Optic disk size and glaucoma

Does Inter-Eye Asymmetry of Disc Area Explain Differences in Onset of Nonarteritic Anterior Ischemic Optic Neuropathy?

BACKGROUND

Nonarteritic anterior ischemic optic neuropathy (NAION) is the most common acute optic neuropathy in individuals over the age of 50 years. It is associated with conventional vascular risk factors and structural vulnerabilities including "disc-at-risk." We aim to ascertain if a correlation exists between optic nerve head size and the onset of NAION.

METHODS

We performed a retrospective chart review of patients with an ICD-10 diagnosis of unilateral or bilateral NAION who underwent optical coherence tomography (OCT) and visual field testing. The primary outcome measure was the disc area as measured on OCT at a follow-up (minimum 6 months after acute vision loss) of the involved (or first involved for bilateral cases) vs fellow eye. The secondary outcome was the cup-to-disc ratio (CDR) of the first vs fellow eye.

RESULTS

Seventy-three patients were included, of which 58 (79%) had unilateral and 15 (21%) had bilateral NAION, with a median follow-up of 23 months. Between the first eye involved and the fellow eye, there were no statistically significant differences in the mean disc area (1.69 ± 0.29 vs 1.71 ± 0.29, P = 0.7). However, average CDR (0.41 ± 0.20 vs 0.28 ± 0.18, P < 0.001) and vertical CDR (0.42 ± 0.20 vs 0.28 ± 0.19, P < 0.0001) were significantly larger in the involved eye.

CONCLUSIONS

Despite no statistically significant differences in the disc area between the affected eye and the fellow eye, CDR was larger in eyes with a history of NAION compared with fellow eyes. Further research is required to elucidate local factors that may increase the risk of NAION in one eye relative to the other.

Deep Learning Evaluation of Glaucoma Detection Using Fundus Photographs in Highly Myopic Populations

OBJECTIVES

This study aimed to use deep learning to identify glaucoma and normal eyes in groups with high myopia using fundus photographs.

METHODS

Patients who visited Tri-Services General Hospital from 1 November 2018 to 31 October 2022 were retrospectively reviewed. Patients with high myopia (spherical equivalent refraction of ≤-6.0 D) were included in the current analysis. Meanwhile, patients with pathological myopia were excluded. The participants were then divided into the high myopia group and high myopia glaucoma group. We used two classification models with the convolutional block attention module (CBAM), an attention mechanism module that enhances the performance of convolutional neural networks (CNNs), to investigate glaucoma cases. The learning data of this experiment were evaluated through fivefold cross-validation. The images were categorized into training, validation, and test sets in a ratio of 6:2:2. Grad-CAM visual visualization improved the interpretability of the CNN results. The performance indicators for evaluating the model include the area under the receiver operating characteristic curve (AUC), sensitivity, and specificity.

RESULTS

A total of 3088 fundus photographs were used for the deep-learning model, including 1540 and 1548 fundus photographs for the high myopia glaucoma and high myopia groups, respectively. The average refractive power of the high myopia glaucoma group and the high myopia group were -8.83 ± 2.9 D and -8.73 ± 2.6 D, respectively (p = 0.30). Based on a fivefold cross-validation assessment, the ConvNeXt_Base+CBAM architecture had the best performance, with an AUC of 0.894, accuracy of 82.16%, sensitivity of 81.04%, specificity of 83.27%, and F1 score of 81.92%.

CONCLUSIONS

Glaucoma in individuals with high myopia was identified from their fundus photographs.

Automated Classification of Physiologic, Glaucomatous, and Glaucoma-Suspected Optic Discs Using Machine Learning

In order to generate a machine learning algorithm (MLA) that can support ophthalmologists with the diagnosis of glaucoma, a carefully selected dataset that is based on clinically confirmed glaucoma patients as well as borderline cases (e.g., patients with suspected glaucoma) is required. The clinical annotation of datasets is usually performed at the expense of the data volume, which results in poorer algorithm performance. This study aimed to evaluate the application of an MLA for the automated classification of physiological optic discs (PODs), glaucomatous optic discs (GODs), and glaucoma-suspected optic discs (GSODs). Annotation of the data to the three groups was based on the diagnosis made in clinical practice by a glaucoma specialist. Color fundus photographs and 14 types of metadata (including visual field testing, retinal nerve fiber layer thickness, and cup-disc ratio) of 1168 eyes from 584 patients (POD = 321, GOD = 336, GSOD = 310) were used for the study. Machine learning (ML) was performed in the first step with the color fundus photographs only and in the second step with the images and metadata. Sensitivity, specificity, and accuracy of the classification of GSOD vs. GOD and POD vs. GOD were evaluated. Classification of GOD vs. GSOD and GOD vs. POD performed in the first step had AUCs of 0.84 and 0.88, respectively. By combining the images and metadata, the AUCs increased to 0.92 and 0.99, respectively. By combining images and metadata, excellent performance of the MLA can be achieved despite having only a small amount of data, thus supporting ophthalmologists with glaucoma diagnosis.

Current Status and Future Perspectives of Optic Nerve Imaging in Glaucoma

Being the primary site of degeneration, the optic nerve has always been the focus of structural glaucoma assessment. The technical advancements, mainly of optical coherence tomography (OCT), now allow for a very precise quantification of the optic nerve head and peripapillary retina morphology. By far the most commonly used structural optic nerve parameter is the thickness of the parapapillary retinal nerve fiber, which has great clinical utility but also suffers from significant limitations, mainly in advanced glaucoma. Emerging novel imaging technologies, such as OCT angiography, polarization-sensitive or visible-light OCT and adaptive optics, offer new biomarkers that have the potential to significantly improve structural glaucoma diagnostics. Another great potential lies in the processing of the data already available. Artificial intelligence does not only help increase the reliability of current biomarkers but can also integrate data from various imaging modalities and other clinical measures to increase diagnostic accuracy. And it can, in a more efficient way, draw information from available datasets, such as an OCT scan, compared to the current concept of biomarkers, which only use a fraction of the whole dataset.

Predictors of Glaucomatous Progression in Individuals with Small and Large Optic Discs

PURPOSE

To identify factors associated with glaucomatous progression in individuals with small and large optic discs.

DESIGN

Retrospective review.

SUBJECTS

4505 individuals with glaucoma at UCLA; 233 (59.7%) with small discs, 157 (40.3%) with large discs.

METHODS

Small and large disc sizes were defined by OCT or Heidelberg Retinal Tomography as disc area ≤ 5% (≤ 1.3 mm2) and ≥ 95% (≥ 2.9 mm2), respectively. Medical records were reviewed for demographics, systemic comorbidities, glaucoma type, ocular comorbidities, and ocular surgery. Logistic regression was used to identify predictors of visual field (VF) progression in individuals with small and large discs and predictors of large versus small discs.

MAIN OUTCOME MEASURES

The VF deterioration with mean deviation, pointwise linear regression, and glaucoma rate index (GRI); large vs. small disc.

RESULTS

In individuals with small discs, Asian versus non-Hispanic White ethnicity was associated with increased progression (adjusted odds ratio [aOR] = 4.05; 95% confidence interval [CI] = 1.12-14.59 for GRI). Higher intraocular pressure (IOP) range and peak were associated with increased progression in individuals with both small discs (aOR = 1.12; 95% CI = 1.00-1.27 and aOR = 1.05; 95% CI = 1.00-1.10 per 1 mmHg for range and peak with GRI) and large discs (aOR = 1.35; 95% CI = 1.12-1.66 and aOR = 1.11; 95% CI = 1.03-1.20 per 1 mmHg for range and peak with GRI). Multivariable predictors of having large vs. small discs included vasospastic phenotype (aOR = 2.58; 95% CI = 1.35-5.19) and Black (aOR = 20.46; 95% CI = 8.33-61.84), Hispanic/Latino (aOR = 9.65; 95% CI = 4.14-25.39), Asian (aOR = 4.87; 95% CI = 2.96-8.1), and other (aOR = 2.79; 95% CI = 1.69-4.63) versus non-Hispanic White ethnicity.

CONCLUSIONS

Increased odds of glaucomatous progression were associated with Asian vs. non-Hispanic White ethnicity in glaucoma patients with small optic discs, as well as with increased IOP range and peak in those with small and large discs. Individuals with a vasospastic phenotype and those from racial and ethnic minority backgrounds had increased odds of having large vs. small optic discs. Further characterization of discernible phenotypes would improve disease prognostication and help individualize glaucoma treatment.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Correction Method for Optical Scaling of Fundoscopy Images: Development, Validation, and First Implementation

Purpose

Although fundus photography is extensively used in ophthalmology, refraction prevents accurate distance measurement on fundus images, as the resulting scaling differs between subjects due to varying ocular anatomy. We propose a PARaxial Optical fundus Scaling (PAROS) method to correct for this variation using commonly available clinical data.

Methods

The complete optics of the eye and fundus camera were modeled using ray transfer matrix formalism to obtain fundus image magnification. The subject's ocular geometry was personalized using biometry, spherical equivalent of refraction (RSE), keratometry, and/or corneal topography data. The PAROS method was validated using 41 different eye phantoms and subsequently evaluated in 44 healthy phakic subjects (of whom 11 had phakic intraocular lenses [pIOLs]), 29 pseudophakic subjects, and 21 patients with uveal melanoma.

