Intraocular Lens Power Research Articles

Spherical equivalent prediction analysis in intraocular lens power calculations using Eyetemis: a comprehensive approach.

To compare 2 different datasets, using Eyetemis, an online analytical tool designed for assessing the spherical equivalent prediction errors (SEQ-PEs) of intraocular lens (IOL) power calculation formulas after cataract surgery. Institutional. Retrospective case series. The study comprised 2 distinct datasets of patients who had undergone successful cataract surgery. Dataset 1 includes standard eyes, whereas Dataset 2 includes eyes with keratoconus. An online tool was used for SEQ-PE analysis across the 2 datasets, adhering to ISO standards for evaluating accuracy based on trueness and precision. The tool incorporates robust t tests for comparing the trimmed mean of the data, adjusting for heteroscedasticity. IOL constants in Dataset 1 were optimized for the comparison of Hoffer Q, Holladay 1, SRK/T, Haigis, and Barrett Universal II (BUII) formulas. In Dataset 2, IOL constants from the IOLCon website were used for the comparison of the BUII and its designated KCN version: Barrett TrueK Keratoconus (TrueK [KCN]). For Dataset 1, the trimmed mean SEQ-PE values of all formulas were not significantly different from zero. BUII had superior precision and accuracy compared with all other formulas, except from Haigis ( P ≤ .04). For Dataset 2, BUII's trimmed-mean SEQ-PE was significantly different from zero (0.59 diopters [D], P < .01), unlike the TrueK (KCN) (0.12 D, P = .10). In addition, TrueK (KCN) exhibited enhanced precision and accuracy relative to BUII ( P < .01). The online analysis tool provides a streamlined approach for assessing the prediction accuracy of SEQ refraction after cataract surgery, effectively evaluating trueness, precision, and overall accuracy through the use of advanced statistical methods.

Effect of Ramadan Fasting on Biometric Readings of Eye

Purpose: To determine change in biometric values of eye after fasting and to elucidate whether this change is significant enough to delay the refractive and cataract surgeries during fasting. Study Design: Cross sectional observational. Place and Duration of Study: Eye department, DHQ-UTH, Gujranwala, from April 2021 to May 2021. Methods: Thirty subjects of either gender between 20-40 years of age who participated in both phases were enrolled in this study. Phase 1 was conducted one week before Ramadan and 2nd phase in the last week of Ramadan. After routine ophthalmic examination, keratometric(K) values were obtained with Auto Ref-Keratometer (Canon), while Axial length (AL), Anterior chamber depth (ACD), andIntraocular lens power (IOLp)were obtained from Master-Vu A-scan (Sonomed, Model # MV4500). Data was analyzed using SPSS version 25. Results: Out of 30 participants, 66.6% were female and 33.3%were male with mean age of 29.8 years. Mean K1 increased to 43.03 D during fasting from non-fasting reading of 42.24 D, while Mean K2 increased to 43.87 D during fasting from non-fasting reading of 43.28 Dwith significantp-value (&lt;0.05). Mean ACD was 3.15mm in non-fasting that also increased to 3.21D in fasting state. Mean AL in non-fasting state was 23.41mm that remains the same in fasting state as well. Mean IOLp in non-fasting state was 21.18D that reduced to 20.42D in fasting state with significant p-value. Conclusion: Fastingincreased thekeratometry andACD values with no effect on AL but that reduced overall intraocular lens power.

Biometric description of 34 589 eyes undergoing cataract surgery: sex differences.

