Search Results (63)

Background/Objectives: Premium intraocular lens (IOL) implantation after laser vision correction (LVC) is increasingly common among post-refractive patients seeking cataract and presbyopia management. Therefore, this review aimed to provide a comprehensive updated synthesis of the challenges and outcomes of premium IOL implantation in post-refractive eyes, including visual quality, patient satisfaction, complications, and practical management approaches for patient selection, refractive surprises, and dysphotopsias. Methods and Search Strategies: In this narrative review, relevant articles published in English (January 2016–January 2026) were searched for using appropriate keywords and database indexing terms. The databases used in this review were PubMed/MEDLINE, Embase, Web of Science, and Scopus. Results: A total of 127 studies were included. Across post-LVC subgroups, including LASIK, PRK, SMILE, RK, and hyperopic ablation, premium IOL implantation provided good distance and intermediate-range vision, significant spectacle independence, and high patient satisfaction. Modern techniques, including total keratometry, posterior corneal evaluation, swept-source optical coherence tomography biometry, current post-refractive equations, multi-method comparison, and selective intraoperative aberrometry, have enhanced refractive targeting, with ±0.50 D of target refraction commonly used as a key accuracy benchmark, though not all outliers have been eliminated. However, several key challenges persist, including accurate corneal power estimation, personalization, and accurate lens position, which predispose patients to refractive surprises and a high frequency of dysphotopsias. Furthermore, there is heterogeneity in identifying visual outcomes and vision quality across studies. Conclusions: This review suggests that successful premium IOL implantation in patients after LVC requires individualized planning and structured management protocols. Future studies should standardize quality-of-vision outcomes that compare emerging optics, adjustable technologies, and AI-assisted prediction across post-refractive subgroups. Full article

Background and Objectives: Contact gonioscopy and optical biometry often happen at the same preoperative visit, with no defined interval between them. We asked whether uncomplicated Goldmann three-mirror gonioscopy was followed by short-term changes in optical biometry and calculated intraocular lens (IOL) power and whether any mean change could be positively affirmed as small enough not to matter clinically. Materials and Methods: Sixty-four cataract patients (128 eyes) underwent NIDEK AL-Scan biometry at baseline and 5, 15 and 30 min after unilateral Goldmann three-mirror gonioscopy in this prospective repeated-measures study (2015–2016). The untreated fellow eye served as an internal control. Our primary analysis was a within-patient paired difference-in-differences (DiD) comparison, which modeled the paired-eye structure directly; nested patient/eye mixed-effects models followed as a sensitivity analysis. We recomputed IOL power as a continuous variable for four formulas, SRK/T, Haigis, Hoffer Q and Holladay 1, using the published constants for the implanted lens. Equivalence within ±0.25 D was tested by two one-sided tests (TOSTs), with Holm adjustment across the twelve tests performed. Results: Central corneal thickness (CCT) rose by 3.14 µm at 5 min (95% CI, 1.94 to 4.35; p < 0.001) and by 1.66 µm at 15 min (p = 0.015), returning to baseline by 30 min. That signal sat inside the ±6.2 µm short-term repeatability seen in untreated control eyes. Keratometry moved by no more than 0.11 D, and all four IOL formulas behaved almost identically, the largest mean difference being −0.18 D at 15 min. Equivalence within ±0.25 D was confirmed in unadjusted testing at 5 and 30 min for all four formulas and at 15 min for SRK/T; after Holm adjustment only the four 30 min conclusions and the 5 min conclusion for SRK/T were retained. The selected 0.5 D lens power changed in 33–47% of study eyes and in a comparable 31–52% of untreated control eyes. Conclusions: Procedure-related differences in calculated IOL power were small throughout. The largest was −0.18 D, inside the ±0.25 D margin and well below the 0.5 D interval on which lenses are supplied. Demonstrated equivalence was a narrower claim. After adjustment for multiplicity, it held at 30 min for all four formulas and at 5 min for SRK/T, and at 15 min it was not demonstrated for Haigis, Hoffer Q or Holladay 1. These data therefore do not establish that biometry is unaffected across the whole first half hour, and we make no recommendation about deferring it. The transient CCT signal fell within device repeatability. Step-level changes in selected lens power were as common in eyes that never underwent gonioscopy. All analyses were exploratory and limited to a partial-coherence-class biometer of the study period and to the four formulas tested. Full article