Results

Validation of the PAROS method showed small differences between model and actual image magnification (maximum 3.3%). Relative to the average eye, large differences in fundus magnification were observed, ranging from 0.79 to 1.48. Magnification was strongly inversely related to RSE (R2 = 0.67). In phakic subjects, magnification was directly proportional to axial length (R2 = 0.34). The inverse relation was seen in pIOL (R2 = 0.79) and pseudophakic (R2 = 0.12) subjects. RSE was a strong contributor to magnification differences (1%-83%). As this effect is not considered in the commonly used Bennett-Littmann method, statistically significant differences up to 40% (mean absolute 9%) were observed compared to the PAROS method (P < 0.001).

Conclusions

The significant differences in fundus image scaling observed among subjects can be accurately accounted for with the PAROS method, enabling more accurate quantitative assessment of fundus photography.

The Use of ChatGPT to Assist in Diagnosing Glaucoma Based on Clinical Case Reports

INTRODUCTION

The purpose of this study was to evaluate the capabilities of large language models such as Chat Generative Pretrained Transformer (ChatGPT) to diagnose glaucoma based on specific clinical case descriptions with comparison to the performance of senior ophthalmology resident trainees.

METHODS

We selected 11 cases with primary and secondary glaucoma from a publicly accessible online database of case reports. A total of four cases had primary glaucoma including open-angle, juvenile, normal-tension, and angle-closure glaucoma, while seven cases had secondary glaucoma including pseudo-exfoliation, pigment dispersion glaucoma, glaucomatocyclitic crisis, aphakic, neovascular, aqueous misdirection, and inflammatory glaucoma. We input the text of each case detail into ChatGPT and asked for provisional and differential diagnoses. We then presented the details of 11 cases to three senior ophthalmology residents and recorded their provisional and differential diagnoses. We finally evaluated the responses based on the correct diagnoses and evaluated agreements.

RESULTS

The provisional diagnosis based on ChatGPT was correct in eight out of 11 (72.7%) cases and three ophthalmology residents were correct in six (54.5%), eight (72.7%), and eight (72.7%) cases, respectively. The agreement between ChatGPT and the first, second, and third ophthalmology residents were 9, 7, and 7, respectively.

CONCLUSIONS

The accuracy of ChatGPT in diagnosing patients with primary and secondary glaucoma, using specific case examples, was similar or better than senior ophthalmology residents. With further development, ChatGPT may have the potential to be used in clinical care settings, such as primary care offices, for triaging and in eye care clinical practices to provide objective and quick diagnoses of patients with glaucoma.

Peripapillary Vitreous Traction Syndrome: Expanding the Spectrum of Anterior Optic Neuropathies

BACKGROUND

Peripapillary vitreous traction (PVT) occurring without any underlying eye disease has been contemplated as a distinct entity from nonarteritic ischemic optic neuropathy (NAION) for many years and is sometimes difficult to differentiate from classical NAION. We report 6 new cases to analyze the clinical features of PVT syndrome that would expand the clinical spectrum of anterior optic neuropathies.

METHODS

Prospective case series.

RESULTS

PVT syndrome seems to affect optic discs with a small area with a small cup-to-disc (C/D) ratio. The C/D ratio does not significantly increase in the chronic stage, as in NAION. Vitreous traction without detachment can either lead to mild retinal nerve fiber layer (RNFL) injury with attendant ganglion cell layer/inner plexiform layer (GCL/IPL) thinning in 29% or no injury at all in 71%. Eighty-six percent had good visual acuity (VA) and had no relative afferent pupillary defect (RAPD), whereas 14% had a transient RAPD; 71% had no color defect. Vitreous detachment after a period of severe and persistent traction can lead to more damage to the optic nerve head and RNFL that may look like NAION. Our hypothesized mechanically induced injury to the superficial optic nerve head may not lead to much visual impairment. In our study, no further therapeutic interventions were required.

CONCLUSIONS

Based on our analysis of previously published cases and our own prospective case series of 6 patients, the PVT syndrome falls within the spectrum of anterior optic neuropathies, often affecting small optic discs with a small C/D ratio. Vitreous traction can lead to a partial or complete anterior optic neuropathy. The PVT syndrome may be a "more" anterior optic neuropathy distinct from classical NAION.

Discrimination of glaucomatous from non-glaucomatous optic neuropathy with swept-source optical coherence tomography

OBJECTIVE

To assess the ability of optic nerve head (ONH) parameters, peripapillary retinal nerve fiber layer (pRNFL), and macular ganglion cell layer (GCL) thickness measurements with swept-source optical coherence tomography (SS-OCT), to discriminate between glaucomatous and non-glaucomatous optic neuropathy (GON and NGON).

METHODS

This retrospective cross-sectional study involved 189 eyes of 189 patients, 133 with GON and 56 with NGON. The NGON group included ischemic optic neuropathy, previous optic neuritis, and compressive, toxic-nutritional, and traumatic optic neuropathy. Bivariate analyses of SS-OCT pRNFL and GCL thickness and ONH parameters were performed. Multivariable logistic regression analysis was employed to obtain predictor variables from OCT values, and the area under the receiver operating characteristic curve (AUROC) was calculated to differentiate between NGON and GON.

RESULTS

Bivariate analyses showed that the overall and inferior quadrant of the pNRFL was thinner in the GON group (P=0.044 and P<0.01), while patients with NGON had thinner temporal quadrants (P=0.044). Significant differences between the GON and NGON groups were identified in almost all the ONH topographic parameters. Patients with NGON had thinner superior GCL (P=0.015), but there were no significant differences in GCL overall and inferior thickness. Multivariate logistic regression analysis demonstrated that vertical cup-to-disc ratio (CDR), cup volume, and superior GCL provided independent predictive value for differentiating GON from NGON. The predictive model of these variables along with disc area and age achieved an AUROC=0.944 (95% CI 0.898-0.991).

CONCLUSIONS

SS-OCT is useful in discriminating GON from NGON. Vertical CDR, cup volume, and superior GCL thickness show the highest predictive value.

Optical Coherence Tomography Angiography for the Differentiation of Glaucoma from Pituitary Macroadenoma Related Optic Disc Measurements

OBJECTIVE

To determine the potential of optical coherence tomography (OCT) and OCT angiography (OCTA) to distinguish between glaucoma and pituitary macroadenoma by optic disc appearance.

METHODS

This prospective case-control study comprised 31 patients: 23 with glaucoma (18 male, 5 female) and 8 with pituitary macroadenoma and chiasmatic compression (3 male, 5 female). The corresponding mean ages were 72.8 years (range 58-90) and 60.7 years (range 43-73). All participants underwent complete ophthalmological examination, spectral domain OCT and OCTA, and visual field testing. Clinical, imaging, and visual field results were compared between the groups.

RESULTS

On OCT analysis, the glaucoma group had relatively lower peripapillary retinal nerve fiber layer (RNFL) thickness (65.79 ± 15.46, 86.0 ± 11.37, respectively, P = .002) and lower rim area (1.00 ± 0.22 mm2 and 1.2 ± 0.15 mm2, respectively, P = .005). On OCTA, peripapillary vessel density was significantly lower in all quadrants in the glaucoma group. The significance of these between-group differences was maintained when patients were stratified by visual field mean deviation.

CONCLUSIONS

This is the first comparative analysis of optic disc morphology between glaucoma and pituitary macroadenoma using combined OCT and OCTA. The results yielded lower peripapillary RNFL thickness, lower rim area, and lower peripapillary vessel density in the glaucoma group. These parameters may aid in the initial differentiation between these two optic neuropathies.

Analysis of volumetric 3D reconstruction of lamina cribrosa images from swept-source optical coherence tomography in glaucomatous and healthy subjects

This study demonstrates the 3D visualization of the lamina cribrosa (LC) structure and its correlation with volumetric data, pore volume, and disc area in glaucomatous and non-glaucomatous eyes. The participant cohort included 65 glaucomatous and 58 non-glaucomatous eyes (13 suspected glaucoma and 45 normal). An ophthalmologist diagnosed glaucoma patients and all subjects were over 18 years old, passed a visual field test, and underwent optical coherence tomography (OCT) examinations. LC images were obtained using the DRI OCT Triton, while optic disc images were obtained from the enface image of the Cirrus HD-OCT 5000. Since LC images alone did not provide clear edge information, we used optic disc images as a reference for edge detection. To achieve this, we employed a fine-tuned model, specifically a pre-trained U-shaped Encoder-Decoder Network with Attention. This model was used to obtain a segmented mask, which was then aligned and utilized to locate the edge of the LC in the LC images. A blood vessel mask was created to remove blood vessels, as they can interfere with the accurate visualization and analysis of LC characteristics. This step allowed for the 3D reconstruction of the LC structure without the presence of blood vessels. Correlations between LC volume, pore volume, and pore volume to LC volume were calculated separately for glaucomatous and non-glaucomatous eyes. We divided the areas for considering the LC structure into three types: overall, quadrants, and 12-clock-hour sectors. Based on the experimental results, we found that the pore volume and pore-to-LC volume were different between glaucoma and normal across all areas considered. In conclusion, this research generated 3D images of the LC from OCT images using computer techniques, showcasing a microstructure that closely resembles the actual LC. Statistical methods were employed to calculate and analyze the differences observed between the two groups of samples.

