Retinal ganglion cell atrophy correlated with automated perimetry in human eyes with glaucoma

Retinal Organoids from Induced Pluripotent Stem Cells of Patients with Inherited Retinal Diseases: A Systematic Review

BACKGROUND

Currently, most inherited retinal diseases lack curative interventions, and available treatment modalities are constrained to symptomatic approaches. Retinal organoid technology has emerged as a method for treating inherited retinal diseases, with growing academic interest in recent years. The purpose of this review was to systematically organize the current protocols for generating retinal organoids using induced pluripotent stem cells from patients with inherited retinal disease and to investigate the application of retinal organoids in inherited retinal disease research.

METHODS

Data were collected from the PubMed, Scopus, and Web of Science databases using a keyword search. The main search term used was "retinal organoid," accompanied by secondary keywords such as "optic cup," "three-dimensional," and "self-organizing." The final search was conducted on October 2, 2024.

RESULTS

Of the 2,129 studies retrieved, 130 were included in the qualitative synthesis. The protocols for the generation of retinal organoids in inherited retinal disease research use five major approaches, categorized into 3D and a combination of 2D/3D approaches, implemented with modifications. Disease phenotypes have been successfully reproduced via the generation of retinal organoids from the induced pluripotent stem cells of individuals with inherited retinal diseases, facilitating the progression of research into novel therapeutic developments. Cells have been obtained from retinal organoids for cell therapy, and progress toward their potential integration into clinical practice is underway. Considering their potential applications, retinal organoid technology has shown promise across various domains.

CONCLUSION

In this systematic review, we organized protocols for generating retinal organoids using induced pluripotent stem cells from patients with inherited retinal diseases. Retinal organoid technology has various applications including disease modeling, screening for novel therapies, and cell replacement therapy. Further advancements would make this technology a clinically significant tool for patients with inherited retinal diseases.

Retinal Ganglion Cell Subtypes and Their Vulnerability in Glaucoma

The detection of selective retinal ganglion cell damage in glaucoma has been a long sought-after goal, not just for the development of clinical tests for the early detection of glaucoma but for the elucidation of potential mechanisms underlying retinal ganglion cell loss. Early reports of the selective vulnerability of larger retinal ganglion cells (RGCs) in human studies did not translate simply to the loss of a particular class of RGC but more likely reflected shrinkage and degeneration across all RGC classes. Subsequent studies of nonhuman primate (NHP) models of glaucoma indicated some selectivity with great damage to the magnocellular vs parvocellular pathways. More recently, rodent models of experimental glaucoma have highlighted a selective vulnerability of OFF-centered RGCs-particularly those with transient responses. Selectivity for OFF pathway damage is also seen as a trend in a rat model of glaucoma. These data support the concept that some RGCs are more vulnerable to the effects of glaucoma damage. This chapter covers some of the methods to elucidate RGC damage and the relevance of model selection to mimic human glaucoma rather than just RGC death.

Evaluating retinal thickness classification in children: A comparison between pediatric and adult optical coherence tomography databases

PURPOSE

This study investigates the agreement of children's retinal thickness classification by color category between Topcon 3D OCT-1's built-in adult reference data and our new pediatric database and assesses the correlation of retinal thickness with age and spherical equivalent (SE).

METHODS

160 eyes of 160 healthy children (74 boys, 86 girls) aged 6-18 years (mean: 11.60 ± 3.28 years) were evaluated in this cross-sectional study. The peripapillary retinal nerve fibre layer (pRNFL) and macular thickness were determined for the 1st, 5th, 95th, and 99th percentile points. Cohen's κ value and specific agreement between pediatric data and adult reference database were estimated. The correlation between retinal thickness with age and SE was also determined.

RESULTS

The mean thickness for the total RNFL, average macular, and central macula were 112.05±8.65 μm, 280.24±12.46 μm, and 220.55±17.53 μm, respectively. The overall agreement between the classification of the adult database and pediatric data for pRNFL was ≥90%, with discrepancies in 46 out of 150 eyes (30.67%); for macula, it was above 72%, with discrepancies in 93 out of 153 eyes (60.78%); and for ganglion cell complex and ganglion cell + inner plexiform layer (GCIPL) the agreement was above 84% and 85%, respectively. A significant level of agreement between pediatric data and adult reference data was achieved for temporal RNFL (κ = 0.65), macular perifoveal superior (κ = 0.67), and inferior (κ = 0.63) and inferior GCIPL (κ = 0.67). The correlations between age and retinal thickness were not significant (all p>0.05). Most retinal thickness parameters were positively associated with SE (Pearson's coefficient, r = 0.26 to 0.49, all p<0.05).

CONCLUSIONS

The overall agreement for pRNFL and macular thickness measurements in children with the adult reference database was between 72% and 90%. Children's retinal thickness was not significantly correlated with age but was positively associated with spherical equivalent.

Peripapillary retinal thickness and its risk factors in dry-type high myopia

INTRODUCTION

To evaluate the alterations in the peripapillary retinal thickness and its risk factors in dry-type high myopia (HM).

METHODS

One hundred and twenty eyes in 69 HM subjects were collected from March 2023 to July 2023 with the age, refractive diopter, axial length (AL), posterior scleral staphyloma, type of myopic maculopathy, and peripapillary retinal thickness. Divided into three groups according to the international photo-graphic classification system: Category 0 (C0) with no myopic retinal degenerative lesions, Category 1 (C1) with tessellated fundus, and Category 2 (C2) with diffuse chorioretinal atrophy. Peripapillary retinal thickness was assessed using swept-source optical coherence tomography (SS-OCT) B-scans. All data were analyzed with the SPSS software version 23.0 by one-way ANOVA test among three groups. Linear regression and pearson correlation analysis were used to determine the relationships among measurements.

RESULTS

The retinal thickness of the peripapillary was measured from the superior, nasal, inferior, and temporal directions around the optic disc. The superior, nasal, and inferior peripapillary retinal thickness in the C2 group decreased significantly in all three groups. The retinal thicknesses decreased significantly with the increase of AL in the superior, nasal, and inferior. The retinal thicknesses increased significantly with the increase of refractive diopter, except for the temporal sector. The retinal thickness decreased significantly with the increase of age in dry-type HM. There was no significant difference between peripapillary retinal thickness and the wide macular staphyloma.

CONCLUSIONS

Individuals in the C2 group had a thinner peripapillary retinal thickness than other groups, except for the temporal sector. The retinal thicknesses of the peripapillary decreased significantly with the increase of AL and increased significantly with the increase of refractive diopter, except for the temporal sector. With the increase of age, the retinal thickness of the peripapillary decreased significantly. Ophthalmologists and HM patients should pay attention to changes in the thickness of the peripapillary retina and the growth of age.

Contrast Sensitivity Is Impaired in Suspected Primary Open-Angle Glaucoma Patients

PURPOSE

To assess spatial contrast sensitivity (CS) in suspected primary open-angle glaucoma (POAG) patients.

METHODS

CS was measured using sinusoidal gratings of 4 cycles/degree. First, foveal and peripheral CS were assessed in 34 suspected POAG patients and compared with 71 and 28 age-matched healthy individuals for foveal and peripheral conditions, respectively. Second, foveal CS was assessed in 34 early POAG patients age-matched with suspected POAG patients. Analyses were performed considering two age ranges: Under and Over 50 y.o. Correlations were evaluated between CS and clinical parameters. Diagnostic accuracy was also analyzed.

RESULTS

Peripheral CS was lower in older suspected POAG patients (23.4 ± 16.1) than the control group (39.1 ± 28.2) (p = 0.040). Foveal CS was reduced in suspected POAG participants (Under 50: 146.8 ± 63.3; p = 0.004. Over 50: 110.5 ± 65.0; p = 0.044) and in early POAG patients (Under 50: 141.2 ± 72.6; p = 0.002. Over 50: 80.2 ± 54.5 p < 0.001), both compared to the control group (Under 50: 213.5 ± 66.2. Over 50: 138.6 ± 71.7). CS was lower in early POAG than in POAG suspected in older patients (p = 0.042). Foveal CS was correlated with age (Early: p = 0.001. Suspect: p = 0.002) and with the cup-disc ratio only in early POAG patients (p < 0.001). Foveal CS had fair (AUC = 0.74) diagnostic accuracy for early POAG patients.

CONCLUSIONS

CS in suspected POAG patients is lower than in healthy individuals. Our findings evidence the spatial vision loss before the onset of POAG.

Peripapillary Retinal Nerve Fiber Layer and Macular Ganglion Cell-Inner Plexiform Layer Parameters and Their Associated Factors in Cynomolgus Macaques

Purpose

The purpose of this study was to define the normal range of peripapillary retinal nerve fiber layer (pRNFL), macular ganglion cell layer (mGCL), and macular inner plexiform layer (mIPL) thickness in cynomolgus macaques, and explore their inter-relationship and correlation with age, refractive errors, and axial length (AL).

Methods

In this cross-sectional study, we measured biometric and refractive parameters, and pRNFL/mGCL/mIPL thickness in 357 healthy cynomolgus macaques. Monkeys were divided into groups by age and spherical equivalent (SE). Correlation and regression analyses were used to explore the relationship between pRNFL and mGCL/mIPL thickness, and their correlation with the above parameters.

Results

The mean age, SE, and AL were 14.46 ± 6.70 years, -0.96 ± 3.23 diopters (D), and 18.39 ± 1.02 mm, respectively. The mean global pRNFL thickness was 95.06 ± 9.42 µm (range = 54-116 µm), with highest values in the inferior quadrant, followed by the superior, temporal, and nasal quadrants (P < 0.001). Temporal pRNFL thickness correlated positively with age (r = 0.218, P < 0.001) and AL (r = 0.364, P < 0.001), and negatively with SE (r = -0.270, P < 0.001). In other quadrants, pRNFL thickness correlated negatively with age and AL, but positively with SE. In the multivariable linear regression model, adjusted for sex and AL, age (β = -0.350, P < 0.001), and SE (β = 0.206, P < 0.001) showed significant associations with global pRNFL thickness. After adjusting for age, sex, SE, and AL, pRNFL thickness positively correlated with mGCL (β = 0.433, P < 0.001) and mIPL thickness (β = 0.465, P < 0.001).