To describe gender differences in the biometric parameters of a large sample of patients with cataract. Cataract surgery has evolved from a vision restoration to a refractive procedure, and population-based studies are vital to optimize normative databases and postsurgical outcomes. Miguel Servet University Hospital, Zaragoza, Spain. Retrospective single-center observational study. The study included 34 589 eyes (20 004 patients with cataract). Biometric data were obtained from IOL Master 700 and Pentacam HR. Linear mixed models were used to account for intereye correlation. HofferQST formula was used to calculate the hypothetical distribution of intraocular lens (IOL) power (arbitrary lens; A = 119.2). Most biometric variables showed significant differences between sexes ( P < .0001), such as 0.53 mm shorter eyes found in females, of which 0.16 mm are explained by shorter aqueous depth. Steeper anterior keratometries (∼0.75 diopter [D]) were found in women, to end up in no difference on anterior astigmatism magnitude, but different orientation ( P < .0001). The distribution of IOL power differed between sexes ( P < .001), with the interquartile range shifting 1 D toward more powerful lenses in women and odds ratio (power >26 D) = 2.26, P < .0001 (Fisher). Large sample size studies provide smaller margin of error, higher power, and controlled risk of reporting false (negative or positive) findings. Highly significant differences between sexes in ocular biometry were found; this supports the idea that including sex as a parameter in IOL calculation should be explored and may improve results. In addition, the distribution of IOL powers was provided, which may be useful for manufacturers and hospital stock planning.

A simultaneous post-LASIK sequential bilateral implantation of multifocal IOLs aimed at refraction correction. A clinical case

The article presents a clinical example of intraocular presbyopia correction in a patient who previously underwent laser vision correction by LASIK for mild myopia. Before the surgery, the distance VA mono- and binocular was 1.0, ADD for reading distance 40 cm +2.0 D, objective refraction sph +0.5 D cyl -0.25 D ax 980, left eye sph +0.75 D cyl -0.25 D ax 660. The patient was given a simultaneous bilateral refractive lens exchange with an implantation of a trifocal aspheric intraocular lens in the right eye and a trifocal toric aspheric intraocular lens in the left eye. We used the following IOL calculation formulas: ASCRS mean IOL power, Shammas formula, Barrett true K formula, Masket formula, Modified Masket formula, Haigis-L formula. 1 week postop: UDVA OU = 1.0, UNVA 40 cm = 1.0, UVA 70 cm = 0.7. The objective refraction OD was sph +0.0, D cyl -0.75 D ax 163, OS sph +0.25 D, cyl -0.0 D. The compliance with the modified algorithms of pre-and intraoperative behavior of the operating team, thorough preparation of the patient, careful calculation of the IOL allowed us to obtain the predictive refractive result with a high level of visual satisfaction and absence of undesirable postoperative phenomena. The patient underwent the examination with Salzburg reading desk before and after the surgery, to confirm the excellent functional results of the treatment. Despite the fact that simultaneous same day IOL implantation in both eyes, especially in eyes with previously operated corneas, is still disputable, the above case confirms that with modern equipment, precise multi formula calculation, and ample experience help achieve excellent functional and refractive results.

Choosing the formula for calculating optical power of intraocular lens on "short" eyes using the potential of artificial intelligence

Objective: to carry out a comparative analysis of IOL fitting accuracy in patients with eye length less than 22.0 mm using Barrett Universal II, Kane, Hoffer Q and artificial intelligence formulas. Material and methods. The results of 88 phacoemulsification cataract operations with implantation of monofocal lOLs were analyzed. Preoperative biometry and IOL calculations were performed on the IOL Master 700. The accuracy of IOL fitting was also determined using the LensCalc program, which is based on artificial intelligence (DecisionTreeClassifier). Results. The eye length of the patients ranged from 19.8 to 22 mm. The prediction of the target refraction hit was the most accurate when using Barrett Universal II formulas as opposed to Hoffer Q (Z=2.12; p=0.034). The mean value of the target refraction hit error was not different when using the Barrett Universal II formula compared to the Kane formula (p&gt;0.05). Using artificial intelligence it was found that higher accuracy in the results of IOL optical power determination was achieved when using the Barrett Universal II formula. Conclusion. Based on a comparative analysis of the study results and assessment of IOL fitting accuracy using artificial intelligence, it was found that the Barrett Universal II formula (4th generation) is more accurate in determining the optical power of lOLs in "short" eyes than the Hoffer Q formula (3rd generation). The results obtained using the Barrett Universal II formula, in contrast to the Hoffer Q formula, do not differ from the data calculated using the Kane formula (5th generation), which, according to the results of most studies, is the most accurate IOL selection formula at present (p&gt;0.05).

