

Influence of pupil dilation on the Barrett universal II (new generation), Haigis (4th generation), and SRK/T (3rd generation) intraocular lens calculation formulas: a retrospective study.

BACKGROUND: Despite the surge in the number of cataract surgeries, there is limited information available regarding the influence of pupil dilation on predicted postoperative refraction and its comparison with recommended various intraocular lens power calculated using the different parameters. We used three different IOL power calculation formulas: Barrett Universal II (Barrett) (5-variable formula), Haigis (3-variable formula), and SRK/T (2-variable formula), in order to investigate the potential effect of pupil dilation on the predicted postoperative refraction (PPR) and recommended intraocular lens (IOL) power calculation. METHODS: This retrospective study included 150 eyes. All variables were measured and calculated using a ZEISS IOL Master 700. The following variables were measured before and after dilation: anterior chamber depth (ACD), lens thickness (LT), white-to-white (WTW). PPR and recommended IOL power were calculated by Barrett, Haigis, and SRK/T IOL calculation formulas. The change in each variable before and after dilation, and the correlations between all changes were analyzed using the Wilcoxon signed-rank test and the Spearman's rank-order correlation test, respectively. RESULTS: The mean absolute change (MAC) in PPR before and after dilation was found to be highest in the Barrett formula. Significant differences were found between each MAC (P <  0.0001). Significant changes were observed before and after dilation in ACD and LT (P <  0.0001), but not in WTW. Using the Barrett and Haigis formulas, there was a significant positive correlation between the change in PPR and change in ACD (P <  0.0001), and a negative correlation between change in PPR and change in LT (P <  0.0001). The correlations were strongest with the Barret formula followed by the Haigis, particularly in terms of LT. Changes in PPR determined by the Barrett formula also demonstrated a significant positive correlation with changes in WTW (P = 0.022). The recommended IOL power determined using Barrett and Haigis changed before and after dilation in 23.3 and 19.3% cases respectively, while SRK/T showed no change. CONCLUSIONS: In terms of PPR and recommended IOL power, pupil dilation influenced mostly the Barrett formula. Given the stronger correlation between the changes in PPR when using Barrett and the changes in ACD, LT, and WTW, changes in ACD, LT, and WTW significantly affect how dilation influences the Barrett formula. Determining how dilation influences each formula and other variables is key to improving the accuracy of IOL calculations.

Influence of corneal power on intraocular lens power of the second eye in the SRK/T formula in bilateral cataract surgery.

BACKGROUND: To evaluate the effect of different adjustments of the refractive outcome of the first eye according to corneal power (K) in order to improve the intraocular lens (IOL) power calculation of the second eye in the SRK/T formula. METHODS: One hundred thirty-four patients who underwent uncomplicated bilateral, sequential phacoemulsification with AcrySof IQ implantation were enrolled. The optimal partial adjustment of the refractive outcome of the first eye according to K was retrospectively analyzed using a regression formula. RESULTS: In all patients, the optimal partial adjustment of the refractive outcome of the first eye was calculated as 56%. For K values between 42.8 D and 44.6 D, the optimal partial adjustment was calculated as 30%; however, this adjustment of the first eye did not significantly improve the refractive outcome in the second eye of the subgroup with K values between 42.8 D and 44.6 D. For K values greater than 44.6 D or less than 42.8 D, the optimal partial adjustments were calculated as 69% and 81%, respectively. According to these results, the adjustment of the first eye significantly improved the refractive outcome in the second eye from 0.36 to 0.26 D (P < 0.001) in the entire data set. This result was significantly lower than that using a single partial adjustment (56%) (0.28 D; P = 0.027). CONCLUSIONS: For K values greater than 44.6 D or less than 42.8 D, an approximately 70-80% adjustment of the first eye error should be considered. In contrast, for K values between 42.8 D and 44.6 D, a 30% or less adjustment should be considered in the SRK/T formula.

Performance of the SRK/T formula using A-Scan ultrasound biometry after phacoemulsification in eyes with short and long axial lengths.

