PURPOSE:To develop and validate an automated corneal opacity detection algorithm for optical coherence tomography (OCT) images, utilizing an incidence-angle- and depth-dependent model of corneal reflectance. DESIGN:Retrospective, cross-sectional diagnostic accuracy study. SUBJECTS:Training used 95 healthy eyes from 49 volunteers. Testing included 50 eyes from 42 patients with corneal opacities and 35 healthy eyes from 35 volunteers. METHODS:Normal-eye OCT scans were used to model normative incidence-angle-dependent reflectance across corneal layers. The algorithm detected pixels above the normal reflectance range using model-based thresholds, binned percentile analysis, and morphological operations. Eye-level performance was evaluated against slit-lamp examination as clinical ground truth and compared with 5 trained physician annotators. Pixel-level agreement with consensus annotations (≥3 of 5 annotators) was assessed with Dice similarity coefficient. MAIN OUTCOME MEASURES:Eye-level accuracy, F1-score, sensitivity, and specificity; pixel-level Dice similarity coefficient and segmented-area agreement versus consensus annotations. RESULTS:At the eye level, the algorithm achieved accuracy of 0.93, F1-score of 0.94, sensitivity of 0.96, and specificity of 0.89. Human annotators had a mean accuracy of 0.83 ± 0.06, F1-score of 0.85 ± 0.04, sensitivity of 0.84 ± 0.09, and specificity of 0.80 ± 0.27. At the pixel level, mean Dice similarity coefficient versus consensus was 0.58 for the algorithm and 0.71 ± 0.05 for annotators. The algorithm's total segmented opacity area was close to the consensus pixel count (98% of consensus). CONCLUSION:An algorithm that incorporates incidence angle and depth-specific reflectance thresholds detects and segments corneal opacities. It demonstrated favorable accuracy at the eye level and produced quantitative opacity maps on OCT.

Purpose:To develop quantitative biomarkers that characterize the effect of upper eyelid motion (lid-wiper effect) during blinking on corneal epithelial thickness. Design:A retrospective study analyzing corneal epithelium thickness maps through Zernike polynomial decomposition. Subjects:Three hundred thirty-six maps from 135 healthy eyes of 69 subjects. Methods:A total of 5-mm diameter epithelial thickness maps were acquired using spectral-domain OCT. Maps from left eyes were mirror-imaged and pooled with right eyes for analysis. Zernike polynomial decomposition was performed, and average coefficients were obtained. The lowest-order Zernike terms with single-angle dependence-tilt and primary coma-were analyzed as vectors to determine the lid-wiper axes. The lid-wiper gradient (μm/mm) and lid-wiper coma (μm) were calculated by projecting the tilt and coma vectors along their lid-wiper axes. Correlation analysis was performed between the lid-wiper gradient and lid-wiper coma, primary astigmatism, and higher-order aberrations. Main Outcome Measures:The lid-wiper gradient and lid-wiper coma, which are quantitative biomarkers of epithelial remodeling in response to the lid-wiper effect. Results:The average epithelial thickness map showed superotemporal thinning with relative inferonasal thickening. Average tilt and coma coefficients were nonzero (P = 0.004 to <0.001). The population centroids (mean ± standard deviation) of the lid-wiper gradient and lid-wiper coma were 0.51 ± 0.57 μm/mm at 298.06 ± 56˚, and 0.21 ± 0.55 μm at 311.59 ± 83.53˚, respectively. The lid-wiper gradient and coma were positively correlated with each other (R 2 = 0.08, P = 0.001). Conclusions:A significant epithelial thickness gradient exists in the average normal cornea, consistent with eyelid blink dynamics described in the literature. The significant but weak correlation between the lid-wiper gradient and coma suggests the lid-wiper effect may be among various factors contributing to higher-order aberrations in the epithelium. The lid-wiper gradient and coma may serve as quantitative biomarkers of epithelial remodeling in response to the lid-wiper effect. Financial Disclosures:Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Assessing postoperative inflammation following trans-PRK and FS-LASIK remains challenging. This study proposes a multimodal fusion framework supported by inflammatory dynamics physical descriptors. The model uses modality-specific encoders for ocular imaging and structured clinical or biomarker sequences, uses explicit observation masks for unavailable modalities, and learns visit-level fusion weights using cross-modal attention modules. In the four de-identified retrospective data partitions evaluated in this study, the proposed fusion model increases the accuracy of the strongest baseline reported in each partition by 2.66 to 4.10% points, and shows similar improvements in F1 score and AUROC. The results indicate that intermediate multimodal fusion can support postoperative inflammation assessment. Before clinical deployment, larger external validation cohorts, calibration analyses, and direct comparisons with medical multimodal fusion methods are still required.