Conclusions

The pRNFL/mGCL/mIPL thickness distribution and relationship with age, AL, and SE in cynomolgus macaques were highly comparable to those in humans, suggesting that cynomolgus monkeys are valuable animal models in ophthalmic research.

Impact of Glaucomatous Ganglion Cell Damage on Central Visual Function

Glaucoma, a leading cause of irreversible blindness, is characterized by the progressive loss of retinal ganglion cells (RGCs) and subsequent visual field defects. RGCs, as the final output neurons of the retina, perform key computations underpinning human pattern vision, such as contrast coding. Conventionally, glaucoma has been associated with peripheral vision loss, and thus, relatively little attention has been paid to deficits in central vision. However, recent advancements in retinal imaging techniques have significantly bolstered research into glaucomatous damage of the macula, revealing that it is prevalent even in the early stages of glaucoma. Thus, it is an opportune time to explore how glaucomatous damage undermines the perceptual processes associated with central visual function. This review showcases recent studies addressing central dysfunction in the early and moderate stages of glaucoma. It further emphasizes the need to characterize glaucomatous damage in both central and peripheral vision, as they jointly affect an individual's everyday activities.

Recognition of Glaucomatous Fundus Images Using Machine Learning Methods Based on Optic Nerve Head Topographic Features

PRCIS

Machine learning classifiers are an effective approach to detecting glaucomatous fundus images based on optic disc topographic features making it a straightforward and effective approach.

STUDY DESIGN

Retrospective case-control study.

OBJECTIVE

The aim was to compare the effectiveness of clinical discriminant rules and machine learning classifiers in identifying glaucomatous fundus images based on optic disc topographic features.

METHODS

The study used a total of 800 fundus images, half of which were glaucomatous cases and the other half non-glaucomatous cases obtained from an open database and clinical work. The images were randomly divided into training and testing sets with equal numbers of glaucomatous and non-glaucomatous images. An ophthalmologist framed the edge of the optic cup and disc, and the program calculated five features, including the vertical cup-to-disc ratio and the width of the optic rim in four quadrants in pixels, used to create machine learning classifiers. The discriminative ability of these classifiers was compared with clinical discriminant rules.

RESULTS

The machine learning classifiers outperformed clinical discriminant rules, with the extreme gradient boosting method showing the best performance in identifying glaucomatous fundus images. Decision tree analysis revealed that the cup-to-disc ratio was the most important feature for identifying glaucoma fundus images. At the same time, the temporal width of the optic rim was the least important feature.

CONCLUSIONS

Machine learning classifiers are an effective approach to detecting glaucomatous fundus images based on optic disc topographic features and integration with an automated program for framing and calculating the required parameters would make it a straightforward and effective approach.

Values of peripapillary retinal nerve fibre layer thickness are different in children and adults

CLINICAL RELEVANCE

The detection of abnormal values of peripapillary nerve fibre layer (pRNFL) thickness measured with optical coherence tomography (OCT) is important for detecting optic nerve disease in children.

BACKGROUND

To evaluate the level of agreement between the adult reference database supplied with an OCT device and the present paediatric study database for the measurement of pRNFL thickness in children. This study also aimed to provide reference values for pRNFL thickness according to the spherical equivalent in the paediatric population.

METHODS

This was a cross-sectional study. One hundred and twenty-six healthy children were included, who had undergone a full ophthalmological examination including cycloplegic refraction and examination of pRNFL thickness using the Topcon 3D OCT 2000 device (Topcon Corporation, Tokyo, Japan). Values equal to or below the fifth percentile (≤p5) and above the 95th percentile (>p95) were considered abnormal. Observed agreement and specific agreement were investigated between OCT measurements classified with paediatric and adult reference values for normality.

RESULTS

Values ≤ p5 in the adult database were recorded for 2 of the 30 values (6.6%) of the pRNFL values by quadrants ≤p5 in the paediatric database and 17 of the 88 (19.3%) values by sectors ≤p5. For values >p95 in the adult database, 88% by quadrants and 72% by sectors would have been classified as being within the normal range using the paediatric database.

CONCLUSION

The use of adult reference values currently available in OCT devices can lead to classification errors concerning the normal range of pRNFL thickness in a large proportion of paediatric patients. The use of normative paediatric databases, such as the one discussed in this study, should be taken into consideration.

Tractometry of Human Visual White Matter Pathways in Health and Disease

Diffusion-weighted MRI (dMRI) provides a unique non-invasive view of human brain tissue properties. The present review article focuses on tractometry analysis methods that use dMRI to assess the properties of brain tissue within the long-range connections comprising brain networks. We focus specifically on the major white matter tracts that convey visual information. These connections are particularly important because vision provides rich information from the environment that supports a large range of daily life activities. Many of the diseases of the visual system are associated with advanced aging, and tractometry of the visual system is particularly important in the modern aging society. We provide an overview of the tractometry analysis pipeline, which includes a primer on dMRI data acquisition, voxelwise model fitting, tractography, recognition of white matter tracts, and calculation of tract tissue property profiles. We then review dMRI-based methods for analyzing visual white matter tracts: the optic nerve, optic tract, optic radiation, forceps major, and vertical occipital fasciculus. For each tract, we review background anatomical knowledge together with recent findings in tractometry studies on these tracts and their properties in relation to visual function and disease. Overall, we find that measurements of the brain's visual white matter are sensitive to a range of disorders and correlate with perceptual abilities. We highlight new and promising analysis methods, as well as some of the current barriers to progress toward integration of these methods into clinical practice. These barriers, such as variability in measurements between protocols and instruments, are targets for future development.

Comparison of diagnostic capability of macular ganglion cell complex vs retinal fiber layer thickness in primary open angle glaucoma patients of Indian origin

PURPOSE

Comparison of diagnostic capability of macular ganglion cell complex thickness vs. retinal nerve fiber layer (RNFL) thickness in patients of primary open-angle glaucoma (POAG).

SETTINGS AND DESIGN

This cross-sectional observational study was carried out between June 2021 and October 2022 at a tertiary care hospital in North India.

METHODS

A total of 118 eyes were included in the study with 30 control and the rest 88 eyes with POAG were divided into three groups based on visual field loss Group 1 (30 eyes): early field loss with mean deviation (MD) < -6 dB; Group 2 (30 eyes): moderate field loss with MD -6 to -12 dB; and Group 3 (28 eyes): severe field loss with MD > -12 dB. Optical coherence tomography (OCT) scans to measure RNFL loss and ganglion cell inferior plexiform layer (GCIPL) loss were taken for each patient.

STATISTICAL ANALYSIS USED

Categorical variables were analyzed using either the Chi-square test or Fisher's exact test. A receiver operating characteristics analysis was calculated to determine optimal cut-off values of superior, inferior, and average GCIPL and RNFL for determining the severity of field loss as compared to controls (30 normal eyes).

RESULTS

In the mild field loss group the sensitivity of superior, inferior, and average GCIPL was 86.7, 96.7, and 96.7%, respectively. Similarly, the specificity was 96.7, 93.3, and 100%, respectively. In the same group, the sensitivity of superior, inferior, and average RNFL was 70, 93, and 66%, respectively. Similarly, the specificity was 46.7, 83.3, and 70%, respectively. In the moderate and severe groups, the results were comparable.

CONCLUSION

The sensitivity and specificity of GCIPL loss are significantly better than that of RNFL parameters in the mild field loss group.

Rates of retinal nerve fiber layer loss in early-stage pseudoexfoliation and primary open-angle glaucoma patients using optical coherence tomography

PURPOSE

To characterize glaucoma progression in early-stage patients with retinal nerve fiber layer (RNFL) using the change analysis software (CAS), which was utilized to track RNFL thinning.

METHODS

We retrospectively analyzed 92 eyes of 92 patients with early-stage glaucoma. Patients were divided into two subgroups based on their diagnosis of pseudoexfoliation glaucoma (PEG) and primary open-angle glaucoma (POAG). A complete ophthalmologic examination was performed on all patients. Additionally, automated perimetry was conducted on each patient. Furthermore, Fourier-domain optical coherence tomography (OCT) was employed to measure RNFL and central corneal thickness. Using the OCT device's CAS, we computed the annual rate of total and glaucomatous RNFL thinning for each patient.

RESULTS

A total of 44 PEG and 48 POAG patients were included in the study. The right eye measurements of these patients were analyzed and compared. The two groups were not significantly different in age, gender, and the number of visits per year (p > 0.05, for each). However, the difference between the mean RNFL thickness at baseline (91.39 ± 10.71 and 96.9 ± 8.6 µm) and at the last visit (85.2 ± 15.76 µm and 91.56 ± 9.58 µm) was statistically significant between the two groups (p = 0.043, p = 0.039, respectively). Additionally, the difference in annual RNFL thinning rates (1.43 ± 0.81 µm and 1.07 ± 0.32 µm) between the two groups was statistically significant (p = 0.009).

CONCLUSION

The annual rate of glaucomatous RNFL loss in early-stage PEG patients (1.23 µm) was higher than in POAG patients (0.87 µm). However, despite these loss rates, scotoma was not detected in the visual field tests of these patients. Therefore, using CAS in the follow-up of early-stage glaucoma patients is a useful alternative for monitoring glaucomatous progression. Furthermore, this method can be utilized in future research for the diagnosis and follow-up of glaucoma in special populations (e.g., those with pathological myopia or high hyperopia) that are not included in normative databases.

The prophylactic value of TNF-α inhibitors against retinal cell apoptosis and optic nerve axon loss after corneal surgery or trauma

BACKGROUND AND PURPOSE

Late secondary glaucoma is an often-severe complication after acute events like anterior segment surgery, trauma and infection. TNF-α is a major mediator that is rapidly upregulated, diffusing also to the retina and causes apoptosis of the ganglion cells and degeneration of their optic nerve axons (mediating steps to glaucomatous damage). Anti-TNF-α antibodies are in animals very effective in protecting the retinal cells and the optic nerve-and might therefore be useful prophylactically against secondary glaucoma in future such patients. Here we evaluate (1) toxicity and (2) efficacy of two TNF-α inhibitors (adalimumab and infliximab), in rabbits by subconjunctival administration.

