Holladay Formula Research Articles

Does blepharospasm effect biometric parameters and intraocular lens power calculations?

To investigate the effect of botulinum toxin-A (BTX-A) treatment on corneal topography, ocular biometry and keratometry in patients with benign essential blepharospasm (BEB) and hemifacial spasm (HFS). This study comprised 66 eyes of 33 patients with BEB and 5 eyes of 5 patients with HFS who underwent BTX-A injections consecutively. Refractive error values, tear break-up time (TBUT), corneal topography [corneal power of flat axis (K1) and steep axis (K2), mean corneal power (Km), corneal astigmatism (K2-K1)] and ocular optical biometry [axial length (AL), anterior chamber depth (ACD)] were recorded before BTX-A treatment and 1 month after BTX-A treatment. The researchers calculated the expected emmetropic intraocular lens power (emm-IOL) using the SRK-T, Holladay, Hoffer-Q and Haigis formulas at each examination. K1 (43.48 ± 2.02 vs. 43.57 ± 2.08, p = 0.036), Km (43.91 ± 1.99 vs. 43.99 ± 2.06, p = 0.024) and ACD (3.22 (2.77-3.76) vs. 3.41 (2.99-4.02), p < 0.001) values were found to be significantly higher. The expected emm-IOL according to the SRK-T (21.04 ± 1.6 vs. 20.93 ± 1.6, p = 0.048), Holladay (21.05 ± 1.6 vs. 20.91 ± 1.62, p = 0.037) and Hoffer-Q (21.08 ± 1.65 vs. 20.94 ± 1.68, p = 0.038) decreased significantly. The expected emm-IOL according to the Haigis formula slightly decreased, but it was not significant (p = 0.386). Additionally, TBUT was found to be significantly lower (p < 0.001) after BTX-A injection. Other parameters were not statistically significant (p > 0.05). Our study is the first in the literature to compare optic biometry data and intraocular lens power calculation formulas before and after BTX-A injection in eyes with BEB and HFS. BTX-A injection could play an important role in changing the keratometric and ACD values. It should be considered that IOL power calculations that might be unpredictable due to blepharospasm, so repeated measurements and especially measurements after releasing the spasm with BTX-A injections, are necessary in BEB and HFS.

Performance of a simplified strategy for formula constant optimisation in intraocular lens power calculation.

To investigate the performance of a simple prediction scheme for the formula constants optimised for a mean refractive prediction error. Analysis based on a dataset of 888 eyes before and after cataract surgery with IOL implantation (Hoya Vivinex). IOLMaster 700 biometric data, power of the implanted lens and postoperative spherical equivalent refraction were used to calculate the optimised constants (.)opt for SRKT, HofferQ, Holladay and Haigis formula with an iterative nonlinear optimisation. For detuning start values by ±1.5 from (.)opt, the predicted formula constants (.)pred were calculated and compared with (.)opt. Formula performance metrics mean (MPE), median (MEDPE), mean absolute (MAPE), median absolute (MEDAPE), root mean squared (RMSPE) and standard deviation (SDPE) of the formula prediction error were analysed for (.)opt and (.)pred. (.)pred - (.)opt showed a 2nd order parabolic behaviour with maximal deviations up to 0.09 at the tails of detuning and a minimal deviation up to -0.01 for all formulae. The performance curves of different metrics of PE as functions of detuning variations show that the formula constants for zeroing MPE and MEDPE yield almost identical formula constants, optimisation for MAPE, MEDAPE and RMSPE yielded formula constants very close to (.)opt, and optimisation for SDPE could result in formula constants up to 0.5 off (.)opt which is unacceptable for clinical use. This simple prediction scheme for formula constant optimisation for zero mean refraction error performs excellently in our monocentric dataset, even for larger deviations of the start value from (.)opt. Further studies with multicentric data and larger sample sizes are required to investigate the performance in a clinical setting further.

Predictability of Existing IOL Formulas After Cataract Surgery in Patients with a Previous History of Radial Keratotomy: A Retrospective Cohort Study and Literature Review.