Background/Objectives: Corneal power has the largest impact on the variability of intraocular lens (IOL) power predictions, and corneal data from different biometers cannot be used interchangeably. We quantified the systematic differences between the Zeiss IOLMaster 700 (IOLM) and the Heidelberg Engineering Anterion and derived strategies for using both devices interchangeably in IOL power calculation. Methods: In this retrospective single-centre study, 837 eyes of 837 cataract patients were measured preoperatively with both biometers. Harmonic mean corneal front and back surface radii were derived from the flat and steep meridians, and corneal power referenced to the front apex plane was expressed as spherocylindrical power vectors (spherical equivalent, SEQ; astigmatic components C0 and C45). Three mapping strategies were compared using Bland–Altman and double-angle plots: linear regression of corneal radii without (MR) and with (MRI) intercept and multivariate linear regression of the power vector components (MMV). Results: Corneal front surface radii agreed well between devices (MR slope 1.000), whereas the IOLM reported systematically flatter posterior radii (MR slope 0.943), giving a systematically higher total corneal power (43.105 D versus 42.760 D). MRI mapping largely removed the systematic offset in the corneal radii but did not fully correct the astigmatic centroids, whereas MMV mapping aligned both the SEQ and the astigmatic centroids at the origin and yielded smaller confidence ellipses. Conclusions: Measurements from the two devices are not directly interchangeable, primarily because of systematic discrepancies in the reported posterior corneal curvature. Where identical IOL calculation concepts and formula constants are used across devices, conversion of corneal data is mandatory, and multivariate power vector mapping provides superior harmonisation compared with radius-based approaches. Full article

Objectives: To assess how differences in keratometric measurement principles affect intraocular lens (IOL) power calculation, we compared front-surface reflection-based (FSR) and anterior segment optical coherence tomography (AS-OCT)-derived keratometry (K) values. Methods: This retrospective study included 160 eyes of 160 Japanese patients who underwent cataract surgery with implantation of a CNA0T0 (Alcon) IOL between March 2023 and October 2025. FSR-based keratometry (OA-K, 2.5 mm averaged output ring) was obtained using the OA-2000 (Tomey), whereas AS-OCT-derived keratometry (CA-K, 2.5 mm single ring) and Fourier keratometry (CA-FK, 3.0 mm Fourier analysis zone) were obtained using CASIA2 (Tomey). Predicted refractions were calculated using Barrett Universal II (B-UII) and SRK/T formulas with each K value. Results: Mean K values were 44.14 ± 1.51 D (OA-K), 44.28 ± 1.51 D (CA-K), and 44.40 ± 1.55 D (CA-FK). With the B-UII, the mean absolute error (MAE) was lowest with OA-K (0.27 ± 0.24 D), followed by CA-K (0.28 ± 0.22 D) and CA-FK (0.31 ± 0.23 D). Corresponding MAEs with SRK/T were 0.30 ± 0.26 D, 0.31 ± 0.24 D, and 0.33 ± 0.28 D, respectively. Exploratory subgroup analyses suggested a tendency toward lower prediction accuracy in steep corneas. Differences among keratometric methods were smaller with SRK/T than with B-UII. Conclusions: AS-OCT-derived keratometry did not demonstrate superiority over conventional FSR-based keratometry for IOL power calculation. Further studies are warranted to determine whether AS-OCT-derived keratometry may provide clinical advantages under specific conditions. Full article