METHODS

For drug toxicity, animals with normal, unburned corneas were injected with adalimumab (0.4, 4, or 40 mg), or infliximab (1, 10, or 100 mg). For drug efficacy, other animals were subjected to alkali burn before such injection, or steroids (for control). The rabbits were evaluated clinically with slit lamp and photography, electroretinography, optical coherence tomography, and intraocular pressure manometry. A sub-set of eyes were stained ex vivo after 3 days for retinal cell apoptosis (TUNEL). In other experiments the optic nerves were evaluated by paraphenylenediamine staining after 50 or 90 days. Loss of retinal cells and optic nerve degeneration were quantified.

RESULTS

Subconjunctival administration of 0.4 mg or 4.0 mg adalimumab were well tolerated, whereas 40.0 mg was toxic to the retina. 1, 10, or 100 mg infliximab were also well tolerated. Analysis of the optic nerve axons after 50 days confirmed the safety of 4.0 mg adalimumab and of 100 mg infliximab. For efficacy, 4.0 mg adalimumab subconjunctivally in 0.08 mL provided practically full protection against retinal cell apoptosis 3 days following alkali burn, and infliximab 100 mg only slightly less. At 90 days following burn injury, control optic nerves showed about 50% axon loss as compared to 8% in the adalimumab treatment group.

CONCLUSIONS

Subconjunctival injection of 4.0 mg adalimumab in rabbits shows no eye toxicity and provides excellent neuroprotection, both short (3 days) and long-term (90 days). Our total. accumulated data from several of our studies, combined with the present paper, suggest that corneal injuries, including surgery, might benefit from routine administration of anti-TNF-α biologics to reduce inflammation and future secondary glaucoma.

Retinal and choroidal structure and vascularity in Chinese emmetropic and myopic children

PURPOSE

This study evaluated the structural features of the retinal and choroidal regions and their correlations with ocular biometric and vascular parameters in Chinese children using optical coherence tomography angiography (OCTA).

METHODS

A total of 159 children, 6-13 years of age, were included in this prospective study. The sample consisted of 55 emmetropes (spherical equivalent ≤ +0.75 and > -0.50 D), 53 low-moderate myopes (≤ -0.50 to > -6.00 D) and 51 high myopes without pathological changes (≤ -6.00 D). Optical coherence biometry was used to measure axial length (AL) and anterior segment parameters. Swept-source optical coherence tomography/OCTA was used to assess the macular structures and vascular characteristics in a 6 × 6 mm region centred on the macula.

RESULTS

In a comprehensive analysis adjusting for age, sex, AL, macular blood perfusion, intraocular pressure and anterior segment parameters, retinal thickness (RT) showed a significant positive association with deep retinal vascular density and superficial retinal vascular density in the foveal area, but not with AL. Moreover, RT exhibited a significant negative association with AL in the parafoveal and perifoveal regions. Further, a significant positive correlation was observed between choroidal thickness and both choroidal vascular volume and choriocapillaris perfusion area, along with a negative correlation with AL across the entire macular region.

CONCLUSIONS

This study showed that the thickness of retina and choroid in Chinese children was not only associated with AL but also showed dynamic properties such as the blood perfusion of the retina and choroid, particularly in the foveal area.

Pattern electroretinogram, blue-yellow visual evoked potentials and the risk of developing visual field defects in glaucoma suspects: a longitudinal "survival" analysis with a very long follow-up

PURPOSE

Estimating glaucoma suspects' risk for visual field defects helps to avoid under- and over-treatment. In this retrospective, longitudinal cohort study with a very long follow-up, we studied whether pattern electroretinograms (PERG) amplitudes and blue-on-yellow visual evoked potential (BY-VEP) latencies can predict visual field defects.

METHODS

Participants of the Erlangen Glaucoma Study were examined with PERG and BY-VEP between 9/1991 and 8/2001. Stimuli were created using an optical bench with Maxwellian view and consisted of vertical gratings (0,88 cpd) in a 32° field for both PERG and BY-VEP. Patients were treated according to clinical standards and performed standard automated perimetry (SAP) annually. Retrospectively, patients with normal SAP at baseline were selected. Primary endpoint was conversion to perimetric glaucoma. Predictive value was modeled using Kaplan-Meier analyses and a multivariate cox proportional hazards model with the continuous variables PERG amplitude, BY-VEP peak time and SAP square-root of loss variance (sLV) after stratification for Jonas classification of the optic discs.

RESULTS

Of 412 patients (288: Jonas 0, 103: I, and 21: II; baseline age: 20-60 years), 65 converted to perimetric glaucoma during follow-up (0.5-23.3 years; median 5.5 years). Optic disc classification was a strong risk factor for conversion (log rank p < 0.0001), and patients with more advanced changes progressed earlier. In the multivariate analysis (log rank p = 0.005), only PERG amplitude remained an independent risk factor after stratification for optic disc morphology (p = 0.021), with a ~ 30% higher risk per μV amplitude decrease.

CONCLUSIONS

PERG helps to estimate glaucoma suspects' risk for visual field defects.

Associations between Nocturnal Hypoxemia and Retinal Nerve Fiber Layer Thinning: The Nagahama Study

Rationale: There have been meta-analyses that showed reduced retinal nerve fiber layer (RNFL) thickness, which is a surrogate marker of glaucoma, in patients with obstructive sleep apnea (OSA). However, the sample sizes in these reports were small (<300), and the mechanism of RNFL thinning in patients with OSA was not revealed.Objectives: To investigate the relationship of RNFL thickness with nocturnal hypoxemia or hypoxemic burden in a large-scale study.Methods: In this epidemiological study, 8,309 community residents were enrolled. The actigraphy-modified 3% oxygen desaturation index (acti-ODI3%) and cumulative percentage of sleep time with oxygen saturation <90% (acti-CT90) modified by objective sleep duration using actigraphy were measured. The hypoxemic burden is shown as acti-CT90. Circumpapillary RNFL thickness was determined using optical coherence tomography.Results: Multivariable logistic analysis models revealed that an increase in acti-CT90 was significantly associated with mean RNFL thinning after adjusting for several factors in participants without glaucoma diagnosed or treated previously (β = -0.037; P = 0.009). There were significant differences in mean RNFL thickness among participants stratified according to acti-CT90 (>1.5 vs. ⩽1.5; P = 0.04). Although acti-ODI3% was significantly associated with acti-CT90 (β = 0.72; P < 0.0001), acti-ODI3% was not significantly associated with mean RNFL thickness in the multivariable logistic analysis (β = -0.011; P = 0.48). In addition, acti-CT90 was significantly associated with mean RNFL thickness both in the elderly (⩾60 yr; β = -0.058; P = 0.002) and nonelderly (<60 yr; β = -0.054; P = 0.007).Conclusions: Acti-CT90, but not acti-ODI3%, was associated with mean RNFL thinning in participants irrespective of age in the elderly or nonelderly. Further prospective studies are required to investigate whether the prevention of hypoxic burden, which was shown as acti-CT90 in this study, is favorable for RNFL thinning.

Study of the ganglion cell complex of the macula by optical coherence tomography in the diagnosis of glaucoma progression

INTRODUCTION

The aim of this work is to evaluate the usefulness of the study of the ganglion cell complex of the macula using the OCT technique to estimate the progression of glaucoma according to its severity.

MATERIAL AND METHODS

This is a retrospective cross-sectional study. It includes 205 eyes of 131 patients with glaucoma or ocular hypertension followed for a mean of 5.7 years. The parameters and rates of three tests have been analyzed using the progression software of each instrument: visual field, optical coherence tomography (OCT) in the ganglion cell complex of the macula and in the nerve fiber layer of the optic nerve. The results of each test, the concordance between them and how they differ according to severity stage have been evaluated.

RESULTS

Visual field classifies more cases of progression in moderate-advanced glaucoma, while in mild glaucoma its capacity is limited. Optic nerve fiber layer OCT classifies more cases of progression in mild glaucoma than in moderate-advanced glaucoma, as it is artifacted by the floor effect. OCT of the macular ganglion cell complex is the test that classifies more cases of progression and has the highest agreement with visual field, regardless of severity.

CONCLUSION

In both mild and moderate-advanced glaucoma, OCT of the macula ganglion cell complex may be a better biomarker of progression than OCT of the macula ganglion cell complex.

Correlations between Steady-State Pattern Electroretinogram and Humphrey Visual Field Analyzer Global Indices and Their Associations with Retinal Ganglion Cell Layer-Inner Plexiform Layer Thickness in Glaucoma Suspects

Purpose

The purpose of this study was to investigate the utility of steady state pattern electroretinogram (ss-PERG) in detecting retinal ganglion cell (RGC) dysfunction in glaucoma suspects (GS) who had normal 24-2 Humphrey Visual Fields (HFA).

Materials and Methods

This was a prospective cohort study of GS patients who were identified based on optic disc appearance with normal HFAs. Patients received a complete eye examination, standard automated perimetry (SAP), optical coherence tomography (OCT), and ss-PERG measurements. The ss-PERG parameters, Magnitude (Mag), Magnitude D (MagD), and MagD/Mag ratio, were examined, along with their relationships between HFA and OCT measurements.

Results

Twenty-five patients were included in this study, with a total of 49 eyes. Fifteen eyes had abnormal ss-PERG parameters and when compared to GS eyes with normal ss-PERG parameters, there were significant differences in HFA 24-2, retinal nerve fiber layer (RNFL) thickness, and ganglion cell layer and inner plexiform layer (GCL + IPL) thickness. All ss-PERG parameters were significantly correlated with 24-2 VF mean deviation (MD) and visual field index (VFI), as well as 10-2 VF MD after controlling for age, sex, intraocular pressure, central corneal thickness, and spherical equivalent. When controlled for age, spherical equivalent, and IOP, MagD/Mag ratio significantly contributed to the variance in average GCL + IPL thicknesses, whereas 24-2 VF MD and 10-2 VF MD did not. MagD/Mag ratio also significantly accounted for variance in all macular GCL + IPL sectors, while 10-2 VF MD did not.