Artificial intelligence in ophthalmology

One of the fields of medicine in which artificial intelligence techniques have made progress is ophthalmology. Artificial intelligence (A.I.) applications for preventing vision loss in eye illnesses have developed quickly. Artificial intelligence uses computer programs to execute various activities while mimicking human thought. Machine learning techniques are frequently utilized in the field of ophthalmology. Ophthalmology holds great promise for advancing artificial intelligence, thanks to various digital methods like optical coherence tomography (OCT) and visual field testing. Artificial intelligence has been used in ophthalmology to treat eye conditions impairing vision, including macular holes (M.H.), age-related macular degeneration (AMD), diabetic retinopathy, glaucoma, and cataracts. The more common occurrence of these diseases has led to artificial intelligence development. It is important to get annual screenings to detect eye diseases such as glaucoma, diabetic retinopathy, and age-related macular degeneration. These conditions can cause decreased visual acuity, and it is necessary to identify any changes or progression in the disease to receive appropriate treatment. Numerous studies have been conducted based on artificial intelligence using different algorithms to improve and simplify current medical practice and for early detection of eye diseases to prevent vision loss. Abbreviations: AI = artificial intelligence, AMD = age-related macular degeneration, ANN = artificial neural networks, AAO = American Academy of Ophthalmology, CNN = convolutional neural network, DL = deep learning, DVP = deep vascular plexus, FDA = Food and Drug Administration, GCL = ganglion cell layer, IDP = Iowa Detection Program, ML = Machine learning techniques, MH = macular holes, MTANN = massive training of the artificial neural network, NLP = natural language processing methods, OCT = optical coherence tomography, RBS = Radial Basis Function, RNFL = nerve fiber layer, ROP = Retinopathy of Prematurity, SAP = standard automated perimetry, SVP = Superficial vascular plexus, U.S. = United States, VEGF = vascular endothelial growth factor.

Deep learning classification of early normal-tension glaucoma and glaucoma suspect eyes using Bruch's membrane opening-based disc photography

Purpose

We aimed to investigate the performance of a deep learning model to discriminate early normal-tension glaucoma (NTG) from glaucoma suspect (GS) eyes using Bruch's membrane opening (BMO)-based optic disc photography.

Methods

501 subjects in total were included in this cross-sectional study, including 255 GS eyes and 246 eyes of early NTG patients. BMO-based optic disc photography (BMO overview) was obtained from spectral-domain optical coherence tomography (OCT). The convolutional neural networks (CNN) model built from scratch was used to classify between early NTG and GS. For diagnostic performances of the model, the accuracy and the area under the curve (AUC) of the receiver operating characteristic curve (ROC) were evaluated in the test set.

Results

The baseline demographics were age, 48.01 ± 13.03 years in GS, 54.48 ± 11.28 years in NTG (p = 0.000); mean deviation, -0.73 ± 2.10 dB in GS, -2.80 ± 2.40 dB in NTG (p = 0.000); and intraocular pressure, 14.92 ± 2.62 mmHg in GS, 14.79 ± 2.61 mmHg in NTG (p = 0.624). Our CNN model showed the mean AUC of 0.94 (0.83-1.00) and the mean accuracy of 0.91 (0.82-0.98) with 10-fold cross validation for discriminating between early NTG and GS.

Conclusion

The performance of the CNN model using BMO-based optic disc photography was considerably good in classifying early NTG from GS. This new disc photography of BMO overview can aid in the diagnosis of early glaucoma.

Optic disc drusen in patients diagnosed with normal tension glaucoma

PURPOSE

To investigate the prevalence of optic disc drusen (ODD) and optic nerve head (ONH) morphology in patients diagnosed with normal tension glaucoma (NTG).

METHODS

In this prospective cross-sectional study, we included patients diagnosed with NTG from two glaucoma units. In both eyes, dense enhanced depth imaging optical coherence tomography volume scans of the ONH by means of standardized scanning guidelines were performed to examine for presence of ODD, and radial ONH scans were used for investigating parameters such as scleral canal diameter, cup/disc ratio and cup depth.

RESULTS

We found ODD in 7 (3.6%) of 195 eyes, in 6 (6.1%) out of 98 patients diagnosed with NTG. The ODD were not ophthalmoscopically visible in five out of six patients. Eyes with ODD had lower cup/disc ratio, 0.44 ± 0.4 (p = 0.040), and less-prominent cup depth, 236.6 ± 204.4 μm (p = 0.041) compared to eyes without ODD, 0.81 ± 0.2 and 437.8 ± 139.1 μm, respectively. We found no significant difference in scleral canal diameter between the eyes without (1602.8 ± 193 μm) and those with ODD (1492 ± 123.4 μm, p = 0.057).

CONCLUSION

The prevalence of ODD in patients diagnosed with NTG is substantially higher than in the background population. A low cup/disc ratio correlates with ODD presence. Therefore, due to the challenges associated with NTG diagnosis, we recommend examining the deep layers of the ONH in NTG patients with a cup/disc ratio lower than 0.5 to avoid misdiagnosing ODD as NTG.

Practical Application of Artificial Intelligence Technology in Glaucoma Diagnosis

Purpose. By comparing the performance of different models between artificial intelligence (AI) and doctors, we aim to evaluate and identify the optimal model for future usage of AI. Methods. A total of 500 fundus images of glaucoma and 500 fundus images of normal eyes were collected and randomly divided into five groups, with each group corresponding to one round. The AI system provided diagnostic suggestions for each image. Four doctors provided diagnoses without the assistance of the AI in the first round and with the assistance of the AI in the second and third rounds. In the fourth round, doctor B and doctor D made diagnoses with the help of the AI and the other two doctors without the help of the AI. In the last round, doctor A and doctor B made diagnoses with the help of AI and the other two doctors without the help of the AI. Results. Doctor A, doctor B, and doctor D had a higher accuracy in the diagnosis of glaucoma with the assistance of AI in the second ( $p=0.036$ , $p=0.003$ , and $p\le 0.000$ ) and the third round ( $p=0.021$ , $p\le 0.000$ , and $p\le 0.000$ ) than in the first round. The accuracy of at least one doctor was higher than that of AI in the second and third rounds, in spite of no detectable significance ( $p=0.283$ , $p=0.727$ , $p=0.344$ , and $p=0.508$ ). The four doctors’ overall accuracy ( $p=0.004$ and $p\le 0.000$ ) and sensitivity ( $p=0.006$ and $p\le 0.000$ ) as a whole were significantly improved in the second and third rounds. Conclusions. This “Doctor + AI” model can clarify the role of doctors and AI in medical responsibility and ensure the safety of patients, and importantly, this model shows great potential and application prospects.

Case series: Megalopapillae in twins - Congenital or hereditary?

To the best of the author’s knowledge, bilateral megalopapilla are entities with an unknown inheritance pattern, and this is the first case presentation of bilateral megalopapilla in twin siblings. One of the twins presented to the outpatient department with a frontal headache, while the other was asymptomatic. Upon examination of the first family members, the asymptomatic paternal grandfather had a similar presentation of megalopapilla. As a result, this report will help in determining the genetic pattern of development of this optic disc anomaly, as well as its crucial differential diagnosis.

Optic disc area frequency distribution in a large sample of retinographic images

Objective

To describe a new method to estimate the frequency distribution of optic nerve disc area, using digital retinographic images.

Methods and analysis

We analysed 492 023 fundus images obtained with seven fundus cameras, mainly in Caucasian subjects. They were grouped by resolution and zoom. They were automatically segmented by identifying the inner edge of the Elschnig scleral ring. For this purpose, a neural network trained by deep learning previously described was used. The number of pixels contained within the segmentation and their frequency distribution were calculated. The results of each camera, using different number of images, were compared with the global results using the Kolmogorov-Smirnov test to confront frequency distributions.

Results

The frequency distribution was non-Gaussian, more limited in small sizes than in large ones. If the median is assigned a theoretical value of 1.95 mm2, the 1th, 5th, 25th, 50th, 75th, 95th and 99th percentiles would correspond to 1.29, 1.46, 1.73, 1.95, 2.20, 2.64 and 3.03 mm2 in all the dataset. The overall differences were significant for the smaller series, but for each percentile their mean value was only 0.01 mm2 and the maximum 0.10 mm2, so they can be considered similar for practical purposes in all cameras.

Conclusion

By automatically segmenting the edges of the optic nerve and observing the frequency distribution of the number of pixels it delimits, it is possible to estimate the frequency distribution of the disc area in the population as a whole and that of each individual case.

Optic disc morphology and peripapillary atrophic changes in diabetic children and adults without diabetic retinopathy or visual impairment

PURPOSE

To investigate the changes in optic disc morphology and peripapillary atrophy (PPA) in diabetic children and adults without diabetic retinopathy (DR) or visual impairment (VI).

METHODS

This cross-sectional study included two groups of subjects. One group included 91 children with type 1 diabetes mellitus (T1DM) and 86 healthy children, and the other group included 444 adults with T2DM and 442 healthy controls. The optic disc parameters including major and minor axis lengths, optic disc ovality (ODO), optic disc tilt, optic disc area and β-PPA area were analysed in all subjects. Optic disc rotation and the Bergmeister papilla were analysed only in children. Patients with diabetes and healthy controls were compared in each group of the study population.