Purpose:To enrich stromal riboflavin concentration and reduce epithelial riboflavin in transepithelial corneal collagen crosslinking (CXL). Methods:Ex vivo experiments on rabbit corneas were performed. The control group followed the standard (epi-off) Dresden CXL: a 30-minute epi-off application of 0.1% riboflavin and 20% dextran. The transepithelial riboflavin solutions consisted of various riboflavin concentrations in 1% hydroxypropyl methylcellulose in 0.45% saline, with or without 0.01% benzalkonium chloride (BAK). The novel soak-and-rinse protocol consists of 0.8% riboflavin with 0.01% BAK and 1% hydroxypropyl methylcellulose (hypotonic) applied for 20 minutes, followed by a 10-minute saline rinse. Stromal and epithelial thicknesses were measured by optical coherence tomography; riboflavin concentrations were quantified by spectrophotometry on 3-mm stromal buttons and epithelial eluates. Statistical analysis employed one-way analysis of variance, linear regression, and one-tailed unpaired t-tests. Results:The 20-minute soak increased stromal riboflavin compared to the 10-minute soak. A 76% higher stromal concentration was achieved by adding BAK to the transepithelial 0.8% riboflavin solution (P < 0.05). The 10-minute rinse achieved a Dresden-equivalent stromal riboflavin level and reduced epithelial riboflavin by 5.9-fold compared to a 20-second rinse (P < 0.0001). Conclusions:Stromal riboflavin concentrations equivalent to those achieved with the epi-off protocol can be achieved by transepithelial application of the novel high-concentration riboflavin formulation. The additional 10-minute rinse effectively reduced epithelial riboflavin levels, facilitating the delivery of ultraviolet light and oxygen into the stroma during CXL. Translational Relevance:The novel transepithelial riboflavin soak-and-rinse protocol may potentially enhance the efficacy of transepithelial CXL by reducing epithelial consumption of ultraviolet light and oxygen and increasing the stromal CXL reaction.

Purpose:To train and validate a convolutional neural network (CNN) to detect the history of laser-assisted in situ keratomileusis (LASIK) surgeries using corneal optical coherence tomography (OCT) maps. Methods:Five corneal OCT maps (pachymetry, epithelial thickness, posterior mean curvature, anterior axial power, and anterior stroma reflectance) were utilized as the input of a lightweight CNN model. OCT scans of healthy volunteers and patients who had undergone myopic or hyperopic LASIK were included. Repeated fivefold cross-validation was used to train and evaluate the proposed CNN. In addition, a separate group of post-LASIK participants, who were not included in the cross-validation, was used for out-of-sample testing to assess the CNN model performance. Results:In the cross-validation, the proposed CNN model achieved an overall balanced accuracy of 90.2% ± 3.6% with 93.5% ± 5.2% sensitivity and 97.8% ± 1.7% area under the receiver operating characteristic curve (AUC) in detecting myopic LASIK and 90.2% ± 5.8% sensitivity and 98.2% ± 1.9% AUC in identifying the hyperopic LASIK. In the out-of-sample test, all eyes were classified correctively. Conclusions:The lightweight CNN model with corneal OCT maps provides a useful tool for detecting LASIK history. Translational Relevance:Artificial intelligence-assisted OCT may offer better management for patients with LASIK history who need cataract surgeries.