Purpose: To examine concordance in biometry, keratometry, and intraocular lens (IOL) calculation between the Heidelberg Anterion Cataract App and the Zeiss IOLMaster 700 in a US population presenting for cataract evaluation. Methods: In this retrospective cross-sectional study, 64 eyes of 40 patients presenting for cataract evaluation underwent imaging with both devices. Agreement was assessed for axial length (AL), anterior chamber depth (ACD), lens thickness (LT), white-to-white distance (WTW), central corneal thickness (CCT), pupil diameter (PD), and anterior, posterior, and total keratometry using Lin’s concordance correlation coefficient (CCC), Bland–Altman analysis and generalized estimating equations. Non-toric and toric IOL calculations were performed with the Barrett Universal II and Barrett True-K Toric formulas, respectively. Results: Concordance was excellent for AL, ACD, LT, and CCT (CCC > 0.980), with no significant difference in AL. Compared with IOLMaster 700, Anterion measured larger PD (+0.56 mm), deeper ACD (+0.07 mm), thicker LT (+0.07 mm), thinner CCT (−3.19 μm), and smaller WTW (−0.22 mm; all p < 0.01). Anterior keratometry showed excellent concordance (CCC ≥ 0.980) despite small flatter offsets in average K, K1, K2 and difference in (Δ)K (−0.13, −0.08, −0.16 D, −0.10). Concordance was poor for posterior keratometry (average K: CCC = 0.529; Anterion steeper by 0.34 D), fairly good for total keratometry (average K: CCC = 0.891, Anterion flatter by 0.68 D), and these systematic inter-device offsets may be clinically relevant. For non-toric calculations, unrounded spherical IOL power agreed within 0.50 D in 88.88% (N = 56/63) of eyes and predicted residual refractive error within 0.25 D in 95.24% (N = 60/63). For toric calculations, predicted residual refractive error and residual astigmatism agreed within 0.25 D in 95.16% (N = 59/62) and 85.48% (N = 53/62) of eyes, respectively. Conclusions: Anterion and IOLMaster 700 showed strong agreement in core biometry, anterior keratometry, and predicted refractive outcomes, though posterior and total keratometry differed systematically. Postoperative refractive outcome studies are needed before the devices can be considered interchangeable in routine practice. Full article

Background: The most accurate intraocular lens power calculation formula for highly myopic eyes remains uncertain. The objective of this study was to perform a systematic review and network meta-analysis to compare and rank IOL power calculation formulas in eyes with an axial length greater than 26 mm. Methods: A literature search was conducted in PubMed, the Cochrane Library, Scopus, and Web of Science. The main outcome for comparison was the percentage of eyes with a refractive prediction error <0.25 diopters, <0.50 diopters, and <1.00 diopter. A network meta-analysis was performed, and Surface Under the Cumulative Ranking Curve values were calculated to rank formulas across the three prediction error thresholds. Forest plots were generated comparing all formulas with Barrett Universal II as the reference. Results: Ten studies were finally included. Based on Surface Under the Cumulative Ranking Curve values, Kane and Holladay 1 (with the original Wang–Koch axial length adjustment) ranked among the top three formulas across all prediction error thresholds. Hill-RBF 3.0, EVO, and Barrett Universal II ranked among the top three for the <0.25 diopters, <0.50 diopters, and <1.00 diopter thresholds, respectively. The Kane and Holladay 1 (with the original Wang–Koch axial length adjustment) formulas were the only ones showing odds ratios favouring their accuracy over Barrett Universal II across all prediction error thresholds in the forest plots, although differences were not statistically significant. Conclusions: The Kane and Holladay 1 (with the original Wang–Koch axial length adjustment) formulas showed the most consistent performance in highly myopic eyes. Hill-RBF 3.0, EVO, and Barrett Universal II also demonstrated high precision and may be considered reliable alternatives. Full article

