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To compare anterior segment and ocular biometric parameters in unaffectedfellow eyes of patients with a previous attack of acute angle closure (AAC), primary angle closure suspect (PACS) eyes, and normal eyes; and to identify eyes at high risk of AAC among primary angle closure suspects. In this case-control study, 16 unaffected fellow eyes of patients with aprevious attack of AAC (group I), 20 PACS eyes (group II) and 18 normal eyes (group III) underwent Pentacam and A-scan echography. Mean anterior chamber volume was 72±18, 77±18 and 176±44 µl in groupsI, II, and III, respectively (P<0.001). Corresponding values for anterior chamber angle in the same order were 24.8±4.6, 22.6±6.3 and 35.8±6.9 degrees (P<0.001), and that for anterior chamber depth measured from the corneal endothelium were 1.80±0.26, 1.93±0.23 and 3.13±0.59 mm, respectively (P<0.001). Using receiver operating characteristic (ROC) curves, anterior chamber volume ≤100 µl was associated with a high risk of AAC with sensitivity of 93.3% and specificity of 100%. Corresponding values for anterior chamber depth ≤2.1 mm were 86.7% and 100%, and that for anterior chamber angle ≤26° were 73.3% and 88.2%, respectively. Age, sex, central corneal thickness, and lens thickness were comparable among the study groups (all P values >0.05). Eyes with anterior chamber volume ≤100 µl, depth ≤2.1 mm and angle≤26° may be considered at high risk for developing AAC. These criteria could be helpful for making decisions regarding prophylactic laser peripheral iridotomy.

Purpose: To evaluate the agreement among Pentacam, Orbscan and ultrasound (US) pachymetry for measurement of central corneal thickness (CCT) in thin corneas with normal topographic pattern. Methods: We included 88 eyes of 44 refractive surgery candidates with thinnest pachymetric readings of 500 micrometers (μm) or less on Orbscan, a normal topographic pattern, no sign of keratoconus, and best corrected visual acuity (BCVA) of 20/20. Pentacam, Orbscan and US were performed in one session by the same examiner. Exclusion criteria were history of ocular surgery, topographic abnormalities suggesting forme fruste keratoconus or keratectasia, and recent contact lens wear. Results: The difference in CCT measurements by US pachymetry and Orbscan II [using an acoustic factor (AF) of 0.92] ranged from −34 to +34 μm. The difference between the thinnest point and central readings measured by US reached 16 μm with Orbscan II (AF: 0.92) and 2 μm with Pentacam. Mean differences between the employed devices were 0.2 μm for Pentacam versus US (P = 0.727), 30.1 μm for uncorrected Orbscan versus US (P < 0.001), 10.4 μm for Orbscan II (AF = 0.92) versus US (P < 0.001), and 0.2 μm for Orbscan II (AF = 0.94) versus US (P = 0.851). Conclusion: In normal thin corneas, Pentacam demonstrated better agreement with US pachymetry as compared to corrected Orbscan readings. Results achieved by Orbscan were better consistent with US pachymetry using an AF of 0.94. We speculate that a dynamically graded AF in reverse proportion to CCT constitutes a better approach for correcting Orbscan measurements.

AimTo compare the diagnostic ability of corneal tomography and corneal dynamic response measurements in normal and keratoconus eyes.MethodsConsecutive patients with grade II–III keratoconus and age-matched normal subjects were recruited. Corneal imaging was performed using Pentacam (Oculus Optikgeräte, Wetzlar, Germany) and Corvis (Oculus Optikgeräte). A beta version of Corvis software was used with three additional parameters: maximal change of arc length, deformation amplitude (DA) ratio 1 and DA ratio 2. Diagnostic ability of both devices to differentiate normal and keratoconus eyes was evaluated using receiver-operating characteristic (ROC) curves. The areas under the ROC curve (AUC) and partial AUC (pAUC) for specificity ≥80% for each parameter of Corvis and final D value of Belin/Ambrosio Enhanced Ectasia Display (BAD) were compared.ResultsForty-two eyes of 42 patients (21 patients with keratoconus and 21 normal subjects) were included. Both groups were age matched (p=0.760). The ROC analysis showed that the final D value of BAD had the highest AUC (0.994) and pAUC (0.194). Maximum inverse radius had the highest AUC (0.954) but a relatively lower pAUC (0.158), while DA ratio 2 had the second highest AUC (0.946) together with the highest pAUC (0.177) among Corvis parameters. There was no significant difference between AUC and pAUC of BAD compared with those of DA ratio 1 (p≥0.162) and DA ratio 2 (p≥0.208).ConclusionsThe results of our study suggest that Corvis measurements have the potential to differentiate keratoconus and normal eyes. The diagnostic ability of novel parameters on Corvis was comparable to Pentacam.

