OBJECTIVE: This study evaluates the accuracy of modern intraocular lens (IOL) calculation formulas using axial length (AL) data obtained by ultrasound biometry (UBM) compared to the third-generation SRK/T calculator.
METHODS: The study included 230 patients (267 eyes) with severe lens opacities that prevented optical biometry, who underwent phacoemulsification (PE) with IOL implantation. IOL power calculation according to the SRK/T formula was based on AL and anterior chamber depth obtained by UBM (Tomey Biometer Al-100) and keratometry on the Topcon KR 8800 autorefractometer. To adapt AL for new generation calculators - Barrett Universal II (BUII), Hill RBF ver. 3.0 (RBF), Kane and Ladas Super Formula (LSF) - the retinal thickness (0.20 mm) was added to the axial length determined by UBM, and then the optical power of the artificial lens was calculated. The mean error and its modulus value were used as criteria for the accuracy of IOL calculation.
RESULTS: A significant difference (p=0.008) in the mean IOL calculation error was found between the formulas. Pairwise analysis revealed differences between SRK/T (-0.32±0.58 D) and other formulas - BUII (-0.16±0.52 D; p=0.014), RBF (-0.17±0.51 D; p=0.024), Kane (-0.17±0.52 D; p=0.029), but not with the LSF calculator (-0.19±0.53 D; p=0.071). No significant differences between the formulas were found in terms of mean error modulus (p=0.238). New generation calculators showed a more frequent success in hitting target refraction (within ±1.00 D in more than 95% of cases) than the SRK/T formula (86%).
CONCLUSIONS: The proposed method of adding 0.20 mm to the AL determined by UBM allows using this parameter in modern IOL calculation formulas and improving the refractive results of PE, especially in eyes with non-standard anterior segment structure.
UNASSIGNED: Оценка точности современных формул расчета интраокулярных линз (ИОЛ) с использованием данных о длине переднезадней оси (ПЗО), полученных при ультразвуковой биометрии (УЗБ), по сравнению с калькулятором третьего поколения SRK/T.
UNASSIGNED: В исследование включено 230 пациентов (267 глаз) с выраженными помутнениями хрусталика, препятствовавшими выполнению оптической биометрии, которым была проведена факоэмульсификация (ФЭ) с имплантацией ИОЛ. Калькуляция оптической силы ИОЛ по формуле SRK/T основывалась на длине ПЗО и глубине передней камеры, полученных с помощью контактной УЗБ (Tomey Biometer Al-100) и кератометрии на авторефрактокератометре Topcon KR 8800. В целях адаптации ПЗО для калькуляторов нового поколения — Barrett Universal II (BUII), Hill RBF ver. 3.0 (RBF), Kane и Ladas Super Formula (LSF) — к определяемой с помощью УЗБ аксиальной длине добавлялась толщина сетчатки (0,20 мм), а затем вычислялась оптическая сила искусственного хрусталика. В качестве критериев точности расчета ИОЛ использовались средняя ошибка и модуль ее значения.
UNASSIGNED: Обнаружена значимая разница (p=0,008) в средней ошибке расчета ИОЛ между формулами. Попарный анализ выявил различия между SRK/T (–0,32±0,58 дптр) и другими формулами — BUII (–0,16±0,52 дптр; p=0,014), RBF (–0,17±0,51 дптр; p=0,024), Kane (–0,17±0,52 дптр; p=0,029), но не с калькулятором LSF (–0,19±0,53 дптр; p=0,071). Значимых различий между формулами по параметру модуля средней ошибки найдено не было (p=0,238). Калькуляторы новых поколений показали более частое попадание в рефракцию цели (в пределах ±1,00 дптр более чем в 95% случаев), чем формула SRK/T (86%).
UNASSIGNED: Предложенный метод добавления 0,20 мм к определяемой с помощью УЗБ длине ПЗО позволяет использовать данный параметр в современных формулах расчета ИОЛ и улучшать рефракционные результаты ФЭ, особенно в глазах с нестандартным строением переднего отрезка.