Background/Objectives: The choice of appropriate intraocular lens (IOL) power calculation formulas depends on the axial length of the eye. This study compares the accuracy of twenty formulas in medium-long eyes (24.50–25.99 mm). Methods: Data of patients with medium-long eyes, who underwent uneventful phacoemulsification between January 2018 and September 2023, were retrospectively reviewed. Preoperative IOL power was calculated using the IOLMaster 700 with six formulas: Barrett Universal II, Haigis, Hoffer Q, Holladay 1, Holladay 2, and SRK/T. Three months postoperatively, refraction was measured. Postoperative IOL power calculations were then performed using fourteen additional formulas: Castrop, EVO 2.0, Hoffer QST, K6, Kane, Karmona, Ladas Super Formula AI (LSF AI), Naeser 2, Olsen (OLCR), Olsen (standalone), PEARL-DGS, T2, VRF CMAL, and VRF-G. The main outcome measures included standard deviation (SD) of the prediction error (PE) and the percentage of eyes with PE within ±0.25 D, ±0.50 D, ±0.75 D, and ±1.00 D. Results: Ninety-five eyes with axial lengths ranging from 24.52 mm to 25.97 mm were included. SD values among the twenty formulas ranged from 0.179 (SRK/T) to 0.468 (Olsen OLCR). The percentage of eyes with PE within ±0.50 D ranged from 75.79% (Olsen OLCR) to 98.95% (SRK/T). The SRK/T formula, followed by Holladay 1, demonstrated significantly higher accuracy than most other formulas, while Olsen (OLCR) and Castrop were the least accurate. Conclusions: SRK/T provided the highest accuracy in medium-long eyes, with Holladay 1 performing similarly well. All evaluated formulas achieved PE within ±0.50 D in over 74% of cases. Full article

Background/Objectives: To derive and validate a simplified modification of the Haigis intraocular lens (IOL) power calculation formula by reducing the three-constant effective lens position (ELP) model to a single constant while introducing an optimized keratometer index and axial length correction. Methods: In this retrospective study, a large multicentric dataset (Dataset 1; 22,466 eyes, 113 IOL models) was used to optimize the Haigis constant triplet and keratometer index using nonlinear programming with Cooke’s axial length correction. A second independent dataset (Dataset 2; 3181 eyes, six IOL models) was used for cross-validation. Three approaches were compared: classical Haigis, modified triplet, and two single-constant models acting on IOL power (H1) or ELP (H2). Results: The optimized keratometer index (1.3296 ± 0.0003) was significantly lower than the classical value, indicating systematic overestimation of corneal power. Modified triplet and single-constant approaches achieved comparable or slightly lower prediction errors than the classical formula. The H1 approach showed marginally superior performance. Bootstrapping confirmed parameter stability. Conclusions: A single-constant modification of the Haigis formula incorporating an optimized keratometer index and axial length correction maintains prediction accuracy while simplifying clinical implementation. Full article

Background/Objectives: To assess the accuracy of several intraocular lens power calculation formulas in phacotrabeculectomy for open angle glaucoma. Methods: Patients who underwent phacotrabeculectomy for open angle glaucoma were included. Refraction and biometry measurements were repeated at 3, 6 and ≥12 months. Prediction error (PE) and absolute error (AE) were calculated using the SRK/T, Holladay 1, Hoffer Q, Haigis, Kane, Emmetropia Verifying Optical (EVO) and Barrett Universal II formulas at ≥12 months, and their accuracy was compared using linear mixed-effects models accounting for repeated measurements within the same eye and inter-eye correlation. Results: Sixty eyes from 40 patients were included. The linear mixed-effects model showed a significant overall effect of formula on PE (χ²(6) = 119.14, p < 0.001). Most formulas showed a tendency toward a hyperopic refractive shift, whereas Haigis showed a negative PE. Based on estimated marginal mean AE, the formulas were ranked as follows: EVO (0.548 D), Barrett Universal II (0.551 D), Holladay and SRK/T (0.561 D), Haigis (0.572 D), Kane (0.577 D) and Hoffer Q (0.617 D). However, the AE did not significantly differ among the formulas (χ²(6) = 3.75, p = 0.711). The percentage of eyes within ± 1.00D of PE ranged from 81.7% to 90% across the formulas (p > 0.05). Significant axial length shortening, anterior chamber deepening and mean keratometry reduction were detected postoperatively at ≥12 months (p < 0.05). Conclusions: Despite postoperative ocular anatomic changes, all formulas showed acceptable refractive accuracy after phacotrabeculectomy. Although no significant difference in the AE was detected among the formulas, the PE differed significantly, with most formulas showing a tendency toward a hyperopic shift and Haigis showing a myopic shift. This inter-formula difference should be considered when selecting the refractive target, particularly when using formulas that tend toward hyperopic PE. Full article