BACKGROUND: The SRK/T formula is one of the third generation IOL calculation formulas. The purpose of this study was to evaluate the performance of the SRK/T formula in predicting a target refraction ±1.0D in short and long eyes using ultrasound biometry after phacoemulsification. METHODS: The present study was a retrospective analysis, which included 38 eyes with an AL < 22.0 mm (short AL), and 62 eyes ≥24.6 mm (long AL) that underwent uncomplicated phacoemulsification. Preoperative AL was measured by ultrasound biometry and SRK/T formula was used for IOL calculation. Three different IOLs were implanted in the capsular bag. The prediction error was defined as the difference between the achieved postoperative refraction, and attempted predicted target refraction. Statistical analysis was performed with SPSS V21. RESULTS: In short ALs, the mean age was 65.13 ± 9.49 year, the mean AL was 21.55 ± 0.45 mm, the mean K1 and K2 were 45.76 ± 1.77D and 46.09 ± 1.61D, the mean IOL power was 23.96 ± 1.92D, the mean attempted (predicted) value was 0.07 ± 0.26D, the mean achieved value was 0.07 ± 0.63 D, the mean PE was 0.01 ± 0.60D, and the MAE was 0.51 ± 0.31D. A significant positive relationship with AL and K1, K2, IOL power and a strong negative relationship with PE and achieved postoperative was found. In long ALs, the mean age was 64.05 ± 7.31 year, the mean AL was 25.77 ± 1.64 mm, the mean K1 and K2 were 42.20 ± 1.57D and 42.17 ± 1.68D, the mean IOL power was 15.79 ± 5.17D, the mean attempted value was -0.434 ± 0.315D, the mean achieved value was -0.42 ± 0.96D, the mean PE was -0.004 ± 0.93D, the MAE was 0.68 ± 0.62D. A significant positive relationship with AL and K1, K2 and a significant positive relationship with PE and achieved value, otherwise a negative relationship with AL and IOL power was found. There was a little tendency towards hyperopic for short ALs and myopic for long ALs. The majority of eyes (94.74 %) for short ALs and (70.97 %) for long ALs were within ±1 D of the predicted refractive error. No significant relationship with PE and IOL types, AL, K1, K2, IOL power, and attempted value, besides with MAE and AL, K1, K2, age, attempted, achieved value were found in both groups. CONCLUSION: The SRK/T formula performs well and shows good predictability in eyes with short and long axial lengths.

Accuracy of 20 Intraocular Lens Power Calculation Formulas in Medium-Long Eyes.

INTRODUCTION: The aim of this work is to compare 20 intraocular lens (IOL) power calculation formulas in medium-long eyes (24.50-25.99 mm) in terms of root mean square absolute error (RMSAE), median absolute error (MedAE), and percentage of eyes with prediction error (PE) within ± 0.50 D. METHODS: The data of patients who underwent uneventful phacoemulsification between January 2017 and September 2023 were reviewed. Pre-surgery IOL power was calculated using Holladay1, SRK/T, Hoffer Q, Holladay 2, and Haigis. Three months after phacoemulsification, refraction was measured. Post-surgery IOL power calculations were performed utilizing the following formulas: Barrett Universal II, Kane, K6, Olsen (OLCR), Olsen (standalone), PEARL-DGS, Ladas Super Formula AI (LSF AI), T2, EVO, VRF, Hoffer QST, Castrop, VRF-G, Karmona, and Naeser 2. RMSAE, MedAE, and percentage of eyes with PE within ± 0.25 D, ± 0.50 D, ± 0.75 D and ± 1.00 were calculated. RESULTS: One hundred twenty-four eyes with axial length ranges between 24.52 and 25.97 mm were studied. The SRK/T formula yielded the lowest RMSAE (0.206) just before Holladay 1 (0.260) and T2 (0.261). In terms of MedAE, the best outcome was obtained by SRK/T (0.12) followed by Barrett Universal II (0.15) and LSF AI (0.15). The highest percentage of eyes with prediction error within ± 0.50 D was achieved by SRK/T, T2, and Holladay 1 (97.58, 93.55, and 93.55%, respectively). CONCLUSIONS: Third-generation formulas (SRK/T, Holladay 1) provided highly accurate outcomes in medium-long eyes and still can be wildly used to calculate IOL power.

