Optical Coherence Tomography Optic Nerve Head Research Articles

Assessing the efficacy of 2D and 3D CNN algorithms in OCT-based glaucoma detection

Glaucoma is a progressive neurodegenerative disease characterized by the gradual degeneration of retinal ganglion cells, leading to irreversible blindness worldwide. Therefore, timely and accurate diagnosis of glaucoma is crucial, enabling early intervention and facilitating effective disease management to mitigate further vision deterioration. The advent of optical coherence tomography (OCT) has marked a transformative era in ophthalmology, offering detailed visualization of the macula and optic nerve head (ONH) regions. In recent years, both 2D and 3D convolutional neural network (CNN) algorithms have been applied to OCT image analysis. While 2D CNNs rely on post-prediction aggregation of all B-scans within OCT volumes, 3D CNNs allow for direct glaucoma prediction from the OCT data. However, in the absence of extensively pre-trained 3D models, the comparative efficacy of 2D and 3D-CNN algorithms in detecting glaucoma from volumetric OCT images remains unclear. Therefore, this study explores the efficacy of glaucoma detection through volumetric OCT images using select state-of-the-art (SOTA) 2D-CNN models, 3D adaptations of these 2D-CNN models with specific weight transfer techniques, and a custom 5-layer 3D-CNN-Encoder algorithm. The performance across two distinct datasets is evaluated, each focusing on the macula and the ONH, to provide a comprehensive understanding of the models’ capabilities in identifying glaucoma. Our findings demonstrate that the 2D-CNN algorithm consistently provided robust results compared to their 3D counterparts tested in this study for glaucoma detection, achieving AUC values of 0.960 and 0.943 for the macular and ONH OCT test images, respectively. Given the scarcity of pre-trained 3D models trained on extensive datasets, this comparative analysis underscores the overall utility of 2D and 3D-CNN algorithms in advancing glaucoma diagnostic systems in ophthalmology and highlights the potential of 2D algorithms for volumetric OCT image-based glaucoma detection.

Rate of Initial Optic Nerve Head Capillary Density Loss and Risk of Visual Field Progression

Rapid initial optic nerve head capillary density loss may be used to assess the risk of glaucoma visual field progression. To investigate the association between the rate of initial optic nerve head capillary density loss from optical coherence tomography angiography (OCTA) and visual field progression. This was a retrospective study of a longitudinal cohort at a glaucoma referral center. A total of 167 eyes (96 with primary open-angle glaucoma and 71 with glaucoma suspect) of 109 patients were monitored for a mean (SD) of 5.7 (1.4) years from January 2015 to December 2022. Data analysis was undertaken in April 2023. The rates of initial capillary density and average retinal nerve fiber layer loss were calculated from the first 3 optic nerve head OCTA and OCT scans, respectively, during the initial follow-up (mean [SD], 2.0 [1.0] years). Based on the median rate, eyes were categorized into fast and slow progressor groups. The association between initial capillary density change or retinal nerve fiber layer thinning and visual field progression was evaluated using linear-mixed and time-varying Cox models. A total of 167 eyes of 109 patients (mean [SD] age, 69.0 [11.1] years; 56 [51.4%] female and 53 [48.6%] male) were assessed. Eighty-three eyes were slow OCTA progressors, while 84 eyes were fast with mean capillary density loss of -0.45% per year and -1.17% per year, respectively (mean difference, -0.72%/year; 95% CI,-0.84 to -0.60; P < .001). Similarly, 83 eyes were slow OCT progressors, while 84 eyes were fast with mean retinal nerve fiber layer thinning of -0.09 μm per year and -0.60 μm per year, respectively (mean difference, -0.51 μm/year; 95% CI,-0.59 to -0.43; P < .001). The fast OCTA and OCT progressors were associated with more rapid visual field loss (mean difference, -0.18 dB/year; 95% CI,-0.30 to -0.06; P = .004 and -0.17 dB/year; 95% CI,-0.29 to -0.06; P = .002, respectively). Fast OCTA progressing eyes were more likely to have visual field progression (hazard ratio, 1.96; 95% CI, 1.04-3.69; P = .04). Seventeen of 52 eyes (32.7%; 95% CI, 32.5-32.8) with fast OCTA and OCT progression developed subsequent visual field likely progression. Rapid initial optic nerve head capillary density loss from OCTA was associated with a faster rate of visual field progression and a doubling of the risk of developing event progression in this study. These findings may support clinical use of OCTA and OCT optic nerve head measurements for risk assessment of glaucoma progression.

The Relationship between Lumbar Puncture Opening Pressure and Retinal Nerve Fiber Layer Thickness in the Diagnosis of Idiopathic Intracranial Hypertension: Is a Lumbar Puncture Always Necessary?