The VRF-L and VRF-GL IOL power calculation methods after radial keratotomy.

To investigate the accuracy of the VRF-L and VRF-GL IOL power calculation methods in cataract surgery after radial keratotomy (RK). The VRF-L and VRF-GL methods were collated with nine formulas: Barrett True K (No History), Haigis, Hoffer Q, Hoffer Q (Double-K), Holladay 1 (Double-K), Holladay 2 (Double-K), PEARL-DGS (RK), SRK/T (Double-K), and T2 (Double-K). With SS-OCT biometry (IOLMaster 700, Carl Zeiss Meditec), data of 78 eyes from 78 patients with previous RK was included. Optimised lens constants were sourced from the IOL Con website. Subjective refraction was obtained at 4 to 5 months postoperatively. The root mean square absolute error (RMSAE) and median absolute error (MedAE) were chosen as primary outcomes and the percentage of eyes with PEs within ±0.25 D, ±0.50 D, ±0.75 D, and ±1.00 D were analysed. Statistical significance (Bootstrap-t test, P < 0.05) was shown by VRF-GL, VRF-L, and Haigis formulas with the lowest RMSAE (0.813 D, 0.816 D and 0.824 D) and MedAE (0.511 D, 0.497 D and 0.533 D) values. The Barrett True K formula was less predictable (0.836 and 0.580, respectively). The VRF-L, VRF-GL, and Haigis achieved the highest percentage of eyes with a PE within ±0.50 D (52.56%, 50.00%, and 46.15%) and ±1.00 D (79.49%, 79.49%, and 80.77% respectively). The VRF-L and VRF-GL methods demonstrated higher accuracy and were comparable with existing methods in eyes after RK. The Haigis was an alternative option with a higher percentage of eyes with a PE within ±1.00 D (80.77%).

Evaluation of anterior segment parameters between pregnancy trimesters and postpartum with pentacam scheimflug ımaging: a prospective study

PurposeTo evaluate the effect of pregnancy on the anterior chamber, corneal parameter, and intraocular pressure measurements; and compare the results between trimesters, postpartum and non-pregnant healthy age-matched women.MethodsThis prospective study included 41 pregnant women and 53 non-pregnant women. Four measurements were taken from the pregnant women, in each trimester and postpartum third month, and once from the control group. Of the individuals included in the study, anterior chamber depth (ACD), anterior chamber volume (ACV), K1 (flat keratometry), K2 (steep keratometry), Kmean (mean value of K1 and K2), anterior chamber angle (ACA), central corneal thickness (CCT), thinnest corneal thickness (TCT), astigmatism value (AST), corneal volume (CV), biometry, axial length (AL), spherical equivalent (SFEQ), intraocular lens power (ILP), VA (visual acuity) datas were recorded.ResultsWe observed a statistically significant decrease in K2, CCT, ACD, AL and CV in the postpartum period (p = 0.025, p < 0.001, p = 0.029, p = 0.005, p = 0.004 respectively) and a statistically significant increase in ACV, CCT, and TCT as the gestational week progressed in the pregnant group (p = 0.007, p < 0.001, p = 0.025, respectively). A statistically significant decrease in IOP towards to the third trimester, and an increase in the postpartum period was observed (p < 0.001). We did not observe statistically significant changes in K1, Kmean, AST, ACA, VA, ILP, and SFEQ values.ConclusionIt is important to investigate the physiological changes that may occur during pregnancy, distinguish them from pathological changes, and avoid unnecessary treatment. We consider that it’s also important to guide the timing of anterior segment surgeries such as cataract and refractive surgery and to prescribe glasses/contact lenses.

