Mean Numerical Error Research Articles

Accuracy of intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in short and long eyes.

To compare the accuracy of intraoperative wavefront aberrometry using the ORA VLynk system with different biometry-based formulas in short and long eyes after cataract surgery. This prospective study considered 48 eyes with axial lengths of <22.1 mm and 48 eyes with axial lengths of >25.0 mm. All eyes were implanted with the monofocal AcrySof IQ IOL, the power being determined using the ORA VLynk. The postoperative spherical equivalent (SE) at 3 months was compared to that predicted preoperatively using the SRK/T, Hoffer Q, Haigis, Holladay 2, Barrett Universal II, and Barrett True K formulas and intraoperatively using the ORA VLynk. Mean numerical and absolute errors and the percentage of eyes within ±0.50 D/1.00 D of their target were obtained. For long eyes, the mean absolute error values were 0.35, 0.52, 0.34, 0.30, 0.29, 0.27, and 0.24D for SRK/T, Hoffer Q, Haigis, Holladay 2, Barrett Universal II, Barrett True K, and ORA VLynk, respectively (p < 0.001). These values were 0.55, 0.45, 0.49, 0.40, 0.44, 0.44 and 0.50 D for short eyes, respectively (p < 0.001). The proportions of long eyes within ±0.50 D of the target were 77.08, 50, 75, 85.42, 83.33, 79.17, and 87.50%, respectively; and 50, 66.67, 60.42, 66.67, 60.42, 60.42, and 58.33%, respectively, for short eyes. The ORA VLynk performs better than all biometry-based formulas in long eyes and, in short eyes, it is as effective as SRK/T, Haigis, Barrett Universal II, and Barrett true K, with the Hoffer Q and Holladay 2 being the most accurate; however, the differences between the calculation methods were small. Identifier DRKS000028106.

Performance of IOL calculation formulas that use measured posterior corneal power in eyes following myopic laser vision correction.

To compare the predictive accuracy of the biometer-embedded Barrett True-K TK and new total corneal power methods of intraocular lens (IOL) power calculation in eyes with prior laser vision correction (LVC) for myopia. Academic clinical practice. Retrospective case series. IOL power formulas were assessed using measurements from a swept-source optical coherence biometer. Refractive prediction errors were calculated for the Barrett True-K TK, EVO 2.0, Pearl-DGS, and HofferQST, which use both anterior and posterior corneal curvature measurements. These were compared with the Shammas, Haigis-L, Barrett True-K No History (NH), optical coherence tomography, and 4-formula average (AVG-4) on the ASCRS postrefractive calculator, and to the Holladay 1 and 2 with non linear axial length regressions (H1- and H2-NLR). The study comprised 85 eyes from 85 patients. Only the Barrett True-K TK and EVO 2.0 had mean numerical errors that were not significantly different from 0. The EVO 2.0, Barrett True-K TK, Pearl-DGS, AVG-4, H2-NLR, and Barrett True-K NH were selected for further pairwise analysis. The Barrett True-K TK and EVO 2.0 demonstrated smaller root-mean-square absolute error compared with the Pearl-DGS, and the Barrett True-K TK also had a smaller mean absolute error than the Pearl-DGS. The Barrett True-K TK and EVO 2.0 formulas had comparable performance to existing formulas in eyes with prior myopic LVC.

Accuracy of intraoperative aberrometry versus modern preoperative methods in post-myopic laser vision correction eyes undergoing cataract surgery with capsular tension ring placement