Objective: Develop a multi-functional imaging system that combines 1.7 mu m optical coherence tomography/angiography (OCT/OCTA) to accurately interrogate Hereditary Hemorrhagic Telangiectasia (HHT) skin lesions. Methods: The study involved imaging HHT skin lesions on five subjects including lips, hands, and chest. We assessed the attributes of both HHT lesions and the healthy vasculature around them in these individuals, employing quantifiable measures such as vascular density and diameter. Additionally, we performed scans on an HHT patient who had undergone anti-angiogenic therapy, allowing us to observe changes in vasculature before and after treatment. Results: The results from this pilot study demonstrate the feasibility of evaluating the HHT lesion using this novel methodology and suggest the potential of OCTA to non-invasively track HHT lesions over time. The average percentage change in density between HHT patients' lesions and control was 37%. The percentage increase in vessel diameter between lesion and control vessels in HHT patients was 23.21%. Conclusion: In this study, we demonstrated that OCTA, as a functional extension of OCT, can non-invasively scan HHT lesions in vivo. We scanned five subjects with HHT lesions in various areas (lip, ear, finger, and palm) and quantified vascular density and diameter in both the lesions and adjacent healthy tissue. This non-invasive method will permit a more comprehensive examination of HHT lesions. Significance: This method of non-invasive imaging could offer new insights into the physiology, management, and therapeutics of HHT-associated lesion development and bleeding.

The differential diagnosis of uveitis is broad and challenging. A key indicator of intraocular inflammation is the presence of cells in the aqueous or vitreous humor. Optical coherence tomography (OCT) methods have been developed to measure intraocular inflammatory cell composition using reflectance intensity or cell size distributions. However, these methods are ineffective at low cell densities. We developed a lightweight convolutional neural network (CNN) model to classify intraocular inflammatory cell types with ultrahigh-resolution OCT. OCT images of known cell types (mononuclear cells and granulocytes) were used to train and optimize the model. The CNN model achieved an accuracy of 88.4 +/- 0.7% with an area under the receiver operating characteristic curve of 94.3 +/- 0.4%. The inflammatory cell compositions predicted by the trained model from OCT images were consistent with the clinical diagnoses of uveitis patients. This method is valuable for uveitis diagnosis and monitoring of intraocular inflammation.

Purpose:To characterize the directional reflectance properties of the cornea using optical coherence tomography (OCT) imaging and develop a mathematical model describing corneal reflectance as a function of depth and incidence angle across different corneal layers. Methods:A retrospective analysis was conducted on OCT scans from normal subjects using the Visionix Avanti OCT system (840 nm). Reflectance values for the epithelium, Bowman's layer, stroma, and endothelium/Descemet's membrane were extracted and analyzed as functions of incidence angle and corneal depth. Reflectance distributions were assessed for normality. Exponential functions were fitted to the mean and 97th percentile reflectance data to model directional reflectance for each corneal layer. Results:Reflectance values exhibited non-normal leptokurtic distributions with right-tailed skewness, requiring non-parametric methods for percentile calculations. The exponential model incorporating angular dependence achieved R² values of 0.987 and 0.963 for mean and 97th percentile reflectance, respectively. The mean reflectance of the epithelium was modeled by a single exponential function, with half-reflectance angles of 15.9° to 26.6°. The stromal layers required two exponential components, with the anterior stroma exhibiting the highest reflectance and most pronounced directionality (half-reflectance angle of 0.17°). The 97th percentile reflectance differed, with higher reflectance values in the middle and posterior stroma. No statistically significant age or gender related variability in reflectance was measured. Conclusions:This study provides a detailed mathematical model of corneal directional reflectance, highlighting the importance of incidence angle and layer depth in OCT image analysis. Translational Relevance:The developed cornea reflectance model may improve OCT-based diagnostics by identifying early microstructural changes, aiding in the diagnosis and management of corneal diseases.

