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Abstract The objective is to evaluate the parameters significantly related to calculating the power of the implanted lens and to determine the importance of different biometric, retina, and corneal aberrations variables. A retrospective cross-sectional observational study used a database of 422 patients who underwent cataract surgery at the Oftalvist Center in Almeria between January 2021 and December 2022. A random forest based on machine learning techniques was proposed to classify the importance of preoperative variables for calculating IOL power. Correlations were explored between implanted IOL power and the most important variables in random forests. The importance of each variable was analyzed using the random forest technique, which established a ranking of feature selections based on different criteria. A positive correlation was found with the random forest variables. Selection: axial length (AL), keratometry preoperative, anterior chamber depth (ACD), measured from corneal epithelium to lens, corneal diameter, lens constant, and astigmatism aberration. The variables coma aberration (p-value = 0,12) and macular thickness (p-value = 0,10) were almost slightly significant. In cataract surgery, the implanted IOL power is mainly correlated with axial length, anterior chamber depth, corneal diameter, lens constant, and preoperative keratometry. New variables such as astigmatism and anterior coma aberration and retina variables such as the preoperative central macular thickness could be included in the new generation of biometric formulas based on artificial intelligence techniques.

AIM: To evaluate the effect of capsular tension ring(CTR)on the stability and accuracy of Barrett universal Ⅱ intraocular lens(IOL)calculation formula in patients with high myopia and cataract.METHODS:Prospective study. A total of 40 cases(80 eyes)of high myopia and cataract that visited our hospital from January to June 2022 were selected. The patients were divided into CTR group and blank group by random number table method, with 40 eyes in each group. All patients were measured by IOL Master, and the actual implanted IOL power and predicted postoperative power were calculated according to Barrett universal Ⅱ formula. The uncorrected visual acuity(UCVA)and best corrected visual acuity(BCVA)at 6 mo after surgery were recorded, and the mean absolute error(MAE)was compared at 6 mo after surgery. Furthermore, the stability of postoperative refractive status and the relationship between the predicted postoperative diopter and CTR were evaluated.RESULTS:The UCVA and BCVA of the two groups were improved at 6 mo after operation(P>0.05), and there was no significant difference in UCVA and BCVA between the two groups at each time point(all P>0.05). After the implantation of IOL in 80 eyes based on the Barrett universal Ⅱ formula, the predicted postoperative diopter was -2.01±0.71 D, the actual postoperative diopter was -1.64±0.88 D, and the MAE was 0.37±0.98 D in the CTR group; in the blank group, the predicted diopter was -2.12±0.64 D, the actual diopter was -1.54±0.88 D, and the MAE was 0.58±0.31 D. The difference between the two groups was statistically significant(P0.05). With the grouth of axial length, the MAE value increased. The postoperative MAE value of patients with axial length ≥30 mm was statistically different between the two groups(P

AIM: To compare and observe the accuracy of five intraocular lens(IOL)power calculation formulas in patients with cataracts who have previously undergone corneal refractive surgery.METHODS: Prospective case series study. A total of 23 cataract patients(34 eyes)with a history of myopic corneal refractive surgery at Jinan Mingshui Eye Hospital from September 2021 to March 2023 were collected, including 1 eye treated with photorefractive keratectomy(PRK)and 22 patients(33 eyes)treated with laser-assisted in situ keratomileusis(LASIK). Preoperative ocular biometry was performed using the IOL Master 700, while corneal true net refractive power(TNP)was measured via Pentacam analyzer. Anterior segment optical coherence tomography(OCT)was used to assesse net corneal power(NCP), posterior corneal refractive power, and central corneal thickness(CCT). The Shammas, Haigis-L, Potvin-Hill Pentacam, OCT, and Barrett True K formulas were utilized for IOL power calculations, with the optimal power selected accordingly. At 1 mo postoperatively, actual refractive outcomes were determined through subjective refraction, based on objective optometry results. The refractive prediction error(RPE)and refractive absolute error(RAE)of each formula were calculated and compared, and the percentage of eyes with RAE ≤0.5 D and ≤1.0 D was counted.RESULTS: No significant statistical difference was found in the RPE of the five formulas when compared to zero(all P>0.05), nor were there significant differences in RPE and RAE among the formulas(F=0.554, P=0.696; H=4.402, P=0.354). The RAE was within ≤0.5 D for 26 eyes(76%)using the Potvin-Hill Pentacam formula and for 24 eyes(71%)using the Barrett True K formula, with both formulas achieving an RAE within ≤1.0D in 33 eyes(97%).CONCLUSIONS: The Barrett True K and Potvin-Hill Pentacam formulas demonstrated high predictive accuracy for IOL power calculations in post-corneal refractive surgery cataract patients. Given the variability in corneal refractive power among these patients, further research on IOL power calculation is warranted. Clinically, it is advisable to consider a range of formulas for optimal outcomes.

This study considered two questions associated with intraocular lens (IOL) power and refraction: (1) Given a refraction with a particular IOL in the eye, what will be the refraction for the IOL or another IOL if located differently with regard to tilt or anterior–posterior position? (2) For a target refraction, what is the power of another IOL if located differently with regard to tilt or position? A thin lens technique was developed to address these questions. For the first question, light was traced through the initial correcting spectacle lens to the cornea, refracted at the cornea, transferred to the position of the initial IOL, refracted at this IOL, transferred to the position of a new IOL (which may be the same IOL but with a different position and/or tilt), refracted backwards through the new IOL, transferred to the cornea and refracted out of the eye to give a new correcting spectacle lens power. For the second question, light was traced through the initial correcting spectacle lens to the cornea, refracted at the cornea, transferred to the position of the initial IOL, refracted at the initial IOL and transferred to the position of a new IOL. Light was also traced through the second correcting spectacle lens, refracted at the cornea and transferred to the position of the second IOL. The difference between the reduced image vergence for the first raytrace and the reduced object vergence for the second raytrace gave the effective power of the second IOL, and from this, the power of the second IOL was determined. Examples are presented for different situations, including a case report. [ABSTRACT FROM AUTHOR]

Abstract Introduction The aim of this study was to investigate the influence of ocular biometry parameters on the predictive accuracy of 10 intraocular lens (IOL) power formulas in patients with high myopia (HM). Methods We analyzed 202 eyes of 202 patients. The ocular biometry was determined preoperatively using an IOLMaster 700. The associations between the biometry parameters and the prediction error (PE) 1 month postoperatively were assessed. HM was defined as an axial length exceeding 26.50 mm. Results In patients with HM (n = 108), the K6, Emmetropia Verifying Optical (EVO), Olsen, and Barrett Universal II (BUII) formulas had the lowest absolute PEs among the 10 formulas. The ocular biometry parameters were not associated with the PE of K6, EVO, Olsen, or BUII. A longer axial length in HM eyes was associated with myopic outcomes by Kane, Hoffer QST, and VRF and hyperopic outcomes by Holladay 2 and T2. Steeper keratometry, a deeper anterior chamber, and a thicker lens were associated with a hyperopic shift in HM eyes when using VRF, Kane, and Hoffer QST, respectively. In patients without HM (n = 94), there was no difference between the formulas in absolute PE. The significant associations between the biometry parameters and PE in patients with HM were not present in patients without HM. Conclusions K6, EVO, Olsen, and BUII displayed high accuracy in HM eyes and were not influenced by preoperative biometry parameters. For the remaining formulas, the preoperative keratometry, anterior chamber depth, lens thickness, and axial length were possible error sources underlying an inaccurate IOL power prediction in patients with HM.