Background/Objectives: Toric intraocular lens (IOL) implantation is the standard approach for correcting corneal astigmatism during cataract surgery and refractive lens exchange (RLE). Evidence on outcomes in eyes with high corneal astigmatism (≥2.00 diopters, D), particularly in heterogeneous real-world settings, remains limited. This study evaluated visual, refractive, and astigmatic vector outcomes of toric IOL implantation in a consecutive high-astigmatism cohort and investigated predictors of residual astigmatic error. Methods: This single-center, single-surgeon retrospective analysis of prospectively collected data included 161 eyes (118 patients) with preoperative corneal astigmatism ≥ 2.00 D undergoing cataract surgery or RLE with toric IOL implantation (June 2023–December 2025). Primary outcomes at one month included visual acuity, manifest refraction, and Alpins vector analysis at the corneal plane. Secondary analyses comprised refractive stability assessment (n = 75 eyes, median seven months), comparison of astigmatic outcomes between emmetropia-targeted and intentional myopia-targeted eyes, and multivariate regression of predictors of residual astigmatic error. Results: Mean postoperative UDVA and CDVA were 0.19 ± 0.24 and 0.09 ± 0.15 logMAR, respectively. Spherical equivalent prediction error was −0.19 ± 0.42 D (69.6% within ±0.50 D of target). Mean residual cylinder was 0.52 ± 0.49 D; 62% and 88.8% of eyes achieved ≤0.50 D and ≤1.00 D, respectively. Vector analysis demonstrated a mean difference vector of 0.53 ± 0.44 D, a correction index of 1.04 ± 0.20, and near-zero centroid deviation (0.03 D @ 43°), indicating the absence of systematic directional prediction error. Refractive outcomes were stable at medium-term follow-up. Astigmatic correction accuracy was equivalent between emmetropia-targeted and intentional myopia-targeted eyes (p > 0.05 for all primary metrics). Multivariate regression identified IOL cylinder power (β = 0.051, p = 0.031) and oblique astigmatism orientation (β = 0.299 vs. WTR, p = 0.032) as independent predictors of greater residual astigmatic error. No sight-threatening complications occurred. Conclusions: Toric IOL implantation provides safe, predictable, and stable correction of high corneal astigmatism in a real-world mixed cohort. Astigmatic accuracy is maintained regardless of intended spherical refractive strategy, supporting the use of toric IOLs in highly myopic patients targeted for residual myopia. Oblique astigmatism orientation is an independent predictor of reduced correction accuracy, consistent with known limitations of current toric calculators for this meridian. Full article

Purpose: The aim of this study was to develop a concept for adjustment planning of intraocular lens orientation axes after cataract surgery with implantation of toric intraocular lenses (tIOLs) and to predict the spectacle refraction after tIOL re-alignment. Methods: This calculation concept based on paraxial spherocylindrical vergence transformations uses the actual spherocylindrical refraction at the spectacle plane, corneal power, and the labelled power and measured axis of the implanted tIOL to minimise the refractive cylinder by simulating the rotation of the tIOL in the eye. The axial lens position is derived from simple prediction models using anterior chamber depth and lens thickness or axial length from preoperative biometry or the equivalent tIOL power. The new target axis is predicted together with the spherocylindrical refraction after re-alignment of the tIOL. Results: To show the applicability of this calculation model, we provide four clinical working examples: example 1 deals with keratometric power values; example 2 deals with keratometric curvature values, including surgically induced astigmatism and a statistical posterior astigmatism correction for the cornea (both examples with a thin cornea model); example 3 deals with corneal curvature data for the front and back surface; and example 4 deals with keratometric power data and corneal back surface power data, including surgically induced astigmatism (both examples with a thick cornea model). Conclusions: The effect of tIOL axis adjustment after cataract surgery can be predicted based on actual refraction, corneal power, tIOL power and the measured axis, and a simulation of the tIOL axis rotation enables the best orientation with the lowest refractive cylinder at the spectacle plane to be found. Full article