Conclusions

ss-PERG has significant correlations with HFA global indices and was predictive of GCL + IPL thickness in GS patients. Clinical Significance. ss-PERG may serve as a useful functional tool for detecting and measuring RGC dysfunction in GS. It appears to be more sensitive than HFA in the detection of early changes in GCL + IPL thicknesses and may be helpful to use in conjunction with current diagnostic studies to improve the ability of monitoring GS progression.

An Artificial Intelligence Enabled System for Retinal Nerve Fiber Layer Thickness Damage Severity Staging

Purpose

To develop an objective glaucoma damage severity classification system based on OCT-derived retinal nerve fiber layer (RNFL) thickness measurements.

Design

Algorithm development for RNFL damage severity classification based on multicenter OCT data.

Subjects and Participants

A total of 6561 circumpapillary RNFL profiles from 2269 eyes of 1171 subjects to develop models, and 2505 RNFL profiles from 1099 eyes of 900 subjects to validate models.

Methods

We developed an unsupervised k-means model to identify clusters of eyes with similar RNFL thickness profiles. We annotated the clusters based on their respective global RNFL thickness. We computed the optimal global RNFL thickness thresholds that discriminated different severity levels based on Bayes' minimum error principle. We validated the proposed pipeline based on an independent validation dataset with 2505 RNFL profiles from 1099 eyes of 900 subjects.

Main Outcome Measures

Accuracy, area under the receiver operating characteristic curve, and confusion matrix.

Results

The k-means clustering discovered 4 clusters with 1382, 1613, 1727, and 1839 samples with mean (standard deviation) global RNFL thickness of 58.3 (8.9) μm, 78.9 (6.7) μm, 87.7 (8.2) μm, and 101.5 (7.9) μm. The Bayes' minimum error classifier identified optimal global RNFL values of > 95 μ m , 86 to 95 μ m , 70 to 85 μ m , and < 70 μ m for discriminating normal eyes and eyes at the early, moderate, and advanced stages of RNFL thickness loss, respectively. About 4% of normal eyes and 98% of eyes with advanced RNFL loss had either global, or ≥ 1 quadrant, RNFL thickness outside of normal limits provided by the OCT instrument.

Conclusions

Unsupervised machine learning discovered that the optimal RNFL thresholds for separating normal eyes and eyes with early, moderate, and advanced RNFL loss were 95 μ m , 85 μm, and 70 μ m , respectively. This RNFL loss classification system is unbiased as there was no preassumption or human expert intervention in the development process. Additionally, it is objective, easy to use, and consistent, which may augment glaucoma research and day-to-day clinical practice.

Financial Disclosures

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

IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors

There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.

Structure-function relationship and diagnostic value of macular ganglion cell complex measurement using Fourier-domain OCT in glaucoma

PURPOSE

To evaluate the relationship between visual function and macular ganglion cell complex (GCC) thickness measured by Fourier-domain optical coherence tomography (OCT) and evaluate the diagnostic value of GCC measurement compared to retinal nerve fiber layer (RNFL) thickness and macular thickness in detecting early, moderate, and severe glaucomas.

METHODS

Subjects underwent standard automated perimetry (SAP), OCT imaging with optic nerve head mode and GCC mode. The relationship between OCT parameters (mean GCC thickness, mean RNFL thickness, and macular thickness) and perimetry global indices (mean deviation [MD] and pattern standard deviation [PSD]) was evaluated by regression analysis. Diagnostic values of mean RNFL thickness, GCC parameters, and macular thickness were compared with the area under the receiver operating characteristic curves (AUC).

RESULTS

A total of 84 eyes, 42 of each normal and primary open-angle glaucoma patients were included in the study. Compared with linear models, second-order polynomial models better described relationships between GCC thickness and MD ( P < 0.001), and between GCC thickness and PSD ( P = 0.00). RNFL parameter, inferior RNFL thickness had the highest AUC for detecting early glaucoma. The AUC of mean GCC thickness for early glaucoma was higher than that of mean RNFL; however, the difference was not significant ( P = 0.09), which was higher than that of macular thickness.

CONCLUSION

The relationship between visual field (VF) sensitivity and GCC thickness is best expressed by the curvilinear function. Macular GCC thickness and RNFL thickness showed similar diagnostic values but were better than macular thickness for detecting early glaucoma but inferior to macular thickness and RNFL thickness for detecting moderate glaucoma.

Hemifield-based analysis of pattern electroretinography in normal subjects and patients with preperimetric glaucoma

This prospective cross-sectional study investigated the visual function of preperimetric glaucoma (PPG) patients based on hemifield (HF) pattern electroretinogram (PERG) amplitudes. Thirty-two (32) normal subjects and 33 PPG patients were enrolled in control and PPG groups, respectively. All of the participants had undergone full ophthalmic examinations, including spectral-domain optical coherence tomography (SD-OCT), visual field (VF) examination and pattern electroretinography (PERG). The PERG parameters along with the HF ratios of SD-OCT and PERG were compared between the control and PPG groups. Pairwise Pearson's correlation coefficients and linear regression models were fitted to investigate the correlations. The PERG N95 amplitudes were significantly lower in the PPG group (P < 0.001). The smaller/larger HF N95 amplitude ratio of the PPG group was found to be smaller than that of the control group (0.73 ± 0.20 vs. 0.86 ± 0.12; P = 0.003) and showed positive correlations with affected HF average ganglion cell-inner plexiform layer (GCIPL) thickness (r = 0.377, P = 0.034) and with average GCIPL thickness (r = 0.341, P = 0.005). The smaller/larger HF N95 amplitude ratio did not significantly change with age (β =  - 0.005, P = 0.195), whereas the full-field N95 amplitude showed a negative correlation with age (β =  - 0.081, P < 0.001). HF analysis of PERG N95 amplitudes might be particularly useful for patients with early glaucoma.

Comparison of the Circumpapillary Structure-Function and Vasculature-Function Relationships at Different Glaucoma Stages Using Longitudinal Data

Purpose

This study investigated the global and regional correlations between longitudinal structure-function (S-F) and vasculature-function (V-F) data using circumpapillary retinal nerve fiber layer thickness (cpRNFLT) measurements from optical coherence tomography (OCT), circumpapillary vessel density (cpVD) from OCT angiography (OCTA), and the corresponding visual field mean sensitivities at different glaucoma stages.

Methods

A total of 107 eyes from 107 glaucoma patients with progressive visual field (VF) changes followed up for an average of 3.33 ± 1.39 years were enrolled, including early-to-moderate (51 eyes) and advanced (56 eyes) stages. The rates of longitudinal change in the VF mean deviation (MD), cpRNFLT, and cpVD were evaluated using linear mixed-effects models and compared between different glaucoma stages. Longitudinal global and regional S-F and V-F relationships were assessed by repeated measures correlation analysis by glaucoma stage.

Results

No significant differences were found in the rates of VF MD and cpVD changes (P > 0.05) between the two glaucoma stage groups. CpRNFLT decreased more rapidly in the early-to-moderate stage group (P < 0.001) in which significant longitudinal global and regional correlations were found in both S-F and V-F relationships (all P < 0.05), except for the nasal sector. Significant global and regional correlations were only found in V-F relationship in advanced stage cases (all P < 0.05).

Conclusions

Significant longitudinal V-F relationships exist globally and regionally regardless of glaucoma stage but no longitudinal S-F relationship is present in advanced glaucoma. Longitudinal follow-up of cpVD parameters may be useful for monitoring glaucomatous VF progression at all disease stages.

Macular Oxygen Saturation in Glaucoma Using Retinal Oximetry of Visible Light Optical Coherence Tomography

Purpose

Oxygen saturation (sO2) plays a critical role in retinal pathophysiology, especially at the macula, which undergoes significant energy consumption. While macular damage has been suggested to be involved in early-stage glaucoma, there has been no report to date on non-invasive macular sO2 in glaucoma. Therefore, we conducted this study to compare macular sO2 associated with other clinical measurements between normal and glaucoma subjects and evaluate whether there are significant differences.

Method

This is a cross-sectional study. We used visible light optical coherence tomography (VIS-OCT) for retinal oximetry in perifoveal vessels. The subjects from groups of normal, suspect/pre-perimetric glaucoma (GS/PPG) and perimetric glaucoma (PG) were scanned using VIS-OCT in the macular region with a sampling density of 512×256 in an area of 5×5 mm2. 48 eyes (16 normal, 17 GS/PPG and 15 PG) were included for the analysis. For each eye, we measured the sO2 of arterioles (AsO2), venules (VsO2), and calculated the difference between arterioles and venules (A-V sO2=AsO2-VsO2), oxygen extraction (OE=(AsO2-VsO2)/AsO2 ×100%). Additionally, we included Zeiss Cirrus OCT scans and 24-2 visual field test (VFT) for clinical benchmark. One-way ANOVA was used to compare the differences among the three groups. Spearman correlation tests were used for correlation sO2 markers to standard metrics including the thickness of ganglion cell layer and inner plexiform layer (GCL+IPL), circumpapillary retinal nerve fiber layer (cpRNFL) and mean deviation (MD) in VFT.

Result

Significant differences were found among three groups for all VIS-OCT, Zeiss OCT, and VFT variables. Macular AsO2, A-V sO2, OE decreased, and VsO2 increased along with severity. Macular AsO2 and A-V sO2 were statistically correlated with GCL+IPL and cpRNFL in all eyes, as well as only PG eyes. Within PG eyes, the correlation between AsO2 and GCL+IPL is dominant in more damaged lower hemifield.

Conclusion

The GS/PPG and PG subjects had significantly higher macular VsO2, lower A-V sO2 and OE indicating less oxygen consumption. The sO2 measured by retinal oximetry of VIS-OCT can be a potential metric for the early diagnosis of glaucoma.

The ganglion cell complex damage in coronary artery disease

PURPOSE

This study aims to investigate the correlation between macular thickness, retinal nerve fiber layer thickness, ganglion cell complex thickness, and Gensini scores in patients who have undergone coronary angiography, using spectral-domain optical coherence tomography.