Idiopathic intracranial hypertension (IIH), is characterized by elevated intracranial pressure (ICP) without an identified cause. Today, lumbar puncture (LP) is the most common method used for diagnosis by measuring cerebrospinal fluid (CSF) pressure to reflect intracranial pressure. This invasive examination has significant disadvantages, such as complications and negative experiences for patients. Therefore, noninvasive methods for ICP measurement are desired. Optical coherence tomography (OCT) is widely used for the diagnosis and follow-up of IIH patients as it reflects papilledema. The aim of this study is to investigate the relationship between CSF pressure and OCT parameters and the ability of OCT in the diagnostic approach. In our study, patients who were followed up with a diagnosis of IIH with complete neuro-ophthalmological examinations, including visual acuity (VA), visual field, and OCT imaging within 24 hours before lumbar puncture, were retrospectively evaluated. CSF pressure, visual acuity LogMAR, mean deviation of visual fields, retinal nerve fiber layer (RNFL) thickness measured by OCT, and treatment protocols were obtained from our hospital data system. A total of 42 eyes of 21 patients were enrolled in the study. A statistically significant positive and moderate correlation was found between CSF pressure values and average RNFL thickness (r=0.507; P=0.001). The same relationship was demonstrated in all 4 quadrants: inferior, superior, nasal, and temporal. Increased peripapillary RNFL thickness in optic nerve head OCT may be correlated with increased ICP in IIH patients. A larger number of patients are needed to better understand the correlation between OCT parameters and CSF pressure in patients with IIH.

Peripapillary Atrophy Area as an Indicator of Glaucomatous Structural and Functional Progression.

To determine whether peripapillary atrophy (PPA) area is an indicator of glaucomatous structural and functional damage and progression. In this retrospective longitudinal analysis from ongoing prospective study we qualified 71 eyes (50 subjects) with glaucoma. All subjects had a comprehensive ophthalmic examination, visual field (VF), and spectral-domain optical coherence tomography (OCT) testing in at least three visits. PPA was manually delineated on en face OCT optic nerve head scans, while observing the corresponding cross-sectional images, as the hyper-reflective area contiguous with the optic disc. The mean follow-up duration was 4.4 ± 1.4years with an average of 6.8 ± 2.2 visits. At baseline, PPA area was significantly associated only with VF's mean deviation (MD; P = 0.041), visual field index (VFI; P = 0.041), superior ganglion cell inner plexiform layer (GCIPL; P = 0.011), and disc area (P = 0.011). Longitudinally, PPA area was negatively and significantly associated with MD (P = 0.015), VFI (P = 0.035), GCIPL (P = 0.009), superior GCIPL (P = 0.034), and disc area (P = 0.007, positive association). Longitudinal change in PPA area is an indicator of glaucomatous structural and functional progression but PPA area at baseline cannot predict future progression. Longitudinal changes in peripapillary atrophy area measured by OCT can be an indicator of structural and functional glaucoma progression.

OCT Optic Nerve Head Morphology in Myopia IV: Neural Canal Scleral Flange Remodeling in Highly Myopic Eyes

PurposeTo compare the prevalence, location and magnitude of optic nerve head (ONH) OCT-detected, exposed neural canal (ENC), externally oblique choroidal border tissue (EOCBT) and exposed scleral flange (ESF) regions in 122 highly myopic (Hi-Myo) versus 362 non-highly myopic healthy (Non-Hi-Myo-Healthy) eyes. DesignCross-sectional study MethodsAfter OCT radial B-scan, ONH imaging, Bruch's membrane opening (BMO), the anterior scleral canal opening (ASCO), and the scleral flange opening (SFO) were manually segmented in each B-scan and projected to BMO reference plane. The direction and magnitude of BMO/ASCO offset and BMO/SFO offset as well as the location and magnitude of ENC, EOCBT and ESF regions, perineural canal (pNC) retinal nerve fiber layer thickness (RNFLT) and pNC choroidal thickness (CT) were calculated within 30° sectors relative to the Foveal-BMO (FoBMO) axis. Hi-ESF eyes were defined to be those with an ESF region ≥ 100 µms in at least one sector. ResultsHi-Myo eyes more frequently demonstrated Hi-ESF regions (87/122) than Non-Hi-myo-Healthy eyes (73/362) and contained significantly larger ENC, EOCBT, and ESF regions (p< 0.001) which were greatest in magnitude and prevalence within the inferior-temporal FoBMO sectors where Hi-Myo pNC-RNFLT and pNC-CT were thinnest. BMO/ASCO offset and the BMO/SFO offset were both significantly increased (p< 0.001) in the Hi-Myo eyes, with the latter demonstrating a greater increase. ConclusionsENC region tissue remodeling that includes the scleral flange is enhanced in Hi-Myo compared to Non-Hi-Myo-Healthy eyes. Longitudinal studies are necessary to determine whether the presence of an ENC region influences ONH susceptibility to aging and/or glaucoma.