The differential diagnosis of uveitis is broad and often challenging. A key indicator of intraocular inflammation is the presence of cells in the aqueous or vitreous humor. We developed a lightweight convolutional neural network (CNN) model capable of classifying intraocular inflammatory cell types using ultrahigh-resolution optical coherence tomography (OCT). The model was trained and optimized using OCT images of known cell types-mononuclear cells and granulocytes-and achieved an accuracy of 88.4 ± 0.6%, with an area under the receiver operating characteristic (ROC) curve of 94.3 ± 0.4%. The inflammatory cell compositions predicted by the model were consistent with clinical diagnoses in uveitis patients. This approach offers a promising tool for the diagnosis and monitoring of intraocular inflammation in uveitis.

Background:To investigate the relationship between tear film thickness, corneal epithelial thickness, tear film breakup location, and dry eye in patients with high- and low-myopia undergoing femtosecond-assisted laser in situ keratomileusis (FS-LASIK). Methods:A total of 52 patients (52 eyes) were enrolled and divided into a low-myopia group (LMG; spherical equivalent ≤-3.00 D; 26 eyes) and a high-myopia group (HMG; spherical equivalent ≥-6.00 D; 26 eyes). The Ocular Surface Disease Index (OSDI), fluorescein tear film breakup time (FBUT), corneal epithelial thickness (CET), tear film thickness (TFT), and other tear film stability markers were evaluated preoperatively. Each parameter was evaluated preoperatively at 1 and 3 months postoperatively. Results:At 1 month postoperatively, the HMG showed significantly higher OSDI scores and CET compared to the LMG (p < 0.05). Conversely, the FBUT and TFT were significantly lower in the HMG at the same time point (p < 0.05). Within a 6- to 7-mm corneal diameter, the TFT was significantly lower in the HMG than in the LMG (p < 0.05). Furthermore, the change in CET from baseline at 1 and 3 months postoperatively was significantly greater in the HMG, especially within the 5-mm corneal diameter (p < 0.05). There were no significant differences in spherical equivalent (SE) or uncorrected distance visual acuity (UDVA) between 1 and 3 months postoperatively within either group (p > 0.05). Conclusion:The observed alterations in tear film thickness, tear film distribution, FBUT, and tear film breakup location, affected by varying corneal stromal ablation depths, contribute to the development of dry eye disease following FS-LASIK. The extent of corneal epithelial remodeling after FS-LASIK correlates with the degree of refractive correction but not with refractive regression, and may play a role in tear film stability recovery.

High-speed anterior segment optical coherence tomography (OCT) offers a non-contact method for high resolution cross-sectional and three-dimensional imaging of the cornea and the anterior segment of the eye. As the first text completely devoted to this topic, Anterior Segment Optical Coherence Tomography comprehensively explains both the scientific principles and the clinical applications of this exciting and advancing technology.Anterior Segment Optical Coherence Tomography enhances surgical planning and postoperative care for a variety of anterior segment applications by expertly explaining how abnormalities in the anterior chamber angle, cornea, iris, and lens can be identified and evaluated using the Visante OCT[trademark].Inside Anterior Segment Optical Coherence Tomography, Dr. Roger Steinert and Dr. David Huang, along with 14 of the field's leading professionals, provide a wealth of useful clinical and physiological material about this new diagnostic imaging technique. Valuable images are included to assist in the pre- and postoperative assessment of various anterior segment disorders. Additionally, this unique resource contains detailed information on biometric measurements to enhance diagnostic capability.On the leading edge of anterior segment imaging, this book covers: Mapping of corneal thickness and keratoconus evaluation; Measurement of LASIK flap and stromal bed thickness; Visualization and measurement of anterior chamber angle and diagnosis of narrow angle glaucoma; Measuring the dimensions of the anterior chamber and assessing the fit of intraocular lens implants; Visualizing and measuring the results of corneal implants and lamellar procedures; and Imaging through corneal opacity to see internal eye structures.With the increase in popularity of anterior chamber imaging, and anterior segment OCT proving to be the best tool for high resolution biometry, Anterior Segment Optical Coherence Tomography is a must-have for anterior segment, refractive, cornea, and glaucoma surgeons.