OBJECTIVE: To compare the accuracy of the Barrett II universal (BU II) formula, Hoffer-Q, and SRKT formulae following lensectomy and IOL implantation in a large pediatric cohort.
METHODS: Retrospective study of children who underwent lensectomy and IOL implantation between 2015 and 2023 at Hadassah-Hebrew University Medical Center, Jerusalem, Israel.
RESULTS: One hundred and fifty-one eyes of 104 children aged 6.0 ± 3.9 years were included. The mean prediction error (PE) was - 0.08 ± 1.54 diopters (D) with BU II, 0.24 ± 1.46 D with Hoffer-Q, and 0.71 ± 1.92 D with SRKT (P = 0.10). In eyes with axial length (AL) < 22 mm, BU II and Hoffer-Q had a smaller PE than SRKT (P = 0.024). In eyes with AL ≥ 22 mm, BU II had a smaller PE than Hoffer-Q (P = 0.048). In children 24 months or older at surgery, BU II had a smaller PE than SRKT and Hoffer-Q (P = 0.012). However, in younger children, no difference was found between the formulae (P = 0.61). For mean k-values ≥ 44.5 D, BU II and Hoffer-Q had a smaller PE than SRKT (P = 0.002). An absolute prediction error < 1.0 D was obtained with BU II in 66% of eyes and SRKT in 35% (P = 0.01).
CONCLUSIONS: The BU II formula performed well with a small prediction error. No significant difference in PE was detected overall between the formulae. However, only BU II demonstrated a stable prediction error at varying axial lengths, K-readings, and ages. As the biometric parameters of the developing eye change with growth, the BU II formula offers a reliable and stable option for pediatric IOL calculation.

OBJECTIVE: The proper choice of an intraocular lens (IOL) power calculation formula is an important aspect of phacoemulsification. In this study, the formulas most commonly used today are described and their accuracy is evaluated.
METHODS: This review includes papers evaluating the accuracy of IOL power calculation formulas published during the period from January 2015 to December 2022. The articles were identified by a literature search of medical and other databases (PubMed/MEDLINE, Crossref, Web of Science, SciELO, Google Scholar, and Cochrane Library) using the terms \"IOL formulas,\" \"Barrett Universal II,\" \"Kane,\" \"Hill-RBF,\" \"Olsen,\" \"PEARL-DGS,\" \"EVO,\" \"Haigis,\" \"SRK/T,\" and \"Hoffer Q.\" Twenty-nine of the most recent peer-reviewed papers in English with the largest samples and largest number of formulas compared were considered.
RESULTS: Outcomes of mean absolute error and percentage of predictions within ±0.5 D and ±1.0 D were used to evaluate the accuracy of the formulas. In most studies, Barrett achieved the smallest mean absolute error and PEARL-DGS the highest percentage of patients with ±0.5 D in short eyes, while Kane obtained the highest percentage of patients with ±0.5 D in long eyes.
CONCLUSIONS: The third- and fourth-generation formulas are gradually being replaced by more accurate ones. The Barrett Universal II among vergence formulas and Kane and PEARL-DGS among artificial intelligence-based formulas are currently most often reported as the most precise.

BACKGROUND: To investigate the possible effect of implantable collamer lens (ICL) V4c on ocular biometric measurements by a new biometer Pentacam-AXL and partial coherence interferometry (PCI)-based IOLMaster 500 and intraocular lens power calculation using fourth-generation formula.
METHODS: We retrospectively enrolled patients who underwent ICL (EVO-V4c, STAAR Surgical Co. Nidau, Switzerland) implantation surgery from September 2020 to November 2021. The Pentacam-AXL and IOLMaster 500 biometers were used to measure axial length (AL), anterior chamber depth (ACD), keratometry (K), white to white (WTW), and central corneal thickness (CCT) values before and at least 2 months after ICL V4c implantation. The IOL power was calculated using the Barrett Universal II formula.
RESULTS: The study included 45 eyes in 28 patients. There was a significant increase in ALs (average 0.03 ± 0.07 mm, p = 0.01) and a significant decrease of ACDs (average 0.19 ± 0.17 mm, p < 0.001) based on Pentacam-AXL. Similar changes in ALs and ACDs were also found in IOLMaster 500. In addition, the difference in WTWs in the two devices and that of CCTs in Pentacam-AXL were statistically significant. However, the preoperative and postoperative K1 and K2 were separately comparable using either device. The IOL power calculated by the Barrett Universal II formula did not change significantly either by the software built in Pentacam-AXL or by manually putting the parameters of the IOLMaster 500 into the formula manually (p = 0.058, p = 0.675, respectively).
CONCLUSIONS: Ocular parameters including ALs, ACDs, WTWs, and CCTs using a new Pentacam-AXL and standard PCI-based IOLMaster 500 changed significantly before and after the ICL V4c implantation, while IOL power prediction using the Barrett Universal II formula was little affected.