This study aims to evaluate the accuracy of 12 different intraocular lens (IOL) power calculation formulas for post-radial keratotomy (RK) eyes. The investigation utilizes recent advances in topography/tomography devices and artificial intelligence (AI)-based calculators, comparing the results to those reported in current literature to assess the efficacy and predictability of IOL calculations for this patient group. In this retrospective study, 37 eyes from 24 individuals with a history of RK who underwent cataract surgery at Hoopes Vision Center were analyzed. Biometry and corneal topography measurements were taken preoperatively. Subjective refraction was obtained 6 months postoperatively. Twelve different IOL power calculations were used, including the American Society of Cataract and Refractive Surgery (ASCRS) post-RK online formula, and the Barrett True K, Double K modified-Holladay 1, Haigis-L, Panacea, Camellin-Calossi, Emmetropia Verifying Optical (EVO) 2.0, Kane, and Prediction Enhanced by Artificial Intelligence and output Linearization-Debellemanière, Gatinel, and Saad (PEARL-DGS) formulas. Outcome measures included median absolute error (MedAE), mean absolute error (MAE), arithmetic mean error (AME), and percentage of eyes achieving refractive prediction errors (RPE) within ± 0.50 D, ± 0.75 D, and ± 1 D for each formula. A search of the literature was also performed by two independent reviewers based on relevant formulas. Overall, the best performing IOL power calculations were the Camellin-Calossi (MedAE = 0.515 D), the ASCRS average (MedAE = 0.535 D), and the EVO (MedAE = 0.545 D) and Kane (MedAE = 0.555 D) AI-based formulas. The EVO and Kane formulas along with the ASCRS calculation performed similarly, with 48.65% of eyes scoring within ± 0.50 D of the target range, while the Equivalent Keratometry Reading (EKR) 65 Holladay formula achieved the greatest percentage of eyes scoring within ± 0.25 D of the target range (35.14%). Additionally, the EVO 2.0 formula achieved 64.86% of eyes scoring within the ± 0.75 D RPE category, while the Kane formula achieved 75.68% of eyes scoring within the ± 1 D RPE category. There was no significant difference in MAE between the established and newer generation formulas (P > 0.05). The Panacea formula consistently underperformed when compared to the ASCRS average and other high-performing formulas (P < 0.05). This study demonstrates the potential of AI-based IOL calculation formulas, such as EVO 2.0 and Kane, for improving the accuracy of IOL power calculation in post-RK eyes undergoing cataract surgery. Established calculations, such as the ASCRS and Barrett True K formula, remain effective options, while under-utilized formulas, like the EKR65 and Camellin-Calossi formulas, show promise, emphasizing the need for further research and larger studies to validate and enhance IOL power calculation for this patient group.

Effect of vault on predicting postoperative refractive error for posterior chamber phakic intraocular lens based on a machine learning model

Purpose: To investigate how vault and other biometric variations affect postoperative refractive error of implantable collamer lenses (ICLs) by integrating artificial intelligence and modified vergence formula. Setting: Eye and ENT Hospital of Fudan University, Shanghai, China. Design: Artificial intelligence and big data-based prediction model. Methods: 2845 eyes that underwent uneventful spherical ICL or toric ICL implantation and with manifest refraction results 1 month postoperatively were included. 1 eye of each patient was randomly included. Random forest was used to calculate the postoperative sphere, cylinder, and spherical equivalent by inputting variable ocular parameters. The influence of predicted vault and modified Holladay formula on predicting postoperative refractive error was analyzed. Subgroup analysis of ideal vault (0.25 to 0.75 mm) and extreme vault (&lt;0.25 mm or &gt;0.75 mm) was performed. Results: In the test set of both ICLs, all the random forest-based models significantly improved the accuracy of predicting postoperative sphere compared with the Online Calculation &amp; Ordering System calculator (P &lt; .001). For ideal vault, the combination of modified Holladay formula in spherical ICL exhibited highest accuracy (R = 0.606). For extreme vault, the combination of predicted vault in spherical ICL enhanced R values (R = 0.864). The combination of predicted vault and modified Holladay formula was most optimal for toric ICL in all ranges of vault (ideal vault: R = 0.516, extreme vault: R = 0.334). Conclusions: The random forest-based calculator, considering vault and variable ocular parameters, illustrated superiority over the existing calculator on the study datasets. Choosing an appropriate lens size to control the vault within the ideal range was helpful to avoid refractive surprises.

Surrogate optimisation strategies for intraocular lens formula constant optimisation.