Abstract Background The objective of this study is to illustrate the changes in the choroidal vasculature in individuals with diffuse chorioretinal atrophy (DCA, early-stage myopic maculopathy) and investigate the association between them. Methods This study included 1418 highly myopic eyes from 720 participants aged 18 − 60 years from the Wenzhou High Myopia Cohort Study. These participants underwent comprehensive ophthalmic assessments. Myopic maculopathy classification followed the Meta-PM system, with pathological myopia defined as myopic maculopathy of DCA or severer. Eyes with myopic maculopathy categorized as no macular lesions (C0), tessellated fundus (C1), and DCA (C2) were enrolled in the analysis. Choroidal images were obtained from swept-source optical coherence tomography (SS-OCT), and the images were processed with a deep learning-based automatic segmentation algorithm and the Niblack auto-local threshold algorithm. Results DCA was detected in 247 eyes (17.4%). In comparison to eyes with C0, those with C2 exhibited significant reductions in choroidal thickness (ChT), luminal area (LA), and stromal area (SA) across all evaluated regions (all P < 0.001). An increase in choroidal vascular index (CVI) was observed in all regions, except for the nasal perifoveal (N2) and inferior perifoveal (I2) regions (all P < 0.01). Multivariable logistic regression analysis revealed a negative association between the presence of DCA and increases in choroidal LA and SA (odds ratio ≤ 0.099, P < 0.001). Multivariable linear regression analysis showed that the mean deviation of the visual field test was positively associated with LA and SA at the vertical meridian (B = 1.512, P < 0.001 for LA; B = 1.956, P < 0.001 for SA). Furthermore, the receiver operating characteristic curve analyses showed the optimal ChT to diagnose pathological myopia was 82.4 µm in the N2 region, the LA was 0.076 mm2 and the SA was 0.049 mm2, with area under the curves of 0.916, 0.908, and 0.895, respectively. Conclusions The results of this study indicated that both the presence of DCA and visual function impairment were associated with reductions in choroidal perfusion and stromal components. Moreover, we established threshold values for choroidal parameters in diagnosing pathological myopia, offering valuable references for clinical diagnosis and management.

BACKGROUND:To assess the predictive value of pretreatment corneal elevation asymmetry vector (CEAV) for severe orthokeratology (Ortho-k) lens decentration (LD) in Chinese myopic adolescents. METHODS:A retrospective analysis of 247 myopic participants over one year employed a novel MATLAB algorithm to calculate CEAV and precise LD vector. Subjects were categorized into mild (<1 mm) and severe (≥1 mm) yearly averaged LD (YALD) groups. Logistic regression and ROC analysis evaluated the relationship between corneal parameters and severe YALD. RESULTS:LD reached stability within the first month, with severe YALD compromising visual quality and corneal health. Notably, univariate linear regression revealed a paradoxical correlation between axial length elongation (ALE) and YALD: ALE negatively correlated with YALD in the mild group (standardised β = -0.546, P < 0.05), contrasting with a positive correlation in the severe group (standardised β = 0.599, P < 0.05). Horizontal CEAV (standardised β =  - 0.237, < 0.05) and curvature differences between nasal and temporal quadrants at 8 mm (KTN) (standardised β = 0.227, P < 0.01) significantly correlated with horizontal YALD, while vertical CEAV vector associated with vertical YALD (standardised β =  - 0.237, < 0.05). Multivariate analysis identified CEAV as an independent predictor of severe YALD (OR = 3.145, 95 % CI: 1.334 ∼ 4.607, P < 0.01). Other risk factors included larger horizontal visible iris diameter (HVID) (OR = 2.430, 95 % CI:0.6136 ∼ 10.07, P < 0.05), corneal astigmatism (CA) (OR = 1.506, 95 % CI: 1.017 ∼ 2.244, P < 0.05), and KTN (OR = 1.864, 95 % CI: 0.934 ∼ 3.864, P < 0.05). CEAV magnitude alone predicted severe YALD with AUC = 0.698 (95 %CI: 0.615-0.783, P < 0.001), improving to AUC = 0.732 (95 % CI: 0.660-0.805, P < 0.001) when combined with other risk factors. CONCLUSIONS:Pretreatment CEAV may emerge as a viable predictor of severe Ortho-k YALD, warranting its consideration in further tailored lens fitting to improve outcomes.