A thin lens technique was developed to determine how the effective powers of toric monofocal intraocular lenses (IOLs) are influenced by tilt and the refractive errors associated with the tilt. A series of steps determined the effective power of the cornea at the IOL, the IOL power, the effective power of the tilted IOL, the correction required at the front of the eye and the power of an IOL that would compensate for the tilt. The correction was determined by starting at the ideal reduced image vergence at the IOL, backwards raytracing to obtain a reduced image vergence at the cornea, and subtracting the cornea power from this reduced image vergence. Examples are presented for different situations where the IOL is either tilted about the vertical or an oblique axis. Raytracing with a thick lens verified the accuracy of the technique. [ABSTRACT FROM AUTHOR]

Purpose: To determine the accuracy of different biometric formulae for intraocular lens power (IOL) calculation in predicting a target postoperative refraction within ± 1.0 diopters in patients with long axial length undergoing phacoemulsification. Study Design: Cross sectional study. Place and Duration of Study: Department of Ophthalmology and visual sciences, Unit 1 Dow University of Health Sciences, Dr. Ruth KM Phau Civil Hospital Karachi from February 2019 to August 2019. Methods: The study included 45 eyes with cataract and preoperative uncorrected visual acuity ranging from 6/60-6/12, axial length of 24.5 to 27.0 mm with no other ocular problem. IOL power was calculated with SRK-T, Holladay 1 and Haigis formula installed in optical biometer AL-Scan (Nidek Co, Ltd., Gamagori, Japan) and by Barrett universal 2 formula from http://www.apacrs.org/barrett_universal2/. Patients underwent phacoemulsification by single surgeon. Follow up included refractive status usingAutorefracto-keratometer,URK-700 (Unicos Co., Ltd., Korea) at 6th week post-operatively. Deviation of actual postoperative refraction from the predicted target preoperative refraction were calculated and values within ± 1.0 diopter were considered accurate. Data was analyzed using SPSS version 22. Results: Outcome in terms of postoperative refractive error (+1D to -1D) with respect to biometric formula showed 100% accuracy using Haigis formula, 90% accuracy using SRK-T formula, 72.72% accuracy using Barrett universal II formula and 66.67% accuracy using Holladay-1 formula. Conclusion: Haigis formula proved to be more reliable and accurate than SRK-T, Holladay 1 and Barrett universal II formulae for calculation of intraocular lens power in eyes with long axial length. [ABSTRACT FROM AUTHOR]

Introduction: The aim of this study was to investigate the influence of ocular biometry parameters on the predictive accuracy of 10 intraocular lens (IOL) power formulas in patients with high myopia (HM). Methods: We analyzed 202 eyes of 202 patients. The ocular biometry was determined preoperatively using an IOLMaster 700. The associations between the biometry parameters and the prediction error (PE) 1 month postoperatively were assessed. HM was defined as an axial length exceeding 26.50 mm. Results: In patients with HM (n = 108), the K6, Emmetropia Verifying Optical (EVO), Olsen, and Barrett Universal II (BUII) formulas had the lowest absolute PEs among the 10 formulas. The ocular biometry parameters were not associated with the PE of K6, EVO, Olsen, or BUII. A longer axial length in HM eyes was associated with myopic outcomes by Kane, Hoffer QST, and VRF and hyperopic outcomes by Holladay 2 and T2. Steeper keratometry, a deeper anterior chamber, and a thicker lens were associated with a hyperopic shift in HM eyes when using VRF, Kane, and Hoffer QST, respectively. In patients without HM (n = 94), there was no difference between the formulas in absolute PE. The significant associations between the biometry parameters and PE in patients with HM were not present in patients without HM. Conclusions: K6, EVO, Olsen, and BUII displayed high accuracy in HM eyes and were not influenced by preoperative biometry parameters. For the remaining formulas, the preoperative keratometry, anterior chamber depth, lens thickness, and axial length were possible error sources underlying an inaccurate IOL power prediction in patients with HM. [ABSTRACT FROM AUTHOR]

AIM: To compare the accuracy between Wang-Koch axial length adjustment formulas(SRK/TWK, Holladay ⅠWK)and SRK/T, Haigis, Holladay Ⅰ, Hoffer Q in calculating intraocular lens power of cataract patients with high myopia.METHODS: A total of 42 cataract patients with high myopia(57 eyes)were collected. All eyes underwent phacoemulsification combined with intraocular lens implantation surgery in our Hospital from September 2019 to March 2022. They were divided into two groups according to the axial length(AL): group A(27mm≤AL0.05). MAE were statistically different among the formulas in group A(27mm≤AL0.05). In group B(AL≥30mm), the MAE of each formulas was statistically different after surgery(P

BackgroundSilicone oil tamponade is widely used in vitreoretinal surgery. In some cases, silicone oil may not be extracted for a long time or even permanently and is referred to as silicone oil-dependent eyes. In this study, we aimed to deduce a theoretical formula for calculating intraocular lens power for silicone oil-dependent eyes and compare it with clinical findings.MethodsA theoretical formula was deduced using strict geometric optical principles and the Gullstrand simplified eye model. The preoperative and postoperative refractive statuses of patients with silicone oil-dependent eyes who underwent intraocular lens implantation were studied (Group A, n = 13). To further test our derived theoretical formula, patients with silicone oil tamponade and first-stage intraocular lens implantation were included (Group B, n = 19). In total, 32 patients (32 eyes) were included in the study.ResultsIn group A, the calculated intraocular lens power based on our formula was 24.96 ± 3.29 diopters (D), and the actual refraction of the patients was 24.02 ± 4.14D. In group B, the theoretical intraocular lens power was 23.10 ± 3.08D, and the clinical intraocular lens power was 22.84 ± 3.42D. There was no significant difference between the theoretical and clinical refractive powers, and the intraclass correlation coefficient was 0.771 for group A and 0.811 for group B (both p ≤ 0.001). The mean absolute error for silicone oil-dependent eyes of the formula was 1.66 ± 2.09D. After excluding data for two patients with a flat cornea (corneal refractive power

PurposeTo compare the measurement accuracy of new/updated intraocular lens (IOL) power calculation methods, namely, Kane, Emmetropia Verifying Optical (EVO), with existing methods (Barrett Universal II, Olsen, Haigis, Hoffer Q, Holladay 1, SRK/T) in Chinese eyes with axial lengths ≤ 22.5 mm.MethodsThe study included data from patients who underwent uneventful cataract surgery with the insertion of ZCB00 IOL. Refractive prediction errors were determined by calculating the difference between postoperative refraction and the predicted refraction using each formula. Various parameters were evaluated, including mean prediction error (ME), mean absolute error (MAE), median absolute error (MedAE), and the percentage of eyes with prediction errors (PE) within different ranges.ResultsThe study enrolled 38 eyes of 38 patients, and the Barrett Universal II formula demonstrated the lowest MAE and MedAE among the tested formulas. Post hoc analysis using Wilcoxon signed-rank pairwise comparisons for non-parametric samples with Bonferroni correction revealed no significant difference in postoperative refractive prediction among all the formulas (P > 0.05). The percentage of eyes with PE within ± 0.5 D was as follows: Barrett Universal II, 81.58%; Haigis, 78.95%; EVO, 76.32%; Olsen, 76.32%; Holladay I, 73.68%; SRK/T, 71.05%; Kane, 68.42%; and Hoffer Q, 65.79%.ConclusionThe Barrett Universal II formula was more accurate than the other formulas for Chinese eyes with AL ≤ 22.5 mm.