To investigate surrogate optimisation (SO) as a modern, purely data-driven, nonlinear adaptive iterative strategy for lens formula constant optimisation in intraocular lens power calculation. A SO algorithm was implemented for optimising the root mean squared formula prediction error (rmsPE, defined as predicted refraction minus achieved refraction) for the SRKT, Hoffer Q, Holladay, Haigis and Castrop formulae in a dataset of N = 888 cataractous eyes with implantation of the Hoya Vivinex hydrophobic acrylic aspheric lens. A Gaussian Process estimator was used as the model, and the SO was initialised with equidistant datapoints within box constraints, and the number of iterations restricted to either 200 (SRKT, Hoffer Q, Holladay) or 700 (Haigis, Castrop). The performance of the algorithm was compared to the classical gradient-based Levenberg-Marquardt algorithm. The SO algorithm showed stable convergence after fewer than 50/150 iterations (SRKT, HofferQ, Holladay, Haigis, Castrop). The rmsPE was reduced systematically to 0.4407/0.4288/0.4265/0.3711/0.3449 dioptres. The final constants were A = 119.2709, pACD = 5.7359, SF = 1.9688, -a0 = 0.5914/a1 = 0.3570/a2 = 0.1970, C = 0.3171/H = 0.2053/R = 0.0947 for the SRKT, Hoffer Q, Holladay, Haigis and Castrop formula and matched the respective constants optimised in previous studies. The SO proves to be a powerful adaptive nonlinear iteration algorithm for formula constant optimisation, even in formulae with one or more constants. It acts independently of a gradient and is in general able to search within a (box) constrained parameter space for the best solution, even where there are multiple local minima of the target function.

Accuracy of Intraocular Lens Power Prediction Using 9 Formula

Purpose: To compare the accuracy of nine intraocular lens (IOL) power calculation formulas.Methods: This study is retrospective consecutive case series. A total of 228 eyes of 228 patients who underwent uncomplicated cataract surgery between October 2015 and March 2021 were included. The accuracy of nine IOL calculation formulas (Kane, Emmetropia verifying optical version, Hill-radial basis function, Olsen, Barrett Universal II [Barrett II], Haigis, Holladay, Hoffer, and SRK/T) was compared and analyzed using differences between the predicted refractive power and actual refractive power at 2 months after cataract surgery. Mean prediction error (ME), mean absolute error (MAE), median absolute error (MedAE), and the percentage of eyes that were within ± 0.50 diopters (D), ± 0.75 D, and ± 1.00 D of the target refraction were calculated for each formula.Results: For all eyes, Haigis formula was the most accurate in MAE, followed by Barrett II formula. Comparing the probability of MAE within 0.50 D, Haigis formula showed the highest accuracy. A total of 20 eyes of 20 patients had more than 25 mm axial length. Regarding MAE, Hoffer Q was the most accurate, followed by the Olsen formula. Comparing the probability of MAE within 0.50 D, the Hoffer Q formula was the most accurate. A total of 24 eyes of 24 patients had more than 46 D keratometry. Regarding MAE and MedAE, Haigis was the most accurate, followed by the Barrett II formula. Comparing the probability of MAE within 0.5 D, Holladay formula was the most accurate.Conclusions: Barrett II and Haigis formulas showed greater accuracy for all patients when we determined IOL power before cataract surgery. Hoffer Q, Olsen, and Barrett II formulas showed higher accuracy for long axial length. And Haigis and Barrett II were the most accurate for steep keratometry.

Total Keratometry Measured With a Swept-Source Optical Biometer Versus Anterior Keratometry: From Planning to Postoperative Results.

To compare the influence of total keratometry (TK) versus anterior keratometry (K) measured with the swept-source optical biometer IOLMaster 700 (Carl Zeiss Meditec AG) on the planning of toric intraocular lenses (IOLs), and the error in predicted residual astigmatism (PRA). This single-center retrospective study included 247 eyes of 180 patients. In eyes undergoing cataract surgery, the optimal toric IOL was calculated based on K or TK measured with the IOLMaster 700. Two formulas were used to estimate IOL power: Holladay and Barrett Toric. Optimal cylinder power and alignment axis change induced by using TK versus K were reported. PRA by each calculation method was compared with manifest refractive astigmatism. Postoperative refractive astigmatism prediction error was calculated using vector analysis. The optimal toric IOL based on TK compared with K was different in 39.3% of cases with the Holladay formula and 31.6% of cases with the Barrett Toric formula. The use of TK rather than K reduced the centroid error in PRA when calculated with the Holladay formula (P < .001), but not when calculated with the Barrett Toric formula (P = .19). The against-the-rule astigmatism subgroup analysis with the Barrett Toric formula showed a statistically significant decrease of centroid error in PRA with the use of TK compared with K (P = .01). TK compared with K measured with the IOL-Master 700 resulted in a change of optimal toric IOL in almost one-third of cases and decreased the error in PRA in patients with against-the-rule astigmatism. [J Refract Surg. 2023;39(4):257-264.].

Evaluation of Phakic IOL Power Calculation Using the New LHC Formula and Comparison with Four Conventional Methods.