OBJECTIVE: To develop an alternative method of intraocular lens (IOL) power calculation in eyes with mature cataract and axial length (AL) of less than 22.0 mm using modern formulas Barrett Universal II and Hill RBF.
METHODS: The study enrolled 41 patients (41 eyes) who underwent phacoemulsification (PE). Ultrasound biometry (Tomey Biometer Al-100) and keratometry (Topcon-8800) were used for IOL power calculation by SRK/T and Haigis formulas. To calculate IOL power by Barrett Universal II and Hill RBF formulas, 0.2 mm were added to AL measured with ultrasonography (retinal thickness). One month after PE, spherical equivalent of refraction was compared with target refraction (calculated by the formulas listed above), and based on that a conclusion was made on the accuracy of calculations.
RESULTS: Haigis formula was found to be the least accurate (IOL calculation error -0.39±0.79 D). The calculation error in SRK/T (0.04±0.79 D), Barrett Universal II (0.02±0.79 D) and Hill RBF (-0.05±0.73 D) formulas was much lower. However, among them Hill RBF had the lowest spread of the mean absolute IOL calculation error. Pairwise comparison revealed significant difference of mean IOL calculation error by Haigis formula versus the others. There was no significant difference in the following pairs: SRK/T - Barrett Universal II (p=0.855), and SRK/T - Hill RBF (p=0.167), but there was a significant difference (p=0.043) in the Barrett Universal II - Hill RBF pairdue to the tendency for slight hypermetropic calculation error in the former and the inherent slight myopic shift in the latter..
CONCLUSIONS: The proposed alternative method of IOL power calculation in eyes with mature cataract and short AL using modern formulas (Barrett Universal II and Hill RBF) shows higher accuracy compared to the formulas embedded in ultrasound biometer (SRK/T and Haigis), and can be recommended for use in everyday practice.
UNASSIGNED: Разработка алгоритма расчета оптической силы интраокулярных линз (ИОЛ) в глазах со зрелой катарактой и длиной переднезадней оси (ПЗО) <22,0 мм с использованием калькуляторов Barrett Universal II и Hill RBF.
UNASSIGNED: Исследуемую группу составили пациенты (n=41; 41 глаз), которым выполнялась факоэмульсификация (ФЭ). Расчет ИОЛ (по формулам SRK/T и Haigis) производился на основании данных, полученных при кератометрии и аппланационной ультразвуковой биометрии. Для расчета по формулам Barrett Universal II и Hill RBF к измеренной ультразвуковым методом длине ПЗО добавляли 0,2 мм (толщина сетчатки). Спустя 1 мес после ФЭ показатель сфероэквивалента клинической рефракции сравнивался с расчетной (согласно вышеперечисленным формулам) рефракцией, на основании чего делался вывод о точности попадания в рефракцию цели.
UNASSIGNED: Наибольшей ошибкой расчета ИОЛ сопровождалось применение формулы Haigis (–0,39±0,79 дптр). Величина отклонения от целевой рефракции при использовании SRK/T (0,04±0,79 дптр), Barrett Universal II (0,02±0,79 дптр) и Hill RBF (–0,05±0,73 дптр) оказалась намного меньшей. Минимальный разброс абсолютной ошибки расчета ИОЛ характерен для уравнения Hill RBF. При попарном сравнении средних значений ошибки расчета формула Haigis существенно отличалась от всех остальных. В парах SRK/T и Barrett Universal II (p=0,855), SRK/T и Hill RBF (p=0,167) значимых различий не отмечалось, однако при сравнении Barrett Universal II (с ее тенденцией к легкой гиперметропической ошибке расчета) и Hill RBF (которой присущ незначительный миопический сдвиг) была найдена значимая разница (p=0,043).
UNASSIGNED: Предложенный нами альтернативный метод расчета ИОЛ, использующий современные калькуляторы (Barrett Universal II, Hill RBF), показал более высокую точность по сравнению со встроенными в ультразвуковой биометр формулами (SRK/T, Haigis) и может быть использован в повседневной клинической практике для расчета ИОЛ.