Comparison of Refractive Prediction Error by Axial Length in Flanged Intrascleral Intraocular Lens Fixation.

Purpose: To evaluate the refractive prediction error in flanged intrascleral intraocular lens (IOL) fixation using the SRK/T formula and compare the axial length using a single IOL. Methods: Seventy-six eyes from 70 patients (45 males and 25 females) were included in this study. The mean age at the time of surgery was 73.4 ±12.3 years. The patients underwent flanged IOL fixation using a PN6A (Kowa). All surgeries were performed by two surgeons (Y. K. and T. O.) between Jan 2020 and Dec 2022 at Jikei University Daisan Hospital. IOL power was calculated using the SRK/T formula with IOL Master 700 (Carl Zeiss) as the bag power. The recommended value of 119.0 was used for the A-constant. The actual refractive spherical equivalent was calculated and compared with preoperative predictions. Refractive prediction errors were defined as the deviation of the actual postoperative spherical equivalent refraction in diopters from the predicted preoperative spherical equivalent refraction. The patients were divided into three groups according to axial length: <22.0 mm (short eyes), 22.0-24.5 mm (medium eyes), and >24.5 mm (long eyes), and the refractive prediction errors and mean absolute errors were compared. Results: The mean refractive prediction error was -0.20 ± 0.52D. The mean absolute error was 0.44 ± 0.33D. The mean refractive prediction errors were not significantly different between the 22.0-24.5 mm (medium eyes) and >24.5 mm (long eyes) groups. (P=0.06) The mean absolute errors were not significantly different between the two groups (P=0.10). Conclusion: The SRK/T formula worked well regardless of whether the eyes were medium or long according to the axial length in the flanged intrascleral IOL fixation.

Cataract Outcomes Following Scleral Buckle Surgery for Retinal Detachment.

Purpose: To investigate refractive, visual, and safety outcomes of cataract surgery performed after scleral buckling (SB) for retinal detachment (RD). Patients and methods: A chart review at an academic medical center identified eyes with history of SB followed by subsequent cataract extraction between 2010 and 2022. Eyes with less than 3 weeks follow-up, silicone oil at time of biometry measurement, previous cornea surgery, or co-existing pathology impacting refractive outcomes were excluded. Predicted postoperative spherical equivalents (SE) were calculated with the Barrett Universal II (BU2), Kane, and SRK/T formulas for the implanted intraocular lens (IOL), and complications occurring within 1 year of surgery were abstracted. Results: Sixty eyes of 60 patients met criteria for inclusion, and 40 (66.7%) had postoperative refraction recorded. Absolute prediction errors were 0.49, 0.45, and 0.52D with BU2, Kane, and SRK/T, respectively. Actual postoperative refraction was within 0.5 and 1.0 D of predicted in 26 (65.0%) and 36 (90.0%) using BU2, 23 (58%) and 37 (93%) using Kane, and 21 (52.5%) and 36 (90.0%) using SRK/T. In eyes with macula-on RD, corrected distance visual acuity (CDVA) of logMAR 0.301 (≈20/40) and logMAR 0.544 (≈20/70) or better was achieved in 12 (75.0%) and 15 (93.8%) of eyes. For macula-off RD eyes, these proportions were 19 (63.3%) and 24 (80.0%), respectively. Posterior capsular opacification requiring Nd: YAG capsulotomy was the most frequent complication in 30 (56.7%) eyes. Conclusion: Refractive outcomes of cataract surgery following SB may be modestly reduced, even when using modern formulas. Nevertheless, cataract surgery in this population results in favorable visual outcomes.

The retina is the part of the eye that is responsible for converting incoming light into a signal that the brain can interpret. A retinal detachment is an emergent condition in which the retina is torn away from its normal position. Scleral buckling is one method of surgically reattaching the retina. Although quite successful, scleral buckling can cause changes to the shape of the eye, and also increases the risk of opacification of the natural lens of the eye, otherwise known as a cataract. The purpose of this study is to investigate the outcomes of cataract surgery in eyes with prior scleral buckle surgery. The results show that despite advancements in methods of measuring the shape of the eye, calculating the appropriately powered IOL to implant, and surgical technique, cataract surgery in eyes with prior scleral buckling may result in poorer outcomes compared to eyes with no history of scleral buckling.