Evaluating the accuracy of phakic intraocular lens power calculation in a middle European patient cohort. Eyelaser Clinic, Linz, Austria. Single center, single surgeon retrospective consecutive case series. ology: Inclusion of patients after uneventful phakic IOL surgery implanting 91 non-toric and toric Visian ICL model V4c. OCOS Software, JPhakic Software, Olsen-Feingold formula, Holladay Formula and Linz-Homburg-Castrop (LHC) formula were compared. When possible, lens constants were optimized for the patient cohort. Data of one single eye per patient was included. Outcome measures were: mean absolute prediction error (MAE), median absolute prediction error, mean prediction error with standard deviation and median prediction error, as well as percentage of eyes with an absolute prediction error within limits of 0.25 Dpt, 0.5 Dpt, 0.75 Dpt and 1.0 Dpt. A total of 91 eyes of 91 patients were assessed. After application of the Cochrane Q test, the Olsen-Feingold formula achieved a significantly lower percentage of eyes within an absolute prediction error of 1.0 Dpt than all other methods. In our patient cohort OCOS Software, JPhakic Software, Holladay and LHC formulae showed equal results and can be cross-checked. The LHC formula was not published before. A ready-to-use Excel sheet is available as an addendum.

OKULIX ray-tracing software versus third generation formulas: compatibility or superiority?

Purpose The aim of this retrospective study was to compare the accuracy of intraocular lens (IOL) power calculation using the OKULIX ray-tracing software compared with third generation IOL power calculation formulas. Patients and methods The study included 80 consecutive eyes of 80 patients (26 males and 54 females, with a mean age of 58.8±15.1 years), for whom phacoemulsification and IOL implantation was performed following biometry using the OKULIX ray-tracing software and third-generation IOL power calculation formulas for IOL power calculation. Accuracy of IOL power calculation was investigated by subtracting the attempted and achieved spherical equivalent 1 month postoperatively and was recorded as the mean absolute error. Results OKULIX ray-tracing software calculated IOL power was 17.1±8.5 diopters (D), which was statistically significantly different from Sanders, Retzlaff, Kraff (SRK)-T, Hoffer Q, SRK II, and Holladay formulas (16.7±8.3, 16.6±8.7, 16.8±8, and 16.7±8.5 D, respectively, P<0.001). The OKULIX ray-tracing software mean absolute error was 0.2±0.2 D, which was statistically significantly less than that of the SRK-T, Hoffer Q, SRK II, and Holladay formulas (0.5±0.5, 0.6±0.5, 0.8±0.7, and 0.6±0.5 D, respectively, P<0.001). Conclusions The OKULIX ray-tracing software seems to deliver reliable and more accurate results in comparison to the third generation IOL power calculation formulas.

Hyperopic shift after refractive lens surgery in a patient with prior history of radial keratotomy

Radial keratotomy (RK) was a popular refractive procedure in the 90s. However, more reproducible laser-assisted surgeries are currently preferred. Furthermore, RK patients who undergo cataract surgery experience variable refractive and keratometric changes during the early postoperatory period. Unfortunately, those post-RK patients currently require cataract surgery. A 58-year-old male with a history of RK in both eyes (OU) presented with a 2-year history of night glare and progressive vision loss due to a subcapsular cataract in OU. Using the double-K Holladay formula, bilateral phacoemulsification was performed. At 1 week, refraction was + 2.25/-1.00/27° (power [Pwr]: 39.25D) in oculus dextrus (OD) and + 3.00/−0.75/171° in oculus sinister (OS) (Pwr: 37.41D), achieving a best-corrected visual acuity (BCVA) of 20/30 OU. At 6 weeks, refraction was + 0.75/−0.75/18° (Pwr: 39.71D) in OD and + 1.00/−0.25/180° (Pwr: 38.33) in OS. BCVA remained 20/30 OU. The resulting transitory hyperopic shift after surgery demands a careful and comprehensive intraocular lens calculation preferably aiming toward myopic overcorrection.

The effect of pterygium surgery on intraocular lens power and ocular biometric parameters.

To evaluate the effect of pterygium surgery on intraocular lens (IOL) power and ocular biometric parameters and to evaluate the factors affecting these parameters. Twenty-eight eyes of 25 patients diagnosed with pterygium were evaluated. Axial length (AL), mean keratometry (Sim K), K1, K2, anterior chamber depth (ACD), corneal astigmatism, and ocular biometry parameters were obtained with a dual Scheimpflug analyzer. Pterygium sizes (horizontal, vertical) were measured manually, and pterygium height was analyzed with anterior segment optic coherence tomography. IOL power was calculated according to SRK/T, SRK II, Hoffer Q, Haigis, and Holladay formulas. Limbal conjunctival autograft was performed in all patients after excisional pterygium surgery. Preoperative and postoperative 1st month measurements were analyzed and compared. The mean age of the patients was 51.5 ± 13.8 years. Mean horizontal pterygium length, vertical width, height, and percentage extension of the pterygium were 2.4 ± 0.9, 4.7 ± 1.0 mm, 297 ± 93µm, and 20.2 ± 7.2%, respectively. There was a significant increase in Sim K, K1, and K2 values postoperatively. Postoperative IOL power was significantly lower than preoperative values in all formulas. The change in IOL power after surgery was -0.3 ± 0.6D in the SRKT, -0.3 ± 0.5D in SRK II, -0.4 ± 0.7D in Hoffer Q, -0.5±0.7D in Haigis, and -0.3 ± 0.7D in Holladay 2 formulas. The change in IOL power has a moderate positive linear correlation with the horizontal and vertical sizes of the pterygium and a high positive linear correlation with the percentage extension of the pterygium. Pterygium surgery causes a significant decrease in calculated IOL power obtained with all formulas. It becomes more pronounced with the increase in the size of the pterygium.