PurposeTo assess the accuracy of intraoperative wavefront aberrometry (IWA) versus modern intraocular lens formulas in post-myopic laser vision correction (LVC) patients undergoing cataract surgery with capsular tension ring placement.MethodsThis is a retrospective chart review conducted at an academic outpatient center. All post-myopic LVC eyes undergoing cataract surgery with IWA from a single surgeon from 05/2017 to 12/2019 were included. All patients received a capsular tension ring (CTR). Mean numerical error (MNE), median numerical error (MedNE), and percentages of prediction error within 0.50D, 0.75D, and 1.00D were calculated for the above formulas.ResultsTwenty-seven post-myopic LVC eyes from 18 patients were included. In post-myopic LVC, MNE with Optiwave Refractive Analysis (ORA), Barrett True K (BTK), Haigis, Haigis-L, Shammas, SRK/T, Hill-RBF v3.0, and W-K AL-adjusted Holladay 1 were + 0.224, − 0.094, + 0.193, − 0.231, − 0.372, + 1.013, + 0.860, and + 0.630 (F = 8.49, p < 0.001). MedNE were + 0.125, − 0.145, + 0.175, + 0.333, + 0.333, + 1.100, + 0.880, and + 0.765 (F = 7.89, p < 0.001), respectively. BTK provided improved accuracy in both MNE (p < 0.001) and MedNE (p = .033) when compared to ORA in pairwise analysis. If the ORA vs. BTK-suggested IOL power were routinely selected, 30% and 15% of eyes would have projected hyperopic outcomes, respectively (p = 0.09).ConclusionsOur study suggests that in post-myopic LVC eyes undergoing cataract surgery with CTRs, BTK performed more accurately than ORA with regard to accuracy and yielded a lower percentage of eyes with hyperopic outcomes. Haigis, Haigis-L, and Shammas yielded similar results to ORA with regard to accuracy and percentage of eyes with hyperopic outcomes. On average, Shammas and Haigis-L suggested IOLs that would yield outcomes more myopic than expected when compared to BTK.

Accuracy of Different Intraocular Lens Calculation Formulas in Patients with High Axial Myopia

Background The two main problems encountered in calculation of intra ocular lens power are the measurement of the proper axial length (AL), and the lack of accuracy of the available formulas that calculate the power of the intra ocular lens in cases of eyes with high axial length. Aim of the Work To compare the accuracy of intraocular lens (IOL) calculation formulae (Holladay I, Haigis, SRK/T, Hoffer Q, Holladay II, and Barrett Universal II) in the prediction of postoperative refraction for eyes with AL 26.0 mm or more. Patients and Methods A prospective study was carried on forty-seven eyes of forty-seven patients. All the patients were managed at Ain Shams University Hospitals in cooperation with a specialized centre between April 2019 and March 2020. Results Mean absolute error (MAE) was calculated for each formula showed that the least MAE is for Barrett Universal II formula. SRK/T formula is the 2nd lower MAE followed by Haigis formula and the last is Holladay II formula. The scatter plots between AL and absolute error from each of the six calculations formulae was done and showed that Barrett universal II has negative correlation with AL. As for SRK/T and Haigis formulae there is a linear correlation. Numerical Predictive Error showed that SRK/T formula had the lowest mean numerical error followed by Haigis formula then Barrett Universal II and last came Holladay II formula. Conclusion for high axial myopic eyes, the Barrett Universal II formula is the best in this group of patients and provide the lowest mean absolute error, highest percentage of eyes within ≤ ± 0.50 D and the lowest risk of refractive surprise compared to other IOL power calculation formulae. Then comes Haigis and SRK/T formulae which performed similarly and provide a good predictable outcome then at last came Holladay II formula.

Comparison of Keratoconus Specific to Standard IOL Formulas in Patients With Keratoconus Undergoing Cataract Surgery.

To assess the performance of multiple intraocular lens (IOL) formulas in eyes with keratoconus. Eyes with stable keratoconus scheduled for cataract surgery with biometry measurements on the Lenstar LS900 (Haag-Streit) were included. Prediction errors were calculated using 11 different formulas, including two with keratoconus modifiers. Primary outcomes compared standard deviations, mean and median numerical errors, and percentage of eyes within diopter (D) ranges across all eyes with subgroup analysis according to anterior keratometric values. Sixty-eight eyes from 44 patients were identified. In eyes with keratometric values less than 50.00 D, prediction error standard deviations ranged from 0.680 to 0.857 D. Percentages of eyes within ±0.50 D of target ranged from 57.89% to 73.68% with no statistical differences among formulas. In eyes with a keratometric value of more than 50.00 D, prediction error standard deviations ranged from 1.849 to 2.349 D and were not statistically different with heteroscedastic analysis; percentages of eyes within ±0.50 D of target ranged from 0% to 18.18% with no statistical differences among formulas. Only keratoconus-specific formulas (Barrett-KC and Kane-KC) and the Wang-Koch axial length adjustment version of SRK/T resulted in median numerical errors not significantly different than 0, regardless of keratometric values. In keratoconic eyes, IOL formulas are less accurate than in normal eyes and result in hyperopic refractive outcomes that increase with steeper keratometric values. Using keratoconus-specific formulas and the Wang-Koch axial length adjustment version of SRK/T for axial lengths of 25.2 mm or greater improved IOL power prediction accuracy compared to other formulas. [J Refract Surg. 2023;39(4):242-248.].