RESULTS

In both groups, patients with diabetes and healthy controls were matched for age, sex and axial length (AL). Among the children, β-PPA area was significantly smaller in those with diabetes (0.29 ± 0.43 mm² ) than in the healthy controls (0.46 ± 0.58 mm² , p < 0.05). Multiple linear regression analysis showed that diagnosis of DM was negatively associated with β-PPA area. Longer AL and higher body mass index (BMI) were positively associated with β-PPA area. Among adults, ODO was significantly larger in those with diabetes (1.14 ± 0.09) than in healthy controls (1.12 ± 0.06, p < 0.05). Multiple linear regression analysis showed that the BMI and DM were potential risk factors affecting ODO.

CONCLUSION

Hyperglycaemia had different effects on the optic disc in children and adults. Unlike in healthy controls, hyperglycaemia had an impact on the peripapillary tissue in children and on optic disc shape in adults before DR and VI development.

Evaluation of the Cirrus High-Definition OCT Normative Database Probability Codes in a Black American Population

PURPOSE

Race-adjusted interpretation of data from Cirrus high-definition OCT (HD-OCT) devices is not standard practice. The aim of this study is to evaluate differences in peripapillary retinal nerve fiber layer (RNFL) thickness between healthy Black Americans and the Cirrus HD-OCT normative database.

DESIGN

This is a cross-sectional observational study using control patients recruited from the greater Philadelphia, Pennsylvania, area.

PARTICIPANTS

A total of 466 eyes were included in this study. Subjects were retrospectively identified from the control cohort of the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study.

METHODS

Using an age-stratified or linear regression method, we reclassified white-green-yellow-red color probability codes for RNFL thicknesses by quadrant.

MAIN OUTCOME MEASURES

The distribution of reclassified color codes was compared with the expected 5%-90%-4%-1% percentiles and to the original color codes by the Cirrus machine.

RESULTS

Average RNFL thickness in the POAAGG control cohort was thinner than in the Cirrus normative database in all except the nasal quadrant. The original color codes of the POAAGG cohort did not fall into the expected distributions, with more RNFL measurements assigned as white and red codes than expected (9.5% and 1.7%) and fewer measurements assigned as green and yellow codes than expected (85.3% and 3.5%) (P < 0.001). Compared with the original Cirrus machine, reclassification using linear regression produced color codes closest to the expected distributions (P = 0.09). The proportion of abnormal results shifted closer to the expected 5% in the nasal (1.3%, P < 0.001 vs. 3.0%, P = 0.048) and temporal (8.2%, P = 0.002 vs. 3.6%, P = 0.18) quadrants.

CONCLUSIONS

Results further establish the presence of structural differences in the RNFL of Black American patients. Color code reclassification suggests that the existing Cirrus database may not be accurately evaluating glaucomatous nerves in patients of African descent. This study addresses an unmet need to assess Cirrus HD-OCT color probability codes in a Black American population.

PERG adaptation for detection of retinal ganglion cell dysfunction in glaucoma: a pilot diagnostic accuracy study

It has been previously demonstrated that the adaptive phase changes of steady-state pattern electroretinogram (SS-PERG), recorded during 4-min presentation of patterned stimuli, are reduced in glaucoma suspects and patients compared to normal subjects. Our study aims at testing the hypothesis that adaptive changes of SS-PERG, recorded using the novel optimized Next Generation PERG (PERGx) protocol, differ between glaucoma patients and controls. In this pilot cross-sectional study, we included 28 glaucoma patients and 17 age-matched normal subjects. Both patients and controls underwent a full ophthalmologic examination, visual field testing, OCT and PERGx. The PERGx signal was sampled over 2 min (providing 1 noise and 9 signal packets) in response to alternating gratings generated on an OLED display. PERGx amplitude and phase were analyzed to quantify adaptive changes over recording time. Receiver operating characteristic (ROC) curves were used to study the diagnostic accuracy of PERGx parameters in distinguishing glaucoma patients from normal subjects. PERGx amplitude and phase data showed declining trends in both groups. PERGx amplitude slope and grand-average vector amplitude and phase were significantly different in patients compared to controls (p < 0.01), whereas phase angular dispersion was greater in patients but not significantly different between the two groups. The area under the ROC curves were 0.87 and 0.76 for PERGx amplitude slope and grand-average vector amplitude, and 0.62 and 0.87 for PERGx angular dispersion and grand-average vector phase, respectively. The PERGx paradigm resulted highly accurate in detecting the reduction of amplitude adaptive changes in glaucoma patients, presumably due to the loss of functional retinal ganglion cell autoregulation. Thus, PERG adaptation, recorded by this new protocol, might be helpful in the identification and diagnosis of early glaucomatous dysfunction.

Spotlight on the Disc-Damage Likelihood Scale (DDLS)

The disc damage likelihood scale (DDLS) is a tool for classifying glaucomatous structural changes to the optic disc based on the radial width of the neuroretinal rim at its thinnest location, or if no rim is present, the extent of absence of the rim. Unlike cup disc ratio (CDR), the DDLS also considers disc size. Twenty years after its first description, the aim of this review was to critically appraise evidence for the DDLS and evaluate its role in current practice. A literature search by two independent authors identified 33 relevant articles for inclusion. Five studies evaluated reproducibility, 5 diagnostic performance, and 2 studies examined ability to detect progression. Eleven studies evaluated correlation between DDLS and other markers of glaucoma. Despite the widespread availability of imaging devices such as optical coherence tomography (OCT), clinical examination of the optic disc remains an essential component of glaucoma diagnosis and monitoring. The DDLS provides a reliable method for semi-quantitative clinical grading of the optic disc in glaucoma, with higher reproducibility than methods such as CDR.

Glaucoma Diagnostic Testing: The Influence of Optic Disc Size

BACKGROUND

There are various imaging techniques for the assessment of the optic disc in glaucoma patients. However, anatomically conspicuous, large or small optic discs can be quite challenging for an examiner.

OBJECTIVE

The Bruch's membrane opening (BMO) by spectral domain optical coherence tomography (SD-OCT) is a modern approach for the quantitative measures of retinal nerve fibre layer (RNFL). The study focuses on comparison analysis of the BMO method and the widely used Heidelberg retina tomograph (HRT) method - in terms of detection of glaucoma for different optic disc sizes.

METHODS

216 Patients examinations during glaucoma consultation hours. Macro- (Ma) and micro-optic discs (Mi) detected by HRT are analysed via BMO analysis in SD-OCT. Correlation between BMO area and optic disc measured by HRT has been investigated and examined in terms of severity of visual field defect (MD [dB]).

RESULTS

The results of study show that for micro and macro-optic discs there is a modest correlation between the size of optic disc measured by BMO and the size of optic disc measured by HRT by applying funduscopic examination (correlation rate r = 0,53; Mi: n = 111, Ma: n = 105). For micro-optic discs with a very small BMO area (< 1.5 mm²), there is a significant tendency (linear trend test p < 0.05) towards deeper visual field defects (MD < - 5 dB).

CONCLUSION

The BMO parameter of SD-OCT allows an assessment of glaucoma for a large range of optic disc sizes. BMO area and optic disc size measured by HRT are not correlated. Micro optic discs with a small BMO area lead to a higher risk of deep visual field defects.

Change of ocular parameters in children with large cup-to-disc ratio and interocular cup-to-disc ratio asymmetry

BACKGROUND

Enlarged optic disc cupping and interocular cup-to-disc ratio (CDR) asymmetry are often important indicators of glaucoma. Clinically, we occasionally encounter children with large CDR and interocular CDR asymmetry during vision screening. This study aimed to report longitudinal change of ocular parameters in children with large cup-to-disc ratio (CDR) and interocular CDR asymmetry.

METHODS

This was a retrospective, observational case series of 160 eyes of 160 children with large CDR who visited a tertiary eye center from January 2010 to June 2016. Average CDR ≥ 0.6 were considered large CDR values, and CDR asymmetry was defined as an interocular difference ratio value greater than 0.2. All included patients showed interocular pressure (IOP) < 21 mmHg at least three ophthalmic examinations conducted at total intervals of at least 30 months.

RESULTS

The mean age of children included in the study was 7.14 ± 2.42 years, with a follow-up period of 54.46 ± 19.82 months. Changes in refractive error and axial length were significantly different between initial and final examination (p < 0.001). However, optic nerve head (ONH) analysis and retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer (mGCIPL) thicknesses were not significantly different between initial and final examination. In interocular comparisons of patients with CDR asymmetry, changes of refractive error, axial length, ONH analysis, and RNFL and mGCIPL thickness were not significantly different between the two eyes.

CONCLUSIONS

There were no significant differences in the changes of ONH analysis, and RNFL and mGCIPL thicknesses in children with large CDR, or those with interocular CDR asymmetry over the study period. Our results provide helpful information for the establishment of guidelines for managing children with large CDR and interocular CDR asymmetry.

