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To evaluate the comparability of biometric measurements obtained using the swept-source optical coherence tomography (SS-OCT) biometer (Anterion) and the optical low-coherence reflectometry (OLCR) biometer (Lenstar LS900). This observational study included 150 cataract patients undergoing preoperative biometry at the General University Hospital of Elche. Measurements from the Anterion and Lenstar LS900 were compared for axial length (AL), mean keratometry (Km), anterior chamber depth (ACD), lens thickness (LT), and central corneal thickness (CCT). Bland-Altman plots and statistical analyses were conducted to assess differences and correlations. The mean AL measurements showed no significant difference between the two devices (mean difference -0.004 ± 0.053 mm, P = 0.420). ACD and LT measurements displayed statistically significant differences, with Anterion showing greater mean values (ACD difference: 0.054 ± 0.037 mm, P < 0.001; LT difference: 0.107 ± 0.079 mm, P < 0.001). Mean keratometry was significantly flatter by 0.074 ± 0.259D (P = 0.001) in Anterion compared to Lenstar, primarily due to differences in steep keratometry. No correlation was found between keratometry differences and corneal asphericity. Estimated intraocular lens (IOL) power for emmetropia was significantly higher using Anterion by 0.146 ± 0.398D (P < 0.001), necessitating an A-constant adjustment of approximately 0.16 to equal mean IOL power in both devices. a good correlation was found between both biometers. However, due to the differences found between biometric measurements between devices, these two biometers should not be considered interchangeable and clinicians should adjust IOL constants accordingly. Future studies will be necessary to determine whether one biometer is superior to the other in terms of refractive outcome predictability.

In the absence of a measured posterior keratometry input, toric intraocular lens power formulae in patients with a history of myopic laser keratorefractive surgery (M-LVC) predict the posterior corneal astigmatism. These formulae assume that the posterior corneal curvature is essentially unchanged post M-LVC and hence its characteristics in this demographic of patients would be the same as virgin eyes. We aim to describe astigmatism measured by a swept-source optical coherence tomography biometer in such patients. Retrospective consecutive case review of eyes with prior M-LVC, followed by subsequent cataract surgery. Pre-operative biometric data was collected using the IOLMaster 700 (Carl Zeiss Meditec). Magnitude and orientation of the steep and flat meridian of standard keratometry (SK), posterior keratometry (PK) and total keratometry (TK) were recorded. Relationships between corneal astigmatism, age, and gender were assessed. Statistical analysis was performed using linear regression, Mann Whitney -test and Chi squared test. A total of 341 eyes (218 patients) were studied. Mean SK was 39.65D ± 2.16D. Mean PK was -5.82D ± 0.24D. Mean TK was 39.15D ± 2.34D. SK astigmatism (SKA) was predominantly vertical (57.8%, n = 197 eyes) with a mean magnitude of 0.85D ± 0.47D. Posterior corneal astigmatism (PCA) was predominantly vertical (91.5%, n = 312 eyes) with a mean magnitude of 0.29D ± 0.14D. TK astigmatism (TKA) was predominantly vertical (42.2%, n = 144 eyes) with a mean magnitude of 0.83D ± 0.47D. There was a positive correlation between magnitude of TKA with SKA and PCA (P < 0.001). A negative correlation between age and magnitude of SKA, PCA and TKA was noted (P < 0.001). No statistically significant relationship with gender was noted. PCA orientation of post M-LVC eyes is similar to published data of virgin eyes. This reinforces the assumption made in toric intraocular lens power formulae that posterior corneal astigmatism in these eyes share the same characteristics as virgin eyes.