Introduction: Accurate assessment of the corneal shape is important in cataract and refractive surgery, both in screening of candidates as well as for analyzing postoperative outcomes. Although corneal topography and tomography are widely used, it is common that these technologies are confused. The aim of this study was to present the current developments of these technologies and particularly distinguish between corneal topography and tomography. Methods: The PubMed, Web of Science and Embase databases were the main resources used to investigate the medical literature. The following keywords were used in various combinations: cornea, corneal, topography, tomography, Scheimpflug, Pentacam, optical coherence tomography. Results: Topography is the study of the shape of the corneal surface, while tomography allows a three-dimensional section of the cornea to be presented. Corneal topographers can be divided into large- and small-cone Placido-based devices, as well as devices with color-LEDs. For corneal tomography, scanning slit or Scheimpflug imaging and optical coherence tomography may be employed. In several devices, corneal topography and tomography have been successfully combined with tear-film analysis, aberrometry, optical biometry and anterior/posterior segment optical coherence tomography. Conclusion: There is a wide variety of imaging techniques to obtain corneal power maps. As different technologies are used, it is imperative that doctors involved in corneal surgery understand the science and clinical application of devices for corneal evaluation in depth.

Accurate assessment of anterior segment parameters is essential for clinical decision-making and ophthalmic research. With the increasing availability of domestically developed anterior segment imaging systems, independent evaluation of their measurement characteristics relative to established devices is required. This study aimed to compare anterior segment measurements obtained using Scansys TA517, a domestically developed Scheimpflug-based imaging system, with those from Pentacam HR. A total of 214 eyes were examined using both devices during the same visit. Anterior chamber depth (ACD), anterior chamber angle (ACA), anterior chamber volume (ACV), white-to-white corneal diameter (WTW), pupil diameter (PD), and the ACD/WTW ratio were analyzed. Inter-device differences were evaluated using Bland-Altman analysis, and proportional bias was assessed by linear regression of inter-device differences against the mean of the two measurements. Inter-device differences varied substantially across parameters. ACD and the ACD/WTW ratio demonstrated minimal mean bias, narrow limits of agreement, and no proportional bias, indicating high inter-device stability and reliability. In contrast, ACA and ACV exhibited larger bias, wider limits of agreement, and significant proportional bias. WTW and PD showed intermediate stability with evidence of magnitude-dependent discrepancies. In conclusion, inter-device agreement between Scansys TA517 and Pentacam HR is parameter-dependent. Linear and ratio-based parameters demonstrated greater stability than angle- and volume-based measurements, and proportional bias was present for several parameters. These findings highlight the importance of parameter-specific and device-specific interpretation when comparing anterior segment measurements across imaging systems.

Background to evaluate corneal optical densitometry (COD) and its associations with age, refractive error, central corneal thickness (CCT), anterior chamber depth (ACD), and corneal curvature in healthy Upper Egyptian subjects. Methods This prospective cross-sectional study included 379 eyes of 379 healthy subjects aged 16 years or older. All participants underwent a comprehensive ophthalmologic evaluation. Corneal optical densitometry was assessed using the Oculus Pentacam, which measures COD in grayscale units (GSU) across four annular zones and three lamellar layers. Cases with a history of corneal or intraocular surgery, habitual contact lens use, or systemic diseases were excluded. Results The mean COD over the entire cornea (0–12 mm) was 16.1 ± 2.6 GSU. A strong positive correlation was found between age and COD across all zones and layers ( p  < 0.001). Negative correlations were observed between COD and mean refractive spherical equivalent (MRSE) in the 10–12 mm zone ( p  < 0.001) and between COD and CCT in the 0–2 mm zone ( p  = 0.004). Anterior chamber depth (ACD) was negatively correlated with COD in multiple zones ( p  < 0.05). Positive correlations were identified between COD and keratometry readings (K m and K max ) across all zones and layers ( p  < 0.001). Conclusion This study highlights the associations between corneal optical densitometry and basic population characteristics in healthy Upper Egyptian subjects. This enhances understanding of factors influencing corneal transparency and underscores the importance of considering these variables in clinical and research settings.

This study proposes a deep learning-based, non-contact method for detecting elevated intraocular pressure (IOP) by integrating Scheimpflug images with corneal biomechanical features. Glaucoma, the leading cause of irreversible blindness worldwide, requires accurate IOP monitoring for early diagnosis and effective treatment. Traditional IOP measurements are often influenced by corneal biomechanical variability, leading to inaccurate readings. To address these limitations, we present a multi-modal framework incorporating CycleGAN for data augmentation, Swin Transformer for visual feature extraction, and the Kolmogorov–Arnold Network (KAN) for efficient fusion of heterogeneous data. KAN approximates complex nonlinear relationships with fewer parameters, making it effective in small-sample scenarios with intricate variable dependencies. A diverse dataset was constructed and augmented to alleviate data scarcity and class imbalance. By combining Scheimpflug imaging with clinical parameters, the model effectively integrates multi-source information to improve high IOP prediction accuracy. Experiments on a real-world private hospital dataset show that the model achieves a diagnostic accuracy of 0.91, outperforming traditional approaches. Grad-CAM visualizations identify critical anatomical regions, such as corneal thickness and anterior chamber depth, that correlate with IOP changes. These findings underscore the role of corneal structure in IOP regulation and suggest new directions for non-invasive, biomechanics-informed IOP screening.