Purpose: To test the ability of the corneal epithelial pattern standard deviation (PSD) to distinguish between normal and cases with corneal ectatic condition. Setting: Instituto de Olhos Renato Ambrósio, Rio de Janeiro, Brazil. Design: Cross-sectional retrospective study. Methods: Patients were stratified into 4 groups based on clinical data and corneal tomography. Groups 1 and 2 comprised 1 eye randomly selected from 105 patients with normal corneas (N) and 86 patients with bilateral keratoconus (KC). Groups 3 and 4, respectively, comprised 11 ectatic eyes with no surgical treatment for KC (very asymmetric ectasia [VAE]-E) from patients whose fellow eyes (61) presented with normal topographic patterns (VAE-NT). Corneas were scanned using an OCT system (RT Vue) and Scheimpflug corneal tomography (Pentacam) and also had biomechanical assessment through the Corvis ST. Corneal epithelial thickness maps were analyzed, and the PSD value was calculated. The area under the receiver operating characteristic curve analysis was used to evaluate the diagnostic accuracy of the indices. Results: A total of 105 normal eyes, 86 keratoconic eyes, and 11 ectatic eyes whose fellow eyes (61) presented normal topographic patterns were evaluated. Epithelial PSD was significantly different across the 4 groups ( P < .0001). The pairwise comparison revealed that the normal group presented significantly lower values than both ectasia groups (KC and VAE-E, P < .0001) and the VAE-NT group ( P = .0008). There was no statistical significant difference between KC and VAE-E ( P = .4284), while they were significantly higher than the VAE-NT group ( P < .0001 and P = .0004). Conclusions: Epithelial PSD can be used to detect abnormal epithelial thickness patterns. Corneal epithelial thickness changes could be detected accurately in patients with KC, even in the form fruste of the disease.

PURPOSE:To present a new method for 3-dimensional external limbal demarcation on corneoscleral topography derived from optical coherence tomography (OCT). Limbal shape is investigated and compared to other landmarks. METHODS:Images from the anterior segment were obtained with a ultrawide-field (20 mm) OCT. An automated algorithm was developed to demarcate the topographic limbus based on the transition from corneal to scleral curvature. The internal limbus was manually identified as the scleral spur on the OCT images. The external topographic limbus was fit with a circle on a plane. Ellipticity and ovality were defined by the lateral limbal deviation from the best-fit circle. Toricity was defined by the axial deviation from the best-fit plane. Repeatability was assessed by the within-subject standard deviation from two repeated measurements. For comparison, the white-to-white (WTW) diameter was obtained from Pentacam HR. RESULTS:18 eyes from 11 subjects were analyzed. The topographic limbal diameter was 12.16 ± 0.68 mm (mean ± standard deviation) horizontally and 11.18 ± 0.65 mm vertically. The repeatability for the topographic limbal diameter was 0.054 mm. The internal and WTW horizontal limbal diameters were significantly smaller (linear mixed-effects model (GLMM), p <.017). The vertical internal limbal diameter was significantly larger (GLMM p <.05). The topographic limbus had significant ellipticity (0.25 ± 0.13 mm, wider horizontally, repeatability of 0.07 mm) and toricity (0.15 ± 0.08 mm, flatter horizontally, repeatability of 0.10 mm). Low coefficients of determination were found for the topographical limbus with the internal limbus (R2=0.021 and R2=0.039, for horizontal and vertical diameters respectively) and with the WTW (R2=0.146 for the horizontal diameter). CONCLUSION:The proposed method to demarcate the 3D external topographical limbus is repeatable. The topographic limbal shape and size cannot be accurately derived from WTW nor internal limbus measures. This new technology may improve the process of scleral lens fitting.