Comparative analysis of two optical biometry devices: high wavelength swept source OCT versus partial coherence interferometry

PurposeTo study the reproducibility of measurements performed with a recently developed multimodal high resolution swept source optical coherence tomography (SSOCT) and to make comparisons with a partial coherence interferometry (PCI) biometer.MethodsOne hundred and fifty-two eyes of 152 subjects were involved in this study with a mean age of 65.71 ± 13.86 years (26–85 years). Anterior surface keratometry (K), anterior chamber depth (ACD), white-to-white (WTW) and axial length (AL) values were recorded by the SSOCT (ANTERION, Heidelberg Engineering Ltd, Germany) and PCI (IOLMaster 500, version 5.5, Carl Zeiss Meditec, Germany). Intraocular lens (IOL) power was calculated based on ANTERION and IOLMaster keratometry values by using five traditional vergence formulas.ResultsAnterior surface simulated keratometry values did not differ significantly between the IOLMaster and ANTERION (P > 0.05). AL measurements were successful in 95% of the cases both with the SSOCT and PCI. No significant difference was disclosed between the two instruments (P = 0.229). For WTW measurements, a significant difference was observed between the two optical biometers (P < 0.0001). The difference between PCI and SSOCT in IOL powers was statistically significant for SRK/T, Hoffer and Holladay formulas (P < 0.001).ConclusionOur results implicated an overall good reproducibility of anterior keratometry, AL, ACD and WTW measurements for IOLMaster and ANTERION. The discrepancies between their measurements resulted in significant difference in the calculated IOL power for SRK/T, Hoffer and Holladay formulas, but not for Haigis formula.

Influence of upper blepharoplasty on intraocular lens calculation.

To determine the effect of upper blepharoplasty on corneal topography and intraocular lens power calculation using Galilei and IOLMaster. Thirty patients submitted to upper blepharoplasty from May 2014 to March 2017 at the Hospital Oftalmológico de Sorocaba (São Paulo, Brazil) were included in this observational case series. All patients underwent imaging sessions with Galilei and IOLMaster preoperatively (baseline) and at 1 and 6 months postoperatively. Primary outcome measures using both devices included flattest, average, and steepest corneal curvature, corneal astigmatism, and blepharoplasty-induced corneal astigmatism. Determination of axial length and lens power calculation were performed using only IOLMaster (Holladay formula). Paired t-test and vectorial analysis were used for statistical analysis. Sixty eyes from 30 patients were prospectively included. Vectorial analysis showed that 6 months after surgery, blepharoplasty induced on average 0.39 D and 0.31 D of corneal astigmatism, as measured with Galilei and IOLMaster, respectively. IOLMaster measurements showed that average corneal curvature (44.56 vs 44.64 D, p=0.01), steepest corneal curvature (45.17 vs 45.31, p=0.01) and corneal astigmatism (1.22 vs 1.34, p=0.03) were higher 6 months after surgery. IOLMaster measurements also showed that intraocular lens power was significantly smaller 6 months after surgery (22.07 vs 21.93, p=0.004). All other parameters showed no change for comparisons between baseline and 6 months (p>0.05 for all comparisons). Upper eyelid blepharoplasty influenced intraocular lens calculation using the IOLMaster. However, the influence was not clinically significant. No topographic changes were found using Galilei.

Accuracy of intraocular lens calculation formulas in cataract patients with steep corneal curvature.