Objective: To compare optical biometry and A-scan for calculating intraocular lens power in patients with nuclear cataract at tertiary care eye hospital. Study Design: Cross sectional comparative study. Place and Duration of Study: Armed Forces Institute of Ophthalmology, Pak Emirates Military Hospital, Rawalpindi, from Jul to Dec 2018. Methodology: In this study 70 eyes of 70 patients planned for cataract surgery by phacoemulsification underwent both optical biometry with intraocular lens master and ultrasound biometry applanation by A scan after informed consent. Intraocular lens power calculated by these two methods of biometry was compared. Phacoemulsification surgery was performed through a 2.3 mm superior temporal clear corneal incision. All patients underwent in the bag implantation of the same intraocular lens type. Results: The mean age of the patients was 62.89 ± 6.69 years. A significant (p-value<0.001) difference in intraocular lens power calculation was noted (20.96 ± 1.76 vs. 22.03 ± 1.61) with optical biometry and A-scan respectively. Association on the basis of age groups showed a significant (p-value<0.001) difference in both strata that was among patients having age ≤65 years and patients having age >65 years. Conclusion: Optical biometry was found efficient and safe method for calculation of intraocular lens power. Optical biometry is noncontact method having very less chance of infection and suitable for most of the eye types.

Purpose. To analyze possible refractive errors when calculating IOL power in patients after ARK (anterior radial keratotomy). Material and methods. The data of Intraocular lens (IOL) power calculation in 46 patients (46 eyes) with anterior radial keratotomy (ARK) who also underwent cataract surgery were analyzed. The IOL calculation was performed taking into account the data obtained by the Lenstar LS 900 (HAAG-STREIT AG, Switzerland) and keratotopography (Pentacam HR, Oculus, Germany), with a target refraction corresponding to emmetropia up to ±0.50 D. Results. The analysis of the clinical efficacy of phacoemulsification with IOL implantation in patients after ARK with the refractive error (RE) calculation and refractive prediction error (RPE) calculation according to the basic formulas were performed. It was found that emmetropia (up to ±0.5 D) in the postoperative period was achieved in 52% of cases. The value of the postoperative RPE had no reliable dependence on the values of the eyeball length, it was depended on the corneal optical power in the central zone of the cornea only with some formulas for IOL calculation (Barrett, Barrett Universal II, MIKOFRK/ALF). The obtained results of the analysis provide justification for a deeper study of post keratotomy corneal deformation as a pathological condition with the presence of hidden risk factors. Conclusion. Phacoemulsification with IOL implantation in patients with previously performed ARK is accompanied by the achievement of target refraction in 52% of cases. The high proportion of IOL calculation errors in cataract surgery in patients after ARK largely depends on hidden factors, which determines the need for a detailed study of post keratotomy corneal deformation as a pathological condition. Key words: IOL power calculation, anterior radial keratotomy, emmetropia

Yang Xiang,1,2 Liangpin Li,2 Haiqiang Yu,1,2 Liyun Yuan,2,3 Maoyu Cai,4 Liwei Zhang,5 Xia Hua,6,7,* Xiaoyong Yuan1,2,* 1Clinical College of Ophthalmology, Tianjin Medical University, Tianjin, People’s Republic of China; 2Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin Eye Hospital, Tianjin, People’s Republic of China; 3School of Medicine, Nankai University, Tianjin, People’s Republic of China; 4Department of Ophthalmology, The Affiliated Hospital of Guizhou Medical University, Guiyang, People’s Republic of China; 5Affiliated Hospital of Yunnan University, The Second Hospital of Yunnan Province, Yunnan Eye Hospital, Kunming, People’s Republic of China; 6Tianjin Aier Eye Hospital, Tianjin University, Tianjin, People’s Republic of China; 7Changsha Aier Eye Hospital, Changsha, People’s Republic of China*These authors contributed equally to this workCorrespondence: Xiaoyong Yuan, Clinical College of Ophthalmology, Tianjin Medical University, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin Eye Institute, Tianjin Eye Hospital, No. 4 Gansu Road, Heping District, Tianjin, 300020, People’s Republic of China, Email yuanxy_cn@hotmail.com Xia Hua, Tianjin Aier Eye Hospital, 102 Fukang Road, Nankai District, Tianjin, 300191, People’s Republic of China, Email cathayhuaxia@163.comPurpose: To evaluate the predictive accuracy of eight traditional and contemporary intraocular lens (IOL) power calculation formulas in Chinese cataract patients with prior radial keratotomy (RK).Patients and Methods: RK patients who underwent phacoemulsification with IOL implantation were retrospectively recruited. Refractive prediction errors (RPE)were calculated for eight formulas: Haigis-L, Shammas, Barrett True-K, Camellin Calossi Camellin (CCC), Kane, EVO, Pearl-DGS, and Jin-AI. The study compared RPE, mean absolute error (MAE), median absolute error (MedAE), and percentages of eyes achieving prediction errors within ± 0.25, ± 0.50, ± 0.75, ± 1.0, and ± 2.0 diopters.Results: This retrospective study analyzed 34 eyes from 21 patients with prior RK surgery. The superior performing IOL power calculation formulas were Jin-AI (MAE = 0.64 D, MedAE = 0.49 D), Barrett True-K (MAE = 0.58 D, MedAE = 0.535 D), and EVO (MAE=0.59 D, MedAE = 0.538 D). These three formulas demonstrated comparable accuracy, with 47.1%, 44.1%, and 44.1% of eyes achieving prediction errors within ± 0.50 D, respectively. The Haigis-L and Pearl-DGS formulas exhibited significantly higher prediction errors in eyes with more than 12 RK incisions.Conclusion: The Jin-AI, Barrett True-K, and EVO formulas demonstrated superior accuracy for IOL power calculation in Chinese cataract patients with prior RK. The Jin-AI formula, a novel artificial intelligence-based formula derived from Chinese individuals, presents a promising option for post-RK IOL calculation, while external validation studies across diverse ethnic groups are essential.Keywords: radial keratotomy, cataract, IOL power calculation, refractive prediction errors