OBJECTIVE: To compare the accuracy of the Barrett Universal II (BUII) five-variable formula to previous generation formulae in calculating intraocular lens (IOL) power following paediatric cataract extraction.
METHODS: Retrospective study of consecutive paediatric patients who underwent uneventful cataract extraction surgery along with in-the-bag IOL implantation between 2012 and 2018 in the Hospital for Sick Children, Toronto, Ontario, Canada. The accuracy of five different IOL formulae, including the BUII, Sanders-Retzlaff-Kraff Theoretical (SRK/T), Holladay I, Hoffer Q and Haigis, was evaluated. Constant optimization was performed for each IOL and for each formula separately. Mean prediction error (PE) and the mean and median absolute PE (APE) were calculated for the five different IOL formulae investigated.
RESULTS: Sixty-six eyes of 66 children (59% males) with a median age at surgery of 6.2 years (IQR, 3.2-9.2 years) were included in the study. The mean IOL power that was implanted was 23.3 ± 5.1 D (range; 12.0-39.0 D). Overall, the BUII had a comparable median APE to the Hoffer Q, Holladay I, SRK/T and Haigis formulae (BUII: 0.49D versus 0.48D, 0.61D, 0.74D and 0.58D respectively; p = 0.205). The BUII, together with Hoffer Q, produced better predictability within 0.5D from target refraction compared with the SRK/T formula (BUII:51.5%, Hoffer Q:51.5% versus SRK/T:31.8%, p = 0.002 for both).
CONCLUSIONS: The BUII formula had comparable accuracy to other tested formulae and outperformed the SRK/T formula, when calculating IOL power within the 0.5D range from target refraction in paediatric eyes undergoing cataract surgery with in-the-bag IOL implantation.

OBJECTIVE: To assess refractive outcomes of phacoemulsification (PE) with additional capsular tension ring (CTR) implantation.
METHODS: In total, 37 eyes of 37 patient who underwent PE with intraocular lens (IOL) implantation were divided into 2 groups: study group (n = 18) with CTR co-implantation (inclusion criteria was preoperative irido-phacodonesis) and control group (n = 19) without CTR. Optical biometry (IOL-Master 500) was performed for each patient before PE. Barrett Universal II Formula was used for IOL calculation. IOL power calculation error was assessed by comparing target refraction and final refraction measured by Topcon-8800 autorefractometer 1 month after surgery.
RESULTS: Despite almost identical preoperative values in both groups refractive result was different. Patients with CTR co-implantation had more hyperopic IOL power calculation error of 0.41 ± 0.52 D versus 0.04 ± 0.59 D in the control group (p = 0.043). Postoperative spherical equivalent in study group was more hyperopic (-0.40 ± 1.47 D) than in control group (-0.77 ± 1.24), nevertheless, this difference was insignificant (p = 0.166).
CONCLUSIONS: CTR co-implantation in patients with weak zonules and preoperative irido-phacodonesis leads to more hyperopic IOL power calculation error compared with control group.

UNASSIGNED: To compare the commonly used formulas for intraocular lens (IOL) selection using IOLMaster®700 (Carl Zeiss Meditec) and to evaluate the Barrett Universal II (BU-II) formula accuracy when using the Vivinex™ iSert® XY1 IOL (Hoya Corporation Medical Division).
UNASSIGNED: A retrospective chart review was performed that included patients who underwent uneventful cataract surgery with in-the-bag insertion of Vivinex™ iSert® XY1 IOL. Prediction errors at 3 months postoperative of IOLMaster® 700 with Haigis, Holladay 1, SRK/T, and BU-II formulas were compared. As a subgroup analysis, we focused on the axial length (AL) and IOL power. AL subgroup analysis was based on the following AL subgroups: short (<22.5 mm), medium (22.5-25.5 mm), and long (>25.5 mm). IOL power subgroup analysis was based on the following IOL power subgroups: low (≤18.0 diopters [D]), medium (18.5-24.0 D), and high (≥24.5 D).
UNASSIGNED: This study included 590 eyes of 590 patients. Overall, the four IOL calculation formulas appeared to be similarly accurate. In the long AL subgroup, the BU-II formula had a significantly lower absolute error (AE) than the Holladay 1 formula. In the low-power subgroup, the BU-II formula had a significantly lower AE than the Holladay 1 and SRK/T formulas. On the other hand, in the high-power subgroup, the BU-Ⅱ formula was significantly less accurate than the SRK/T formula and also appeared to be worse than the Holladay 1 formula (P = 0.052).
UNASSIGNED: The BU-II formula might be less accurate when using a Vivinex™ iSert® XY1 IOL of 24.5 D or greater.