METHODS

We retrospectively evaluated optical coherence tomography results from patients who had undergone coronary angiography between January 2019 and January 2021 due to coronary artery disease, with angiography performed within one month of the optical coherence tomography examination. Based on their Gensini scores, patients were classified into two groups: mild coronary artery disease (Gensini score ≤ 20, Group 1) and severe coronary artery disease (Gensini score > 20, Group 2).

RESULTS

Group 1 comprised 28 patients with an average age of 61.3 ± 10.2, while Group 2 consisted of 25 patients with an average age of 65.4 ± 9.6. While there was no statistically significant difference found in retinal nerve fiber layer and macular thickness between the groups, the ganglion cell complex thickness was significantly thinner in Group 2 in the inner superior temporal (112.55 ± 34.12 µm vs. 99.68 ± 37.81 µm, p = 0.026), inner superior nasal (121.14 ± 32.92 µm vs. 108.36±24.53 µm, p = 0.012), inner inferior nasal (120.81 ± 32.34 µm vs. 108.45 ± 12.53 µm, p = 0.048), and superior (99.11 ± 25.91 µm vs. 88.77 ± 16.75 µm, p = 0.020) regions. Furthermore, a significant negative correlation was observed between the Gensini score and the ganglion cell complex thickness in both the inner superior nasal and superior regions.

CONCLUSION

Compared to patients with mild coronary artery disease, those with severe disease exhibited a significant decrease in ganglion cell complex thickness in the superior and inner superior nasal regions.

Prediction of Central Visual Field Measures From Macular OCT Volume Scans With Deep Learning

Purpose

Predict central 10° global and local visual field (VF) measurements from macular optical coherence tomography (OCT) volume scans with deep learning (DL).

Methods

This study included 1121 OCT volume scans and 10-2 VFs from 289 eyes (257 patients). Macular scans were used to estimate 10-2 VF mean deviation (MD), threshold sensitivities (TS), and total deviation (TD) values at 68 locations. A three-dimensional (3D) convolutional neural network based on the 3D DenseNet121 architecture was used for prediction. We compared DL predictions to those from baseline linear models. We carried out 10-fold stratified cross-validation to optimize generalizability. The performance of the DL and baseline models was compared based on correlations between ground truth and predicted VF measures and mean absolute error (MAE; ground truth - predicted values).

Results

Average (SD) MD was -9.3 (7.7) dB. Average (SD) correlations between predicted and ground truth MD and MD MAE were 0.74 (0.09) and 3.5 (0.4) dB, respectively. Estimation accuracy deteriorated with worsening MD. Average (SD) Pearson correlations between predicted and ground truth TS and MAEs for DL and baseline model were 0.71 (0.05) and 0.52 (0.05) (P < 0.001) and 6.5 (0.6) and 7.5 (0.5) dB (P < 0.001), respectively. For TD, correlation (SD) and MAE (SD) for DL and baseline models were 0.69 (0.02) and 0.48 (0.05) (P < 0.001) and 6.1 (0.5) and 7.8 (0.5) dB (P < 0.001), respectively.

Conclusions

Macular OCT volume scans can be used to predict global central VF parameters with clinically relevant accuracy.

Translational Relevance

Macular OCT imaging may be used to confirm and supplement central VF findings using deep learning.

Clinical usefulness of layer-by-layer deviation maps of Spectralis OCT: comparison with Cirrus OCT

BACKGROUND/AIMS

To compare the diagnostic abilities of Spectralis (Heidelberg Engineering, Heidelberg, Germany) and Cirrus (Carl Zeiss Meditec, Dublin, California, USA) spectral domain-optical coherence tomography (OCT) for retinal nerve fibre layer (RNFL) defect detection among patients with preperimetric glaucoma (PPG) and early glaucoma (EG).

METHODS

In this cross-sectional study, a total of 144 eyes (47 healthy, 43 PPG, 54 EG; MD≥-6 dB) of 144 participants underwent Spectralis and Cirrus OCT on the same day. The presence of RNFL defect on red-free RNFL photography and the respective deviation maps of Spectralis and Cirrus OCT was rated. Areas under the receiver operating characteristic curves (AUCs), sensitivities and specificities were analysed for each deviation layer to discriminate healthy eyes from PPG and EG eyes.

RESULTS

The RNFL, ganglion cell layer (GCL) and retinal layers of Spectralis OCT and the RNFL and macular ganglion cell-inner plexiform layer of Cirrus OCT showed high diagnostic performance (all AUCs >0.8) in discriminating PPG and EG eyes from healthy eyes. Among them, RNFL layer of Cirrus OCT had the largest AUC (0.840 for PPG, 0.959 for EG) but showed no statistical differences from RNFL and retinal layers of Spectralis OCT. The inner plexiform layer (IPL) of Spectralis OCT had the smallest AUC (0.563 for PPG, 0.799 for EG).

CONCLUSIONS

The Spectralis and Cirrus OCT deviation maps showed good diagnostic abilities except for the IPL layer of Spectralis. In the clinical setting, both Spectralis and Cirrus OCT can be useful for detection of RNFL defects in PPG and EG eyes.

Regional Vessel Density Reduction in the Macula and Optic Nerve Head of Patients With Pre-Perimetric Primary Open Angle Glaucoma

PRCIS

Capillary and neuronal tissue loss occur both globally and with regional specificity in pre-perimetric glaucoma patients at the level of the optic nerve and macula, with perifovea regions affected earlier than parafovea areas.

PURPOSE

To investigate optic nerve head (ONH) and macular vessel densities (VD) and structural parameters assessed by optical coherence tomography angiography in pre-perimetric open angle glaucoma (ppOAG) patients and healthy controls.

MATERIALS AND METHODS

In all, 113 healthy and 79 ppOAG patients underwent global and regional (hemispheric/quadrants) assessments of retinal, ONH, and macular vascularity and structure, including ONH parameters, retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness. Comparisons between outcomes in ppOAG and controls were adjusted for age, sex, race, BMI, diabetes, and hypertension, with P <0.05 considered statistically significant.

RESULTS

In ppOAG compared with healthy controls: RNFL thicknesses were statistically significantly lower for all hemispheres, quadrants, and sectors ( P <0.001-0.041); whole image peripapillary all and small blood vessels VD were statistically significantly lower for all the quadrants ( P <0.001-0.002), except for the peripapillary small vessels in the temporal quadrant (ppOAG: 49.66 (8.40), healthy: 53.45 (4.04); P =0.843); GCC and inner and full macular thicknesses in the parafoveal and perifoveal regions were significantly lower in all the quadrants ( P =0.000- P =0.033); several macular VD were significantly lower ( P =0.006-0.034), with the exceptions of macular center, parafoveal superior and inferior quadrant, and perifoveal superior quadrant ( P >0.05).

CONCLUSIONS

In ppOAG patients, VD biomarkers in both the macula and ONH, alongside RNFL, GCC, and macular thickness, were significantly reduced before detectable visual field loss with regional specificity. The most significant VD reduction detected was in the peripheric (perifovea) regions. Macular and ONH decrease in VD may serve as early biomarkers of glaucomatous disease.

The Curvature, Collagen Network Structure, and Their Relationship to the Pressure-Induced Strain Response of the Human Lamina Cribrosa in Normal and Glaucoma Eyes

The lamina cribrosa (LC) is a connective tissue in the optic nerve head (ONH). The objective of this study was to measure the curvature and collagen microstructure of the human LC, compare the effects of glaucoma and glaucoma optic nerve damage, and investigate the relationship between the structure and pressure-induced strain response of the LC in glaucoma eyes. Previously, the posterior scleral cups of 10 normal eyes and 16 diagnosed glaucoma eyes were subjected to inflation testing with second harmonic generation (SHG) imaging of the LC and digital volume correlation (DVC) to calculate the strain field. In this study, we applied a custom microstructural analysis algorithm to the maximum intensity projection of SHG images to measure features of the LC beam and pore network. We also estimated the LC curvatures from the anterior surface of the DVC-correlated LC volume. Results showed that the LC in glaucoma eyes had larger curvatures p≤0.03), a smaller average pore area (p = 0.001), greater beam tortuosity (p < 0.0001), and more isotropic beam structure (p = 0.01) than in normal eyes. The difference measured between glaucoma and normal eyes may indicate remodeling of the LC with glaucoma or baseline differences that contribute to the development of glaucomatous axonal damage.

Structure-function relationship in glaucoma: Optical coherence tomography en face imaging vs. red-free fundus photography

BACKGROUND/OBJECTIVES

To analyse retinal nerve fibre layer (RNFL) defect measurements obtained from red-free fundus photography and optical coherence tomography (OCT) en face imaging, respectively, and to compare them for the strength of the structure-function association.

SUBJECTS/METHODS

Two hundred and fifty-six glaucomatous eyes of 256 patients with localized RNFL defect on red-free fundus photography were enrolled. A subgroup analysis included 81 highly myopic eyes (≤ -6.0 dioptres). Angular width of RNFL defect was compared between red-free fundus photography (i.e., red-free RNFL defect) and OCT en face imaging (i.e., en face RNFL defect). The correlation between angular width of each RNFL defect and functional outcomes, reported as mean deviation (MD) and pattern standard deviation (PSD), were assessed and compared.

RESULTS

The angular width of en face RNFL defect was measured smaller than that of red-free RNFL defect in 91.0% eyes (mean difference, 19.98°). The association of en face RNFL defect with MD and PSD was stronger (R2 = 0.311 and R2 = 0.372, respectively) than that of red-free RNFL defect with MD and PSD (R2 = 0.162 and R2 = 0.137, respectively) (P < 0.05 for all). Especially in highly myopic eyes, the association of en face RNFL defect with MD and PSD was much stronger (R2 = 0.503 and R2 = 0.555, respectively) than that of red-free RNFL defect with MD and PSD (R2 = 0.216 and R2 = 0.166, respectively) (P < 0.05 for all).

CONCLUSIONS

En face RNFL defect showed a higher correlation with severity of visual field loss than did red-free RNFL defect. The same dynamic was observed for highly myopic eyes.