Optic nerve head dimension as biomarker in Leber hereditary optic neuropathy

Aims/Purpose: To study the optic nerve head (ONH) dimension in symptomatic and asymptomatic patients with Leber hereditary optic neuropathy (LHON) and to correlate ONH parameters with genotype and clinical phenotype.Methods: Seventy‐eight affected patients, 175 asymptomatic carriers, and 29 age‐matched healthy controls were enrolled in the study. All patients underwent ONH optical coherence tomography (OCT) measurements by DRI OCT Triton (Topcon, Japan) and were analysed with the Orion custom software (Volexeron, CA, USA). The following parameters were obtained for each eye: disc area, horizontal and vertical diameter; retinal nerve fibre layer (RNFL) and ONH volume. For the comparison of the different parameters the ANOVA with Bonferroni post‐hoc test was performed.Results: LHON‐affected patients appeared to have smaller ONH size parameters compared to control cases, but only the vertical disc diameter of patients with mutations 11 778 and 14 484 were statistically significant. Also, carrier patients with the mutation 11 778 presented a statistical significantly smaller vertical disc diameter compared to controls, instead 14 484 carriers presented a bigger diameter. ONH volume of all affected patients was significantly smaller. Moreover, asymptomatic 11 778 carriers older than 35 years were significantly smaller. Linear regression sustained the relationship between age, volume, and RNFL, unlike between age and disc area.Conclusions: This study exposed the differences of ONH size in LHON‐affected and ‐carrier patients with different mutations: smaller disc in 11 778 affected and unaffected patients and larger disc in 14 484 carriers. A strong correlation was found between ONH volume both in affected patients and carriers older than 35 years old. These results highlight the importance of the 3D ONH structure as a potential biomarker to support clinicians in the characterization of symptomatic LHON patients and possibly at‐risk mutation carriers with different genetic mutations and clinical course.

Deep Optic Nerve Head Morphology in Tilted Disc Syndrome and Its Clinical Implication on Visual Damage.

To study deep optic nerve head (ONH) morphology in tilted disc syndrome (TDS) and identify factors associated with retinal nerve fiber layer (RNFL) defect. In patients with TDS, we evaluated the optic disc shape using the Bruch's membrane opening (BMO)-anterior scleral canal opening (ASCO) offset and measured the border tissue (BT) length, depth, and angle in the direction of the tilt, using radial ONH optical coherence tomography (OCT). We compared the parameters between the TDS groups with and without RNFL defects. Twenty-one eyes had no glaucomatous RNFL defect, and 38 eyes had a glaucomatous RNFL defect. The group with RNFL defects had a higher baseline IOP, larger tilt axis of BMO-ASCO optic disc margin (76.4° ± 14.5° vs. 87.9° ± 15.4°, P = 0.012), larger BMO-lamina cribrosa insertion (LCI) angle (25.6° ± 9.3° vs. 43.6° ± 15.2°, P < 0.001), and more lamina cribrosa (LC) defects (4.3% vs. 30.6%, P = 0.028) than without RNFL defects. The tilt axis and BMO-LCI angle were significant factors after adjusting for baseline IOP and LC defect. The BMO-LCI angle had excellent diagnostic power for glaucomatous RNFL defect in TDS, similar to the visual field mean deviation. OCT-based large deep ONH BT angle and tilt axis were factors associated with the presence of RNFL defects in TDS. The results suggest a mechanism of RNFL defect associated with structural ONH deformation. Further investigations are warranted to understand the role of ONH structures in a general population with and without optic disc tilt.

Optical Coherence Tomographic Optic Nerve Head Morphology in Myopia III: The Exposed Neural Canal Region in Healthy Eyes—Implications for High Myopia