Accuracy of intra ocular lens calculation formulae in patients with pseudoexfoliation syndrome

BackgroundThe purpose of this study was to investigate the visual and refractive outcomes in patients with pseudoexfoliation (PXF) undergoing routine cataract surgery and to compare the accuracy of intraocular lens (IOL) power calculation formulae.MethodsRetrospective case-series study from Shamir medical center, a public hospital, Israel. Medical records of patients who underwent routine cataract surgery between January 2019 and August 2021 were investigated. Postoperative visual acuity and manifest refraction were examined. The error in predicted refraction and IOL power calculation accuracy within a range of ± 0.50 to ± 1.00 diopters were compared between different IOL calculating formulae.Results151 eyes of 151 patients ages 73.9 ± 7.1 years were included in this study- 58 eyes in the PXF group and 93 eyes in the control group. The mean absolute error (MAE) for the BUII formula was 0.63D ± 0.87 for the PXF group and 0.36D ± 0.48 for the control group (p < 0.05). The MAE for the Hill-RBF 3.0 formula was 0.61D ± 0.84 for the PXF group and 0.42D ± 0.55 for the control group (p = 0.05). There were significant differences in MAE and MedAE between PXF group and control group measures (p < 0.05). In the PXF group there were no significant differences between the different formulae.ConclusionsThere were significant differences in accuracy of IOL power calculations in all formulae between PXF group and control group measures. PXF patients show hyperopic shift from predicted refraction. Barret universal II formula had the highest proportion of eyes with absolute error in prediction below or equal to 0.50 D in both PXF and control groups.

Hotspots and trends of artificial intelligence in the field of cataracts: a bibliometric analysis

PurposeTo analyze the hotspots and trends in artificial intelligence (AI) research in the field of cataracts.MethodsThe Science Citation Index Expanded of the Web of Science Core Collection was used to collect the research literature related to AI in the field of cataracts, which was analyzed for valuable information such as years, countries/regions, journals, institutions, citations, and keywords. Visualized co-occurrence network graphs were generated through the library online analysis platform, VOSviewer, and CiteSpace tools.ResultsA total of 222 relevant research articles from 41 countries were selected. Since 2019, the number of related articles has increased significantly every year. China (n = 82, 24.92%), the United States (n = 55, 16.72%) and India (n = 26, 7.90%) were the three countries with the most publications, accounting for 49.54% of the total. The Journal of Cataract and Refractive Surgery (n = 13, 5.86%) and Translational Vision Science & Technology (n = 10, 4.50%) had the most publications. Sun Yat-sen University (n = 25, 11.26%), the Chinese Academy of Sciences (n = 17, 7.66%), and Capital Medical University (n = 16, 7.21%) are the three institutions with the highest number of publications. We discovered through keyword analysis that cataract, diagnosis, imaging, classification, intraocular lens, and formula are the main topics of current study.ConclusionsThis study revealed the hot spots and potential trends of AI in terms of cataract diagnosis and intraocular lens power calculation. AI will become more prevalent in the field of ophthalmology in the future.

Comparing the accuracy of intraocular lens power calculation formulas using artificial intelligence and traditional formulas in highly myopic patients: a meta-analysis.

The accuracy of intraocular lens (IOL) calculations is one of the key indicators for determining the success of cataract surgery. However, in highly myopic patients, the calculation errors are relatively larger than those in general patients. With the continuous development of artificial intelligence (AI) technology, there has also been a constant emergence of AI-related calculation formulas. The purpose of this investigation was to evaluate the accuracy of AI calculation formulas in calculating the power of IOL for highly myopic patients. We searched the relevant literature through August 2023 using three databases: PubMed, EMBASE, and the Cochrane Library. Six IOL calculation formulas were compared: Kane, Hill-RBF, EVO, Barrett II, Haigis, and SRK/T. The included metrics were the mean absolute error (MAE) and percentage of errors within ± 0.25 D, ± 0.50 D, and ± 1.00 D. The results showed that the MAE of Kane was significantly lower than that of Barrett II (mean difference = - 0.03 D, P = 0.02), SRK/T (MD = - 0.08 D, P = 0.02), and Haigis (MD = - 0.12 D, P < 0.00001). The percentage refractive prediction errors for Kane at ± 0.25 D, ± 0.50 D, and ± 1.00 D were significantly greater than those for SRK/T (P = 0.007, 0.003, and 0.01, respectively) and Haigis (P = 0.009, 0.0001, and 0.001, respectively). No statistically significant differences were noted between Hill-RBF and Barret, but Hill-RBF was significantly better than SRK/T and Haigis. The AI calculation formulas showed more accurate results compared with traditional formulas. Among them, Kane has the best performance in calculating IOL degrees for highlymyopic patients.