Modification of the Barrett Universal II formula by the combination of the actual total corneal power and virtual axial length.

This study aims to investigate whether a combination of the total corneal power (TCP) and virtual axial length (AL) based on Gaussian optics makes the refractive prediction accuracy of the Barrett Universal II (BUII) formula better than the conventional anterior keratometry (K) and axial length. The TCP and the virtual AL were calculated in two ways: the corneal index strategy and the TK index strategy. The former uses the corneal refractive index n1 as a variable, and the latter uses the TK index nx as a variable. In a dataset of 225 eyes, the calculated TCP and the virtual AL were input into the BUII formula along with the anterior chamber depth, lens thickness, and white-to-white measured with the IOLMaster 700, and the refractive prediction accuracy was evaluated by the mean numerical prediction error (MNE), standard deviation (SD), mean absolute prediction error (MAE), median absolute prediction error (MedAE), percentages of eyes with prediction error (PE) within ± 0.50 diopter, and IOL formula performance index (FPI). The refractive prediction outcomes also underwent subgroup analyses and were compared with those of the anterior keratometry-based BUII-K of the IOLMaster 700. In the corneal index strategy, the FPI had the highest value at approximately n1 = 1.346. In the TK index strategy, the FPI had the highest value at approximately nx = 1.3858. There was no tendency for the refractive prediction outcomes of the BUII-n1 = 1.346 and the BUII-nx = 1.3858 to be inferior to those of the BUII-K, particularly in the medium range of subgroups. The combination of the actual TCP and the virtual AL based on Gaussian optics may lead to a better refractive prediction accuracy of the BUII formula than that of BUII-K.

Lower refractive prediction accuracy of total keratometry using intraocular lens formulas loaded onto a swept-source optical biometer.

To compare refractive outcomes calculated using intraocular lens (IOL) power calculation formulas loaded onto the IOLMaster 700 with the employment of anterior keratometry (K) and total keratometry (TK). A total of 225 eyes of 225 patients underwent uneventful cataract surgery and implantation of a single model of nontoric monofocal IOL by a single surgeon. All eyes underwent preoperative ocular biometric measurements with the IOLMaster 700. Refractive outcomes, including the mean numerical prediction error (MNE); standard deviation (SD); adjusted mean absolute prediction error (MAE); adjusted median absolute prediction error (MedAE); percentages of eyes with adjusted prediction error (PE) within ± 0.25, ± 0.50, ± 0.75, and ± 1.00 diopter; and IOL Formula Performance Index (FPI), were compared between the K-based formula and the TK-based formula of Barrett Universal II (BUII), Haigis, SRK/T, Holladay 2, and Hoffer Q. Axial length (short, medium, and long) subgroup analyses and anterior and posterior keratometry (flat, medium, and steep) subgroup analyses were conducted. The K-based formula performed better than the TK-based formula in the accuracy of refractive prediction of each IOL calculation formula: BUII-K (FPI 0.690), BUII-TK (0.677), Haigis-K (0.617), Haigis-TK (0.584), SRK/T-K (0.608), SRK/T-TK (0.595), Holladay 2-K (0.419), Holladay 2-TK (0.406), Hoffer Q-K (0.364), and Hoffer Q-TK (0.356). The subgroup analyses of refractive prediction outcomes showed that TK influenced the refractive outcomes in eyes with relatively normal ranges of axial length and anterior keratometry. Using TK instead of K leads to lower refractive prediction accuracy of the IOL power calculation formulas loaded on the IOLMaster 700.

Comparison of the Accuracy of Intraoperative Aberrometry in Intraocular Lens Implantation Between Myopic Eyes with Emmetropia and Myopia Targets.