OBJECTIVE: To assess the impact of pseudoexfoliation syndrome (PEX) on the accuracy of intraocular lens (IOL) power calculation.
METHODS: The study included 243 patients who underwent phacoemulsification (PE); they were divided into the control (no PEX signs, n=131) and study (signs of PEX, n=112) groups. Barrett Universal II formula was used for IOL calculation by optical biometry (IOL-Master 500). Obtained refraction (autorefractometer Topcon-8800) was compared with target refraction to assess IOL calculation accuracy 1 month after PE.
RESULTS: Patients with PEX had significantly shallower anterior chamber compared to the control group (2.86±0.43 versus 3.0±0.43 mm, p=0.003) and steeper corneal curvature (44.31±1.5 versus 43.7±2.59 D, p=0.052). There was significant difference in absolute error of IOL calculation between the groups (-0.02±0.45 versus 0.17±0.55 D for control and study groups, respectively, p=0.004). There was no difference in IOL calculation error depending on the implanted IOL models (AcrySof SA60AT and Akreos Adapt AO) in the control group. However, implantation of SA60AT in the study group showed significant difference in IOL calculation error compared with Akreos (0.3±0.57 versus 0.04±0.51 D, p=0.01). Using linear regression, optimized A-constants were suggested for these types of IOLs for patients with PEX (118.83 for SA60AT and 118.44 for Akreos).
UNASSIGNED: Изучить влияние псевдоэксфолиативного синдрома (ПЭС) на точность расчета интраокулярных линз (ИОЛ).
UNASSIGNED: Из 243 перенесших факоэмульсификацию (ФЭ) пациентов были сформированы две группы: исследуемая (n=112; с признаками ПЭС) и контрольная (n=131; без признаков ПЭС). Расчет ИОЛ производился по формуле Barrett Universal II с помощью оптической биометрии (IOL-Master 500). Для оценки точности предоперационных расчетов через месяц после ФЭ показатель сфероэквивалента рефракции сравнивали с целевой рефракцией.
UNASSIGNED: У пациентов с ПЭС выявлено статистически значимое уменьшение глубины передней камеры (2,86±0,43 против 3,0±0,43 мм; p=0,003) и некоторое усиление преломляющей силы роговицы (44,31±1,5 против 43,7±2,59 дптр; p=0,052). Обнаружена значимая (p=0,004) разница ошибки расчета ИОЛ в исследуемой группе (0,17±0,55 дптр) по сравнению с контрольной (–0,02±0,45 дптр). Наличие ПЭС приводило к значимому снижению предсказуемости рефракционных результатов ФЭ, что выражалось в большей абсолютной ошибке расчета ИОЛ (0,44±0,38 против 0,35±0,28 дптр; p=0,045). Тип имплантируемой ИОЛ (AcrySof SA60AT или Akreos Adapt AO) не влиял на точность расчета в контрольной группе. Однако у пациентов с ПЭС имплантация SA60AT приводила к появлению слабой гиперметропической ошибки по сравнению с Akreos (0,3±0,57 против 0,04±0,51 дптр; p=0,01). С помощью линейной регрессии были оптимизированы A-константы данных моделей ИОЛ для их использования на фоне ПЭС (118,83 для SA60AT и 118,44 для Akreos).
UNASSIGNED: Высокие рефракционные результаты ФЭ должны достигаться и в осложненных ПЭС случаях. Нежелательных ошибок расчета ИОЛ можно избежать, используя предложенные нами оптимизированные A-константы.

OBJECTIVE: To examine the contribution of anterior chamber depth (ACD), lens thickness (LT), and white-to-white (WTW) measurements to intraocular lens (IOL) power calculations using the Barrett Universal II (BUII) formula.
METHODS: Measurements taken with the IOLMaster 700 (Carl Zeiss, Meditec AG, Jena, Germany) swept-source biometry of 501 right eyes of 501 consecutive patients undergoing cataract extraction surgery between January 2019 and March 2020 were reviewed. IOL power was calculated using the BUII formula, first through the inclusion of all measured variables and then by using partial biometry data. For each calculation method, the IOL power targeting emmetropia was recorded and compared for the whole cohort and stratified by axial length (AL) of the measured eye.
RESULTS: The mean IOL power calculated for the entire cohort using all available parameters was 19.50 ± 5.11 diopters (D). When comparing it to the results obtained by partial biometry data, the mean absolute difference ranged from 0.05 to 0.14 D; p < 0.001. The optional variables (ACD, LT, WTW) had the least effect in long eyes (AL ≥ 26 mm; mean absolute difference ranging from 0.02 to 0.07 D; p < 0.001), while the greatest effect in short eyes (AL ≤ 22 mm; mean absolute difference from 0.10 to 0.21 D; p < 0.001). The percentage of eyes with a mean absolute IOL dioptric power difference more than 0.25 D was the highest (32.0%) among the short AL group when using AL and keratometry values only.
CONCLUSIONS: Using partial biometry data, the BUII formula in small eyes (AL ≤ 22 mm) resulted in a clinically significant difference in the calculated IOL power compared to the full biometry data. In contrast, the contribution of the optional parameters to the calculated IOL power was of little clinical importance in eyes with AL longer than 22 mm.