Comparison of the effectiveness of different corneal curvature measurement methods for IOL implantation in traumatic aphakic eyes with corneal injury.

To assess the refractive outcomes of secondary intraocular lenses (IOL) in patients with traumatic aphakic eyes with corneal penetrating injury and compare different corneal curvature measurement methods. Patients with unilateral penetrating eye injuries underwent corneal wound repair and cataract extraction, followed by secondary IOL implantation. Corneal curvature measurements were taken on the contralateral healthy eye (Group A), from the affected eye before removing corneal sutures (Group B), or after suture removal (Group C). The refractive outcomes were compared among the three groups. The study included 261 eyes. The Mean Absolute Error (MAE) in Group C (0.99 ± 0.85 D) was significantly smaller than that in Group A (1.87 ± 1.71 D) and Group B (1.37 ± 1.20 D) (both P < 0.001). Moreover, the percentage of eyes with IOL prediction errors within ± 0.50 D in Group C (40%) was higher than that in group A (21.7%) (OR = 2.364, 95%CI: 1.272-4.392, P = 0.006) and group B (28.0%) (OR = 1.714, 95%CI: 0.948-3.099, P = 0.073), and the percentage of eyes with IOL prediction errors within ± 1.0 D in Group C (90.9%) was higher than that in group A (67.9%) (OR = 4.758, 95%CI: 2.131-10.626, P < 0.001) and group B (75.0%) (OR = 3.370, 95%CI: 1.483-7.660, P = 0.003) as well. In traumatic aphakic eyes with corneal sutures, IOL power calculation based on the corneal curvature of the injured eye after removing the corneal sutures yields the best refractive outcomes.

Comparative accuracy of intraocular lens power calculation formulas when targeting myopia

PurposeThis study aims to compare the accuracies of intraocular lens (IOL) power calculation formulas when targeting myopia versus emmetropia. MethodsA total of 450 patients were included, with 225 patients targeting emmetropia and 225 patients aiming for approximately −2.0 diopters of myopia. This retrospective analysis utilized data from a single eye of each patient, with preoperative biometric measurements obtained using the IOL Master 700. The study considered established formulas such as Haigis, Hoffer Q, Holladay 1, Holladay 2, and SRK/T, as well as modern formulas including Barrett Universal II, Cooke K6, EVO 2.0, Hill-RBF, Hoffer QST, Kane, Olsen, and PEARL-DGS. Statistical analyses, including Friedman test and post hoc analysis, were employed to compare the accuracy of each IOL power calculation formula between the two groups. Additionally, a multiple regression analysis was conducted to identify variables influencing the accuracy of intraocular lens power calculation formulas. ResultsIn targeting myopia, all IOL formulas tended to exhibit a greater refractive error compared to when targeting emmetropic eyes. Notably, the Haigis, SRK/T, and Holladay 2 formulas were found to be highly influenced by this trend, while the modern formulas were less affected. ConclusionThe accuracy of IOL power calculation formulas diminishes when targeting myopia in comparison to emmetropia. However, the modern formulas appear less susceptible to this trend. Consequently, when aiming for myopia, the use of the modern formulas is recommended for enhanced accuracy in IOL power calculation.

Total and simulated keratometry measurements using IOLMaster 700 and Pentacam AXL after small incision lenticule extraction.