Background and Objectives: Accurate anterior segment measurements are central to intraocular lens (IOL) power calculation and toric planning, yet different optical platforms may yield non-interchangeable values. This study compared keratometry, astigmatism metrics, and ocular biometry obtained with a swept-source OCT biometer (Argos), an optical low-coherence interferometry biometer (Aladdin), and a combined Scheimpflug–Placido topographer (Schwind Sirius). Methods: This is a retrospective observational study (January 2022–June 2024) including eyes undergoing uncomplicated cataract surgery. All eyes were measured in a single session by one examiner. Outcomes included K1, K2, cylinder, astigmatism axis (degrees; device-reported corneal cylinder axis, labeled “Powerful Angle” in the Sirius export), vector components (J0 and J45), and—where available—lens thickness (LT), axial length (AL), anterior chamber depth (ACD), white-to-white (WTW) distance, and central corneal thickness (CCT). Friedman tests assessed 3-device differences, and pairwise comparisons were evaluated using Wilcoxon signed-rank tests (paired data). Results: A total of 170 eyes (102 patients) were analyzed (mean age: 69.12 ± 10.26 years). Significant inter-device differences were detected for K1 (Argos: 43.45 ± 1.64 D; Aladdin: 43.41 ± 1.70 D; overall: p < 0.001; Argos vs. Aladdin: p = 0.019), K2 (Argos: 44.45 ± 1.67 D; Aladdin: 44.34 ± 1.71 D; overall and pairwise: p < 0.001), and cylinder (Argos: −0.83 ± 0.74 D, Aladdin: −0.77 ± 0.76 D; Sirius: −0.68 ± 0.75 D; overall: p < 0.001). “Powerful Angle” differed across devices (p = 0.003) but not between Argos and Aladdin (p = 0.512). J0 (p = 0.277) and J45 (p = 0.084) did not differ significantly. Argos reported higher ACD (3.19 ± 0.42 vs. 3.13 ± 0.41 mm, p < 0.001) and WTW (11.95 ± 0.42 vs. 11.65 ± 0.39 mm, p < 0.001) values than Aladdin. CCT was similar between Aladdin and Sirius (540.27 ± 33.44 vs. 540.47 ± 33.78 µm, p = 0.169). Conclusions: Several keratometric and biometric parameters differed significantly by device, indicating limited interchangeability—particularly relevant for toric and premium IOL planning—while vector astigmatism components and CCT showed better agreement. Full article

Background/Objectives: Dry-eye disease (DED) is a disorder of the eye surface associated, among other things, with tear film instability. It can lead to abnormal biometry results, especially with respect to keratometry. DED is more common in the elderly population. Its prevalence is often underestimated. Failure to provide adequate treatment prior to biometry may result in refractive errors after cataract surgery. The purpose of this study was to quantify the impact of DED on refractive predictability in cataract surgery and assess whether short, preoperative ocular-surface optimization reduces the mean absolute error (MAE) of postoperative refraction, regardless of DED. Methods: Seventy patients undergoing cataract surgery were divided into three groups: A—individuals with DED who were receiving treatment; B—individuals without DED who were receiving treatment; and C—a control group. In all groups, biometry was performed twice, before and after treatment (groups A and B) or at two-week intervals without treatment (group C). All of the individuals underwent cataract surgery. Refractive error was calculated one month after surgery for both biometry measurements (before and after treatment). Results: After dry eye treatment, a reduction in refractive error was achieved in both groups with and without DED. The MAE in the group with DED was 0.39 ± 0.31 vs. 0.27 ± 0.30 (p < 0.001), and the MAE for those without DED was 0.30 ± 0.25 vs. 0.24 ± 0.20 (p = 0.043). No significant differences in biometric measurements were observed in any of the groups. The most variable parameter was corneal astigmatism in the DED group. Conclusions: Proper preparation of the eye surface for biometric measurement reduces refractive errors after surgery. Full article