PurposeTo compare the accuracy of intraoperative aberrometry (IA) for predicting postoperative refraction between eyes with emmetropia and myopia targets.Patients and MethodsThis retrospective analysis included patients with axial myopia (axial length ≥ 25.0 mm) who underwent uncomplicated phacoemulsification cataract surgery with IA to achieve emmetropia (plano to −0.5 D) or intentional myopia (−2.5 D to −5.0 D). Preoperative ocular biometry was performed in all eyes using an IOLMaster. Refractive prediction errors in IA were compared between eyes with emmetropia and myopia targets. Refractive prediction errors in IA for both groups were also compared with those predicted by intraocular lens power calculation formulas including the SRK/T, Holladay 1, Hoffer Q, Holladay 2, Haigis, and Barrett Universal II formulas.ResultsThirty-nine eyes of 39 patients with a target of emmetropia and 22 eyes of 22 patients with a target of intentional myopia were included in the final analysis. The mean numerical error was significantly different from zero (myopic trend) in myopia-targeted eyes (−0.37 ± 0.54 D, one-sample t-test, P = 0.004, 95% confidence interval: −0.61 to −0.14), while it was close to zero in emmetropia-targeted eyes. The mean absolute error was significantly smaller in emmetropia-targeted eyes (0.28 ± 0.27 D) than in myopia-targeted eyes (0.51 ± 0.41 D, P = 0.01). IA was revealed as the most accurate method for predicting postoperative refraction in eyes with emmetropia target, whereas Barrett Universal II formula was found to be the most accurate for eyes with myopia target.ConclusionIn patients with axial myopia, the performance of IA was altered when targeting intentional myopia compared with emmetropia. Myopic shift in the refractive outcome should be considered when IA is used to target myopia.

Assessing Accuracy of Okulix Ray-Tracing Software in Calculating Intraocular Lens Power in the Long Cataractous Eyes.

Purpose:To investigate the accuracy of Okulix ray-tracing software in calculating intraocular lens (IOL) power in the long cataractous eyes and comparing the results with those obtained from Kane, Holladay 1 with optimized constant, SRK/T with optimized constant, Haigis with optimized constant, and Barret Universal 2 formulas.Methods:The present study evaluates the refractive results of cataract surgery in 85 eyes with axial length > 25 mm and no history of ocular surgery and corneal pathology. IOL power calculation was performed using the Okulix software. The performances of Okulix software in comparison with the five other formulas were evaluated by predicted error, mean absolute error, and mean numerical error 6 months after surgery.Results:The mean calculated IOL power by the Okulix software was +13.48 ± 4.19 diopter (D). The mean of the 6-month postoperative sphere and spherical equivalent were +0.18 ± 0.63 and -0.34 ± 0.78 D, respectively. Also, the 6-month spherical equivalent in 56.6% and 80% of eyes were within ±0.05 and ±1.00 D, respectively. The predicted error (P < 0.001) and the mean numerical error (P < 0.001) were different between the six studied methods; however, we were not able to find any significant differences in the mean absolute error among six studied methods (P: 0.211).Conclusion:The present study showed acceptable performance of the Okulix software in IOL power calculation in long eyes in comparison with the other five methods based on the postoperative refractive error, calculated mean absolute error, and mean numerical error.

Accuracy of Intraocular Lens Power Calculation Formulas in Myopic Eyes with Target Refractions of Emmetropia and Intentional Myopia.

PurposeTo compare the accuracy of the intraocular lens (IOL) power calculation formulas for predicting the postoperative refraction in eyes with a target of emmetropia or intentional myopia.Patients and MethodsThis is a retrospective study conducted at Kobe City Eye Hospital, Kobe, Japan. Fifty eyes of 50 patients with axial myopia who underwent uncomplicated phacoemulsification and single-type IOL implantation for a target of emmetropia (plano to −0.5 D) or intentional myopia (−2.0 D to −3.0 D) were selected. Preoperative ocular biometry was performed using IOLMaster700 in all eyes. Refractive prediction errors of 6 IOL formulas integrated into IOLMaster700 were compared between eyes with a target of emmetropia and intentional myopia.ResultsThe mean numerical errors of SRK/T (Sanders, Retzlaff, and Kraft/theoretical), Holladay 1, Hoffer Q, and Holladay 2 significantly differed between the two groups (p < 0.001, p = 0.008, 0.02, and 0.007, respectively). The values for mean numerical errors in eyes with a target of intentional myopia were smaller, showing relatively myopic outcome, as compared with those in eyes with a target of emmetropia. In eyes with a target of emmetropia, the mean numerical errors of Holladay 1 (p < 0.001, 95% confidence interval [CI]: 0.32 to 0.63), Hoffer Q (p = 0.001, 95% CI: 0.12 to 0.42), and Barrett Universal II (p = 0.007, 95% CI: 0.06 to 0.35) were significantly different from zero (hyperopic trend). Furthermore, in eyes with a target of intentional myopia, the mean numerical error of SRK/T (p = 0.001, 95% CI: −0.61 to −0.17) and Holladay 2 (p = 0.023, 95% CI: −0.43 to −0.04) were significantly different from zero (myopic trend).ConclusionIn patients with axial myopia, some IOL formulas may show a myopic trend in the refractive outcome when targeting intentional myopia as compared to emmetropia.