Calculating the intraocular lens (IOL) in patients after corneal refractive surgery presents a challenge. Because an overestimation of corneal power in cases undergone this surgery leading to a subsequent under-correction of IOL power. However, recent advancements in technology have eliable measurement of total corneal power. The aim of this research was to assess the agreement in simulated keratometry (SimK) and total keratometry (TK) values between IOLMaster 700 and Pentacam AXL. The study involved 99 patients (99 eyes) undergone small incision lenticule extraction (SMILE) surgery. Each patient underwent scans using IOL Master 700 and Pentacam AXL. The following parameters were recorded: SimK1, SimK2, Total K1 (TK1), and Total K2 (TK2) for IOLMaster 700; and SimK1, SimK2, True Net Power (TNP) K1, TNPK2, Total Corneal Refractive Power (TCRP) K1, and TCRP K2 for Pentacam AXL. Agreement between the two devices was evaluated using Bland-Altman plot, while paired t-test was utilized to compare any differences in the same parameter by both instruments. The results revealed a strong correlation between the two devices.Noticeable comparability was identified for all SimK variables. However, there were noticeable differences in TK measurements as well as TK1-TNPK1, TK2-TNP K2, TK1-TCRP K1, and TK2-TCRP K2 parameters when comparing the two devices. The IOLMaster 700 consistently measured steeper values than the Pentacam AXL, with significant and clinically relevant differences of 1.34, 1.37, 0.87, and 0.95 diopters, respectively. While there was a noticeable correlation between the IOLMaster 700 and Pentacam AXL in SimK measurements, a marked difference was noted in TK values. The two devices cannot be used interchangeably when quantifying TK values.

Accuracy of using the axial length of the fellow eye for IOL calculation in retinal detachment eyes undergoing silicone oil removal

PurposeEvaluate whether the axial length of the fellow eye can be used to calculate the intraocular lens (IOL) in eyes with retinal detachment.DesignRetrospective, consecutive case series.MethodsOur study was conducted at...

Сравнительный анализ рефракционных и функциональных результатов имплантации торической интраокулярной линзы с механизмом формирования волнового фронта при хирургическом лечении катаракты у пациентов после сквозной кератопластики

Abstract Comparative analysis of the refractive and functional results of toric intraocular lens with wavefrontshaping mechanism implantation during the surgical treatment of cataracts in patients after penetrating keratoplasty. D.A. Khvan, , G.A. Fedyashev Pacific State Medical University Ministry of Health of Russia, Vladivostok, Russian Federation Primorskii center of eye microsurgery, Vladivostok, Russian Federation Relevance. This study presents a comparative analysis of the effectiveness of toric intraocular lens (IOL) with a wavefront shaping mechanism implantation in cataract surgical treatment in patients after penetrating keratoplasty (PKP). Purpose. To evaluate the effectiveness of toric IOL with a wavefront shaping mechanism implantation in cataract surgical treatment in patients after PKP. Material and methods. This prospective study included 65 patients (65 eyes) who underwent cataract surgery after prevous PKP (the time after removal of corneal sutures averaged 1.4±0.8 years). In the 1st group of patients (34 patients, 34 eyes) the AcrySof IQ Toric IOL was implanted, in the 2nd group – the AcrySof IQ Vivity IOL (31 patients, 31 eyes). In both groups, IOL power was calculated at a target refraction of (–) 0.5 D. The observation period was up to 6 months. Results. In all groups, there was a significant (p&lt;0.001) improvement in uncorrected (UCVA) and best-corrected visual acuity (BCVA) on the first day, after 1, 3 and 6 months. In 1st group, by the 6th month of observation, there was a tendency towards a slight significant (relative to the 3rd month) decrease in UCVA of 0.134±0.1 (p=0.019). In 2nd group, UCVA was significantly (p&lt;0.001) higher than in 1st group at all periods of postoperative follow-up and was 0.075±0.063 before surgery (in 1st group 0.053±0.029), on the first day after surgery 0.348± 0.139 (in the 1st group 0.097±0.05), 1st month 0.516±0.144 (in the 1st group 0.133±0.076), 3rd month 0.642±0.143 and by the 6th month 0.642±0.139 (in 1st group 0.16±0.1 and 0.134±0.1, respectively). Statistically significant (p=0.03) differences were obtained when comparing the error of the spherical equivalent of refraction (SE) from the expected result in the 1st and 2nd groups (1.22±0.875 and 0.76±0.582, respectively) during the observation period up to 6 months. Conclusion. AcrySof IQ Vivity Toric IOL implantation during the cataract surgical treatment in patients with previous keratoplasty allows to obtain significantly higher postoperative UCVA, due to more accurate access to target refraction, which confirmed by a significantly lower spherical equivalent error. Key words: wavefront, cataract, penetrating keratoplasty, EDOF, Vivity