Abstract PurposeTo objectively evaluate changes in lens densitometry in eyes with neovascular age-related macular degeneration (n-AMD) treated with repeated intravitreal ranibizumab injections during a 12-month period and to compare the results with those in untreated healthy fellow eyes and healthy control eyes.MethodsIn this prospective study, the 36 treated eyes and the 37 untreated fellow eyes of 38 patients with n-AMD and the 32 control eyes of 32 healthy individuals were analyzed. Lens densitometry was evaluated using the Scheimpflug imaging. All data in both groups regarding lens densitometry were recorded at baseline and 12 months.ResultsThe mean densitometry of zone 1 in the treated eyes of patients had increased significantly at 12 months compared with the baseline (baseline: 9.3 ± 1.5, 12 months: 11.9 ± 1.7, p = .004) and was significantly greater than those measurements in the fellow eyes (9.8 ± 1.6 p = .02) and control eyes (9.6 ± 1.9, p = .01) at 12 months as well. There were no significant differences in terms of densitometry values between the fellow and control eyes at baseline and 12 months (for all, p > .05).ConclusionsOur results objectively demonstrate early nuclear lens density changes using with Scheimpflug images in eyes with n-AMD that were treated with repeated ranibizumab injections for 12 months.

Keratoconus (KC) is an irreversible blinding eye disease; therefore, early screening of KC suspects (KCS) is crucial for protecting patients’ quality of life. Scheimpflug imaging is a commonly used screening device in clinical practice. We aimed to evaluate the diagnostic ability of a Scheimpflug imaging device (Scansys) for KC and KCS and compared it with other Scheimpflug-based devices (Pentacam and Corvis ST). This prospective case-control study included 107 normal eyes, 72 KCS, and 57 KC. Scansys screening index Keratoconus probability (KCP) showed excellent performance in diagnosing KC at a cutoff value of 16.4 (area under the receiver operating characteristic [AUROC] = 1.000), with 100% sensitivity and 98.11% specificity. KCP had a better KCS diagnostic ability at a cutoff value of 8.9 (AUROC = 0.813) than Corvis biomechanical index (CBI, AUROC = 0.764), reaching 67.61% sensitivity and 85.85% specificity. Pentacam screening index Belin/Ambrósio enhanced ectasia display deviation (BAD-D) showed the best performance with 92.96% sensitivity and 89.62% specificity at a cutoff value of 1.525 (AUROC = 0.970) in diagnosing KCS. Scansys provides accurate KCP parameters in diagnosing KC; however, the efficiency of diagnosing KCS should be further optimized.

To investigate the repeatability of a combined Dual-Scheimpflug placido disc corneal tomographer/topographer (Ziemer Galilei G4) with respect to keratometric indices used to monitor progression of keratoconus (KCN). Patients with KCN were prospectively enrolled. For each eye lacking history of corneal surgery, 5 measurements were taken in succession. Eyes in which 3 or more measurements could be obtained (defined by the device's 4 image quality metrics) were included in the analysis. The repeatability limits (RL) and interclass correlation coefficients (ICC) were calculated for various parameters. Thirty-two eyes from 25 patients met all image quality metrics, and 54 eyes from 38 patients met at least 3/4 criteria (all except the placido image quality metric). RLs for key parameters when 4/4 or ≥3/4 image quality metrics were met included: 0.37 and 0.77 diopters (D) for steep simulated keratometry, 0.79 and 1.65 D for maximum keratometry, 13.80 and 13.88 degrees for astigmatism axis, 0.64 and 0.56 µm for vertical coma magnitude, and 3.76 and 3.84 µm for thinnest pachymetry, respectively. The ICCs for all parameters were excellent (above 0.87) except for spherical aberration (0.77), which was still considered good. The dual-Scheimpflug placido disc corneal tomographer/topographer is highly repeatable in quantifying parameters used in monitoring KCN. Excellent placido images are difficult to capture in eyes with KCN, but when available, increase the reliability of the measurements. When clinicians find that a topographic index changes by more than the RLs defined herein, they can have confidence that this represents real change and may appropriately recommend interventions such as corneal cross-linking or intrastromal corneal ring segments.