Comparison of accuracy between ultrasound B scan and partial coherence interferometry (IOL master) in IOL (intraocular lens) power calculation

Aims and Objectives: To compare the accuracy of ultrasound A scan biometry and IOL master (PCI) biometry in intraocular power calculation, by doing a comparative study of difference in biometry by conventional methods and optical biometry (IOL master). Materials and Methods: Place of study: Aravind Eye Hospital, India. Design of Study: Prospective, non randomised, clinical study. Study Group and Duration: The study involves patients who underwent cataract surgeries at Aravind Eye Hospital, Tirunelveli during the specified time period. The IOL power and predicted refractive outcome were calculated for every patient by both the methods, A scan ultrasound Biometry IOL master (Partial Coherence interferometry) Inclusion Criteria: Only those patients in whom it was possible to secure a reliable IOL master reading (on the basis of good SNR), were included. Results: In a 12 month period, 337 eyes were consecutively enrolled in the study. Both ultrasound A scan and partial coherence interferometry was performed and IOL power implanted as per the IOL master. Inclusion criterion and exclusion criterion used as mentioned. The difference in between the final and predicted refraction is compared for both the groups. The overall Mean absolute error was 0.402 ± 0.407 with the ultrasound A scan & 0.388 ± 0.406 for the IOL master, with the probability value (p-value) 0.3802. The mean numerical error (the difference between the refractive outcome and the predicted spherical equivalent) is -0.226 ± 0.526 (min -2.66 & max 2.06) for the ultrasound scan group and -0.217 ± 0.518 (min -2.41 & max 2.10) for the IOL master group, with the probability value (p-value) being 0.514. We got a comparative result in our study, though not significant, but it is more in favour of IOL master (PCI) as per the mean absolute error and mean numerical error calculations. When analysing the Mean Axial Length readings, the findings were almost similar, with an insignificant p-value. Keywords: Biometry

Comparison of the accuracy of intraocular lens power calculation formulas for eyes after corneal refractive surgery.

In cataract surgery, calculating intraocular lens (IOL) power in patients who have previously received corneal refractive surgery on the same eye presents a clinical challenge. This study aims to compare the accuracy of the Haigis-L, Barrett True-K, and Shammas-PL formulas in predicting the IOL power in eyes following corneal refractive surgery. This study analyzed 32 eyes belonging to 28 patients who underwent cataract surgery and IOL implantation after previously undergoing myopic corneal refractive surgery. The IOL power was calculated using the Haigis-L, Barrett True-K, and Shammas-PL formulas, and the accuracy of the three formulas was compared. The Haigis-L, Barrett True-K, and Shammas-PL formulas had a mean arithmetic IOL prediction error of -0.65, -0.39, and -0.46, respectively. The mean numerical errors of the three formulas were significantly different from zero (P<0.001). The smallest median absolute refraction prediction error (median =0.40) belonged to the Barrett True-K formula, which was significantly smaller than that of the Haigis-L formula (median =0.57, P<0.05) but similar to that of the Shammas-PL formula (median =0.49, P>0.05). There was no significant difference in the percentage of eyes within either ±0.50 D or ±1.00 D of the predicted refraction error across the three formulas. The Barrett True-K formula can predict IOL power in eyes that have previously undergone myopic corneal refractive surgery better than the Haigis-L formula.