Comparison of Ultrasound Biometry with Optical Biometry for Measurement of Axial Length and Calculation of Intraocular Lens Power in Patients Undergoing Routine Cataract Surgery

Objective: To compare the axial length and intraocular lens power calculated by using ultrasound biometry and optical biometry in patients with cataract Methodology: It was prospective randomized control trial carried out at eye department of Pakistan Institute of Medical Sciences Islamabad from Oct 2021-December 2021, comprising of 50 patients undergoing contract surgery in Eye Department of PIMS using non-probability consecutive sampling. After taking informed written consent from patient’s biometry was performed using optical scan and ultrasound biometry (with appalation probe). Axial length and intraocular power calculated by both methods was recorded. Results: The mean axial length measurement by ultrasound of the patients’ eyes was 22.72±0.85 mm and by optical biometry was 22.67±0.86 mm. Similarly the mean intraocular lens power calculated by ultrasound was 20.60±1.56D and by optical was 20.51±1.51D. Optical and ultrasound method showed strong positive correlation in measurements of intraocular lens power and axial length of eyes, i.e. r=0.965 &amp; 0.939 respectively. Conclusion: The findings of this study suggested that optical biometry is good alternate of ultrasound in measurement of axial length and intraocular lens power of patients, as strong correlation exist between both techniques

A New Method to Minimize the Standard Deviation and Root Mean Square of the Prediction Error of Single-Optimized IOL Power Formulas.

The purpose of this study was to develop a simplified method to approximate constants minimizing the standard deviation (SD) and the root mean square (RMS) of the prediction error in single-optimized intraocular lens (IOL) power calculation formulas. The study introduces analytical formulas to determine the optimal constant value for minimizing SD and RMS in single-optimized IOL power calculation formulas. These formulas were tested against various datasets containing biometric measurements from cataractous populations and included 10,330 eyes and 4 different IOL models. The study evaluated the effectiveness of the proposed method by comparing the outcomes with those obtained using traditional reference methods. In optimizing IOL constants, minor differences between reference and estimated A-constants were found, with the maximum deviation at -0.086 (SD, SRK/T, and Vivinex) and -0.003 (RMS, PEARL DGS, and Vivinex). The largest discrepancy for third-generation formulas was -0.027mm (SD, Haigis, and Vivinex) and 0.002mm (RMS, Hoffer Q, and PCB00/SN60WF). Maximum RMS differences were -0.021 and +0.021, both involving Hoffer Q. Post-minimization, the largest mean prediction error was 0.726 diopters (D; SD) and 0.043 D (RMS), with the highest SD and RMS after adjustments at 0.529 D and 0.875 D, respectively, indicating effective minimization strategies. The study simplifies the process of minimizing SD and RMS in single-optimized IOL power predictions, offering a valuable tool for clinicians. However, it also underscores the complexity of achieving balanced optimization and suggests the need for further research in this area. The study presents a novel, clinically practical approach for optimizing IOL power calculations.

Peripheral defocus of monofocal intraocular lenses.