The role of genetic factors in the pathogenesis of primary open-angle glaucoma. Part 1. Connective tissue

The article presents an analytical review of works devoted to molecular and genetic studies in primary open-angle glaucoma from the perspective of the concept of hereditary inferiority of the connective tissue of the eye (scleral component), and the entire body as a whole, as triggers in the development of the disease. The relationship between the main theories of the pathogenesis of glaucoma optical neuropathy and the determining role of molecular and genetic mechanisms of specific changes in the eye tissue is shown. The clinical features of primary open-angle glaucoma in patients with a family history are analyzed. Potentially new directions for preclinical diagnosis of glaucoma and pathogenetically oriented therapy are proposed.

Translaminar Pressure Difference and Ocular Perfusion Pressure in Glaucomatous Eyes with Different Optic Disc Sizes

Purpose

Intracranial pressure (ICP) and ocular perfusion pressure (OPP) are both involved with the pathogenesis of glaucoma. The orbital ICP determines a retrolaminar counter pressure that is antagonistic to the intraocular pressure (IOP). The purpose of this study is to evaluate whether the translaminar pressure difference (TLPD) and the OPP varies in glaucoma patients with different optic disc sizes.

Methods

In this university hospital-based, observational, cross-sectional clinical study, all patients underwent an ophthalmic evaluation. Blood pressure, height, weight, and the results of retinal nerve fiber layer examination with optical coherence tomography examination were recorded. TLPD and OPP were calculated for each patient using proxy algorithms to attain indirect surrogate parameter values. Patients' eyes were stratified into three quantiles according to optic disc sizes and the differences compared. Data from both eyes were used after using the appropriate correction for inter-eye dependency.

Results

The sample consisted of 140 eyes of 73 patients with primary open-angle glaucoma and suspects. Patients with large disc size presented with higher TLPD as compared to those with average and small-sized discs (2.4 ± 4.5, 2.8 ± 3.8, and 3.7 ± 4.7 mmHg for first, second, and third tertile, respectively (P< 0.000). OPP did not vary according to the optic disc size.

Conclusion

Glaucoma patients with larger optic discs have higher TLPD. The pathological significance of this finding warrants further investigation.

Diagnostic capability of different morphological parameters for primary open-angle glaucoma in the Chinese population

BACKGROUND

To assess the diagnostic capability of novel Bruch's membrane opening (BMO)-based disc parameters, the BMO-minimum rim width (BMO-MRW) and the BMO-minimum rim area (BMO-MRA) in the Chinese population and compare them to the retinal nerve fiber layer (RNFL) from optical coherence tomography (OCT) and the rim area (RA) from the Heidelberg retinal tomograph-III (HRT-III).

METHODS

In total, 200 eyes of 77 healthy and 123 primary open-angle glaucoma (POAG) subjects were included in this cross-sectional study. All participants underwent the visual field test and structural measurements by OCT and HRT-III. The areas under the receiver operating characteristic curves (AUCs) of different structural parameters were calculated to assess their diagnostic power and compared using the DeLong test.

RESULTS

In populations with different characteristics, the BMO-MRW and BMO-MRA had better diagnostic power than the RA. In discriminating between all POAG subjects and healthy controls and between early-stage patients and controls, the global BMO-MRW had comparable AUCs with the RNFL, but the BMO-MRA had lower AUCs than the RNFL. In healthy subjects with macrodiscs, both the global and sectoral BMO-MRW were thinner than those in healthy subjects with normal disc size. The AUCs of BMO-MRA, BMO-MRW and RNFL in subjects with macrodiscs were comparable. Additionally, in the myopic population, the BMO-MRA and BMO-MRW had comparable AUCs with the RNFL.

CONCLUSIONS

The BMO-MRW had comparable diagnostic power with the RNFL, and compared with BMO-MRW, the BMO-MRA might have advantages in certain populations, such as macrodiscs. All OCT-derived parameters exceeded the RA in diagnostic capability.

Adaptive finite element eye model for the compensation of biometric influences on acoustic tonometry

BACKGROUND AND OBJECTIVE

Glaucoma is currently a major cause for irreversible blindness worldwide. A risk factor and the only therapeutic control parameter is the intraocular pressure (IOP). The IOP is determined with tonometers, whose measurements are inevitably influenced by the geometry of the eye. Even though the corneal mechanics have been investigated to improve accuracy of Goldmann and air pulse tonometry, influences of geometric properties of the eye on an acoustic self-tonometer approach are still unresolved.

METHODS

In order to understand and compensate for measurement deviations resulting from the geometric uniqueness of eyes, a finite element eye model is designed that considers all relevant eye components and is adjustable to all physiological shapes of the human eye.

RESULTS

The general IOP-dependent behavior of the eye model is validated by laboratory measurements on porcine eyes. The difference between simulation and measurement is below 8 µm for IOP levels from 5 to 40 mmHg. The adaptive eye model is then used to quantify systematic uncertainty contributions of a variation of eye length and central corneal thickness based on input statistics of a clinical trial series. The adaptive eye model provides the required relation between biometric eye parameters and the corneal deflection amplitude, which here is the measured quantity to trace back to the IOP. Implementing the relations provided by the eye model in a Gaussian uncertainty propagation calculation now allows the quantification of the uncertainty contributions of the biometric parameters on the overall measurement uncertainty of the acoustic self-tonometer. As a result, a systematic uncertainty contribution resulting from deviations in eye length dominate stochastic deviations of the sensor equipment by a factor of 3.5.

CONCLUSION

As perspective, the proposed adaptive eye model provides the basis to compensate for systematic deviations of (but not only) the acoustic self-tonometer.

Transient visual blurring during a sexual intercourse in a young woman with surgically corrected myopia and unrecognized pigmentary glaucoma: A rare case report

PURPOSE

To present a rare case of unilateral visual loss episodes occurred during sexual intercourse in a young patient affected by unrecognized pigmentary glaucoma and previously undergone myopic refractive surgery.

CASE DESCRIPTION

The patient presented surgically flattened corneas and markedly asymmetric pigmentary glaucoma.

CONCLUSIONS

Previous refractive surgery, sexual intercourse, and athletic lifestyle might be risk factors for acute pigment dispersion and chronic progression of pigmentary glaucoma in young myopic patients. During their ophthalmic examination prior to refractive surgery, greater attention should be paid to detect early signs of pigmentary dispersion, and awareness of these dangerous situations should be raised in affected patients.

Determinants of lamina cribrosa depth in healthy Asian eyes: the Singapore Epidemiology Eye Study

AIM

To investigate the determinants of lamina cribrosa depth (LCD) in healthy eyes of Chinese and Indian Singaporean adults.

METHODS

The optic nerve head (ONH) of the right eye of 1396 subjects (628 Chinese and 768 Indian subjects) was imaged with optical coherence tomography (OCT, Spectralis, Heidelberg, Germany). LCD was defined as the distance from the Bruch's membrane opening (LCD-BMO) or the peripapillary sclera (LCD-PPS) reference plane to the laminar surface. A linear regression model was used to evaluate the relationship between the LCD and its determinants.

RESULTS

Both LCDs were significantly different between the two races (LCD-BMO: 421.95 (95% CI 365.32 to 491.79) µm in Chinese vs 430.39 (367.46-509.81) µm in Indians, p=0.021; and LCD-PPS: 353.34 (300.98-421.45) µm in Chinese vs 376.76 (313.39-459.78) µm in Indians, p<0.001). In the multivariable regression analysis, the LCD-PPS of the whole cohort was independently associated with females (β=-31.93, p<0.001), Indians subjects (β=21.39, p=0.004) (Chinese as the reference), axial length (Axl) (β=-6.68, p=0.032), retinal nerve fibre layer thickness (RNFL) (β=0.71, p=0.019), choroidal thickness (ChT) (β=0.41, p<0.001), vertical cup disc ratio (VCDR) (β=24.42, p<0.001) and disc size (β=-60.75, p=0.001). For every 1 year older in age, the LCD-PPS was deeper on average by 1.95 µm in Chinese subjects (p=0.01) but there was no association in Indians subjects (p=0.851).

CONCLUSIONS

The LCD was influenced by age, gender, race, Axl, RNFL, ChT, VCDR and disc size. This normative LCD database may facilitate a more accurate assessment of ONH cupping using OCT in Asian populations.

An innovative and simple method, clinically comparable to high-definition optical coherence tomography in quantifying posterior segment lesions in the retina

Purpose:

Methods:

Results:

Conclusion:

The impact of artificial intelligence in the diagnosis and management of glaucoma

Deep learning (DL) is a subset of artificial intelligence (AI), which uses multilayer neural networks modelled after the mammalian visual cortex capable of synthesizing images in ways that will transform the field of glaucoma. Autonomous DL algorithms are capable of maximizing information embedded in digital fundus photographs and ocular coherence tomographs to outperform ophthalmologists in disease detection. Other unsupervised algorithms such as principal component analysis (axis learning) and archetypal analysis (corner learning) facilitate visual field interpretation and show great promise to detect functional glaucoma progression and differentiate it from non-glaucomatous changes when compared with conventional software packages. Forecasting tools such as the Kalman filter may revolutionize glaucoma management by accounting for a host of factors to set target intraocular pressure goals that preserve vision. Activation maps generated from DL algorithms that process glaucoma data have the potential to efficiently direct our attention to critical data elements embedded in high throughput data and enhance our understanding of the glaucomatous process. It is hoped that AI will realize more accurate assessment of the copious data encountered in glaucoma management, improving our understanding of the disease, preserving vision, and serving to enhance the deep bonds that patients develop with their treating physicians.