ObjectiveTo compare the accuracy of five kinds of intraocular lens calculation formulas (SRK/T, Haigis, Hoffer Q, Holladay and Barrett Universal Ⅱ) in cataract patients with steep curvature cornea ≥ 46.0 diopters.MethodsThis is a retrospective study of cataract phacoemulsification combined with intraocular lens implantation in patients with steep curvature cornea (corneal curvature ≥ 46D). The refractive prediction errors of IOL power calculation formulas (SRK/T, Haigis, Holladay, Hoffer Q, and Barrett Universal II) using User Group for Laser Interference Biometry (ULIB) constants were evaluated and compared. Objective refraction results were assessed at one month postoperatively. According to axial length (AL), all patients were divided into three groups: short AL group (<22mm), normal AL group (>22 to ≤24.5mm) and long AL group (>24.5mm). Calculate the refractive error and absolute refractive error (AE) between the actual postoperative refractive power and the predicted postoperative refractive power. The covariance analysis was used for the comparison of five formulas in each group. The correlation between the absolute refractive error and AL from every formula were analyzed by Pearson correlation test, respectively.ResultTotal 112 eyes of 83 cataract patients with steep curvature cornea were collected. The anterior chamber depth (ACD) was a covariate in the short AL group in the covariance analysis of absolute refractive error (P<0.001). The SRK/T and Holladay formula had the lowest mean absolute error (MAE) (0.47D), there were statistically significant differences in MAE between the five formulas for short AL group (P = 0.024). The anterior chamber depth had no significant correlation in the five calculation formulas in the normal AL group and long AL group (P = 0.521, P = 0.609 respectively). In the normal AL group, there was no significant difference in MAE between the five calculation formulas (P = 0.609). In the long AL group, Barrett Universal II formula had the lowest MAE (0.35), and there were statistically significant differences in MAE between the five formulas (P = 0.012). Over the entire AL range, the Barrett Universal II formula had the lowest MAE and the highest percentage of eyes within ± 0.50 D, ± 1.00 D, and ± 1.50 D (69.6%, 93.8%, and 98.2% respectively).ConclusionCompared to SRK/T, Haigis, Hoffer Q, and Holladay, Barrett Universal Ⅱ formula is more accurate in predicting the IOL power in the cataract patients with steep curvature cornea ≥ 46.0 diopters.

Intraoperative Aberrometry Versus Preoperative Biometry for IOL Power Selection After Radial Keratotomy: A Prospective Study

To compare the accuracy of Optiwave Refractive Analysis (ORA) intraoperative aberrometry (Alcon Laboratories, Inc., Fort Worth, TX) with preoperative biometry in predicting residual refractive error after cataract surgery in eyes that underwent radial keratotomy. This was a prospective consecutive case series of patients with cataract and prior radial keratotomy. Each patient underwent a preoperative intraocular lens (IOL) power calculation using partial coherence interferometry (IOLMaster version 5; Carl Zeiss Meditec, Jena, Germany). For each eye, the Barrett True-K formula was used to select an IOL targeting emmetropia. Residual refractive error was predicted preoperatively using the SRK/T, Hoffer Q, Haigis, and Holladay formulas 1 and 2, and the ORA intraoperatively. Between 8 and 12 weeks after cataract extraction with IOL implantation, the postoperative refraction was compared with the preoperative and intraoperative predictions. The study comprised 52 eyes of 34 patients. The median absolute errors associated with each method were as follows: Barrett True-K formula (0.34), ORA aberrometer (0.53), and SRK/T (0.54), Hoffer Q (0.51), Haigis (0.54), SRK/T (0.57), and Holladay formulas 1 and 2 (0.44) (P = .08). The proportion of patients within ±0.50 diopters of the predicted error was 63.5%, 48.1%, 44.2%, 48.1%, 53.8%, 36.5%, and 57.7%, respectively (P = .03). No statistically significant difference was observed in the number of eyes with hyperopic outcomes (P = .68). In eyes with prior radial keratotomy surgery, the ORA aberrometer performance was similar to the Barrett True-K formula and all of the other established formulas, with no significant difference between median absolute error and mean absolute error. The Barrett True-K formula produced significantly more eyes within ±0.50 diopters than the SRK/T, Hoffer Q, and Holladay 1 formulas. [J Refract Surg. 2019;35(10):656-661.].

The effect of ocular biometric factors on the accuracy of various IOL power calculation formulas