This retrospective study compared postoperative prediction errors of recent formulas using standard- or total keratometry (K or TK) for intraocular lens (IOL) power calculation in post-myopic LASIK patients. It included 56 eyes of 56 patients who underwent uncomplicated cataract surgery, with at least 1-month follow-up at Keio University Hospital in Tokyo or Hayashi Eye Hospital in Yokohama, Japan. Prediction errors, absolute errors, and percentage of eyes with prediction errors within ± 0.25 D, ± 0.50 D, and ± 1.00 D were calculated using nine formulas: Barrett True-K, Barrett True-K TK, Haigis-L, Haigis TK, Pearl-DGS, Hoffer QST, Hoffer QST PK, EVO K, and EVO PK. Statistical comparisons utilized Friedman test, Conover’s all-pairs post-hoc, Cochran’s Q, and McNemar post-hoc testing. Root-Mean-Square Error (RMSE) was compared with heteroscedastic testing. Barrett True-K TK had the lowest median predicted refractive error (-0.01). EVO PK had the smallest median absolute error (0.20). EVO PK had the highest percentage of eyes within ± 0.25 D of the predicted value (58.9%), significantly better than Haigis-L ( p  = 0.047). EVO PK had the lowest mean RMSE value (0.499). The EVO PK formula yielded the most accurate IOL power calculation in post-myopic LASIK eyes, with TK/PK values enhancing accuracy.

PurposeTo compare the refractive outcomes following cataract surgery using conventional keratometry (K) and total keratometry (TK) for intraocular lens (IOL) calculation in the SRK/T, HofferQ, Haigis, and Holladay 1 and 2, as well as Barrett and Barrett TK Universal II formulas.MethodsSixty eyes of 60 patients from Siriraj Hospital, Thailand, were prospectively enrolled in this comparative study. Eyes were assessed using a swept-source optical biometer (IOLMaster 700; Carl Zeiss Meditec, Jena, Germany). Posterior keratometry, K, TK, central corneal thickness, anterior chamber depth, lens thickness, axial length, and white-to-white corneal diameter were recorded. Emmetropic IOL power was calculated using K and TK in all formulas. Selected IOL power and predicted refractive outcomes were recorded. Postoperative manifest refraction was measured 3 months postoperatively. Mean absolute errors (MAEs), median absolute errors (MedAEs), and percentage of eyes within ± 0.25, ± 0.50, and ± 1.00 D of predicted refraction were calculated for all formulas in both groups.ResultsMean difference between K and TK was 0.03 D (44.56 ± 1.18 vs. 44.59 ± 1.22 D), showing excellent agreement (ICC = 0.99, all p < 0.001). Emmetropic IOL powers in all formulas for both groups were very similar, with a trend toward lower MAEs and MedAEs for TK when compared with K. The Barrett TK Universal II formula demonstrated the lowest MAEs. Proportion of eyes within ± 0.25, ± 0.50, and ± 1.00 D of predicted refraction were slightly higher in the TK group.ConclusionsConventional K and TK for IOL calculation showed strong agreement with a trend toward better refractive outcomes using TK. The same IOL constant can be used for both K and TK.