PurposeTo determine the prevalence and magnitude of OCT exposed neural canal (ENC), externally oblique choroidal border tissue (EOCBT), and exposed scleral flange (ESF) regions in 362 non-highly myopic (spherical equivalent -6.00 to 5.75 diopters) eyes of 362 healthy subjects. DesignCross-sectional study MethodsAfter OCT optic nerve head (ONH) imaging, Bruch's membrane opening (BMO), the anterior scleral canal opening (ASCO), and the scleral flange opening (SFO) were manually segmented. BMO, ASCO and SFO points were projected to BMO reference plane. The direction and magnitude of BMO/ASCO offset as well as the magnitude of ENC, EOCBT and ESF was calculated within 30° sectors relative to the Foveal-BMO axis. Hi-ESF eyes demonstrated an ESF ≥ 100 µms in at least one sector. Sectoral perineural canal choroidal thickness (pNC-CT) was measured and correlations between the magnitude of sectoral ESF and proportional pNC-CT were assessed. ResultsSeventy-three Hi-ESF (20.2%) and 289 Non-Hi-ESF eyes (79.8%) were identified. BMO/ASCO offset, as well as ENC, EOCBT and ESF prevalence and magnitude were greatest inferior temporally where pNC-CT was thinnest. Among Hi-ESF eyes, the magnitude of each ENC region correlated with BMO/ASCO offset magnitude and the sectors with the longest ESF correlated with the sectors with proportionally thinnest pNC-CT. ConclusionsONH BMO/ASCO offset, either as a cause or result of ONH neural canal remodeling, corresponds with the sectoral location of maximum ESF and minimum pNC-CT in non-highly myopic eyes. Longitudinal studies to characterize the development and clinical implications of ENC Hi-ESF regions in non-highly myopic and highly myopic eyes are indicated.

Study of Clinical Evaluation of Glaucoma with Anterior Segment OCT (Optical Coherence Tomography) and Optic Nerve Head OCT (Optical Coherence Tomography)

Study of Clinical Evaluation of Glaucoma with Anterior Segment OCT (Optical Coherence Tomography) and Optic Nerve Head OCT (Optical Coherence Tomography)

Multimodal Deep Learning Classifier for Primary Open-angle Glaucoma Diagnosis Using Wide-field Optic Nerve Head Cube Scans in Eyes With and Without High Myopia.

An OCT-based multimodal deep learning classification model including texture information is introduced that outperforms single-modal models and multimodal models without texture information for glaucoma diagnosis in eyes with and without high myopia. To evaluate the diagnostic accuracy of a multimodal deep learning (DL) classifier using wide optical coherence tomography (OCT) optic nerve head cube scans in eyes with and without axial high myopia. 371 primary open-angle glaucoma (POAG) eyes and 86 healthy eyes, all without axial high myopia (axial length AL≤26mm) and 92 POAG eyes and 44 healthy eyes, all with axial high myopia (AL>26mm) were included. The multimodal DL classifier combined features of 3 individual VGG-16 models: 1) texture-based en face image, 2) retinal nerve fiber layer (RNFL) thickness map image and 3) confocal scanning laser ophthalmoscope (cSLO) image. Age, AL, and disc area adjusted area under the receiver operating curves (AUROC) were used to compare model accuracy. Adjusted AUROC for the multimodal DL model was 0.91 (95% CI = 0.87, 0.95). This value was significantly higher than the values of individual models (0.83 [0.79, 0.86] for texture based en face image; 0.84 [0.81, 0.87] for RNFL thickness map; and 0.68 [0.61, 0.74] for cSLO image; all P≤0.05). Using only highly myopic eyes, the multimodal DL model showed significantly higher diagnostic accuracy (0.89 [0.86 , 0.92]) compared to texture en face image (0.83 [0.78 , 0.85]), RNFL (0.85 [0.81 , 0.86]) and cSLO image models (0.69 [0.63 , 0.76]) (all P≤0.05). Combining OCT-based RNFL thickness maps with texture based en face images showed better ability to discriminate between healthy and POAG than thickness maps alone, particularly in high axial myopic eyes.

OCT Optic Nerve Head Morphology in Myopia II: Peri-Neural Canal Scleral Bowing and Choroidal Thickness in High Myopia—An American Ophthalmological Society Thesis