Accuracy of Modern and Traditional Intraocular Lens Power Calculation Formulas in Pediatric Cataract Surgery.

Purpose: To compare the accuracy of modern intraocular lens (IOL) power calculation formulas with that of older formulas, such as SRK/T and Hoffer Q, in pediatric cataract surgery. Methods: This retrospective study included 100 eyes of 100 children who underwent routine cataract surgery with primary IOL implantation in a bag. This study used four IOLMaster 700 integrated formulas: SRK/T, Hoffer Q, Haigis, and Barrett Universal II (BUII). In addition, the following formulas were used: EVO 2.0, Hill RBF 3.0, Hoffer QST, Kane, and PEARL DGS, which are available online. Results: There was a statistically significant difference between SRK/T and most other formulas, except for Hoffer Q, Hoffer QST, and BUII (p < 0.05). SRK/T yielded the lowest median absolute error (MedAE) of 0.63 D. This was followed by the BUII (0.66 D), Hoffer Q, and Hoffer QST (0.68 D). SRK/T also yielded the highest percentage of cases within ± 0.50 D (43% of the cases). For patients aged 2 to 5 years, SRK/T formula yielded statistically significantly better results than all other included formulas (p < 0.05) with MedAE = 0.44 D, 58.33% and 87.50% of the cases were within ± 0.50 D and ± 1.0 D of intended refraction, respectively. Conclusion: The SRK/T formula showed the best IOL power calculation results in pediatric cataract surgery, followed by BUII, Hoffer Q, and Hoffer QST. In children aged 2-5 years, the SRK/T formula outperformed all other formulas, followed by the BUII and Hoffer QST formulas. In children older than 5 years, there was no statistically significant difference between the different formulas (p > 0.05); Hoffer Q and SRK/T showed slightly better MedAE in this age group (5-10 years).

Evaluation of residual refractive prediction accuracy after phacoemulsification using the SRK/T formula.

PURPOSE: The purpose of this study was to determine the accuracy of residual spherical refraction predictability after phacoemulsification (Phaco) intraocular lens (IOL) implant surgery using the SRK/T formula. METHODS: A cross-sectional study was performed with a sample size of 112 patients diagnosed with cataracts and indicated for Phaco surgery. This study was conducted in Saigon Can Tho Eye Hospital, Can Tho City, Vietnam, from January 2022 to June 2022. Preoperative data and postoperative data were collected for each case. Residual refraction data were measured using the IOLMaster 500 and Anterion. RESULTS: The mean preoperative spherical refraction was 0.04 ± 0.4 diopter. The prediction of residual spherical refraction was -0.11 ± 0.17 diopter (for cases measured by IOLMaster 500: -0.02 ± 0.22 diopter; for cases measured by Anterion: 0.07 ± 0.27 diopter). The mean absolute error of prediction results value in a total of 112 eyes was 0.19 ± 0.21 diopter (for cases measured with the IOLMaster 500: 0.20 ± 0.21 diopter; for cases measured with an Anterion: 0.17 ± 0.26 diopter). CONCLUSION: The predictive result of the SRK/T formula showed relative and acceptable effectiveness and accuracy in predicting postoperative refraction using the SRK/T formula. The results of this study and those of other studies on the same topic are valuable data to help the ophthalmologist in preoperative consultation with the patient.

Accuracy of the SRK/T Formula in Pediatric Cataract Surgery.