To compare the refractive predictive accuracy of three intraocular lens (IOL) power calculation formulas (SRK/T, Barrett Universal II, and Haigis) in patients aged 90 years and older. This retrospective observational study included 62 eyes of 62 patients aged ≥90 years who underwent cataract surgery between April 2021 and March 2023. All procedures were performed by a single surgeon using a single IOL model (HOYA XY1). Preoperative biometry was performed using the IOL Master 700. The accuracy of each formula was evaluated by comparing the predicted spherical equivalent to the manifest refraction at 3 months postoperatively. The primary outcome was the mean absolute error (MAE) and root mean square absolute error (RMSAE), with secondary outcomes including the percentage of eyes within ±0.5 D and ±1.0 D of the predicted refraction. The mean age of the patients was 92.2 ± 2.0 years. The MAE was 0.504 ± 0.363 D for SRK/T, 0.441 ± 0.339 D for Barrett Universal II, and 0.503 ± 0.388 D for Haigis. The RMSAE was 0.607 ± 0.552 D for SRK/T, 0.532 ± 0.463 D for Barrett Universal II, and 0.565 ± 0.496 D for Haigis. No statistically significant difference in MAE and RMSAE was found among the three formulas (p = 0.12, p = 0.54). The proportion of eyes within ±0.5 D of the predicted refraction was highest for the Barrett Universal II formula at 64.5%. Multivariate logistic regression analysis found no biometric parameters to be significant predictors of achieving a refractive error within ±0.5 D. In patients aged ≥90 years, the SRK/T, Barrett Universal II, and Haigis formulas demonstrated comparable refractive accuracy. In this demographic, overall refractive outcomes may be more influenced by the reliability of biometric measurements and the minimization of intraoperative risks than by the choice of formula.

PurposeTo assess the accuracy of intraocular lens power calculation formulas Barrett Universal II (BUII), Hill-Radial Basis Function (RBF) 3.0, Kane, Ladas Super Formula (LSF), Haigis, Hoffer Q, and SRK/T in primary angle-closure disease (PACD).MethodsA total of 129 PACD eyes were enrolled. Prediction refraction was calculated for each formula and compared with actual refraction. Accuracy was determined by formula performance index (FPI), median absolute error (MedAE) and percentage of eyes with a prediction error (PE) within ± 0.50D. Subgroup analysis was performed according to axial length (AL).ResultsOverall, FPI was ranked as follows: Kane (0.067), RBF 3.0 (0.064), Haigis (0.062), SRK/T (0.060), BUII (0.058), Hoffer Q (0.055), and LSF (0.049). Kane got the highest (71.3%) percentage of eyes with PE within ± 0.50 D. In medium AL eyes (22 mm < AL ≤ 25 mm), FPI ranked the same as in total group. MedAEs were equal across all formulas (P = 0.121). In short eyes (AL ≤ 22 mm), FPI was Kane (0.055), RBF 3.0 (0.050), SRK/T (0.050), Haigis (0.049), BUII (0.047), Hoffer Q (0.045), and LSF (0.033). MedAEs were significantly different across all formulas (P = 0.033). Haigis showed the lowest MedAE (0.35 D), Haigis and Kane got the highest percentage (63.6%) of eyes with PE within ± 0.50 D.ConclusionKane outperformed in total PACD eyes; RBF 3.0, Haigis, and SRK/T achieved satisfying performance. When dealing with PACD eyes shorter than 22 mm, Kane achieved the best accuracy. RBF 3.0, SRK/T, Haigis, and BUII achieved comparable outcomes. No formula showed superiority over others for medium AL PACD eyes.