Abstract 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

Purpose: To evaluate the accuracy of newer generation intraocular lens (IOL) power calculation formulas (EVO 2.0 and Kane) with established formulas (Barrett Universal II, Haigis and SRK/T) in pediatric cataract patients. Methods: Retrospective study. We enrolled 110 eyes (110 patients) in Eye Hospital of Wenzhou Medical University. All patients underwent uneventful cataract surgery and implanted with posterior chamber IOL in the bag. We calculate the mean prediction errors (PE) and percentage within 1 diopter (D) at 1 month to assess the accuracy, and percentage > 2D was defined as prediction accident. Then, we performed subgroup analysis according to age and axial length (AL). Results: The mean age and AL were 37.45 ± 23.28 months and 21.16 ± 1.29 mm. The mean PE for all patients was as follows: Barrett (− 0.30), EVO (0.18), Haigis (− 0.74), Kane (− 0.36), and SRK/T (0.58), p < 0.001. In addition, EVO and SRK/T formulas were relatively accurate in patients younger than 24 months and with AL ≤ 21 mm, while EVO got lower prediction accident rate than SRK/T (3/41 vs 8/41, 4/52 vs 5/52). Moreover, Barrett, EVO, and Kane formulas achieved better accuracy and lower prediction accident rate in patients older than 24 months and with AL > 21 mm (both > 51/69 and 43/58, and < 3/69 and 3/58). Conclusions: In patients older than 24 months and with AL > 21 mm, Barrett, EVO, and Kane formulas were relatively accurate, while in patients younger than 24 months and with AL ≤ 21 mm, EVO was more accurate, followed by SRK/T formula. [ABSTRACT FROM AUTHOR]

In patients with eye surface disorders such as dry eye syndrome or Meibomian gland dysfunction (MGD) it is necessary to improve the tear film condition in order to obtain visual system measurements before cataract surgery. The aim of the project was to analyze the Thermal Pulsation System (TPS) impact on the visual system parameters used in cataract surgery qualification. The study included six patients (11 eyes) with MGD diagnosis. All patients were treated with TPS. The obtained results were compared and used to calculate the power and type of the intraocular lens (IOL). As a treatment result, the power of astigmatism has changed in 64% of the eyes. Planned surgical treatment type has changed in 27% of cases. TPS also affected the cylinder axis in three eyes, which was 27% of cases. Based on the calculations, power of the recommended IOL has changed in five eyes (46%). Stabilization of visual system parameters after TPS allowed to improve the accuracy of the results. It also ensured the proper astigmatism treating method during cataract surgery and allowed selection of the proper IOL power and type. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the accuracy of axial length (AL) measurement for intraocular lens (IOL) calculation in patients with cataract and epiretinal membrane (ERM). Methods: This prospective, cross-sectional study was performed in cataract patients with ERM. All subjects were sent for standard optical biometry, prepared for cataract surgery. Signals of AL measurement were detected as double peaks and recorded as AL1 (first peak), and AL2 (second peak). The IOL power was calculated from AL1 and AL2, and reported as IOL1 and IOL2. The IOL2 was chosen for cataract surgery in all cases. Postoperative predictive errors were compared between IOL1 and IOL2. Results: Thirty-seven eyes from 37 patients were included. Mean AL1 was significantly shorter than AL2 (23.13 ± 1.28 vs. 23.60 ± 1.34 mm, p < 0.001), resulting in higher power of IOL1 than IOL2 (mean difference was 1.53 ± 0.96 diopters, p < 0.001). At 3-months post-operation, twenty-nine eyes (78.4%) (95% CI 62.8%–88.6%) showed refractive error within ± 0.5 diopter and all eyes were within ± 1.0 diopter. Postoperative predictive errors including mean arithmetic error (ME) and mean absolute error (MAE) of IOL2 were significantly lower than those of IOL1 (ME: IOL1 vs. IOL2, −0.94 ± 0.91 vs. 0.08 ± 0.51; MAE: 0.97 ± 0.88 vs. 0.39 ± 0.33 diopter, all p < 0.001). Conclusions: AL measurement in ERM can be detected as a double peak signal during biometric measurement. The IOL power calculated from the first and second peak signals is significantly different. However, the IOL power derived from the second peak signal provides better refractive outcomes. The results suggest that the second peak signal represents an accurate AL measurement. [ABSTRACT FROM AUTHOR]

Abstract Purpose To evaluate the influence of corneal ablation patterns on the prediction error after cataract surgery in post-myopic-LASIK eyes. Methods Eighty-three post-myopic-LASIK eyes of 83 patients that underwent uneventful cataract surgery were retrospectively included. Predicted postoperative spherical equivalence (SE) was calculated for the implanted lens using the Haigis-L and Barrett True-K formula. Prediction error at one month postsurgery was calculated as actual SE minus predicted SE. For each eye, area and decentration of the ablation zone was measured using the tangential curvature map. The associations between prediction errors and corneal ablation patterns were investigated. Results The mean prediction error was − 0.83 ± 1.00 D with the Haigis-L formula and − 1.00 ± 0.99 D with the Barrett True-K formula. Prediction error was positively correlated with keratometry (K) value and negatively correlated with ablation zone area using either formula, and negatively correlated with decentration of the ablation zone using the Barrett True-K formula (all P

AIM: To investigate the binocular intraocular lens (IOL) power difference in eyes with short, normal, and long axial lengths (AL) using Lenstar LS 900 optical biometry. METHODS: A total of 716 (1432 eyes) participants were included. The groups were categorized into short (group A: AL25 mm). The central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), AL, anterior corneal keratometry, white-to-white (WTW), pupil diameter (PD), as well as IOL power calculated using embedded Barrett formula were assessed. Bland-Altman plots were used to test the agreement of the binocular parameters. RESULTS: In group A, the CCT of the right eye was significantly thinner than that of the left eye (P=0.044) with a difference of -2±8 μm [95% limits of agreement (LoA), -17.8 to 13.2 μm]. For group B, the PD and IOL power in the right eye were significantly lower than those of the left eye (P=0.001,