Purpose: Determining IOL power is an important step in achieving the desired postoperative refractive target, but this determination remains challenging, as currently the used formulas were developed using IOL power calculations derived from adults. Patients and Methods: This is a retrospective analytical study with the period of June 2018 to May 2019. All of the data were taken from medical records in referral tertiary eye hospital in Indonesia. All type of cataracts underwent uncomplicated surgeries and in-the-bag IOL implantation were included in this study, while aphakia, secondary IOL implantation, primary sulcus implantation, and history of ocular disorders were excluded. The data were analyzed using Wilcoxon sign-rank, paired t, and Kruskal-Wallis tests. Results: Sixty-seven patients (106 eyes) were found to meet the inclusion criteria, average age was 7.35 ± 4.61 years (1.00 to 17.00 years). Average targeted refraction was 1.69 ± 2.06 D (-0.38-+6.99 D), and spherical equivalent (actual postoperative refraction) was -0.90 ± 1.45 D (-4.38 to +2.75 D). There was statistically significant difference between preoperative targeted refraction and actual postoperative refraction (p < 0.001). Mean absolute prediction error (APE) in general was 1.34 ± 1.18 D, 1.22 ± 0.88 D (in short eyes), 1.52 ± 1.37 D (in moderate eyes), and 0.69 ± 0.52 D (in long eyes) (p = 0.202). Mean APE in age group <7 years old was 1.27 ± 1.18 D and ≥7 years-old was 1.42 ± 1.19 D (p = 0.429). Conclusion: SRK/T formula is fairly accurate in calculating IOL power in pediatric cataract surgery. Mean APE in this study was within the range of accurate mean APE in pediatric patients despite differentiated axial length and age.

Accuracy of Traditional and Modern Formulas for Intraocular Lens Power Calculation After Radial Keratotomy Using Standard Keratometry.

Purpose: To compare the accuracy of multiple traditional and modern intraocular lens (IOL) power calculation formulas in post-radial keratotomy (RK) patients undergoing cataract surgery. Methods: This retrospective case series included 50 eyes with prior RK who underwent routine phacoemulsification surgery with single-piece acrylic IOL implantation (A constant = 118.8). Outcomes of multiple formulas were calculated. Included formulas were SRK/T, Holladay 1, Holladay 2, Haigis, Barrett True-K, Haigis and Barrett True-K (target refraction of 0.50 D), Barrett Universal II, Kane, PEARL-DGS, Shammas no history, DK SRK/T, DK SRK/T (target refraction of 0.50 D), Double K (DK) Holladay 1, and DK Holladay 1 (target refraction of 0.50 D). Averages of multiple combinations of best-performing single formulas were calculated. Primary outcome is mean absolute error (MAE). Results: Haigis (with -0.50 D target refraction) and DK SRK/T showed the lowest mean and median absolute errors (MedAE) followed by Haigis, Barrett True-K, and Barrett True-K (with -0.50 D target refraction). Combinations of 3, 4, or 5 of best performing single formulas yielded good results with >60% of cases within +0.50 D of intended refraction and MAE around 0.50 D. The best performing formulas with flatter K readings were PEARL-DGS and Haigis (with additional -0.50 D target refraction) with MAE of 0.72 + 0.71 D and 0.70 + 0.70 D, respectively, followed by Barrett True-K (with intended -0.50 D target refraction) with MAE of 0.75 + 0.63 D. Conclusion: Using an average of three or more Haigis (with -0.50 D target refraction), the Barrett True-K, DK Holladay 1, and DK SRK/T formulas showed better outcomes than using a single formula for IOLMaster 700 standard K readings. The PEARL-DGS formula showed better accuracy in eyes with flatter K readings (<38 D).

Comparison of newer Kane formula with Sanders Retzlaff Kraff/Theoretical and Barrett Universal II for calculation of intraocular lens power in Indian eyes.

Purpose: To compare the efficacy of Kane formula with Sanders Retzlaff Kraff/Theoretical (SRK/T) and Barrett Universal II in predicting intraocular lens (IOL) power in Indian eyes. Methods: This retrospective study conducted in a tertiary care eye hospital. Data from patients having uneventful cataract surgery with Tecnis ZCB00 IOL implantation were obtained from Lenstar and electronic medical records. Eyes were divided into subgroups based on axial length (AL) as short (<22.0 mm), medium (22-24 mm), and long (>24 mm). The predicted refractive outcome for each patient was calculated after optimizing the lens constant. Prediction error was calculated by subtracting the predicted spherical equivalent from achieved spherical equivalent 1 week post-surgery. The mean absolute error (MAE) and median absolute error (MedAE) and percentage of eyes within 0.25, 0.5, 1, and 2 D were calculated for each formula. Friedman test, Cochrane Q test were used for statistical analysis. Results: Out of the 350 eyes included in the study, we found that without lens constant optimization, Barrett formula performed better than SRK/T and Kane (P < 0.0001). Over the entire range of axial lengths, Kane formula performed slightly inferior compared to Barrett and SRK-T, both of which performed equally well (P = 0.006). On subgroup analysis, Kane formula performed inferiorly for medium eyes as compared to the other two. No significant differences were noted between the formulae for short and long eyes. Conclusion: Kane formula did not outperform Barrett Universal II and SRK/T in Indian eyes.