Retinal ganglion cell repopulation for vision restoration in optic neuropathy: a roadmap from the RReSTORe Consortium

Retinal ganglion cell (RGC) death in glaucoma and other optic neuropathies results in irreversible vision loss due to the mammalian central nervous system's limited regenerative capacity. RGC repopulation is a promising therapeutic approach to reverse vision loss from optic neuropathies if the newly introduced neurons can reestablish functional retinal and thalamic circuits. In theory, RGCs might be repopulated through the transplantation of stem cell-derived neurons or via the induction of endogenous transdifferentiation. The RGC Repopulation, Stem Cell Transplantation, and Optic Nerve Regeneration (RReSTORe) Consortium was established to address the challenges associated with the therapeutic repair of the visual pathway in optic neuropathy. In 2022, the RReSTORe Consortium initiated ongoing international collaborative discussions to advance the RGC repopulation field and has identified five critical areas of focus: (1) RGC development and differentiation, (2) Transplantation methods and models, (3) RGC survival, maturation, and host interactions, (4) Inner retinal wiring, and (5) Eye-to-brain connectivity. Here, we discuss the most pertinent questions and challenges that exist on the path to clinical translation and suggest experimental directions to propel this work going forward. Using these five subtopic discussion groups (SDGs) as a framework, we suggest multidisciplinary approaches to restore the diseased visual pathway by leveraging groundbreaking insights from developmental neuroscience, stem cell biology, molecular biology, optical imaging, animal models of optic neuropathy, immunology & immunotolerance, neuropathology & neuroprotection, materials science & biomedical engineering, and regenerative neuroscience. While significant hurdles remain, the RReSTORe Consortium's efforts provide a comprehensive roadmap for advancing the RGC repopulation field and hold potential for transformative progress in restoring vision in patients suffering from optic neuropathies.

Intraocular Pressure and Rates of Macular Thinning in Glaucoma

PURPOSE

To evaluate the effect of intraocular pressure (IOP) on the rates of macular thickness (ganglion cell layer [GCL] and ganglion cell-inner plexiform layer [GCIPL]) change over time measured by spectral-domain (SD) OCT.

DESIGN

Retrospective cohort study.

PARTICIPANTS

Overall, 451 eyes of 256 patients with primary open-angle glaucoma.

METHODS

Data were extracted from the Duke Ophthalmic Registry, a database of electronic medical records of patients observed under routine clinical care at the Duke Eye Center, and satellite clinics. All records from patients with a minimum of 6 months of follow-up and at least 2 good-quality Spectralis SD-OCT macula scans were included. Linear mixed models were used to investigate the relationship between average IOP during follow-up and rates of GCL and GCIPL thickness change over time.

MAIN OUTCOME MEASURES

The effect of IOP on the rates of GCL and GCIPL thickness loss measured by SD-OCT.

RESULTS

Eyes had a mean follow-up of 1.8 ± 1.3 years, ranging from 0.5 to 10.2 years. The average rate of change for GCL thickness was -0.220 μm/year (95% confidence interval [CI], -0.268 to -0.172 μm/year) and for GCIPL thickness was -0.231 μm/year (95% CI, -0.302 to -0.160 μm/year). Each 1-mmHg higher mean IOP during follow-up was associated with an additional loss of -0.021 μm/year of GCL thickness (P = 0.001) and -0.032 μm/year of GCIPL thickness (P = 0.001) after adjusting for potentially confounding factors, such as baseline age, disease severity, sex, race, central corneal thickness, and follow-up time.

CONCLUSIONS

Higher IOP was significantly associated with faster rates of GCL and GCIPL loss over time measured by SD-OCT, even during relatively short follow-up times. These findings support the use of SD-OCT GCL and GCIPL thickness measurements as structural biomarkers for the evaluation of the efficacy of IOP-lowering therapies in slowing down the progression of glaucoma.

FINANCIAL DISCLOSURE(S)

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

Using high-density perimetry to explore new approaches for characterizing visual field defects

High-density threshold perimetry has found that conventional static threshold perimetry misses defects due to undersampling. However, high-density testing can be both slow and limited by normal fixational eye movements. We explored alternatives by studying displays of high-density perimetry results for angioscotomas in healthy eyes-areas of reduced sensitivity in the shadows of blood vessels. The right eyes of four healthy adults were tested with a Digital Light Ophthalmoscope that gathered retinal images while presenting visual stimuli. The images were used to infer stimulus location on each trial. Contrast thresholds for a Goldmann size III stimulus were measured at 247 locations of a 13°×19° rectangular grid, with separation 0.5°, extending from 11° to 17° horizontally and -3° to +6° vertically, covering a portion of the optic nerve head and several major blood vessels. Maps of perimetric sensitivity identified diffuse regions of reduced sensitivity near the blood vessels, but these showed moderate structure-function agreement that was only modestly improved when effects of eye position were accounted for. An innovative method termed slice display was used to locate regions of reduced sensitivity. Slice display demonstrated that many fewer trials could yield similar structure-function agreement. These results are an indication that test duration might be reduced dramatically by focusing on location of defects rather than maps of sensitivity. Such alternatives to conventional threshold perimetry have the potential to map the shape of defects without the extensive time demands of high-density threshold perimetry. Simulations illustrate how such an algorithm could operate.

Long-Term Changes in Retinal Nerve Fiber Layer Thickness after Vitrectomy for Epiretinal Membrane Using Optical Coherence Tomography Images

This study investigated the long-term effects of epiretinal membrane (ERM) surgery on peripapillary retinal nerve fiber layer (RNFL) thickness using optical coherence tomography (OCT) images. We included 30 patients with idiopathic ERM who underwent a vitrectomy for ERM removal with internal limiting membrane peeling. The patients were followed up for 5 years after surgery, and their medical records were reviewed for best-corrected visual acuity (BCVA) and OCT parameters. The study population comprised 24 females (80.0%), and the mean age was 65.4 ± 7.2 years. The baseline BCVA significantly improved from 0.28 ± 0.24 to 0.12 ± 0.09 logMAR (p < 0.001) 1 year after surgery and continued to improve for 5 years after surgery. The peripapillary RNFL thickness initially increased after surgery and then gradually decreased. The peripapillary RNFL thicknesses of the global and temporal sectors showed significant reductions 2 years after surgery, whereas those of the nasal sectors did not significantly change. The peripapillary RNFL thickness was thinner in the global and temporal areas of the operated eyes than in those of the fellow eyes 4 and 5 years after surgery. In conclusion, peripapillary RNFL thicknesses decreased in the global and temporal areas after ERM surgery, whereas peripapillary RNFL thicknesses in the nasal sectors did not change significantly during the long-term follow-up.

Assessment of quality of life in glaucoma patients in a tertiary care center in Eastern India

Purpose

The aim of this study is to assess the quality of life (QOL) in glaucoma patients and find out the sociodemographic factors predicting QOL.

Methods

A cross-sectional study was conducted in a tertiary care center from August 2021 to February 2022. Subjects diagnosed with glaucoma for at least 6 months were enrolled. After taking informed consent, demographic details and detailed history were collected for all patients. Comprehensive eye examination (visual acuity, intraocular pressure, gonioscopy, fundoscopy, visual field assessment, ocular coherence tomogram assessment) was done for all and they were asked to fill the WHOQOL-BREF questionnaire. Data were collected and analyzed using SPSS 21.

Results

One hundred and ninety-nine patients were recruited. Mean age of participants was 57.99 ± 10.76 years. Based on various domains and subgroups, QOL values were significant with respect to income (P = 0.016). Gender-wise QOL in females was lower than that of males with respect to all the domains (P = 0.001). While marital status affected both environmental and social domain, literacy affected only the social domain. A variation in intraocular pressure affected the QOL in the psychological domain. QOL was not significantly associated with the severity of the disease. Gender was the most predominant predictor out of all sociodemographic factors.

Conclusion

Chronic diseases affect the QOL of individuals in many ways. Glaucoma being a chronic disease hampers patients' vision irreversibly and by extension the various physical, social, and psychological aspects of the patient's life as well. Hence, knowledge of the change in QOL it brings about can help plan the treatment, counseling, and management of these patients.

Morpho-Functional Assessment of Retinal Ganglion Cells and Visual Pathways in Patients with Optic Disc Drusen: Superficial Drusen Visible Height as a Marker of Impairment

The aim of this study was to assess the morpho-functional involvement of the retinal ganglion cells (RGCs) and of the visual pathways in patients with superficial (ODD-S) or deep (ODD-D) optic disc drusen. This study enrolled 17 patients with ODD (mean age of 59.10 ± 12.68 years) providing 19 eyes and 20 control subjects (mean age 58.62 ± 8.77 years) providing 20 eyes. We evaluated the following: best-corrected visual acuity, visual field mean deviation (MD), the amplitude (A) of Pattern Electroretinogram (PERG), the implicit time (IT) and A of Visual Evoked Potentials (VEPs), retinal nerve fiber layer thickness (RNFL-T) and ganglion cell thickness (GC-T). In ODD-S eyes, the drusen visible height was measured. ODD-D and ODD-S were detected in 26.3% and 73.7% of ODD eyes, respectively. Significantly (p < 0.01) reduced MD, PERG A, VEP amplitude, RNFL-T and GC-T values and significantly (p < 0.01) increased VEP IT values were found in the ODD Group as compared to the Control one. In the ODD Group, no significant correlation (p > 0.01) between PERG As and VEP ITs was found. In ODD-S, the visible height was significantly correlated (p < 0.01) with reduced MD, PERG As and RNFL-T and with increased PSD and VEP IT values. Our findings suggest that ODD might induce morpho-functional changes in RGCs and their fibers and an unrelated visual pathway dysfunction leading or not leading to visual field defects. The observed morpho-functional impairment should be ascribed to an alteration in retrograde (from the axons to the RGCs) and anterograde (from the RGCs up to the visual cortex) axoplasmic transport. In ODD-S eyes, a minimum visible height of 300 microns represented the threshold for the abnormalities, suggesting that "the higher the ODD, the worse the impairment".

Acute and subacute intraocular pressure and macular microvascular structure changes after intravitreal ranibizumab injection in eyes with branch retinal vein occlusion

PURPOSE

To investigate early changes in the intraocular pressure (IOP) and macular microvascular structure in eyes with branch retinal vein occlusion (BRVO) treated with intravitreal Ranibizumab injection.