To use optical coherence tomography (OCT) to characterize optic nerve head (ONH) peri-neural canal (pNC) scleral bowing (pNC-SB) and pNC choroidal thickness (pNC-CT) in 69 highly myopic and 138 healthy, age-matched, control eyes. Cross-sectional, case control study. Within ONH radial B-scans, Bruch membrane (BM), BM opening (BMO), anterior scleral canal opening (ASCO), and pNC scleral surface were segmented. BMO and ASCO planes and centroids were determined. pNC-SB was characterized within 30° foveal-BMO (FoBMO) sectors by 2 parameters: pNC-SB-scleral slope (pNC-SB-SS), measured within 3 pNC segments (0-300, 300-700, and 700-1000 μm from the ASCO centroid); and pNC-SB-ASCO depth relative to a pNC scleral reference plane (pNC-SB-ASCOD). pNC-CT was calculated as the minimum distance between the scleral surface and BM at 3 pNC locations (300, 700, and 1100 μm from the ASCO). pNC-SB increased and pNC-CT decreased with axial length (P < .0133; P < .0001) and age (P < .0211; P < .0004) among all study eyes. pNC-SB was increased (P < .001) and pNC-CT was decreased (P < .0279) in the highly myopic compared to control eyes, and these differences were greatest in the inferior quadrant sectors (P < .0002). Sectoral pNC-SB was not related to sectoral pNC-CT in control eyes, but was inversely related to sectoral pNC-CT (P < .0001) in the highly myopic eyes. Our data suggest that pNC-SB is increased and pNC-CT is decreased in highly myopic eyes and that these phenomena are greatest in the inferior sectors. They support the hypothesis that sectors of maximum pNC-SB may predict sectors of greatest susceptibility to aging and glaucoma in future longitudinal studies of highly myopic eyes. NOTE: Publication of this article is sponsored by the American Ophthalmological Society.

Effect of peripheral laser photocoagulation retinopexy on macular morphology and optic nerve fiber layer thickness; a prospective case series

PurposeThe goal of the research was to determine the incidence of microstructural alterations in the macula and optic nerve head (ONH) occurred in eyes treated with peripheral laser photocoagulation retinopexy.MethodsPatients with retinal breaks, retinal holes, retinal dialysis, and lattice degenerations who required peripheral laser photocoagulation retinopexy were recruited in this prospective case series investigation. We performed preoperative and postoperative evaluations, including best corrected visual acuity (BCVA), slit lamp examination, intraocular pressure (IOP) measurement, funduscopic examination, and macular and ONH optical coherence tomography (OCT).ResultsThirty-three eyes of the twenty-three patients enrolled in this study, 14 of which were female. The mean age of the sample was 45.12 ± 9.12 years. The mean refractive error was − 2.45 ± 1.12 Diopters (D). The most prevalent reason for peripheral laser photocoagulation retinopexy was retinal thinning with symptomatic lattice degeneration (90%), followed by retinal hole and break (7%) and retinal dialysis (3%). Between preoperative and postoperative (6-month) evaluation, there was no statistically significant difference in BCVA (P = 0.82), IOP (P = 0.54), central foveal thickness in macular OCT (P = 0.39), or global retinal nerve fiber layer (RNFL) thickness (P = 0.51). There was no association between changes in central foveal thickness and global RNFL thickness and total laser spot numbers (r = − 0.17 P = 0.21, r = 0.06 P = 0.60, respectively). None of patients developed cystoid macular edema (CME) or macular epiretinal membrane (ERM) .ConclusionWe found that OCT parameters were not significantly affected by laser retinopexy in patients with high-risk peripheral retinal lesions, also none of our patients had developed ERM, vitromacular traction or CME at 6 months follow up periods.

Evaluation of Generative Adversarial Networks for High-Resolution Synthetic Image Generation of Circumpapillary Optical Coherence Tomography Images for Glaucoma

Deep learning (DL) networks require large data sets for training, which can be challenging to collect clinically. Generative models could be used to generate large numbers of synthetic optical coherence tomography (OCT) images to train such DL networks for glaucoma detection. To assess whether generative models can synthesize circumpapillary optic nerve head OCT images of normal and glaucomatous eyes and determine the usability of synthetic images for training DL models for glaucoma detection. Progressively growing generative adversarial network models were trained to generate circumpapillary OCT scans. Image gradeability and authenticity were evaluated on a clinical set of 100 real and 100 synthetic images by 2 clinical experts. DL networks for glaucoma detection were trained with real or synthetic images and evaluated on independent internal and external test data sets of 140 and 300 real images, respectively. Evaluations of the clinical set between the experts were compared. Glaucoma detection performance of the DL networks was assessed using area under the curve (AUC) analysis. Class activation maps provided visualizations of the regions contributing to the respective classifications. A total of 990 normal and 862 glaucomatous eyes were analyzed. Evaluations of the clinical set were similar for gradeability (expert 1: 92.0%; expert 2: 93.0%) and authenticity (expert 1: 51.8%; expert 2: 51.3%). The best-performing DL network trained on synthetic images had AUC scores of 0.97 (95% CI, 0.95-0.99) on the internal test data set and 0.90 (95% CI, 0.87-0.93) on the external test data set, compared with AUCs of 0.96 (95% CI, 0.94-0.99) on the internal test data set and 0.84 (95% CI, 0.80-0.87) on the external test data set for the network trained with real images. An increase in the AUC for the synthetic DL network was observed with the use of larger synthetic data set sizes. Class activation maps showed that the regions of the synthetic images contributing to glaucoma detection were generally similar to that of real images. DL networks trained with synthetic OCT images for glaucoma detection were comparable with networks trained with real images. These results suggest potential use of generative models in the training of DL networks and as a means of data sharing across institutions without patient information confidentiality issues.