Comparative Evaluation of Intraocular Lens Power Calculation Formulas in Children.

Introduction With the advent of newer microsurgical techniques, the results for cataract surgery have become quite promising. An accurate intraocular lens (IOL) power calculation is one of the most important factors in optimizing the results. The aim of this study was to evaluate the accuracy of four IOL power calculation formulas, namely, Barrett Universal II, Holladay 1, SRK/T and Hoffer Q, using optical biometry in children undergoing cataract surgery with primary IOL implantation. Methods This was a cross-sectional study. A total of 60 eyes of 42 children aged 5-16 years with congenital cataract and having undergone uneventful cataract surgery with IOL implantation were included in the study. Eyes were divided into three groups based on the axial length (AL): short (AL <22.00 mm), medium (AL 22-24.50 mm) and medium long (AL 24.50-26.00 mm). Optical biometry was used and the IOL power was calculated using the Barrett Universal II formula. The predicted postoperative refraction with the other three formulas, namely, SRK/T, Holladay 1 and Hoffer Q, using the same IOL power was estimated. This was compared with the actual postoperative refraction (spherical equivalent at 12 weeks) to give the absolute prediction error. The mean of all absolute prediction errors gave the mean absolute prediction error (MAE) values for each formula that were then compared. Results The MAE was 0.64 ± 0.73 for Barrett Universal II, 0.7 ± 0.72 for Holladay 1, 0.71 ± 0.65 for Hoffer Q and 0.8 ± 0.75 for SRK/T. Thus, Barrett Universal II had the lowest MAE across the whole group. The difference in the MAEs was not statistically significant. Conclusion Barrett Universal II had the lowest MAE and thus was predictable for the highest number of eyes in our study, although this was not statistically significant (p=0.176).

A Comparative Study on Accuracy of SRK-T And Haigis Formulas in IOL Power Calculation in Axial Myopes Undergoing Cataract Surgery.

Background and Objective: It has been a significant challenge since the advent of intraocular lens to give the best postoperative visual acuity and prevent refractive surprises due to biometry error. Among myopic eyes, it has been a debate among the various formulas introduced and their efficacy to prevent postoperative refractive surprises. Hence, the need for an accurate formula in high myopic eyes is obligatory. Objectives of the Study: To compare the accuracy of SRK-T and Haigis formulas in IOL power calculation in axial myopic eyes undergoing cataract surgery. Methods: A total of 50 cases with axial length >24 mm were taken up for the study and were examined in detail and error between both formulas were assessed. Results: The mean age of the subjects in the study was 53.50 ± 16.12 years; 27 were males, and 23 were females. The majority of patients had PSC + NS II. Seven out of 50 cases had posterior staphyloma. Most of the patients had average K value in the 44-46-D range. AL of most of the patients (66%) was between 24 and 26 mm. The majority of patients had IOL power >15 D, and 82% (41 eyes) were found to have no post-op complications. Four eyes had severe iritis, and five eyes had striate keratopathy. At the follow-up at 6th week postoperatively, 82% were found to have 6/6-6/9 vision on Snellen's chart. Four eyes had 6/12-6/24 post-op vision, mainly attributed to primary PCO. Five eyes (10%) had <6/24 post op vision at the end of 1 week due to the presence of posterior staphyloma. A higher percentage of eyes in the SRK/T group had a mean error >0.5 D. Upon comparing the mean error between the two groups, P was 0.005; hence, the results are statistically very significant, showing that Haigis formula is better than SRK/T formula in achieving target refraction (-1) in myopic eyes undergoing phacoemulsification. Interpretation and Conclusion: Our study shows that Haigis formula was better than SRK/T formula for achieving the target postoperative refraction in high axial myopes.

Quantitative biometric cutoffs for the choice of the intraocular lens power calculation formula for a recently introduced nondiffractive extended depth-of-focus intraocular lens.