Objectives: This study aims to evaluate the intrasession repeatability of the HBM-1 (Huvitz) optical biometer and to assess its agreement with the IOLMaster 700 (Zeiss) for the main biometric parameters used in intraocular lens (IOL) power calculation and in myopia management. Methods: A cross-sectional observational study was conducted in 82 eyes of 82 patients with the following age distribution: pediatric 26.8%, young adults 35.4%, and older adults 37.8% (total range 6–79 years). Optical biometry was performed three consecutive times with both biometers in the same session by a single trained examiner. HBM-1 repeatability was assessed using the within-subject standard deviation (Sw), the repeatability coefficient, and the intraclass correlation coefficient (ICC). Agreement between biometers was analyzed using Bland–Altman plots (limits of agreement, LoA). Results: The HBM-1 showed excellent intrasession repeatability, with very low Sw values—on the order of hundredths of a millimeter for axial length (AL), anterior chamber depth (ACD), and lens thickness (LT), and hundredths of a diopter for keratometry—with ICC ≥ 0.97 for most parameters. The mean bias (HBM-1 vs. IOLMaster 700) was small: AL 0.012 ± 0.052 mm (p = 0.045; LoA: −0.09 to 0.11 mm), ACD 0.059 ± 0.068 mm (p < 0.001; −0.07 to 0.19 mm), LT 0.052 ± 0.090 mm (p < 0.001; −0.12 to 0.23 mm), and central corneal thickness 0.82 ± 7.12 μm (p = 0.301; −13.1 to 14.8 μm). For corneal diameter and corneal curvature, mean differences were small (≤0.07 D) and not statistically significant in most cases. Age was not associated with discrepancies in AL but showed weak correlations with some anterior segment differences, without clear clinical relevance. Conclusions: The HBM-1 demonstrated excellent intrasession repeatability and a good level of clinical agreement with the IOLMaster 700 in a broad population that included children, young adults, and older adults. Full article

Background/Objectives: To evaluate the predictive accuracy of intraocular lens (IOL) power calculation by ray tracing in eyes with previous radial keratotomy (RK). Methods: A consecutive series of eyes with previous RK was retrospectively analyzed. Preoperatively, all eyes underwent optical biometry to measure the axial length (AL) and anterior segment imaging by the MS-39 (CSO), which combines Placido disk corneal topography and anterior segment optical coherence tomography. The built-in ray tracing software was used to calculate the IOL power. For comparative purposes, the results of the Barrett True-K, EVO, Haigis total keratometry, and PEARL-DGS formulas were also investigated. The refractive outcomes were evaluated with Eyetemis. Results: Twenty-four eyes (24 patients) were investigated. The mean AL and keratometry were, respectively, 27.34 ± 2.88 mm and 35.53 ± 3.66 diopters (D). The mean prediction error (PE) was −0.03 ± 0.65 D (range: from −1.30 to +1.64 D). The mean and median absolute errors were 0.52 and 0.48 D, respectively. The percentages of eyes with a PE within ±0.25 D, ±0.50 D, and ±1.00 D were 29.17%, 62.50%, and 87.50%, respectively. A comparison with the other formulas was possible in 20 eyes and did not reveal any statistically significant differences; the percentage of eyes with a PE within ±0.50 D ranged from 50 to 65%. Conclusions: Ray tracing is a relatively accurate solution for calculating the IOL power in eyes with previous RK. Paraxial formulas provide similar outcomes and should be considered in these patients. The refractive outcomes of IOL power calculation in post-RK eyes are still below modern benchmarks for virgin eyes. Full article