Simple Summary: The scope of this study was to determine if various ocular parameters are associated with parameters indicating thyroid activity. It is well-known that in some pathological thyroid conditions, the eyes can also be affected. Thyroid eye disease is the most extreme example of eye pathology caused by a pathological thyroid condition. In the current study, we measured the plasma levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), thyroglobulin (Tg), thyroglobulin antibodies (TgAb), and thyroid peroxidase antibodies (TPOAb), in addition to 20 ocular parameters in 4633 healthy adults (10 for each eye, including corneal radius, corneal thickness, anterior chamber depth, anterior chamber angle, lens thickness, posterior chamber length, axial length, intraocular lens power (IOL), spherical power, and cylinder power). This is, to the best of our knowledge, the largest study inferring the effect of thyroid activity on ocular parameters. The most important result of this study was that patients with hyperthyroidism had thicker corneas compared to euthyroid individuals. Intraocular lens power was increased in patients with clinical hypothyroidism, while spherical power was increased in euthyroid individuals with positive antibodies. The diagnostic potential of corneal thickness monitoring in patients with hyperthyroidism, which could indicate the later development of thyroid-related eye disease, should be explored in longitudinal studies. During development, thyroid hormones play an important role in eye development, while in adults, some pathological thyroid conditions can affect the normal functioning of the eyes. Thyroid eye disease is the most well-known eye pathology caused by a pathological thyroid condition. Few studies have investigated the association between ocular parameters and thyroid function. Thus, in this study, we aimed to examine whether thyroid activity affects ocular parameters. This cross-sectional study included 4633 healthy adults recruited within the 10,001 Dalmatians project of the Croatian Biobank. The plasma levels of thyroid-stimulating hormone (TSH), free triiodothyronine (fT3), free thyroxine (fT4), thyroglobulin (Tg), thyroglobulin antibodies (TgAb), and thyroid peroxidase antibodies (TPOAb) were measured by an immunoassay. We determined 20 ocular parameters for each participant (10 for each eye, including corneal radius, corneal thickness, anterior chamber depth, anterior chamber angle, lens thickness, posterior chamber length, axial length, intraocular lens power (IOL), spherical power, and cylinder power). Patients with hyperthyroidism had thicker corneas compared to euthyroid individuals. Corneal thickness was also negatively associated with plasma TSH levels. Intra-ocular lens power was higher in patients with clinical hypothyroidism, while spherical power was higher in euthyroid individuals with positive antibodies compared to euthyroid individuals. Intra-ocular lens power negatively correlated with fT4 levels, while spherical power positively correlated with TgAb, TPOAb, and Tg levels and negatively correlated with TSH levels. The anterior chamber angle was positively associated with plasma TSH levels and TPOAb levels and negatively associated with plasma fT4 levels. These findings suggest an interesting interplay between ophthalmic measures and thyroid status, detectable even in the general adult population. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Purpose: Comparison of the accuracy of intraocular lens (IOL) power calculation formulas (SRK II, SRK/T, Holladay 1, Hoffer Q and Barrett II Universal, Haigis) in pediatric cataract surgery using optical biometry. Method: This prospective study included seventy eyes of 70 patients between ages of 3–15 who had undergone cataract surgery with IOL implantation. Anterior segment parameters and axial length (AL) were measured with an optical biometer. Barrett II Universal formula results were used to determine the diopter of implanted IOL. Postoperative refraction was taken at first month, and differences from the estimated refractive value [mean absolute predictive error (APE)] were compared between formulas. Formulas were also compared according to AL. Results: The lowest APE was achieved with Barrett II formula (0.64 ± 0.73D) and the highest with Haigis formula (1.06 ± 0.84D) in the whole study population (p < 0.01). APE values were lowest with Holladay 1 (0.79 ± 0.71D) and highest with Haigis (1.44 ± 0.92D) in patients with an AL ≤ 22 mm; lowest APE was achieved with Barrett II (0.47 ± 0.54D) and highest with Haigis (0.84 ± 0.72D) in patients with an AL > 22 mm. Conclusion: Barrett II formula had the best results in eyes with average AL, and SRK/T and Holladay 1 formulas were better in eyes with shorter AL. Haigis formula statistically had the highest predictive error in all formulas. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the effects of blepharoplasty on intraocular pressure (IOP) and ocular biometric parameters. Methods: A total of 112 eyelids of 56 patients undergoing bilateral blepharoplasty due to upper eyelid dermatochalasis was included. The patients were classified into three groups according to margin reflex distance (MRD) (Group 1 >4 mm MRD, Group 2 2-4 mm MRD, and Group 3 <2 mm MRD). The IOP and ocular biometric parameters obtained baseline and postoperative 3rd month were compared. Results: The demographic characteristics of the groups were similar (p > 0.05, for all). IOP (p = 0.002) and central corneal thickness (p = 0.038) increased in Group 3. The mean amount of the increase in IOP was 0.95mmHg. The keratometric values increased in all groups and corneal astigmatism was also increased in Group 2 and Group 3 (p < 0.001, for all). The mean amount of the increase in corneal astigmatism was 0.54D in Group 3. Anterior chamber depth and axial length did not change (p > 0.05, for all). The intraocular lens powers calculated by six different formulas decreased in Group 3 (p < 0.001, for all), and the mean amount of the decrease was 0.40D. Conclusions: Clinicians should be aware of the potential change in IOP and ocular biometric parameters in patients who underwent blepharoplasty. If a patient has glaucoma risk factors, close follow-up is needed after blepharoplasty. Change in strategy or timing may also be needed for dermatochalasis patients when planning corneal refractive surgery or cataract surgery. Level of Evidence IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266. [ABSTRACT FROM AUTHOR]

AIM: To compare the accuracy of Barrett Universal Ⅱ, Haigis and modified Wang-Koch SRK/T formulas in calculating intraocular lens(IOL)power in eyes with long axial length(AL).METHODS: Eyes were divided into three AL groups as follows: 26.0 to 28.0mm(group A), 28.0 to 30.0mm(group B), and 30.0mm or more(group C). All eyes underwent phacoemulsification cataract surgery. In the 3mo after operation, IOL powers that would have resulted in emmetropia were calculated according to results of subjective refraction. The predictive error(PE)and absolute error(AE)of each formulas were calculated and compared and the factors(AL, keratometry value, the anterior chamber depth)associated with PEs were analyzed.RESULTS: The average PE of Barrett Universal Ⅱ, Haigis and modified Wang-Koch SRK/T formulas were 0.37±0.78D, 0.77±0.88D and 0.36±0.82D respectively. In groups A and B, the PEs and AEs of three formulas were not statistically significant(P>0.05). However, in group C, the PEs and AEs of Barrett Universal Ⅱ and modified Wang-Koch SRK/T formula were significantly less than Haigis formula(P