Comparison of Optic Disc Ovality Index and Rotation Angle Measurements in Myopic Eyes Using Photography and OCT Based Techniques.

PurposeTo compare optic nerve head (ONH) ovality index and rotation angle measurements based on semi-automated delineation of the clinical ONH margin derived from photographs and automated BMO configuration derived from optical coherence tomography (OCT) images in healthy and glaucomatous eyes with high-, mild- and no axial myopia.MethodsOne hundred seventy-five healthy and glaucomatous eyes of 146 study participants enrolled in the Diagnostic Innovations in Glaucoma Study (DIGS) with optic disc photographs and Spectralis OCT ONH scans acquired on the same day were stratified by level of axial myopia (non-myopic [n = 56, axial length (AL) <24 mm], mild-myopic [n = 58, AL 24–26 mm] and high-myopic [n = 32, AL >26 mm]. The clinical disc margin of each photograph was manually annotated, and semi-automated measurements were recorded of the ovality index and rotation angle based on a best-fit ellipse generated using ImageJ software. These semi-automated photograph-based measurements were compared to ovality index and rotation angle generated from custom automated BMO-based analysis using segmented OCT ONH volumes. R2 values from linear mixed effects models were used to describe the associations between semi-automated, photograph-based and automated OCT-based measurements.ResultsAverage (95% CI) axial length was 23.3 (23.0, 23.3) mm, 24.8 (24.7, 25.0) mm and 26.8 (26.6, 27.0) mm in non-myopic, mild-myopic and high-myopic eyes, respectively (ANOVA, p ≤ 0.001 for all). The R2 association (95% CI) between semi-automated photograph-based and automated OCT-based assessment of ONH OI for all eyes was [0.26 (0.16, 0.36); p < 0.001]. This association was weakest in non-myopic eyes [0.09 (0.01, 0.26); p = 0.02], followed by mild-myopic eyes [0.13 (0.02, 0.29); p = 0.004] and strongest in high-myopic eyes [0.40 (0.19, 0.60); p < 0.001]. No significant associations were found between photography- and OCT-based assessment of rotation angle with R2 values ranging from 0.00 (0.00, 0.08) in non-myopic eyes to 0.03 (0.00, 0.21) in high-myopic eyes (all associations p ≥ 0.33).ConclusionsAgreement between photograph-based and automated OCT-based ONH morphology measurements is limited, suggesting that these methods cannot be used interchangeably for characterizing myopic changes in the ONH.

Peripapillary Nerve Fiber Layer Thickness and Optic Nerve Head Parameters in Patients Recovered from COVID-19: A Longitudinal Study.

Purpose To quantify the longitudinal changes of the optic nerve head (ONH) parameters and peripapillary retinal nerve fiber layer (pRNFL) thickness in patients recovered from coronavirus disease 2019 (COVID-19) using spectral-domain optical coherence tomography (OCT) analysis. Materials and Methods In an observational longitudinal study, in patients recovered from COVID-19, ONH OCT images were recorded at least two weeks after recovery from the systemic disease as the baseline and after one and three-month follow-up. Ganglion cell complex (GCC) analysis, ONH parameters, and pRNFL thickness changes were measured. Results A total of 36 eyes from 18 recovered COVID-19 patients including eleven (61.2%) females were studied. The average age was 35.5 ± 7.5 years. The pRNFL thickness in the nasal lower sector significantly decreased from 77 ± 18 μm in the first post-COVID-19 month to 74 ± 10 μm in the third month (P=0.8). The average, superior, and inferior pRNFL thickness remained unchanged. The average cup volume significantly decreased from 0.27 ± 0.15 mm3 at baseline to 0.19 ± 0.15 mm3 in the third post-COVID-19 visit (P=0.028). In terms of ONH morphologies including rim, disc and cup to disc area, and the vertical and horizontal ratio, the changes were not significant over the 3-month study period. Focal loss volume and global loss volume values were not changed significantly. Conclusion Localized defect in the nasal lower sector of pRNFL is observed in 3-month post-recovery from COVID-19. Larger studies with longer follow-ups are required to reveal the exact changes in ONH parameters.