BackgroundTo evaluate how differences in ocular biometry affects the Hoffer Q, Holladay 1, SRK/T, and Haigis intraocular lens power calculation formulae predictions.MethodsThis study was performed on 91 eyes of 91 patients who underwent uneventful cataract surgery. Ocular biometry values were measured using the IOL Master 500, and intraocular lens (IOL) power was calculated using the Haigis, Hoffer Q, Holladay 1, and SRK/T formulas. We calculated the expected difference (ED) of each 3rd generation formula from the Haigis formula by subtracting the predicted refraction of the Haigis formula from the predicted refraction of each 3rd generation formula. Post-operative anterior chamber depth (ACD) was measured at 1 month after surgery using the IOL master. We calculated errors of each formula by subtracting predicted from manifest refraction at post-operative 1 month. Correlation analysis was performed between ocular biometry values, formula expectation values, formula errors and absolute formula errors.ResultsMultiple regression analysis revealed that preoperative ACD was the only significant factor for ED prediction in all of the 3rd generation formulas. For mean errors, axial length and post-operative 1-month change of ACD (delta ACD) correlated significantly with the errors in all 3rd generation formulas, but not with errors of the Haigis formula. Median absolute error (MedAE) of the formulas were 0.40 D for the Hoffer Q formula, 0.37 D for the Holladay formula, 0.34 D for the SRK/T formula, and 0.41 D for the Haigis formula. The MAE of the formulas were 0.50 ± 0.47 D for the Hoffer Q formula, 0.50 ± 0.50 D for the Holladay formula, 0.47 ± 0.51 D for the SRK/T formula, and 0.50 ± 0.47 D for the Haigis formula.ConclusionRegarding ED between the third generation and Haigis formulas, preoperative ACD demonstrated the greatest influence. Calculating mean absolute errors of the formulas, all IOL formulas showed excellent and comparable accuracy. Post-operative change (delta) of ACD correlated significantly with errors of third generation formulas according to simulated ACD.

Intraocular lens power calculation for high myopic eyes with cataract: comparison of three formulas

Objective: To compare the accuracy of three different formulas for intraocular lens power calculation in high myopic eyes with cataract and analyze their influencial factors. Methods: One hundred and three high myopic patients of cataract (103 eyes), with average age of 60.2±8.8 years old (39.0-77.0), including 45 male and 54 female and with axial length ≥ 26 mm were enrolled in this retrospective case-series study. All of them underwent routine ocular examination and IOLMastermeasurement preoperatively and then underwent phacoemulsification through temporal clear-corneal incision with implantation of HumanOptic posterior chamber Intraocular lens (IOL). All analyses were conducted using SPSS version 19.0. Repeated-measures analysis of variance was applied to compare the refractive results one month postoperatively with the predicted IOL powers calculated by SRK/T, Holladay 1, or Haigis formula before surgery. The differences were further compared based on different grouping of axial length (AXL), corneal curvature (K) and corneal astigmatism (CA). The accuracies of the three formulas were analyzed using Bland-Altman analyses and the possible error sources of each formula were analyzed using multiple regression model. Results: The majority of patients enrolled had hyperopic shift after cataract surgery. The mean errors (ME) of the three formulas were SRK/T: 0.70±0.89D, Holladay 1: (1.20±0.88) D and Haigis: (0.60±0.88) D; the mean absolute errors (MAE) of the three formulas were (0.81±0.79) D, (1.23±0.84) D and (0.76±0.74) D, respectively. Both ME and MAE of Holladay formula were significantly greater than the other two formulas (F=86.31, P<0.01). Besides, the proportion of patients having a prediction error within 0.50 D was lower in those using Holladay formula (20.4%, 21/103) than the other two (SRK/T: 38.8%, 40/103, χ(2)=8.41, P<0.01, Haigis: 45.6%, 47/103, χ(2)=14.84, P<0.01). Bland-Altman analyses showed that the accuracies of all the three formulas were acceptable in patients of cataract with high myopia in clinical practice. ME and MAE tended to be larger with longer axial length, larger corneal curvature and astigmatism of the patients in all three formulas. However, in eyes with axial length> 30 mm or corneal curvature ≤43.00 D, the MAE of Haigis formula was lower than that of SRK/T formula (F=63.26,63.94, both P<0.01). The prediction error of SRK/T formula was positively correlated with axial length and corneal astigmatism (F=33.97, r=0.66, β=0.48, P<0.01 and β=0.42, P<0.01), while for Holladay and Haigis formulas, in addition to the previous two factors, the errors were also positively correlated with mean corneal curvature (Holladay 1: F=31.26, r=0.72, AXL: β=0.52, P<0.01, K: β=0.20, P<0.05 and CA: β=0.37, P<0.01; Haigis: F=30.96, r=0.72, AXL: β=0.33, P<0.01, K: β=0.40, P<0.01 and CA: β=0.37, P<0.01). Conclusions: In the selection of IOL formula for high myopic patients with cataract, Haigis or SRK/T would reduce the prediction error and serve as the more accurate formulas than Holladay 1. Haigis formula may be more accurate than SRK/T formula in case of AXL>30 mm or K≤43.00 D. (Chin J Ophthalmol, 2017, 53: 260-265).

Error induced by the estimation of the corneal power and the effective lens position with a rotationally asymmetric refractive multifocal intraocular lens.