Abstract Background Our study aimed to assess and compare the accuracy of 8 intraocular lens (IOL) power calculation formulas (Barrett Universal II, EVO 2.0, Haigis, Hoffer Q, Holladay 1, Kane and PEARL-DGS) in patients submitted to combined phacovitrectomy for vitreomacular (VM) interface disorders. Methods Retrospective chart review study including axial-length matched patients submitted to phacoemulsification alone (Group 1) and combined phacovitrectomy (Group 2). Using optimized constants in both groups, refraction prediction error of each formula was calculated for each eye. The optimised constants from Group 1 were also applied to patients of Group 2 – Group 3. Outcome measures included the mean prediction error (ME) and its standard deviation (SD), mean (MAE) and median (MedAE) absolute errors, in diopters (D), and the percentage of eyes within ± 0.25D, ± 0.50D and ± 1.00D. Results A total of 220 eyes were included (Group 1: 100; Group 2: 120). In Group 1, the difference in formulas absolute error was significative (p = 0.005). The Kane Formula had the lowest MAE (0.306) and MedAE (0.264). In Group 2, Kane had the overall best performance, followed by PEARL-DGS, EVO 2.0 and Barrett Universal II. The ME of all formulas in both Groups 1 and 2 were 0.000 (p = 0.934; p = 0.971, respectively). In Group 3, a statistically significant myopic shift was observed for each formula (p

Purpose: To report two challenging intraocular lens power calculation cases with patients each underwent different successive corneal refractive surgeries, respectively. Observations: Biometry data, including the Back to Front corneal radii ratio (B/F ratio), were collected by Lenstar, IOL Master, and Pentacam AXL for Case 1 (received radial keratotomy (RK) and photorefractive keratectomy (PRK)) and Case 2 (received RK and laser-assisted in situ keratomileusis (LASIK)). The IOL power calculation was determined by several methods, including Shammas, Haigis-L, and Barrett True-K, which are available in the American Society of Cataract and Refractive Surgery online calculator and Pentacam AXL. The Barrett True-K (no history, post-RK) was more accurate in Case 1 (increased B/F ratio), whereas the Shammas, Haigis-L, and Barrett True-K (no history, post-LASIK/PRK) were more accurate in Case 2 (decreased B/F ratio). Conclusion and importance: The B/F ratio may be a factor to be considered when selecting the IOL power calculation formula for patients who undergo two different corneal refractive surgeries. The further study focusing on this issue should be performed to clarify the results in the future.

In patients with eye surface disorders such as dry eye syndrome or Meibomian gland dysfunction (MGD) it is necessary to improve the tear film condition in order to obtain visual system measurements before cataract surgery. The aim of the project was to analyze the Thermal Pulsation System (TPS) impact on the visual system parameters used in cataract surgery qualification. The study included six patients (11 eyes) with MGD diagnosis. All patients were treated with TPS. The obtained results were compared and used to calculate the power and type of the intraocular lens (IOL). As a treatment result, the power of astigmatism has changed in 64% of the eyes. Planned surgical treatment type has changed in 27% of cases. TPS also affected the cylinder axis in three eyes, which was 27% of cases. Based on the calculations, power of the recommended IOL has changed in five eyes (46%). Stabilization of visual system parameters after TPS allowed to improve the accuracy of the results. It also ensured the proper astigmatism treating method during cataract surgery and allowed selection of the proper IOL power and type.

BACKGROUND: To evaluate the predictability of the Kane formula in estimating postoperative refractive outcome with various corneal curvatures and axial lengths (ALs) besides comparing with existing intraocular lens (IOL) formulae. MATERIALS AND METHODS: A prospective cross-sectional study was carried out among patients having uneventful cataract surgery at an eye hospital. A total of 50 eyes were considered for the study. The corresponding A-constant for the model of IOL implanted into the patient's eye was taken along with the actual power of IOL implanted and corresponding predicted power for the IOL power inserted were taken for all the chosen formulae and was termed as "Adjusted Predicted Refractive Power." This was compared with the actual refractive outcome and the absolute error (AE) was measured. The eyes were separated into groups in terms of corneal curvature as flat (46D) corneas. In terms of AL, it was grouped as short (≤22 mm), medium (>22.0–24.0 mm) eyes. RESULTS: The study included 50 eyes and the mean AE for all the selected formulae were calculated for each group. Over the entire corneal curvature range, none of the formulae showed any significance when compared with the Kane formula (P > 0.05). In short AL, SRK-T formula had a statistical significance over the Kane formula (P = 0.043), whereas no other group had any significance over the Kane formula in AL groups. CONCLUSION: The study shows, all formulae (SRK-T, Holladay1, Hoffer Q, Hill RBF, Barrett Universal II, Kane) are interchangeable to predict the IOL power for any of the corneal curvature and ALs.

Purpose: Optimization of lens constants is a critically important step that improves refractive outcomes significantly. Whether lens constants optimized for the entire range of axial length would perform equally well in short eyes is still a matter of debate. The aim of this study was to analyze whether lens constants need to be optimized specifically for short eyes. Methods: This retrospective observational study was conducted at a tertiary care hospital in Central India. Eighty-six eyes of eighty-six patients were included. Optical biometry with IOLMaster 500 was done in all cases and lens constants were optimized using built-in software. Barrett Universal II, Haigis, Hill-RBF, Hoffer Q, Holladay 1, and SRK/T formulae were compared using optimized constants. Mean absolute error, median absolute error (MedAE), and percentage of eyes within ±0.25, ±0.50, ±1.00, and ±2.00 diopter of the predicted refraction, of each formula were analyzed using manufacturer's, ULIB, and optimized lens constants. MedAE was compared across various constants used by Wilcoxon signed-rank test and among optimized constants by Friedman's test. Cochran's Q test compared the percentage of eyes within ± 0.25, ±0.50, ±1.00, and ± 2.00 diopter of the predicted refraction. A value of P < 0.05 was considered statistically significant. Results: Optimized constant of Haigis had significantly lower MedAE (P < 0.00001) as compared to manufacturers. However, there was no statistically significant difference between ULIB and optimized constants. Postoptimization, there was no statistically significant difference among all formulae. Conclusion: Optimizing lens constants specifically for short eyes gives no added advantage over those optimized for the entire range of axial length.

The major challenge these days in pediatric cataract surgery is not the technique of surgery or intraocular lens (IOL) used but the postoperative refractive error. Amblyopia occurring due to postoperative refractive error which the child has; destroys the benefit obtained by a near-perfect and timely surgery. Even if we settle the debate as to what should be the ideal postoperative target refraction, there is a postoperative surprise that is not explained by our conventional insights of an accurate power calculation in children. The role of IOL power calculation formulae in affecting the postoperative refractive error should not be underestimated. Therefore, which age-appropriate formula is to be used for children is unclear. This review is an update on major IOL power calculation formulas used in pediatric eyes. We have tried to define why we should not be using these formulas made for adult eyes and review the literature in this regard.