To quantify the angular dependence of monofocal intraocular lens (IOL) power. Ophthalmic Biophysics Laboratory, Kallam Anji Reddy campus, L V Prasad Eye Institute, Hyderabad, India. Laboratory study. Experiments were performed on IOLs from 2 different manufacturers (APPALENS 207, Appasamy Associates and SN60WF, Alcon Laboratories, Inc.). IOL powers ranged from 17 to 25 diopters (D). The IOLs were mounted in a fluid-filled chamber, and the on-axis and off-axis powers were measured using a laser ray tracing system over the central 3 mm zone with delivery angles ranging from -30 to +30 degrees in 5-degree increments. The position of the best focus was calculated for each IOL at each angle. The angular dependence of IOL power was compared with theoretical predictions. Peripheral defocus increased significantly with increasing incidence angle and power. The peripheral defocus at ±30 degrees increased from 5.8 to 8.5 D when the power increased from 17.5 to 24.5 D for APPALENS 207 and from 4.9 to 7.4 D when the power increased from 17 to 25 D for SN60WF. The mean difference between the measured and theoretical tangential power at ±30 degrees was 0.50 ± 0.16 D for the APPALENS 207 and -0.40 ± 0.10 D for the SN60WF, independent of IOL power. IOLs introduce a significant amount of peripheral defocus which varies significantly with IOL power and design. Given that peripheral defocus is related to lens power, replacement of the crystalline lens (approximately 24 D) with an IOL will produce a significant difference in peripheral defocus profile after surgery.

Investigation of the myopic outcomes of the newer intraocular lens power calculation formulas in Korean patients with long eyes

This study investigated the underlying causes of the myopic outcomes of the optic-based newer formulas (Barrett Universal II, EVO 2.0, Kane, Hoffer-QST and PEARL-DGS) in long Korean eyes with Alcon TFNT intraocular lens (IOL) implantation. Postoperative data from 3100 randomly selected eyes of 3100 patients were analyzed to compare the reference back-calculated effective lens positions (ELPs) based on the Haigis formula using conventional axial length (AL) and Cooke-modified AL (CMAL) with the predicted ELP of each single- and triple-optimized Haigis formula applied to AL- and CMAL. Contrary to the AL-applied Haigis formula, the predicted ELP curve of the CMAL-applied, single-optimized Haigis formula, simulating the methods of the newer formulas, exhibited a significant upward deviation from the back-calculated ELP in long eyes. The relationship between the AL and anterior chamber depth in our long-eyed population differed from that in the base population of the PEARL-DGS formula. The myopic outcomes in long eyes appeared to stem from the substantial overestimation of the postoperative IOL position with AL modification, leading to the implantation of inappropriately higher-powered IOLs. This discrepancy may be attributed to the ethnic differences in ocular biometrics, particularly the relatively smaller anterior segment in East Asian patients with long AL.

Retrospective Analysis of Negative Dysphotopsia After Cataract Surgery

&amp;lt;i&amp;gt;Purpose&amp;lt;/i&amp;gt;: To describe the incidence and characteristics of negative dysphotopsia (ND) as well as the risk factors contributing to it. &amp;lt;i&amp;gt;Methods&amp;lt;/i&amp;gt;: For this retrospective study, data from patients who underwent cataract surgery between January 2018 and December 2019 at our department (Department of Ophthalmology, Hietzing Hospital, Vienna, Austria) was analyzed. A total of 8122 eyes had cataract surgery performed. Three different intraocular lenses (IOLs) have been used (EyeCee® One by Bausch + Lomb, TECNIS® by Johnson &amp; Johnson, HOYA Vivienx ™ by HOYA). Data from patients who postoperatively complained about ND as well as data from a gender and age-matched control group (34 eyes in each) was further analyzed: pupil size, axial length, anterior chamber depth, angle kappa, IOL power and other biometrical factors. The scotomas were depicted on a Harms tangent screen. &amp;lt;i&amp;gt;Results&amp;lt;/i&amp;gt;: An incidence of 1.99% of ND was found, of which 1.58% was transient and 0.42% persistent. The average duration of the symptoms was 5.40 (±6.15) weeks in the transient ND group. In the total cohort of 8122 eyes, there was no difference in the distribution of implanted IOL types or IOL power; neither played the surgeon a significant role in the development of ND. There was no significant difference between ND and control eyes regarding pupil size, axial length, and angle kappa. The anterior chamber was significantly shallower in the ND group: 5.1±0.58mm vs. 5.41±0.61mm (p=0.03). &amp;lt;i&amp;gt;Conclusion&amp;lt;/i&amp;gt;: According to our findings, a shallower anterior chamber poses a risk to the development of ND.