New Circumpapillary Retinal Nerve Fiber Layer Thickness and Bruch's Membrane Opening-Minimum Rim Width Assessment in Nonglaucomatous Eyes with Large Discs

PURPOSE

To compare the new spectral-domain optical coherence tomography (SD-OCT) algorithm for measuring circumpapillary retinal nerve fiber layer (RNFL) thickness centered on Bruch's membrane opening (BMO), RNFLBMO1, with the conventional circumpapillary RNFL thickness measurement centered on the optic disc (RNFLDİ), and assess the BMO-minimum rim width (BMO-MRW) in nonglaucomatous eyes with large discs.

METHODS

This prospective, cross-sectional, observational study included a total of 91 eyes of 91 patients having nonglaucomatous eyes with large discs (Group 1) and 50 eyes of 50 healthy subjects (Group 2). The optic nerve head (ONH) parameters obtained by confocal scanning laser ophthalmoscopy (CSLO), peripapillary RNFL thickness, BMO area, and BMO-MRW were imaged with SD-OCT.

RESULTS

The mean disc size was 3.06 ± 0.42 mm2 (range, 2.61-4.68) in Group 1 and 1.95 ± 0.23 mm2 (range, 1.6-2.43) in Group 2 (p=0.0001). The mean BMO area was 2.9 ± 0.58 mm2 (range, 1.26-4.62) in Group 1 and 2.05 ± 0.31 mm2 (range, 1.51-2.82) in Group 2 (p=0.0001). The difference between RNFLDİ and RNFLBMO1 measurements in Group 1 was stronger than in Group 2 because it was significant in all sectors in large discs. The mean global BMO-MRW thickness was significantly thinner in large discs; it was 252.95 ± 42.16 µ (range, 170-420) in Group 1 and 326.06 ± 73.39 µ (range, 210-440) in Group 2 (p=0.0001). There was a positive correlation between BMO-MRW thickness measurements and RNFL thickness parameters, both with RNFLDİ and RNFLBMO1, in global and all optic nerve sectors except temporal quadrants with r = 0.257-0.431 (p ≤ 0.001-0.01) in Group 1. But in control group, Group 2, there was a weak correlation or no correlation between BMO-MRW thickness measurements and RNFL thickness parameters with r = -0.256-0.328 (p=0.797-0.02).

CONCLUSION

The new circumpapillary RNFL scanning algorithm centered on BMO is better to assess the RNFL thickness and BMO-MRW in large discs for the early diagnosis of glaucoma.

Determinants of maximum cup depth in non-glaucoma and primary open-angle glaucoma subjects: a population-based study

Background/objectives

To study the associations of intraocular pressure (IOP) and retinal vessel diameters: central retinal arteriolar equivalent (CRAE) and central retinal venular equivalent (CRVE) with the maximum cup depth (MCD) in subjects with and without POAG.

Subjects/methods

Eligible subjects from the Handan Eye Study. All participants underwent physical and comprehensive eye examinations. Univariable and multivariable linear regression models assessed the association between MCD and other parameters.

Results

Four thousand one hundred and ninety-four eligible nonglaucoma and 40 POAG subjects were analyzed. On univariable analysis, deeper MCD was significantly associated with younger age, male gender, lower systolic blood pressure (BP), higher IOP, higher estimated cerebro-spinal fluid pressure (ECSFP), lower estimated trans-laminal cribrosa pressure difference (ETLCPD), longer axial length, narrower CRAE, narrower CRVE, larger disc area (DA) and a lower prevalence of hypertension and diabetes. On multivariable analysis, significant independent determinants of MCD were larger DA (P < 0.001; beta: 0.042; B: 0.20; 95% CI: 0.19, 0.22), younger age (P < 0.001; beta: −0.09; B: −0.002; 95% CI: −0.003, −0.001), higher IOP (P < 0.01; beta: 0.040; B: 0.003; 95% CI: 0.001, 0.005), and narrower CRAE (P < 0.001; beta: −0.06; B: −0.001; 95% CI: −0.001, −0.0003). On adding ECSFP and ETLCPD to the model, MCD was associated with IOP but not with estimated CSFP and TLCPD. A 1 μm decrease in CRAE or 1 mmHg increase of IOP was associated with a 1 μm increase of MCD (P < 0.001) and 3 μm increase of MCD respectively (P = 0.009).

Conclusions

Narrow CRVE and higher IOP are associated with an increase in MCD.

Genome-wide association analysis of 95 549 individuals identifies novel loci and genes influencing optic disc morphology

Optic nerve head morphology is affected by several retinal diseases. We measured the vertical optic disc diameter (DD) of the UK Biobank (UKBB) cohort (N = 67 040) and performed the largest genome-wide association study (GWAS) of DD to date. We identified 81 loci (66 novel) for vertical DD. We then replicated the novel loci in International Glaucoma Genetic Consortium (IGGC, N = 22 504) and European Prospective Investigation into Cancer–Norfolk (N = 6005); in general the concordance in effect sizes was very high (correlation in effect size estimates 0.90): 44 of the 66 novel loci were significant at P &lt; 0.05, with 19 remaining significant after Bonferroni correction. We identified another 26 novel loci in the meta-analysis of UKBB and IGGC data. Gene-based analyses identified an additional 57 genes. Human ocular tissue gene expression analysis showed that most of the identified genes are enriched in optic nerve head tissue. Some of the identified loci exhibited pleiotropic effects with vertical cup-to-disc ratio, intraocular pressure, glaucoma and myopia. These results can enhance our understanding of the genetics of optic disc morphology and shed light on the genetic findings for other ophthalmic disorders such as glaucoma and other optic nerve diseases.

Characteristics of Patients Showing Discrepancy Between Bruch's Membrane Opening-Minimum Rim Width and Peripapillary Retinal Nerve Fiber Layer Thickness

Background: To investigate clinical characteristics of patients showing discrepancy between Bruch’s membrane opening minimum rim width (BMO-MRW) and peripapillary retinal nerve fiber layer (RNFL) thickness. Correlation with the visual field (VF) was also inspected. Methods: In this prospective, cross-sectional study, 106 eyes (106 subjects) showing normal BMO-MRW classification but abnormal RNFL classification were included. All patients underwent confocal scanning laser ophthalmoscopy, spectral-domain optical coherence tomography, and standard automated perimetry. Results: Clinical characteristics were as follows: mean age: 52.79 ± 14.75 years; spherical equivalent (SE), −2.52 ± 3.48 diopter (D); SE < −5.0 D, 34 (32.1%) eyes; large disc (>2.43 mm²), 40.6%; small disc (<1.63 mm²), 12.5%; VF index, 96.72 ± 9.58%; mean deviation, −1.74 ± 3.61 dB; β-peripapillary atrophy (PPA), 96.2%; γ-PPA, 75.5%. Majority (86.1%) of these cases demonstrated normal (71.3%) or borderline (14.9%) on VF. Temporal and nasal RNFL showed significant differences among disc size subgroups (all p < 0.05). Nasal RNFL was significantly thicker in a large disc group than other subgroups. Temporal, superotemporal, inferotemporal, inferonasal RNFL, and superior RNFL peak location showed significant differences (all p < 0.05) among SE subgroups. Temporal RNFL was significantly thicker in the high myopia group than other subgroups. Conclusions: Temporalization of RNFL peaks in myopia and nasalization of RNFL peaks in large disc that display abnormal classifications might show normal classification of BMO-MRW. These findings of discrepancy between classifications should be considered in the diagnosis of early glaucoma.

Optical measurement of the corneal oscillation for the determination of the intraocular pressure

Motivation

Glaucoma is currently the most common irreversible cause of blindness worldwide. A significant risk factor is an individually increased intraocular pressure (IOP). A precise measurement method is needed to determine the IOP in order to support the diagnosis of the disease and to monitor the outcome of the IOP reduction as a medical intervention. A handheld device is under development with which the patient can perform self-measurements outside the clinical environment.

Method

For the measurement principle of the self-tonometer the eye is acoustically excited to oscillate, which is analyzed and attributed to the present IOP. In order to detect the corneal oscillation, an optical sensor is required which meets the demands of a compact, battery driven self-tonometer. A combination of an infrared diode and a phototransistor provides a high-resolution measurement of the corneal oscillation in the range of 10 μm–150 μm, which is compared to a reference sensor in the context of this study. By means of an angular arrangement of the emitter and the detector, the degree of reflected radiation of the cornea can be increased, allowing a measurement with a high signal-to-noise ratio.

Results

By adjusting the angle of incidence between the detector and the emitter, the signal-to-noise ratio was improved by 40 dB which now allows reasonable measurements of the corneal oscillation. For low amplitudes (10 μm) the signal-to-noise ratio is 10% higher than that of the commercial reference sensor. On the basis of amplitude variations at different IOP levels, the estimated standard uncertainty amounts to <0.5 mm Hg in the physiological pressure range with the proposed measuring approach.