Background: The purpose of this study was to assess the accuracy of intraocular lens power (IOL) formulas for cataract surgery after deep anterior lamellar keratoplasty (DALK). Methods: This retrospective study included eyes which had previously undergone DALK and underwent standard phacoemulsification with monofocal IOL implantation between January 2012 and January 2021 at Ospedali Privati Forlì "Villa Igea" (Forlì, Italy). The predicted spherical equivalent (SE) was calculated using the Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Hoffer QST, Holladay 1, Holladay II, Kane and SRK/T formulas. Prediction error (PE) was calculated as the actual postoperative SE refraction minus the SE predicted refraction. Results: Eighty-two eyes of 82 patients were included. The mean PE was negative using all formulas. Friedman test revealed a statistically significant difference of the median absolute PE (MedAE) among the different IOL formulas (P = 0.005). On the basis of the MedAE, the formulas were ranked as follows: SRK/T (0.805 D), Kane (0.810 D), EVO (0.845 D), Hoffer QST (0.847 D), Barrett (0.895 D), Holladay 1 (0.915 D), Haigis (1.010 D) and Hoffer Q (1.070 D) formulas. Conclusions: All formulas had a tendency towards a myopic refractive shift in post-DALK eyes. Although the SRK/T, Kane, EVO and Hoffer QST formulas were more accurate, predictability of refractive outcomes was lower than in virgin eyes. [ABSTRACT FROM AUTHOR]

The major challenge these days in pediatric cataract surgery is not the technique of surgery or intraocular lens (IOL) used but the postoperative refractive error. Amblyopia occurring due to postoperative refractive error which the child has; destroys the benefit obtained by a near-perfect and timely surgery. Even if we settle the debate as to what should be the ideal postoperative target refraction, there is a postoperative surprise that is not explained by our conventional insights of an accurate power calculation in children. The role of IOL power calculation formulae in affecting the postoperative refractive error should not be underestimated. Therefore, which age-appropriate formula is to be used for children is unclear. This review is an update on major IOL power calculation formulas used in pediatric eyes. We have tried to define why we should not be using these formulas made for adult eyes and review the literature in this regard. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the prediction accuracy of the intraocular lens (IOL) power calculation using adjusted corneal power according to the posterior/anterior corneal curvature radii ratio in the Haigis formula (Haigis-E) in patients with a history of prior myopic laser vision correction. Methods: Seventy eyes from 70 cataract patients who underwent cataract surgery and had a history of myopic laser vision correction were enrolled. The adjusted corneal power obtained with conventional keratometry (K) was calculated using the posterior/anterior corneal curvature radii ratio measured by a single Scheimpflug camera. In eyes longer than 25.0 mm, half of the Wang-Koch (WK) adjustment was applied. The median absolute error (MedAE) and the percentage of eyes that achieved a postoperative refractive prediction error within ± 0.50 diopters (D) based on the Haigis-E method was compared with those in the Shammas, Haigis-L, and Barrett True-K no-history methods. Results: The MedAE predicted using the Haigis-E (0.33 D) was significantly smaller than that obtained using the Shammas (0.44 D), Haigis-L (0.43 D), and Barrett True-K (0.44 D) methods (P < 0.001, P = 0.001, and P = 0.014, respectively). The percentage of eyes within ± 0.50 D of refractive prediction error using the Haigis-E (78.6%) was significantly greater than that produced using the Shammas (57.1%), Haigis-L (58.6%), and Barrett True-K (61.4%) methods (P = 0.025). Conclusion: IOL power calculation using the adjusted corneal power according to the posterior/anterior corneal curvature radii ratio and modified WK adjustment in the Haigis formula could improve the refraction prediction accuracy after cataract surgery in eyes with prior myopic laser vision correction. [ABSTRACT FROM AUTHOR]

To analyze the agreement of the predicted intraocular lens (IOL) power obtained with ANTERION, IOLMaster 700 and Pentacam AXL biometers. We calculated the monofocal and trifocal IOL power using the SRK/T, Haigis, Barrett Universal II and Hoffer Q formulas for 106 eyes. IOL power agreement between devices was evaluated using the Bland–Altman method. We found significant differences between biometers comparisons (p < 0.001). ANTERION and IOLMaster 700 did not produce significant IOL power differences (p > 0.05), with the same outcomes for medium- and long-eyes. No significant differences were found using the SRK/T, Haigis, or Hoffer Q formulas for short-eyes (p > 0.1). However, Barrett Universal II formula produced significant differences (p < 0.05) and these differences lay between the ANTERION and Pentacam AXL. ANTERION versus IOLMaster 700 comparison showed limits of agreement (LoA) varying from 1.1071D in SRK/T monofocal medium-eyes to 1.6828D in Hoffer Q trifocal all-eyes. The largest LoA (about 3.0D) was found for short-eyes when comparing the Pentacam AXL with the other two devices. These devices provided statistically significant but clinically insignificant mean differences in predicted IOL power. However, wide LoA values suggest that for specific eyes these outcomes could be clinically significant. [ABSTRACT FROM AUTHOR]

Seth M Pantanelli,1 Neal Kansara,1 Gerard Smits2 1Department of Ophthalmology, Penn State College of Medicine, Hershey, PA, USA; 2Computer and Statistical Consultants Incorporated, Santa Barbara, CA, USACorrespondence: Seth M PantanelliDepartment of Ophthalmology, Penn State College of Medicine, 500 University Drive; HU19, Hershey, PA 17033-0850, USATel +1 717-531-5690Fax +1 717-531-5009Email spantanelli@pennstatehealth.psu.eduPurpose: To compare predictability of postoperative refractive astigmatism (RA) using the Emmetropic Verifying Optical (EVO) Toric Formula v2.0 to one that accounts only for anterior corneal astigmatism.Methods: This is a secondary analysis of de-identified data from a clinical trial including 9 sites across the United States. Preoperative biometry was used to predict postoperative RA with the implanted toric IOL using legacy enVista and EVO online calculators. The RA prediction error was computed between back-calculated postoperative RA and predicted residual RA. Outcome measures included vector (centroid) and arithmetic mean RA prediction error.Results: Comparison of calculators was based on 109 eyes, 97 (89%) of which were implanted with a toric IOL with an effective astigmatism power of 1.4 D or less. Centroid of the RA prediction errors was 0.37 D @ 178 and 0.17 D @ 090 for the legacy and EVO calculators, respectively (p < 0.0001). The proportion of eyes with an absolute RA prediction error ≤ 0.5 was 47.3% and 49.1% (p = 0.78), while the proportion of eyes ≤ 1.0 D was 82.7% and 89.1% (p = 0.03). Differences in the proportions ≤ 0.5 D existed for WTR (p = 0.015) but not ATR (p = 0.75) eyes. The proportion in which orientation of the predicted RA (ATR, WTR, or oblique) matched the actual RA was 62% and 78% for legacy and EVO calculators, respectively (p = 0.0029).Conclusion: The EVO Toric Formula v2.0 out-performed the legacy calculator with regards to predictions in eyes with low astigmatism.Keywords: cataract, toric, intraocular lens power, astigmatism, calculators, EVO