METHODS

This study enrolled 30 patients (one eye per patient) who received intravitreal injections (IVI) of ranibizumab for macular edema secondary to BRVO. IOP were measured before, 30 min (min) and 1 month following IVI. Changes in macular microvascular structure were examined via assessment of foveal avascular zone (FAZ) parameters, vascular density (VD) of superficial vascular complex (SVC), and deep vascular complex (DVC) in whole macula, central fovea and parafovea area which were measured automatically by optical coherence tomography angiography (OCTA) on the same time as IOP examinations. Paired t test and Wilcoxon test were used to compare pre- and post-injection values. The correlation between IOP and OCTA findings was assessed.

RESULTS

IOP Measurements at 30 min post-IVI (17.91 ± 3.36 mmHg) increased significantly from baseline (15.07 ± 2.58 mmHg, p < 0.001), then became similar with baseline after 1 month (15.00 ± 3.16 mmHg, p = 0.925). 30 min past the injection, the parameters of VD of the SCP significantly decreased in comparison to baseline, then became similar with baseline after one month, while there were no significant changes in other OCTA parameters, including parameters of VD of the DCP and the FAZ. At 1 month after IVI, in comparison to baseline, no significant changes were observed in all of the OCTA parameters (P > 0.05). There were no significant correlations between IOP and OCTA findings no matter 30 min or 1 month post-IVI (P > 0.05).

CONCLUSIONS

Transient IOP elevation and decreased superficial macular capillary perfusion density were detected 30 min post-IVI, however, no potential continual macular microvascular damage was suspected.

Multifocal electroretinography increases following experimental glaucoma in nonhuman primates with retinal ganglion cell axotomy

PURPOSE

To determine whether short-latency changes in multifocal electroretinography (mfERG) observed in experimental glaucoma (EG) are secondary solely to retinal ganglion cell (RGC) loss or whether there is a separate contribution from elevated intraocular pressure (IOP).

METHODS

Prior to operative procedures, a series of baseline mfERGs were recorded from six rhesus macaques using a 241-element unstretched stimulus. Animals then underwent hemiretinal endodiathermy axotomy (HEA) by placing burns along the inferior 180° of the optic nerve margin in the right eye (OD). mfERG recordings were obtained in each animal at regular intervals following for 3-4 months to allow stabilization of the HEA effects. Laser trabecular meshwork destruction (LTD) to elevate IOP was then performed; first-order kernel (K1) waveform root-mean-square (RMS) amplitudes for the short-latency segment of the mfERG wave (9-35 ms) were computed for two 7-hexagon groupings-the first located within the superior (non-axotomized) macula and the second within the inferior (axotomized) macula. Immunohistochemistry for glial fibrillary acidic protein (GFAP) was done.

RESULTS

By 3 months post HEA, there was marked thinning of the inferior nerve fiber layer as measured by optical coherence tomography. Compared with baseline, no statistically significant changes in 9-35 ms K1 RMS amplitudes were evident in either the axotomized or non-axotomized portions of the macula. Following LTD, mean IOP in HEA eyes rose to 46 ± 9 compared with 20 ± 2 mmHg (SD) in the fellow control eyes. In the HEA + EG eyes, statistically significant increases in K1 RMS amplitude were present in both the axotomized inferior and non-axotomized superior portions of the OD retinas. No changes in K1 RMS amplitude were found in the fellow control eyes from baseline to HEA epoch, but there was a smaller increase from baseline to HEA + EG. Upregulation of GFAP in the Müller cells was evident in both non-axotomized and axotomized retina in eyes with elevated IOP.

CONCLUSIONS

The RMS amplitudes of the short-latency mfERG K1 waveforms are not altered following axotomy but undergo marked increases following elevated IOP. This suggests that the increase in mfERG amplitude was not solely a result of RGC loss and may reflect photoreceptor and bipolar cell dysfunction and/or changes in Müller cells.

FP and EP2 prostanoid receptor agonist drugs and aqueous humor outflow devices for treating ocular hypertension and glaucoma

Prostaglandin (PG) receptors represent important druggable targets due to the many diverse actions of PGs in the body. From an ocular perspective, the discovery, development, and health agency approvals of prostaglandin F (FP) receptor agonists (FPAs) have revolutionized the medical treatment of ocular hypertension (OHT) and glaucoma. FPAs, such as latanoprost, travoprost, bimatoprost, and tafluprost, powerfully lower and control intraocular pressure (IOP), and became first-line therapeutics to treat this leading cause of blindness in the late 1990s to early 2000s. More recently, a latanoprost-nitric oxide (NO) donor conjugate, latanoprostene bunod, and a novel FP/EP3 receptor dual agonist, sepetaprost (ONO-9054 or DE-126), have also demonstrated robust IOP-reducing activity. Moreover, a selective non-PG prostanoid EP2 receptor agonist, omidenepag isopropyl (OMDI), was discovered, characterized, and has been approved in the United States, Japan and several other Asian countries for treating OHT/glaucoma. FPAs primarily enhance uveoscleral (UVSC) outflow of aqueous humor (AQH) to reduce IOP, but cause darkening of the iris and periorbital skin, uneven thickening and elongation of eyelashes, and deepening of the upper eyelid sulcus during chronic treatment. In contrast, OMDI lowers and controls IOP by activation of both the UVSC and trabecular meshwork outflow pathways, and it has a lower propensity to induce the aforementioned FPA-induced ocular side effects. Another means to address OHT is to physically promote the drainage of the AQH from the anterior chamber of the eye of patients with OHT/glaucoma. This has successfully been achieved by the recent approval and introduction of miniature devices into the anterior chamber by minimally invasive glaucoma surgeries. This review covers the three major aspects mentioned above to highlight the etiology of OHT/glaucoma, and the pharmacotherapeutics and devices that can be used to combat this blinding ocular disease.

Early Detection of Primary Open Angle, Angle Closure, and Normal Tension Glaucoma in an Asian Population Using Optical Coherence Tomography

PRCIS

Spectral-domain optical coherence tomography (SD-OCT) facilitates early glaucoma detection in the Chinese population in Taiwan. The best parameters for primary open angle glaucoma (POAG), primary angle closure glaucoma (PACG), normal tension glaucoma (NTG), and suspected glaucoma (GS) detection are temporal inferior Bruch's membrane opening-minimum rim width (BMO-MRW), inner temporal macular ganglion cell layer (mGCL), temporal superior Circumpapillary retinal nerve fiber layer (cpRNFL), and mean global BMO-MRW, respectively.

PURPOSE

We investigated the diagnostic capability of SD-OCT for different types of early glaucoma among the Chinese population in Taiwan.

PARTICIPANTS AND METHODS

One eye each was assessed from 113 individuals with healthy eyes, 125 individuals with suspected glaucoma (GS), and 156 patients with early glaucoma (POAG, 87; PACG, 50; and NTG, 19). Circumpapillary (cp) RNFL thickness (global and sectoral), BMO-MRW, and macular parameters, including the macular RNFL (mRNFL), mGCL, and macular inner plexiform layer (mIPL), were assessed using SD-OCT. The areas under receiver operator characteristic curves (AUCs) were calculated to evaluate the diagnostic capacity of the parameters to differentiate between healthy and early glaucomatous eyes.

RESULTS

The parameters most suitable for detecting early POAG, PACG, NTG, and GS were temporal inferior BMO-MRW (AUC, 0.847), inner temporal mGCL (AUC, 0.770), temporal superior cpRNFL (AUC, 0.861), and mean global BMO-MRW (AUC, 0.768), respectively. Among the macular parameters, the mGCL exhibited the highest diagnostic capacity. The diagnostic capacity of the mGCL was lower than that of cpRNFL and BMO-MRW for POAG and NTG but not PACG. After adjusting for confounding variables in multivariable analysis, the AUC was determined to be 0.935 for POAG and 0.787 for GS.

CONCLUSION

SD-OCT facilitates the detection of early POAG, PACG, and NTG. Using a combination of cpRNFL, BMO-MRW, and macular parameters may enhance their diagnostic capacities. Further studies are necessary to validate these findings.

Basal ganglia lesions may be a risk factor for characteristic features of a glaucomatous optic disc: population-based cohort study in Japan

Background

We conducted a study to investigate the relationship between optic nerve vertical cup-to-disc ratio (VCDR), body and ocular parameters, and brain lesions in middle-aged and above Japanese subjects, because although various risk factors for glaucoma have been previously characterised, it is theorised that there are unidentified neurological components.

Methods

In this population-based, age/gender-stratified, cross-sectional study that involved 2239 Japanese subjects (1127 men and 1112 women) aged 40 years and older (mean age: 59.3±11.7 years) living in the central geographical region of Japan who participated in the National Institute of Longevity Sciences–Longitudinal Study of Aging between 2002 and 2004, 4327 eyes and 2239 obtained MRIs of the head were evaluated. Multivariate mixed model and trend analyses were also performed.

Results

No significant relationship between VCDR and brain lesions, other than basal ganglia lesions, was found. VCDR significantly increased with the high grade of basal ganglia infarct lesions (p=0.0193) and high intraocular pressure (p<0.0001) after adjustment for influential factors using a multivariate mixed model. A significant positive linear trend was observed between the predicted VCDR and the degrees of the basal ganglia lesions (p value trend=0.0096).

Conclusion

Our findings suggest that in subjects with higher grades of basal ganglia lesions, strict attention should be paid to elevated VCDR; however, further studies are needed to support/confirm our results.

Association Between Rate of Ganglion Cell Complex Thinning and Rate of Central Visual Field Loss

Importance

Whether rapid ganglion cell complex (GCC) thinning during an initial follow-up period is associated with rates of central visual field loss over time is unclear but important to understand because risk of glaucoma progression can help guide treatment intensity.

Objective

To investigate the association between the rate of GCC thinning during initial follow-up and the rate of central visual field loss.

Design, Setting, and Participants

This retrospective cohort study assessed patients older than 18 years with glaucoma at a tertiary glaucoma center who were followed up from June 18, 2014, to January 11, 2019. Data analysis for the current study was undertaken in March 2022.