THE EFFECT OF CORNEAL ASTIGMATISM ON RETINAL NERVE FIBER LAYER THICKNESS AND OPTIC NERVE HEAD MEASUREMENTS BY OPTICAL COHERENCE TOMOGRAPHY

ABSTRACT Background: Optical Coherence Tomography (OCT) is a non-invasive investigative technique that functions as a type of optical biopsy. It has been an important diagnostic tool in evaluation of optic nerve head (ONH) and macula. Evaluation of OCT ONH is essential, since the thickness of the RNFL and ONH parameters can be affected in various optic neuropathies like glaucoma, optic atrophy and optic disc edema. Objective: To evaluate the effect of corneal astigmatism on retinal nerve fiber layer (RNFL) thickness and optic nerve head (ONH) parameters measured with spectral-domain optical coherence tomography (OCT). Methods: Forty eyes of 32 patients were included in this study.Group I; 20 non/low astigmatic eyes to be compared with Group II; 20 astigmatic eyes (10 eyes have with the rule corneal astigmatism WTR and 10 eyes have against the rule corneal astigmatism ATR). The average corneal astigmatism in group I was -0.33±0.17 D (range -0.5-0 D), in group II it was -3.18±0.87 D (range -4.5- -2 D) in eyes of with the rule corneal astigmatism, and -3.13±0.84 D (range -4.5- -2.25 D) in eyes of against the rule corneal astigmatism. All forty eyes underwent full ophthalmic examination and performed OCT ONH imaging by SD-OCT Angio Vuein Ophthalmology Department, Faculty of Medicine, Al-Azhar University, Cairo, from January to November 2019. Results: No significant difference was noted in the disc area, rim area, vertical C/D ratio and cup volume (all P values > 0.05). There were no significant differences between the two groups in global average RNFL thickness, as well as superior, inferior, nasal and temporal quadrant RNFL thickness (P values > 0.05). Conclusions: corneal astigmatism had statistically insignificant effect on optic nerve head parameters and retinal nerve fiber layer thickness measured with spectral domain optical coherence tomography.

Using Enhanced Depth Imaging Optical Coherence Tomography-Derived Parameters to Discriminate between Eyes with and without Glaucoma: A Cross-Sectional Comparative Study

Introduction: New technologies have been developed in order to decrease interpersonal influence and subjectivity during the glaucoma diagnosis process. Enhanced depth imaging spectral-domain OCT (EDI OCT) has turned up as a favorable tool for deep optic nerve head (ONH) structures assessment. Objective: A prospective cross-sectional study was conducted to compare the diagnostic performance of different EDI OCT-derived parameters to discriminate between eyes with and without glaucoma. Material and Methods: The following ONH parameters were measured: lamina cribrosa (LC) thickness and area; prelaminar neural tissue (PLNT) thickness and area; average Bruch’s membrane opening – minimum rim width (BMO-MRW), superior BMO-MRW, and inferior BMO-MRW. Peripapillary retinal nerve fiber layer (pRNFL) thickness was also obtained. Results: Seventy-three participants were included. There were no significant differences between AUCs for average BMO-MRW (0.995), PLNT area (0.968), and average pRNFL thickness (0.975; p ≥ 0.089). However, AUCs for each of these 3 parameters were significantly larger than LC area AUC (0.701; p ≤ 0.001). Sensitivities at 80% specificity were: PLNT area = 92.3%, average BMO-MRW = 97.4%, and average pRNFL thickness = 94.9%. Conclusions: Comparing the diagnostic performance of different EDI OCT ONH parameters to discriminate between eyes with and without glaucoma, we found better results for neural tissue-based indexes (BMO-MRW and PLNT area) compared to laminar parameters. In this specific population, these neural tissue-based parameters (including PLNT area, which was investigated by the first time in the present study) had a diagnostic performance comparable to that of the conventional pRNFL thickness protocol.

Visualizing the Consistency of Clinical Characteristics that Distinguish Healthy Persons, Glaucoma Suspect Patients, and Manifest Glaucoma Patients