Janusz Skrzypecki,1,2 Iwona Grabska-Liberek,3 Maria Guszkowska,1 Justyna Izdebska,1 Jacek P Szaflik1 1Department of Ophthalmology, Medical University of Warsaw, Warsaw, Poland; 2Department of Experimental Physiology and Pathophysiology, Medical University of Warsaw, Warsaw, Poland; 3Department of Ophthalmology, Medical Centre for Postgraduate Education, Warsaw, PolandCorrespondence: Janusz Skrzypecki Email jskrzypecki@wum.edu.plBackground: Fourth-generation formulas for intraocular lens power calculations, including the Barrett Universal II formula, the Olsen formula or the Holladay 2 formula, were thoroughly validated with optical biometry measurements. They precisely predict the effective lens position not only in normal eyes but also in eyes with unusual anatomy. However, in the setting of dense nuclear or posterior subcapsular cataracts, optical biometers fail to obtain accurate measurements and third-generation formulas, i.e. the Hoffer Q or the SRK/T, combined with ultrasound measurements are a method of choice. Considering that optical biometry was fine-tuned to immersion ultrasound, we hypothesize that fourth-generation formulas will yield precise intraocular lens power calculations with immersion ultrasound measurements.Methods: We retrospectively analyzed 50 eyes of 50 patients who underwent uneventful cataract surgery. All patients had intraocular lens power calculated based on immersion ultrasound measurements. Refractive error predictions were compared between third-generation formulas and fourth-generation formulas.Results: There were no statistically significant differences in the median absolute error between formulas. In the study, 86%, 88%, 86%, 84%, 88% and 80% of eyes were within 1 D of target refraction for the SRK/T, the Barrett II, the Hoffer Q, the Holladay 1, the Holladay 2 and the Olsen formula respectively.Conclusion: Fourth-generation formulas combined with immersion ultrasound produced similar results to third-generation formulas. However, the percentage of eyes within 1 D of target refraction remains inferior to previously reported results for optical biometry measurements.Keywords: intraocular lens, intraocular lens power, Barrett Universal formula, cataract

Background and Objective: This study aimed at comparing the results of refractive cataract surgery in patients undergoing sequential surgeries in both eyes. Considering the preoperative refraction and final refraction of the first eye, it is possible to correct the refrative result of cataract surgery using the adjustment of the second eye intraocular lens (IOL) power. Materials and Methods: This study was conducted based on a matched-pair clinical-trial design. Regarding the final result of the first eye refraction, the adjustment of the second eye IOL power was determined by 50% of uncorrected refractive error. Finally, the mean spherical equivalent (SE) of the first and second eyes were determined, and the differences were analyzed using a paired t-test at a significant level of 95%. Results: A total of 470 candidates who underwent bilateral sequential cataract surgery were investigated in this study. The refractive errors ranged from -8.25 to + 6.50 and from -6.75 to +7.25 for the first and second eyes, respectively. The mean values of SE for the first and second eyes were 2.55 and 2.48 preoperatively, and 1.13 and 0.47 postoperatively, respectively. Moreover, there was a significant difference between the two groups (P

Purpose: Optimization of lens constants is a critically important step that improves refractive outcomes significantly. Whether lens constants optimized for the entire range of axial length would perform equally well in short eyes is still a matter of debate. The aim of this study was to analyze whether lens constants need to be optimized specifically for short eyes.Methods: : This retrospective observational study was conducted at a tertiary care hospital in Central India. Eighty-six eyes of eighty-six patients were included. Optical biometry with IOLMaster 500 was done in all cases and lens constants were optimized using built-in software. Barrett Universal II, Haigis, Hill-RBF, Hoffer Q, Holladay 1, and SRK/T formulae were compared using optimized constants. Mean absolute error, median absolute error (MedAE), and percentage of eyes within ±0.25, ±0.50, ±1.00, and ±2.00 diopter of the predicted refraction, of each formula were analyzed using manufacturer's, ULIB, and optimized lens constants. MedAE was compared across various constants used by Wilcoxon signed-rank test and among optimized constants by Friedman's test. Cochran's Q test compared the percentage of eyes within ± 0.25, ±0.50, ±1.00, and ± 2.00 diopter of the predicted refraction. A value of P < 0.05 was considered statistically significant.Results: : Optimized constant of Haigis had significantly lower MedAE (P < 0.00001) as compared to manufacturers. However, there was no statistically significant difference between ULIB and optimized constants. Postoptimization, there was no statistically significant difference among all formulae.Conclusion: : Optimizing lens constants specifically for short eyes gives no added advantage over those optimized for the entire range of axial length. [ABSTRACT FROM AUTHOR]

Background: Among the various intraocular lens (IOL) power calculation formulas available in clinical settings, which one can yield more accurate results is still inconclusive. We performed a meta-analysis to compare the accuracy of the IOL power calculation formulas used for pediatric cataract patients.Methods: Observational cohort studies published through April 2021 were systematically searched in PubMed, Web of Science, and EMBASE databases. For each included study, the mean differences of the mean prediction error and mean absolute prediction error (APE) were analyzed and compared using the random-effects model.Results: Twelve studies involving 1,647 eyes were enrolled in the meta-analysis, and five formulas were compared: Holladay 1, Holladay 2, Hoffer Q, SRK/T, and SRK II. Holladay 1 exhibited the smallest APE (0.97; 95% confidence interval [CI]: 0.92–1.03). For the patients with an axial length (AL) less than 22 mm, SRK/T showed a significantly smaller APE than SRK II (mean difference [MD]: −0.37; 95% CI: −0.63 to −0.12). For the patients younger than 24 months, SRK/T had a significantly smaller APE than Hoffer Q (MD: −0.28; 95% CI: −0.51 to −0.06). For the patients aged 24–60 months, SRK/T presented a significantly smaller APE than Holladay 2 (MD: −0.60; 95% CI: −0.93 to −0.26).Conclusion: Due to the rapid growth and high variability of pediatric eyes, the formulas for IOL calculation should be considered according to clinical parameters such as age and AL. The evidence obtained supported the accuracy and reliability of SRK/T under certain conditions.Systematic Review Registration: PROSPERO, identifier: INPLASY202190077.

Background: Our study aimed to assess and compare the accuracy of 8 intraocular lens (IOL) power calculation formulas (Barrett Universal II, EVO 2.0, Haigis, Hoffer Q, Holladay 1, Kane and PEARL-DGS) in patients submitted to combined phacovitrectomy for vitreomacular (VM) interface disorders. Methods: Retrospective chart review study including axial-length matched patients submitted to phacoemulsification alone (Group 1) and combined phacovitrectomy (Group 2). Using optimized constants in both groups, refraction prediction error of each formula was calculated for each eye. The optimised constants from Group 1 were also applied to patients of Group 2 – Group 3. Outcome measures included the mean prediction error (ME) and its standard deviation (SD), mean (MAE) and median (MedAE) absolute errors, in diopters (D), and the percentage of eyes within ± 0.25D, ± 0.50D and ± 1.00D. Results: A total of 220 eyes were included (Group 1: 100; Group 2: 120). In Group 1, the difference in formulas absolute error was significative (p = 0.005). The Kane Formula had the lowest MAE (0.306) and MedAE (0.264). In Group 2, Kane had the overall best performance, followed by PEARL-DGS, EVO 2.0 and Barrett Universal II. The ME of all formulas in both Groups 1 and 2 were 0.000 (p = 0.934; p = 0.971, respectively). In Group 3, a statistically significant myopic shift was observed for each formula (p < 0.001). Conclusion: Surgeons must be careful regarding IOL power selection in phacovitrectomy considering the systematic myopic shift evidenced—constant optimization may help eliminating such error. Moreover, newly introduced formulas and calculation methods may help us achieving increasingly better refractive outcomes both in cataract surgery alone and phacovitrectomy. [ABSTRACT FROM AUTHOR]