Comparative effects of various types of toric intraocular lenses on astigmatism correction

BackgroundCurrently, various types of toric intraocular lenses (IOL) have been manufactured and can be divided into three types according to the location of correction component; front-toric IOL (correction on anterior IOL surface), back-toric IOL (correction on posterior IOL surface), and bi-toric IOL (correction on both anterior and posterior IOL surfaces). In this study, we aimed to investigate the effectiveness of reducing corneal astigmatism of either normal or post-penetrating keratoplasty (PKP) corneas according to the type of implanted toric IOLs.MethodsMedical records were retrospectively reviewed in 370 patients who had undergone phacoemulsification with posterior chamber toric IOL insertion (front-toric IOL, back-toric IOL or bi-toric IOL). Subjects were divided into 2 groups; subjects who had no history of corneal disease with corneal astigmatism more than 1.00 diopters (D) (G1) and subjects who received previous PKP with all corneal sutures removed and had corneal astigmatism more than 1.25 D (G2). Preoperatively intended target from SRK/T was evaluated. Refractive astigmatism and its vector analysis (J0, J45), mean numerical error (MNE) and mean absolute error (MAE) were assessed at least a month after cataract surgery.ResultsMean preoperative corneal astigmatisms were 2.2 D and 4.0 D in G1 and G2, respectively. There was significant reduction of mean postoperative refractive astigmatism to 0.89 D in G1 and to 2.33 D in G2. In G1, bi-toric IOL showed significantly more improved refractive astigmatism than back-toric IOL. In G2, no difference in refractive astigmatism according to toric IOL type was observed. While G2 showed no difference in MNE among toric IOLs, in G1, bi-toric IOL showed significant hyperopic shift compared to back-toric IOL. In both groups, there was no significant difference in MAE according to type of IOL. No postoperative complications were observed.ConclusionOur study suggests that all types of toric IOL are beneficial in correcting astigmatism of normal and post-PKP corneas. Noticeably, bi-toric IOL showed significantly better results in refractive astigmatism than back-toric IOL in normal cornea. However, bi-toric IOL showed a more hyperopic shift compared to back-toric IOL. Among post-PKP corneas, all types of toric IOL showed similar results.

Comparison of six methods for the intraocular lens power calculation in high myopic eyes

The aim of this study was to compare the accuracy of Barrett Universal II and Hill-Radial Basis Function with other four popular formulas for the calculation of intraocular lens power in high myopic eyes. A total of 56 eyes with an axial length of more than 26.0 mm were retrospectively reviewed. Six intraocular lens power calculation methods, including Barrett Universal II, Hill-Radial Basis Function, SRK/T, Haigis, Holladay 2 and Holladay 1, were evaluated. The difference between the postoperative actual refraction and the refraction predicted by the six methods was evaluated as the prediction error. The absolute prediction error was also calculated. The mean numerical prediction error ± standard deviation of the six intraocular lens power calculation methods, in order of lowest to highest, was Barrett Universal II (0.37 ± 0.54 D), Hill-Radial Basis Function (0.40 ± 0.56 D), SRK/T (0.44 ± 0.56 D), Haigis (0.53 ± 0.54 D), Holladay 2 (0.88 ± 0.62 D) and Holladay 1 (1.00 ± 0.60 D). The median absolute errors predicted by the Barrett (0.46 D), Hill-Radial Basis Function (0.47 D), SRK/T (0.53 D) and Haigis (0.58 D) were significantly lower than those of the Holladay 1 (0.90 D) and Holladay 2(1.10 D; all p < 0.001). There was no significant difference among the median absolute errors of Barrett, Hill-Radial Basis Function, SRK/T and Haigis (all p > 0.05). The prediction errors differed for each method in the selection of intraocular lens power for the long eyes. In terms of overall accuracy, the Barrett Universal II formula provided the lowest prediction error. The Hill-Radial Basis Function method was comparable to the theoretical formulas, such as SRK/T and Haigis.

Relationship between early structural changes at cornea incision sites and surgical outcomes after phacoemulsification.

To assess the early structural changes at clear corneal cataract incision sites and surgical outcomes using anterior segment optical coherence tomography (AS-OCT). We evaluated 80 eyes of 59 patients who underwent phacoemulsification with a clear corneal incision. All incisions were evaluated 1wk, 1, and 3mo postoperatively using AS-OCT and analyzed regarding angle, length of the incision, maximal corneal thickness at the incision, and if present, corneal endothelial gap length and incision gap area. The patients were divided into two groups according to whether or not an endothelial gap was present at 1wk postoperatively (endothelial gap, group 1; no endothelial gap, group 2). We analyzed the difference in patient and surgical factors between the two groups, and compared the surgical outcome and the refractive outcome. An endothelial gap was observed in 56 (70.0%) of 80 eyes at 1wk postoperatively but not at 3mo postoperatively. The mean patient age was significantly higher in group 1 than in group 2. The longer the length of the corneal incision and the steeper the incision angle, the greater the length and area of the endothelial gap. In group 1, the mean change in mean keratometry of the anterior cornea was significantly greater than in group 2, and the spherical equivalent (SE) and mean numerical error indicated significant myopic changes at 1wk postoperatively. The risk of an endothelial gap increases with patient age and a long corneal incision and steep incision angle. The presence of an endothelial gap after surgery may affect the early postoperative corneal curvature and SE.