Conclusion

With a compact and cost-effective approach, that suits the requirements for a handheld self-tonometer, the corneal oscillation can be detected with high temporal resolution. The cross-sensitivity of the sensor concept concerning a distance variation can be reduced by adding a distance sensor. Existing systematic influences of corneal biomechanics will be integrated in the sensor concept as a consecutive step.

Rim-to-Disc Ratio Outperforms Cup-to-Disc Ratio for Glaucoma Prescreening

We present a novel and fully automated fundus image processing technique for glaucoma prescreening based on the rim-to-disc ratio (RDR). The technique accurately segments the optic disc and optic cup and then computes the RDR based on which it is possible to differentiate a normal fundus from a glaucomatous one. The technique performs a further categorization into normal, moderate, or severely glaucomatous classes following the disc-damage-likelihood scale (DDLS). To the best of our knowledge, this is the first engineering attempt at using RDR and DDLS to perform glaucoma severity assessment. The segmentation of the optic disc and cup is based on the active disc, whose parameters are optimized to maximize the local contrast. The optimization is performed efficiently by means of a multiscale representation, accelerated gradient-descent, and Green’s theorem. Validations are performed on several publicly available databases as well as data provided by manufacturers of some commercially available fundus imaging devices. The segmentation and classification performance is assessed against expert clinician annotations in terms of sensitivity, specificity, accuracy, Jaccard, and Dice similarity indices. The results show that RDR based automated glaucoma assessment is about 8% to 10% more accurate than a cup-to-disc ratio (CDR) based system. An ablation study carried out considering the ground-truth expert outlines alone for classification showed that RDR is superior to CDR by 5.28% in a two-stage classification and about 3.21% in a three-stage severity grading.

Automatic Optic Disc Detection in Color Retinal Images by Local Feature Spectrum Analysis

The optic disc is a key anatomical structure in retinal images. The ability to detect optic discs in retinal images plays an important role in automated screening systems. Inspired by the fact that humans can find optic discs in retinal images by observing some local features, we propose a local feature spectrum analysis (LFSA) that eliminates the influence caused by the variable spatial positions of local features. In LFSA, a dictionary of local features is used to reconstruct new optic disc candidate images, and the utilization frequencies of every atom in the dictionary are considered as a type of "spectrum" that can be used for classification. We also employ the sparse dictionary selection approach to construct a compact and representative dictionary. Unlike previous approaches, LFSA does not require the segmentation of vessels, and its method of considering the varying information in the retinal images is both simple and robust, making it well-suited for automated screening systems. Experimental results on the largest publicly available dataset indicate the effectiveness of our proposed approach.

Real-Time Imaging of Retinal Ganglion Cell Apoptosis

Monitoring real-time apoptosis in-vivo is an unmet need of neurodegeneration science, both in clinical and research settings. For patients, earlier diagnosis before the onset of symptoms provides a window of time in which to instigate treatment. For researchers, being able to objectively monitor the rates of underlying degenerative processes at a cellular level provides a biomarker with which to test novel therapeutics. The DARC (Detection of Apoptosing Retinal Cells) project has developed a minimally invasive method using fluorescent annexin A5 to detect rates of apoptosis in retinal ganglion cells, the key pathological process in glaucoma. Numerous animal studies have used DARC to show efficacy of novel, pressure-independent treatment strategies in models of glaucoma and other conditions where retinal apoptosis is reported, including Alzheimer’s disease. This may forge exciting new links in the clinical science of treating both cognitive and visual decline. Human trials are now underway, successfully demonstrating the safety and efficacy of the technique to differentiate patients with progressive neurodegeneration from healthy individuals. We review the current perspectives on retinal ganglion cell apoptosis, the way in which this can be imaged, and the exciting advantages that these future methods hold in store.

The distribution of retinal nerve fiber layer thickness and associations with age, refraction, and axial length: the Gutenberg health study

PURPOSE

To evaluate the distribution of peripapillary retinal nerve fiber layer thickness as measured by optical coherence tomography and its associations with ocular parameters in a population-based setting.

METHODS

In the population-based Gutenberg Health Study, 1974 subjects from the Mainz-Bingen region were scheduled for ophthalmologic examinations, including visual acuity, refraction, tonometry, biometry, and measurements of peripapillary retinal nerve fiber layer thickness (pRNFL) by optical coherence tomography (SD-OCT, Spectralis®, Heidelberg Engineering, Germany). The associated factors in the global and sectoral pRNFL data were analyzed using multivariable linear mixed models related to age, sex, and ocular parameters.

RESULTS

Advanced age and longer axial length were associated with a thinner pRNFL, whereas pRNFL thickness was independent of sex, intraocular pressure (IOP), and central corneal thickness (CCT). Spherical equivalent was positively associated with pRNFL thickness, except in the temporal pRNFL sector.

CONCLUSIONS

In this large, population-based study, pRNFL thickness decreased with age. Longer eyes had thinner pRNFL thickness. Sex, IOP, and CCT showed no significant association with pRNFL thickness. These data may improve the interpretation of pRNFL data.

Prevalence of glaucoma in Germany: results from the Gutenberg Health Study

PURPOSE

To determine the prevalence of glaucoma according to the International Society for Geographical and Epidemiological Ophthalmology (ISGEO) classification in an adult German cohort.

METHODS

The Gutenberg Health Study is a population-based, prospective cohort study in the Rhine-Main Region in mid-western Germany with a total of 15,010 participants. In this study, the first 5000 subjects with an age range between 35 and 74 years were included. Optic disk pictures were obtained by a non-mydriatic fundus camera (Visucam™) and analyzed using the Visupac™ software. Glaucoma prevalence was determined in two steps. First, the ISGEO classification was applied using "hypernormal subjects" (normal visual field) as reference. In the second analysis, we additionally considered the disk area (DA) in relation to the vertical cup-to-disk ratio by quantile regression. All results are given as weighted numbers for the population of Mainz/Bingen.

RESULTS

The prevalence of definite glaucoma in our sample was 1.44% (n = 72). The prevalence adjusted for disk area was 1.34% (n = 67). The prevalence gradually increased in both models with each decade of age (from 0.9 to 2.4%, respectively). In both models, none of the glaucoma cases had a small optic disk (< 1.6 mm²). Glaucoma prevalence in medium optic disks was 1.0% (without DA adjustment) vs. 1.6% (with DA adjustment) and in large optic disks 5.6 vs. 2.5%.

CONCLUSIONS

The prevalence of definite glaucoma was similar to other European population-based cohorts, with slightly higher prevalence in younger subjects. Our analysis highlighted the influence of optic disk size in determining the diagnosis of glaucoma based on cup-to-disk ratio in epidemiological studies.

Towards Standardization of Quantitative Retinal Vascular Parameters: Comparison of SIVA and VAMPIRE Measurements in the Lothian Birth Cohort 1936

Purpose

Semiautomated software applications derive quantitative retinal vascular parameters from fundus camera images. However, the extent of agreement between measurements from different applications is unclear. We evaluate the agreement between retinal measures from two software applications, the Singapore "I" Vessel Assessment (SIVA) and the Vessel Assessment and Measurement Platform for Images of the Retina (VAMPIRE), and examine respective associations between retinal and systemic outcomes.

Method

Fundus camera images from 665 Lothian Birth Cohort 1936 participants were analyzed with SIVA and VAMPIRE. Intraclass correlation coefficients (ICC) and Bland-Altman plots assessed agreement between retinal parameters: measurements of vessel width, fractal dimension, and tortuosity. Retinal-systemic variable associations were assessed with Pearson's correlation, and intersoftware correlation magnitude differences were examined with Williams's test.

Results

ICC values indicated poor to limited agreement for all retinal parameters (0.159-0.410). Bland-Altman plots revealed proportional bias in the majority, and systematic bias in all measurements. SIVA and VAMPIRE measurements were associated most consistently with systemic variables relating to blood pressure (SIVA r's from -0.122 to -0.183; VAMPIRE r's from -0.078 to -0.177). Williams's tests indicated significant differences in the magnitude of association between retinal and systemic variables for 7 of 77 comparisons (P < 0.05).

Conclusions

Agreement between two common software applications was poor. Further studies are required to determine whether associations with systemic variables are software-dependent.

Translational Relevance

Standardization of the measurement of retinal vascular parameters is warranted to ensure that they are reliable and application-independent. This would be an important step towards realizing the potential of the retina as a source of imaging-derived biomarkers that are clinically useful.