AIM: To evaluate the effect of different lens constant optimization methods on the accuracy of intraocular lens (IOL) power calculation formulas for highly myopic eyes. METHODS: This study comprised 108 eyes of 94 consecutive patients with axial length (AL) over 26 mm undergoing phacoemulsification and implantation of a Rayner (Hove, UK) 920H IOL. Formulas were evaluated using the following lens constants: manufacturer’s lens constant, User Group for Laser Interference Biometry (ULIB) constant, and optimized constant for long eyes. Results were compared with Barrett Universal II formula, original Wang-Koch AL adjustment method, and modified Wang-Koch AL adjustment method. The outcomes assessed were mean absolute error (MAE) and percentage of eyes with IOL prediction errors within ±0.25, ±0.50, and ±1.0 diopter (D). The nonparametric method, Friedman test, was used to compare MAE performance among constants. RESULTS: Optimized constants could significantly reduce the MAE of SRK/T, Hoffer Q, and Holladay 1 formulas compared with manufacturer’s lens constant, whereas the percentage of eyes with IOL prediction errors within ±0.25, ±0.50, and ±1.0 D had no statistically significant differences. Optimized lens constant for long eyes alone showed non-significant refractive advantages over the ULIB constant. Barrett Universal II formula and formulas with AL adjustment showed significantly higher accuracy in highly myopic eyes (P

PURPOSE: The purpose of this study is to compare the accuracy of new generation formulas to standard formulas for intraocular lens (IOL) power calculations in pediatric patients. SUBJECTS AND METHODS: This retrospective case series compared the postoperative refractions to the predicted refractions after lensectomy and IOL implantation in pediatric patients. Four new generation formulas (Haigis, Holladay II, Olsen, and Barrett Universal II) were compared to four standard formulas (Holladay I, Hoffer Q, SRK/T, and SRKII) 4. The absolute prediction error (APE) was calculated as the absolute difference between the actual postoperative spherical equivalent and predicted spherical equivalent). The Friedman test was used to evaluate the difference between formulas. P < 0.05 was statistically significant. RESULTS: The study sample was comprised 44 eyes from 29 patients (20 males and 9 females) with median age at surgery of 2.85 years (2.04–6.14 years). The Holladay I and II, Barrett Universal II, SRK/T, SRKII, Olsen, and Hoffer Q formulas had comparable median APE (MedAPE) of 1.32 D (0.51–2.11 D), 1.34 D (0.82–1.94 D), 1.28 D (0.73–1.85 D), 1.26 D (0.60–2.08 D), 1.16 D (0.54–1.16 D), 1.34 D (0.80–1.98 D), and 1.27 D (0.63–2.08 D), respectively (P = 1.0). The Haigis formula had the statistically highest MedAPE of 2.00 D (1.27–3.04 D) (P < 0.001). More than 70% of eyes were within ±2.0 D for the Holladay I and II, Barrett Universal II, SRK/T, SRKII, Olsen, and Hoffer Q formulas. Fifty percent of eyes were within ±2.0 D for the Haigis formula. CONCLUSION: New generation IOL formulas do not outperform standard IOL formulas in predicting postoperative refraction for pediatric patients.

In today's world, with the developments in technology to measure ocular biometric parameters more accurately and the availability of sophisticated methods for intraocular lens (IOL) power calculation, cataract surgery has become no less than a refractive surgery. This along with free and easy access to information regarding the latest technology has heightened patient expectations. The demand for a spectacle-free life after cataract surgery is higher than ever. Newer advances in optical biometry, including swept-source optical coherence tomography technology, supplemented by the availability of highly accurate IOL power calculation formulae including ones that use artificial intelligence have the potential to enable surgeons to achieve near-perfect outcomes in majority of their patients. To hit the bull's eye as far as target refraction is concerned, it is necessary to understand the benefits and limitations of currently available cutting edge technology and formulae and apply them to the cataract surgery practice.

Purpose: To prospectively evaluate the biometric changes in Indian pediatric cataract and postoperative refractive status. Methods: A total of 147 patients were recruited into three groups: age

BACKGROUND: To evaluate the predictability of the Kane formula in estimating postoperative refractive outcome with various corneal curvatures and axial lengths (ALs) besides comparing with existing intraocular lens (IOL) formulae. MATERIALS AND METHODS: A prospective cross-sectional study was carried out among patients having uneventful cataract surgery at an eye hospital. A total of 50 eyes were considered for the study. The corresponding A-constant for the model of IOL implanted into the patient's eye was taken along with the actual power of IOL implanted and corresponding predicted power for the IOL power inserted were taken for all the chosen formulae and was termed as "Adjusted Predicted Refractive Power." This was compared with the actual refractive outcome and the absolute error (AE) was measured. The eyes were separated into groups in terms of corneal curvature as flat (<42D), medium (42D–46D), and steep (>46D) corneas. In terms of AL, it was grouped as short (≤22 mm), medium (>22.0–<24.0 mm), and long (>24.0 mm) eyes. RESULTS: The study included 50 eyes and the mean AE for all the selected formulae were calculated for each group. Over the entire corneal curvature range, none of the formulae showed any significance when compared with the Kane formula (P > 0.05). In short AL, SRK-T formula had a statistical significance over the Kane formula (P = 0.043), whereas no other group had any significance over the Kane formula in AL groups. CONCLUSION: The study shows, all formulae (SRK-T, Holladay1, Hoffer Q, Hill RBF, Barrett Universal II, Kane) are interchangeable to predict the IOL power for any of the corneal curvature and ALs. [ABSTRACT FROM AUTHOR]

Abstract Background This review aims to explain the reasons why intraocular lens (IOL) power calculation is challenging in eyes with previous corneal refractive surgery and what solutions are currently available to obtain more accurate results. Review After IOL implantation in eyes with previous LASIK, PRK or RK, a refractive surprise can occur because i) the altered ratio between the anterior and posterior corneal surface makes the keratometric index invalid; ii) the corneal curvature radius is measured out of the optical zone; and iii) the effective lens position is erroneously predicted if such a prediction is based on the post-refractive surgery corneal curvature. Different methods are currently available to obtain the best refractive outcomes in these eyes, even when the perioperative data (i.e. preoperative corneal power and surgically induced refractive change) are not known. In this review, we describe the most accurate methods based on our clinical studies. Conclusions IOL power calculation after myopic corneal refractive surgery can be calculated with a variety of methods that lead to relatively accurate outcomes, with 60 to 70% of eyes showing a prediction error within 0.50 diopters.