Comparison of intraocular lens power calculation formulas in Chinese eyes with axial myopia

To assess the accuracy of intraocular lens (IOL) power calculation formulas in Chinese eyes with axial lengths (ALs) longer than 26.0mm. Department of Cataract Surgery, Shanxi Eye Hospital, China. Prospective case series. This study evaluated (1) two new formulas (Barrett Universal II and Hill-RBF 2.0), (2) three vergence formulas (Haigis, Holladay 1, and SRK/T), and (3) the original and modified Wang-Koch AL adjustment formulas with Holladay 1 and SRK/T. The User Group for Laser Interference Biometry lens constants were used for IOL power calculation. The refractive prediction error was calculated by subtracting the predicted refraction from the actual refraction postoperatively. The mean numerical error (MNE), percentage of eyes with hyperopic outcomes, and mean absolute error (MAE) were determined. The study comprised 136 eyes. The Barrett and Hill-RBF formulas had MNEs close to zero (-0.09 D to 0.03 D), the Haigis, Holladay 1, and SRK/T produced hyperopic MNEs (0.25 to 0.70 D), and the original and modified Wang-Koch AL adjustment formulas induced myopic MNEs (-0.48 to -0.22 D). The original Wang-Koch formulas produced significantly lower percentages of eyes with hyperopic outcomes (15% to 18%) than all other formulas (28% to 91%). There were no significant differences in MAEs between the Barrett, Hill-RBF, Haigis, and original and modified Wang-Koch adjustment with the Holladay 1 (0.32 to 0.41 D). The performances of the Barrett and Hill-RBF were comparable in long eyes. The incidence of hyperopic outcome with the Wang-Koch AL adjustment formula was significantly lower than other formulas.

Intraoperative aberrometry versus preoperative biometry for intraocular lens power selection in short eyes

To compare the accuracy of preoperative biometry-based formulas to intraoperative aberrometry (IA) with respect to predicting refractive outcomes after cataract surgery in short eyes. Private practice and community-based ambulatory surgery center. Retrospective consecutive case series. Eyes with an axial length (AL) shorter than 22.1mm underwent cataract extraction and intraocular lens (IOL) implantation. The predicted residual refractive error was calculated preoperatively using Hoffer Q, Holladay 2, Haigis, Barrett Universal II, and Hill-RBF formulas and intraoperatively using IA. The postoperative spherical equivalent (SE) was compared with the predicted SE to evaluate the accuracy of each aforementioned method. Fifty-one eyes from 38 patients met criteria to be included in the analysis. Without optimizing the formulas specifically for short eyes, the mean numerical errors (MNEs) associated with Hoffer Q, Holladay 2, Haigis, Barrett Universal II, Hill-RBF, and IA were -0.08 (95% confidence interval [CI], -0.30 to 0.13), -0.14 (95% CI, -0.35 to 0.07), +0.26 (95% CI, 0.05 to 0.47), +0.11 (95% CI, -0.10 to 0.32), +0.07 (95% CI, -0.14 to 0.28), and +0.00 (95% CI, -0.21 to 0.21), respectively (P<.001). The proportion of eyes within ±0.5 diopter (D) of the predicted SE were 49.0%, 43.1%, 52.9%, 52.9%, 60.8%, and 58.8%, respectively (P=.06). The prediction outcomes from IA were statistically better than Haigis, but not other formulas. When formula and IA predictions differed by 0.5 D or more, IA's ability to recommend a more emmetropic outcome was no better than chance (50%). Intraoperative aberrometry is not significantly different from the best preoperative biometry-based methods available for IOL power selection in short eyes.

Visual Performance after a Unilateral or Bilateral Implantation of Enlarged Depth-of-Focus Intraocular Lens in Patients with Cataract: A Prospective Clinical Trial.