To evaluate the prediction error in intraocular lens (IOL) power calculation for a rotationally asymmetric refractive multifocal IOL and the impact on this error of the optimization of the keratometric estimation of the corneal power and the prediction of the effective lens position (ELP). Retrospective study including a total of 25 eyes of 13 patients (age, 50 to 83y) with previous cataract surgery with implantation of the Lentis Mplus LS-312 IOL (Oculentis GmbH, Germany). In all cases, an adjusted IOL power (PIOLadj) was calculated based on Gaussian optics using a variable keratometric index value (nkadj) for the estimation of the corneal power (Pkadj) and on a new value for ELP (ELPadj) obtained by multiple regression analysis. This PIOLadj was compared with the IOL power implanted (PIOLReal) and the value proposed by three conventional formulas (Haigis, Hoffer Q and Holladay I). PIOLReal was not significantly different than PIOLadj and Holladay IOL power (P>0.05). In the Bland and Altman analysis, PIOLadj showed lower mean difference (-0.07 D) and limits of agreement (of 1.47 and -1.61 D) when compared to PIOLReal than the IOL power value obtained with the Holladay formula. Furthermore, ELPadj was significantly lower than ELP calculated with other conventional formulas (P<0.01) and was found to be dependent on axial length, anterior chamber depth and Pkadj. Refractive outcomes after cataract surgery with implantation of the multifocal IOL Lentis Mplus LS-312 can be optimized by minimizing the keratometric error and by estimating ELP using a mathematical expression dependent on anatomical factors.

Improving effective lens position : comparison of femtosecond laser vs manual capsulotomy

AbstractPurpose Every IOL formula has its limits in estimating Effective lens position (ELP). The main one is the variability in capsulotomy size and centration. Our purpose was to compare the variability and predictability in ELP based on capsulotomy created by a femtosecond laser with those using manual continual curvilinear capsulorhexis.Methods 32 eyes from 24 patients undergoing cataract surgery had either femtosecond created 5.2 mm capsulotomy (VICTUS™ Femtosecond Laser Platform ‐ Technolas Perfect vision) (n=16) or manual continuous curvilinear capsulorhexis performed with an attempted diameter of 5.2 mm (n=16). One surgeon performed all the surgeries during a period of one month in April 2012, at Percy military hospital, Clamart. Three type of monofocal IOL were implanted in the bag. At one month after surgery, ELP was measured by Pentacam HR and compared to preoperative estimated lens position. Accuracy to target refraction was also calculated, being the difference between target refraction with Iolmaster v5 (Haigis, SRK/T and Holladay formula) and postoperative objective refractionResults Precision of IOL position was improved, as shown by statistically significant reduced variability of ELP (0,27 vs 0,45, p=0,03) in the laser group at one month. Better accuracy to target refraction using SRK/T formula (0,16 vs 0,5, p=0.02) and Holladay formula (0,26 vs 0,50, p=0,02) was also observed in the laser‐treated eyes compared to the manual group.Conclusion Femtosecond laser system provides a perfectly round, well‐centered, and precise diameter capsulotomy. In this study, this translated to more accurate and predictable ELP and IOL power calculation in femtosecond laser group compared to manual group.

Comparison of intraocular lens power prediction using immersion ultrasound and optical biometry with and without formula optimization

Comparison of postoperative refraction results using ultrasound biometry with closed immersion shell and optical biometry. Three hundred and sixty-four eyes of 306 patients (age: 70.6 ± 12.8 years) underwent cataract surgery where intraocular lenses calculated by SRK/T formula were implanted. In 159 cases immersion ultrasonic biometry, in 205 eyes optical biometry was used. Differences between predicted and actual postoperative refractions were calculated both prior to and after optimization with the SRK/T formula, after which we analysed the similar data in the case of Holladay, Haigis, and Hoffer-Q formulas. Mean absolute error (MAE) and the percentage rate of patients within ±0.5 and ±1.0 D difference in the predicted error were calculated with these four formulas. MAE was 0.5-0.7 D in cases of both methods with SRK/T, Holladay, and Hoffer-Q formula, but higher with Haigis formula. With no optimization, 60-65 % of the patients were under 0.5 D error in the immersion group (except for Haigis formula). Using the optical method, this value was slightly higher (62-67 %), however, in this case, Haigis formula also did not perform so well (45 %). Refraction results significantly improved with Holladay, Hoffer-Q, and Haigis formulas in both groups. The rate of patients under 0.5 D error increased to 65 % by the immersion technique, and up to 80 % by the optical one. According to our results, optical biometry offers only slightly better outcomes compared to those of immersion shell with no optimized formulas. However, in case of new generation formulas with both methods, the optimization of IOL-constants give significantly better results.