To use factor analysis to visualize and assess the reproducibility and consistency of clinical quantitative parameters that can optimally distinguish among healthy, glaucoma suspect, and manifest glaucoma patients at a cross-sectional level and thus to describe the transition of quantitative change among the diagnostic categories. Retrospective cross-sectional study. The medical records of healthy, glaucoma suspect, and manifest glaucoma patients (diagnosed by expert clinicians) seen at the Centre for Eye Health in 2015 (n= 148, n= 664, and n= 129, respectively) and 2018 (n= 242, n= 464, and n= 126, respectively) were reviewed. One eye was selected for the study. Quantitative clinical measures (intraocular pressure [IOP], central corneal thickness [CCT], visual field [VF], and OCT) were extracted and binary logistic (backward stepwise) regression was performed to identify factors that dictated separation between diagnostic pairs. These were used systematically as inputs for factor analysis to determine a final model that could potentially predict a clinical diagnosis. Intraocular pressure, CCT, VF (mean deviation and pattern standard deviation) indices, and OCT optic nerve head parameters and thickness values (retinal nerve fiber layer [RNFL] and ganglion cell-inner plexiform layer). Few clinical parameters were identified commonly as significant across all diagnostic pairings for 2015 (3 of 23: IOP, pattern standard deviation, and 7-o'clock RNFL thickness) and 2018 (1 of 23: vertical cup-to-disc ratio). Few parameters overlapped when comparing 2015 and 2018 results, highlighting inconsistencies in the models between years. Factor analysis showed good separation between healthy persons and glaucoma patients. Using biplots to visualize the data in 2-dimensional clusters, glaucoma suspect patients demonstrated substantial overlap with healthy and glaucoma cohorts. The contributions of each parameter to diagnostic separation changed between groups and years. Despite advances in quantitative ocular imaging and perimetry, the transition among healthy, glaucoma suspect, and manifest glaucoma patients remains confounded by a lack of consistent, reproducible combinations of quantitative clinical criteria. These results highlight the nebulousness (at patient-, instrument-, and clinician-related levels) of glaucoma diagnosis that remains contingent on individual clinical expertise and assessment.

Peripapillary Scleral Bowing Increases with Age and Is Inversely Associated with Peripapillary Choroidal Thickness in Healthy Eyes

To use optical coherence tomography (OCT) to 3-dimensionally characterize the optic nerve head (ONH) in peripapillary scleral bowing in non-highly myopic healthy eyes. Cross-sectional, multicenter study. A total of 362 non-highly myopic (+6 diopters [D] > spherical equivalent >-6D) eyes of 362 healthy subjects from 20-90 years old underwent OCT ONH radial B-scan imaging. Bruch's membrane (BM), BM opening (BMO), anterior scleral canal opening (ASCO), and the peripapillary scleral surface were segmented. BMO and ASCO planes were fit, and their centroids, major axes, ovality, areas and offsets were determined. Peripapillary scleral bowing was characterized by 2 parameters: peripapillary scleral slope (ppSS) of 3 anterior peripapillary scleral segments (0-300, 300-700, and 700-1,000μm from the ASCO centroid); and ASCO depth relative to a peripapillary scleral reference plane (ASCOD-ppScleral). Peripapillary choroidal thickness (ppCT) was calculated relative to the ASCO as the minimum distance between the anterior scleral surface and BM. Both ppSS and ASCOD-ppScleral ranged from slightly inward through profoundly outward in direction. Both parameters increased with age and were independently associated with decreased ppCT. In non-highly myopic healthy eyes, outward peripapillary scleral bowing achieved substantial levels, was markedly increased with age, and was independently associated with decreased peripapillary choroidal thickness. These findings provide a normative foundation for characterizing this anatomy in cases of high myopia and glaucoma and in eyes with optic disc tilt, torsion, and peripapillary atrophy.

Gradient-Boosting Classifiers Combining Vessel Density and Tissue Thickness Measurements for Classifying Early to Moderate Glaucoma

To compare gradient-boosting classifier (GBC) analysis of optical coherence tomography angiography (OCTA)-measured vessel density (VD) and OCT-measured tissue thickness to standard OCTA VD and OCT thickness parameters for classifying healthy eyes and eyes with early to moderate glaucoma. Comparison of diagnostic tools. A total of 180 healthy eyes and 193 glaucomatous eyes with OCTA and OCT imaging of the macula and optic nerve head (ONH) were studied. Four GBCs were evaluated that combined 1) all macula VD and thickness measurements (Macula GBC), 2) all ONH VD and thickness measurements (ONH GBC), 3) all VD measurements from the macula and ONH (vessel density GBC), and 4) all thickness measurements from the macula and ONH (thickness GBC). ROC curve (AUROC) analyses compared the diagnostic accuracy of GBCs to that of standard instrument-provided parameters. A fifth GBC that combined all parameters (full GBC) also was investigated. GBCs had better diagnostic accuracy than standard OCTA and OCT parameters with AUROCs ranging from 0.90 to 0.93 and 0.64 to 0.91, respectively. The full GBC (AUROC= 0.93) performed significantly better than the ONH GBC (AUROC= 0.91; P= .036) and the vessel density GBC (AUROC= 0.90; P= .010). All other GBCs performed similarly. The mean relative influence of each parameter included in the full GBC identified a combination of macular thickness and ONH VD measurements as the greatest contributors. GBCs that combine OCTA and OCT macula and ONH measurements can improve diagnostic accuracy for glaucoma detection compared to most but not all instrument provided parameters.