Purpose To investigate visual performances after a unilateral or bilateral implantation of enlarged depth-of-focus intraocular lens in patients with cataract. Methods In this prospective study, uneventful phacoemulsification and TECNIS® Symfony intraocular lens implantation were performed in 20 eyes of 17 patients. At postoperative 1, 4, and 12 weeks, the logarithm of the minimal angle of resolution visual acuity at far, intermediate, and near distances and the spherical equivalent in manifest refraction and automated refraction were measured. A questionnaire was used to investigate glare, spectacle dependency, and satisfaction at 12 weeks. The mean numerical error and mean absolute error were compared between intraocular lens formulas to assess the best-fit formula. Results The logarithm of the minimal angle of resolution visual acuity significantly improved to 0.02 at far, 0.02 at intermediate, and 0.27 at near distances at 12 weeks (p < 0.05). Spherical equivalent was −0.79 D on automated refraction and was significantly lower than −0.26 D measured on manifest refraction. Patients' satisfaction score was 9.06, 8.94, and 6.65 for far, intermediate, and near distances, respectively. Near glasses were required in 5 patients and 2 patients complained of photic phenomenon. Visual performances were not significantly different between bilateral and unilateral implanted patients. No patients reported bilateral imbalance due to unilateral surgery. The mean numerical error was closest to 0 D using the Barrett Universal II formula. The mean absolute error was not significantly different between these formulas. Conclusion Unilateral or bilateral implantation of the enlarged depth-of-focus intraocular lens seems to be equally effective in improving visual performances in patients with cataract.

Precision of intraocular lens power prediction in eyes shorter than 22 mm: An analysis of 6 formulas

To analyze the precision of 6 intraocular lens (IOL) power calculation formulas in predicting refractive outcome in eyes with an axial length (AL) less than 22.0mm. Department of Ophthalmology, All India Institute of Medical Sciences, Raipur, India. Retrospective observational study. Patients with an AL less than 22.0mm were included in the study. If both eyes were eligible, a randomly selected eye was chosen. Optical biometry with partial coherence interferometry (PCI) was performed in all cases. Six formulas were analyzed: Barrett Universal II, Haigis, Hoffer Q, Holladay 2, RBF Method and SRK/T. The mean numerical error was defined as the difference between the actual postoperative spherical equivalent (SE) at the 1-month follow-up and the predicted postoperative SE. The median absolute error was calculated and compared between all 6 formulas after the zeroing of the mean numerical error by adjusting the lens constant individually for each formula. The study comprised 50 eyes of 50 patients. The Friedman test was applied to compare the median absolute errorbetween the 6 formulas after the zeroing of the mean numerical error. Post hoc analysis and Bonferroni correction for multiple comparisons showed no significant statistical difference between them. The Barrett Universal II, Haigis, Hoffer Q, Holladay 2, RBF method and SRK/T formulas were equally accurate in predicting the IOL power in eyes shorter than 22.0mm.

Сравнительная оценка попадания в рефракцию цели у трех монофокальных гибких интраокулярных линз

Purpose. The purpose of this study was to estimate a stability of hit at a target refraction using three types of monofocal IOL: AcrySof IQ (SN60WF), CT Aspira-aAy and Asphina 409M. Material and methods. This retrospective randomized study included 208 patients (208 eyes), which underwent micro-coaxial phacoemulsification. The algorithm in the calculation of IOL optical power was based on 4 formulas: Holladay 1, Haigis, Hoffer Q, SRK/T. Depending on the type of the implanted IOL the patients were divided into 3 groups: AcrySof IQ (SN60WF) – 42, Aspira-aAy – 98, Asphina 409M – 68. Three predicting errors were assessed 1-3 months after each surgery: the mean numerical prediction error (ME), the mean absolute prediction error (MAE), the median absolute prediction error (MedAE). Results. ME, MAE and MedAE were the following: -0.29, +0.01, -0.13; ±0.244, ±0.159, ±0.169 and 0.75, 0.5, 0.5 in IOLs IQ, Aspira and Asphina, respectively. There were detected no statistically significant differences between IOLs (p>0.05). The deviation of ±0.25 diopter in percentage of eyes with prediction errors was obtained in 76%, 77.5%, 77.9% of cases, a ±0.5 diopter deviation – in 85.7%, 92.8%, 89.7%, ±1.0 diopter – in 92.8%, 97.9%, 98.5%, and 2.0 diopter – in 97.6%, 100%, 100% after implantation of IOLs IQ, Aspira and Asphina respectively. Conclusion. All three types of monofocal IOLs have shown a high precision of hit in the target refraction.