Bruch's membrane opening-based optical coherence tomography of the optic nerve head: a useful diagnostic tool to detect glaucoma in macrodiscs

PurposeTo compare Bruch's membrane opening (BMO)-based spectral domain optical coherence tomography (SD-OCT) and margin based confocal scanning laser tomography (CSLT) of the optic nerve head (ONH) to visual field function in large optic discs (macrodiscs) and to assess performance for glaucoma detection.MethodsIn a case-control, cross-sectional study, 125 eyes of 125 patients with disc size >2.45 mm², thereof 44 glaucoma and 11 ocular hypertension (OHT) patients and 70 healthy controls underwent SD-OCT and CSLT examination, visual field testing and clinical evaluation. Mean outcome measures BMO-based minimum rim width (BMO-MRW), retinal nerve fiber layer thickness (RNFLT) in SD-OCT, and rim area measured in CSLT were compared and correlated to visual field function.ResultsAll participants had a mean disc area of 2.91±0.38 mm² in CSLT and a BMO area of 2.45±0.39 mm² (r=0.76;P<0.001). In glaucoma patients, visual field mean deviation was -10.0±6.1 dB. Global BMO-MRW correlated better to visual field function (Spearman's Rho (ρ)=0.71; P<0.001) than RNFLT (ρ=0.52;P<0.001) and CSLT rim area (ρ=0.63; P<0.001). BMO-MRW was significantly decreased with higher visual field loss (P<0.001). In ROC analysis, diagnostic power to differentiate glaucoma patients and healthy controls was highest for BMO-MRW (Area under curve, AUC=0.96; sensitivity at 95% specificity=82%). Rim area in CSLT (AUC=0.91; sensitivity=61.0%; P=0.04) and RNFLT (AUC=0.89; sensitivity=61%; P=0.01) were significantly less powerful.ConclusionsIn macrodiscs, BMO-MRW has the best diagnostic power to discriminate glaucoma patients from normal controls compared to RNFLT and rim area in CSLT. Additionally, BMO-MRW seems to reflect the structure-function relationship better than the other two parameters.

The impact of optic nerve and related characteristics on disc area measurements derived from different imaging techniques

PURPOSE

Optic nerve head (ONH) assessment and its interpretation in healthy patients and those with glaucoma remains a pivotal topic specifically considering rapid advancements in imaging technologies. We undertook a large-scale, mixed cohort, comparative study to assess the correlation of optic disc measurements between different imaging modalities and investigated the impact of patient and disc associated parameters.

METHODS

ONH sizes were obtained from one randomly selected eye of each of 209 patients using stereophotography, confocal scanning laser ophthalmoscopy and two different optical coherence tomographers (OCT). Patient related data, glaucoma status and optic disc variables, specifically oblique insertion, torsion, presence of beta PPA and spherical equivalent were recorded. Measurements between imaging modalities were analysed using Pearson correlation, linear regression analysis and Blend-Altman plots. Individual variables were compared applying multivariate regression analysis, ANOVA and chi square statistics was used to determine correlations between patient and clinical characteristics.

RESULTS

Absolute measurements significantly differed between imaging modalities generally producing smaller measurements for OCT derived measurements of Bruch's membrane opening (BMO). Pairwise correlations between imaging modalities were between 0.83 and 0.93 for discs without myopia, oblique insertion, or beta PPA. These features impacted on measurements for individual modalities and consequently contributed to inconsistencies and variability.

CONCLUSION

In comparison to planimetry, OCT derived BMO measurements are more variable in the presence of oblique insertion, beta PPA or magnification errors due to myopia. Impact of these factors, however, differs between instruments and needs to be considered to accurately interpret optic disc features in particular within the context of glaucoma diagnosis.

Association of Bruch's membrane opening and optic disc morphology to axial length and visual field defects in eyes with primary open-angle glaucoma

PURPOSE

To examine the morphology of Bruch's membrane opening (BMO), optic disc, and peripapillary atrophy (PPA) by scanning laser ophthalmoscopy (SLO) and spectral-domain optical coherence tomography (SD-OCT), and to determine their association with the axial length and visual field defects.

METHODS

This was a cross-sectional study of 94 eyes of 56 subjects; 77 eyes were diagnosed with primary open-angle glaucoma and 17 eyes as normal. The margins of the optic disc were determined in the SLO images, and that of the BMO in the SD-OCT images. The ovality and area of the BMO and the optic disc were measured. The beta and gamma-PPA areas were also measured. The association of each parameter with the axial length and the mean deviation (MD) of the visual field tests was determined by generalized estimating equations (GEEs).

RESULTS

The optic disc ovality was associated with the axial length and the MD (β = -0.47, P = 7.6 × 10^-4 and β = 0.12, P = 0.040). The BMO ovality was not significantly associated with the axial length and the MD. The BMO area was associated with the axial length (β = 0.30, P = 0.029). A larger BMO area was associated with a thinner BMO-based neuroretinal rim width (BMO-MRW) after adjustments for the MD (β = -0.30, P = 2.1 × 10^-4). The beta- and gamma-PPA areas were associated with the axial length (β = 0.50, P = 7.4 × 10^-5 and β = 0.62, P = 4.2 × 10^-6).

CONCLUSIONS

The optic disc ovality was associated with both the axial length and MD, whereas BMO ovality was not. Attention should be paid to the influence of the axial length-related enlargement of the BMO.

Expression QTL analysis of glaucoma endophenotypes in the Norfolk Island isolate provides evidence that immune-related genes are associated with optic disc size

Primary open-angle glaucoma (POAG) is influenced by both genetic and environmental factors. Despite significant progress in identifying genetic variants associated with POAG, there remains a substantial amount of unexplained heritability. Study design features that may enhance knowledge of the genetic architecture include focusing on multiple quantitative traits related to ocular disorders (i.e. endophenotypes), targeting genetic variants that directly influence gene expression (i.e. cis-eQTLs) and utilising genetically isolated populations to reduce genetic and environmental noise and thus enhance association signals. In this study we performed heritability and blood-based eQTL association analysis of five key POAG endophenotypes in 330 individuals from the Norfolk Island (NI) isolate. Results showed evidence of heritability for all five traits, with H² estimates ranging from 0.35 for intraocular pressure (IOP) to 0.82 for central corneal thickness (CCT) (P < 0.05). The primary finding was for BTN3A2, whereby both cis-SNP and transcript were significantly associated with disc size within a conditional regression model. Specifically, this model included rs853676 (β = 0.23,P = 0.008) and transcript (β = 0.23, P = 0.03). We also observed a cis-SNP association between optic disc size and LPCAT2 independent of transcript (P = 0.0004). These genes have specific functions in immune system pathways and suggest a role for an inherited immune component of POAG risk. This study also demonstrates an alternate approach to understanding the functional genetic basis of POAG and ocular health more generally.

Increasing incidence of optic nerve hypoplasia/septo-optic dysplasia spectrum: Geographic clustering in Northern Canada

Introduction

Owing to the shared embryonic origin, defects in development of optic nerves are often seen in conjunction with defects affecting the surrounding brain and pituitary gland. Optic nerve hypoplasia (ONH) and septo-optic dysplasia (SOD) represent a clinical spectrum associated with visual, pituitary and severe central nervous system structural abnormalities (SODplus). Based on changing clinical patterns, our primary objective was to examine trends in annual incidence of ONH/SOD and geographical clustering in Manitoba.

Methods

This was a retrospective 1996 to 2015 chart review with extraction of anthropometric measures, radiologic findings, parental characteristics, endocrinopathies and neurologic symptoms from all involved in care. Postal codes were used to assign map co-ordinates and identify relevant census-based deprivation indices.

Results

Ninety-three children were identified in our catchment area; Poisson regression confirmed a striking 1.11-fold annual increase (95% confidence interval 1.07 to 1.16) or ~800% over two decades. The annual incidence (averaged 2010 to 2014 chart data) reached 53.3 per 100,000, affecting 1 in 1875 live births. Most (~55%) had SODplus. Common presenting features were hypoglycemia, nystagmus, seizures and developmental delay; 40% had hormone deficiencies; 80% had reduced visual acuity, typically bilateral. Many were premature with young, primiparous mothers. Unhealthy maternal lifestyles and severe material deprivation were noted. There was disproportionate clustering in individuals from Northern Manitoba at three times the average provincial rate.

Conclusion

We noted a dramatic rise in the annual incidence of ONH/SOD, which was strongly associated with poverty and northern communities. The pattern was consistent with environmental or nutritional etiologies. Many children were severely affected with increased morbidity and health care burdens.

Variations in optic nerve head morphology by intraocular pressure in open-angle glaucoma

PURPOSE

To compare optic disc topography in eyes in three intraocular pressure (IOP) groups of <15 mmHg, 15-20 mmHg, and ≥21 mmHg using spectral domain optical coherence tomography (SD-OCT) and confocal scanning laser ophthalmoscopy, adjusting for the degree of damage, as measured by retinal nerve fiber layer (RNFL) thickness and average visual field loss.

METHODS

A total of 184 eyes of 112 patients with primary open-angle glaucoma were recruited into groups based on baseline untreated intraocular pressure (IOP) of <15 mmHg (normal-tension glaucoma [NTG], very low), 15-20 mmHg (NTG, medium), or ≥21 mmHg (high-tension glaucoma [HTG]). Patients underwent scanning laser ophthalmoscopy, SD-OCT, and Humphrey visual field testing. Univariate and multivariate models were created, accounting for degree of retinal ganglion cell (RGC) loss by either OCT RNFL thickness or visual field mean deviation (MD).

RESULTS

Univariate and multivariate analyses demonstrated no morphological differences in HRT or OCT parameters among IOP groups that met Bonferroni-corrected statistical significance when using either MD or OCT RNFL as the damage criterion (p < 0.0063). The mean cup depth was shallower for the IOP <15 mmHg group than the IOP ≥21 mmHg group (p < 0.05) for both MD (p < 0.011) and OCT RNFL (p < 0.014).

CONCLUSION

Normal-tension and high-tension glaucoma are not distinguishable by optic nerve head topography with HRT and OCT when the degree of damage by Humphrey visual field testing is taken into account.