PURPOSE: This study aimed to analyze biometry values cutoffs for the choice of the best intraocular lens power calculation formula for AcrySof IQ Vivity intraocular lens. METHODS: The study was designed as interventional case series with 3 months of follow-up. Intraocular lens power calculation formulas included Barrett Universal II and SRK/T. The first was adopted for the intraocular lens power choice. The quantitative analysis focused on the identification of specific biometric cutoffs considering axial length, anterior chamber depth, and corneal powers. We included only the dominant eye in the statistical analysis. RESULTS: One hundred and eight eyes of 54 patients (23 males; mean age 62 ± 5 years) with no ocular diseases were included. Best-corrected visual acuity improved from 0.3 ± 0.2 to 0.0 ± 0.0 logMAR. All the eyes reached spectacles-free far and intermediate visions; a spherical addition of + 1.0D was necessary to adjust near vision. We identified significant quantitative cutoffs based on axial length and anterior chamber depth. Barrett Universal II resulted the best formula for eyes disclosing an axial length >25 mm, whereas SRK/T turned out to be the best choice for the eyes characterized by an anterior chamber depth <2.8 mm. Our analysis disclosed an overall sensitivity of 0.8 and a specificity of 0.7 (p < 0.01). CONCLUSIONS: Axial length and anterior chamber depth influence the choice of Barrett Universal II and SRK/T formulas. Quantitative biometric cutoffs may be useful to discriminate the best formula to be adopted.

Accuracy of Six Intraocular Lens Power Calculations in Eyes with Axial Lengths Greater than 28.0 mm.

The purpose of this study was to compare the accuracy of several intraocular (IOL) lens power calculation formulas in long eyes. This was a single-site retrospective consecutive case series that reviewed patients with axial lengths (AL) > 28.0 mm who underwent phacoemulsification. The Wang−Koch (WK) adjustment and Cooke-modified axial length (CMAL) adjustment were applied to Holladay 1 and SRK/T. The median absolute error (MedAE) and the percentage of eyes with prediction errors ±0.25 diopters (D), ±0.50 D, ±0.75 D, and ±1.00 D were used to analyze the formula's accuracy. This study comprised a total of 35 eyes from 25 patients. The Kane formula had the lowest MedAE of all the formulas, but all were comparable except Holladay 1, which had a significantly lower prediction accuracy with either AL adjustment. The SRK/T formula with the CMAL adjustment had the highest accuracy in predicting the formula outcome within ±0.50 D. The newer formulas (BU-II, EVO, Hill-RBF version 3.0, and Kane) were all equally predictable in long eyes. The SRK/T formula with the CMAL adjustment was comparable to these newer formulas with better outcomes than the WK adjustment. The Holladay 1 with either AL adjustment had the lowest predictive accuracy.

Refractive error after combined phaco-vitrectomy: A multicentric study.

PURPOSE: To study the post-operative refractive error (RE) of patients undergoing combined phaco-vitrectomy and to find out which intraocular lens (IOL)-power formula had the best refractive outcomes. METHODS: In this retrospective multicentric study we compared the preoperative expected target with the postoperative RE of patients undergoing combined phaco-vitrectomy due to vitreomacular traction, macular pucker, full thickness macular hole or lamellar macular hole. A multinomial logistic regression was performed to compare the postoperative REs and the differences between expected and postoperative REs among the SRK-T, Olsen's and Holladay-2 formulas. The correlation between the difference in REs and IOL-power was also studied. RESULTS: Sixty-seven eyes with a mean axial length of 23.73 ± 1.21 mm were included. Forty-two (63%), 14 (21%) and 11 (16%) eyes were implanted with an IOL that was calculated respectively with SRK-T, Olsen's and the Holladay-2 formula. The mean preoperative expected- and post-operative REs were -0.16 ± 0.12D and -0.48 ± 0.17, respectively (p = 0.045). SRK-T and Holladay-2 formulas led to a significant myopic shift whereas Olsen's caused a significant hyperopic error, independently from the IOL power. CONCLUSION: Independently from the IOL power, none of the analyzed formulas is precise at calculating the post-operative RE.