Main Outcomes and Measures

Initial rates of GCC thinning were obtained from global GCC thickness values of the first 3 optical coherence tomography (OCT) scans. Rates of central visual field loss were assessed as the change in central (10-2) visual field mean deviation during the 4.7-year follow-up period by univariable and multivariable linear mixed-effects models. Eyes were categorized as slow (>-1 μm/y) or fast (≤-1 μm/y) progressors based on rates of GCC thinning.

Results

The cohort consisted of 202 eyes of 139 patients (mean [SD] age, 68.7 [10.0] years; 72 male [51.8%]); 44 African American patients (31.7%), 13 Asian patients (9.4%), 80 White patients (57.6%), and 2 patients who identified as other race and ethnicity (1.4%) were analyzed. The rate of GCC change was -0.56 μm/y (95% CI, -0.66 to -0.46 μm/y) during a mean initial follow-up of 1.8 years (95% CI, 1.7-2.0 years). A total of 163 eyes (80.7%) were slow OCT progressors, and 39 (19.3%) were fast OCT progressors, with rates of GCC thinning of -0.3 μm/y (95% CI, -0.4 to -0.2 μm/y) and -1.6 μm/y (-1.8 to -1.3 μm/y), respectively. The rates of 10-2 visual field mean deviation worsening among slow and fast OCT progressors were -0.10 dB/y (95% CI, -0.16 to 0.00 dB/y) and -0.34 dB/y (95% CI, -0.51 to -0.16 dB/y), respectively (difference, -0.26 dB/y; 95% CI, -0.45 to -0.07 dB/y; P = .008).

Conclusions and Relevance

In this cohort study, rapid GCC thinning during an initial follow-up period was associated with faster rates of central visual field decline. These findings support use of longitudinal macular OCT scans assisting clinical decision-making for glaucoma and also may guide possible intensification of therapy in high-risk patients.

The Comparison of Age-related Change in Retinal Nerve Fiber Layer and Ganglion Cell Complex Thicknesses between Glaucoma Suspects and Healthy Individuals

Aim

The purpose of this study is to investigate the difference of change in the retinal nerve fiber layer (RNFL) and the ganglion cell complex (GCC) thickness according to age in glaucoma suspect individuals and healthy subjects.

Materials and methods

Thicknesses of RNFL and GCC were measured with spectral domain optical coherence tomography (SD-OCT) in glaucoma-suspected individuals and healthy subjects. The differences in age, overall mean, four quadrants, and 12 clock-hour sectors of RNFL and overall mean, superior half, and inferior half GCC thicknesses between glaucoma suspects and healthy participants were analyzed and compared using linear regression analyses.

Results

There were 201 glaucoma-suspect individuals and 121 healthy subjects with a mean age of 38.89 and 40.26 years, respectively (p = 0.27). The mean overall RNFL thickness was found to be 97.76 and 97.43 µm in healthy individuals and glaucoma suspects (p = 0.72). The mean overall GCC thickness was found to be 111.30 and 104.67 µm in healthy individuals and glaucoma suspects, respectively (p < 0.001). There was a 0.11 µm decrease per year found in overall GCC thickness in glaucoma suspects and 0.23 µm decreases per year in overall GCC thickness in healthy individuals (p < 0.001). There was a 0.02 µm decrease per year found in overall RNFL thickness in glaucoma suspects and a 0.29 µm decrease per year in overall RNFL thickness in healthy individuals (p < 0.001). However, these per-year decreases in GCC thickness glaucoma suspects and healthy individuals were not found to be statistically significant (p = 0.21); on the other hand, this difference for RNFL thickness was significant (p < 0.001).

Conclusion

It was found that the thicknesses of RNFL and GCC were different between glaucoma suspects and healthy individuals. However, age-related decay in the RNFL and GCC thicknesses was not uniform in healthy individuals and glaucoma suspects.

Clinical significance

It was found that the RNFL thickness and GCC thickness were lower in glaucoma suspects than in healthy controls eyes. However, an age-related decrease of RNFL and GCC thicknesses were found to be less in glaucoma suspects compared with healthy controls.

How to cite this article

Firatli G, Elibol A, Altinbas E, et al. The Comparison of Age-related Change in Retinal Nerve Fiber Layer and Ganglion Cell Complex Thicknesses between Glaucoma Suspects and Healthy Individuals. J Curr Glaucoma Pract 2023;17(1):22-29.

Assessment of optic disk by disk damage likelihood scale staging using slit-lamp biomicroscopy and optical coherence tomography in diagnosing primary open-angle glaucoma

Purpose

The current study was aimed at assessment of optic disk by disk damage likelihood scale (DDLS) staging using slit-lamp biomicroscopy and optical coherence tomography (OCT) in diagnosing primary open-angle glaucoma (POAG) patients.

Methods

This was a cross-sectional observational study of 106 POAG patients, which was conducted from April 2017 to April 2018. All patients underwent slit-lamp fundoscopy with a +78 D lens and high-definition (HD)-OCT, and the vertical cup disk ratios (VCDRs) were recorded. Disk size and neuroretinal rim assessment were done, and the disk was then staged using the recent version, which stages the optic nerve head (ONH) from 1 to 10 as read from the DDLS nomogram table. DDLS scores >5 indicate glaucomatous damage. Pearson coefficient was used to correlate the DDLS staging by slit-lamp biomicroscopy with best-corrected visual acuity (BCVA), intraocular pressure (IOP), disk size, and VCDR and VCDR, mean deviation, and DDLS staging by HD-OCT.

Results

The mean age of the patients was 59.54 ± 6.61 years. The male: female ratio was 2:1. The mean IOP was 16.04 ± 1.97 mmHg, and BCVA was 0.72 ± 0.13 LogMAR units. The mean VCDR on 78 D slit-lamp biomicroscopy was 0.76 ± 0.09 (standard deviation [SD]) (range 0.1-0.77), whereas on HD-OCT, the mean VCDR was 0.81 ± 0.09 (SD) (range 0.07-0.81). The mean deviation on visual field testing in decibels was -14.43 ± 3.31 (SD). The correlation coefficient between DDLS staging by slit-lamp biomicroscopy and DDLS staging by HD-OCT parameters was r = 0.96.

Conclusion

There is a positive correlation between the DDLS system of optic disk evaluation on slit-lamp biomicroscopy and most of the HD-OCT evaluation parameters.

Probing mechanisms and improving management of glaucoma following Boston keratoprosthesis surgery

ENGLISH SUMMARY

Corneal blindness is a leading cause of visual impairment worldwide. The most common treatment is to replace the diseased cornea by standard corneal transplantation. In eyes at high risk of graft failure, the Boston keratoprosthesis type 1 (KPro) can be used to restore vision and is currently the most frequently used artificial cornea in the world. However, glaucoma is a well-known complication of KPro surgery and is the most important threat to vision in KPro-implanted eyes (paper I). This chronic disease is influenced by elevated intraocular pressure (IOP) and damages the optic nerve, leading to progressive vision loss. In KPro patients, glaucoma is highly prevalent and extremely challenging to manage, yet its exact cause remains unknown. The overall purpose of this PhD Thesis (Geoffrion, 2021) was to better understand the mechanisms and how to improve management of glaucoma after KPro implantation. The approaches used in this thesis included investigating one of the largest KPro patient cohorts in North America, with a total of 157 operated patients at that time, as well as studying KPro surgery and outcomes in mice. The first objective was to identify risk factors for glaucoma development and progression after KPro implantation (paper II). Multivariate logistic regression revealed that high preoperative IOP signals a higher risk for both glaucoma development and progression. Stromal and endothelial corneal disorders were less associated with glaucoma progression, while autoimmune and ocular surface diseases precipitated glaucoma development. Second, there is no objective evidence that indicates the best order for glaucoma surgeries and KPro implantation. By comparing medical and surgical management in KPro eyes with either preexisting or de novo glaucoma (paper III), we showed that glaucoma surgery may be performed before or at the time of KPro in eyes with preexisting glaucoma to limit progression without increasing complications. In eyes with de novo glaucoma, glaucoma surgery did not increase complications compared with medications. Third, among glaucoma surgery interventions, the two most frequently implanted glaucoma drainage devices were compared in KPro patients (paper IV). Compared with the Ahmed glaucoma valve, the Baerveldt glaucoma implant was associated with lower failure rates, without increased postoperative complications. Fourth, even with aggressive management, many KPro patients suffer from progressive optic nerve damage, sometimes despite normal IOP. Inflammatory cytokines play an important role in glaucomatous optic neuropathy, but their role in KPro-associated glaucoma is still unknown. By analysing tear fluid of KPro patients by multiplex bead immunoassay (paper V), we identified that cytokines TNF-a, IL-1b, FGF-basic and IFN-g were elevated in KPro patients with glaucoma compared to those without. These cytokines correlated with optic nerve excavation and IOP. For the first time in humans, these results concorded with the elevations of TNF-a and IL-1b documented in the mouse KPro model. Ocular surface inflammation may thus reflect the inflammatory processes that perpetuate glaucoma damage years after KPro surgery. Fifth, we determined that miniaturized mouse KPro implantation requires extensive practice to be used as a reproducible model of glaucoma post-KPro (paper VI). KPro animal models with larger eyes and a full-thickness, 360-degree corneal excision should be prioritized to best validate human outcomes. In conclusion, glaucoma in KPro eyes is a long-lasting and multifactorial process. Most probable mechanisms combine IOP-independent inflammation mediated by TNF-a and IL-1b that prolong glaucoma damage, together with post-surgical angle closure elevating the IOP. Altogether, our results inform glaucoma risk profiling of transplant recipients, improvement of surgical management of KPro patients with glaucoma and development of targeted treatments to minimize glaucomatous damage after KPro. Ultimately, this work has the potential to preserve the vision of thousands of patients who undergo KPro surgery every year worldwide and to provide insight for the role of inflammation in other diseases involving neuronal damage. RÉSUMÉ (FRENCH SUMMARY): La cécité cornéenne est l'une des causes les plus importantes de déficience visuelle dans le monde. Le traitement usuel est de remplacer la cornée malade par une greffe de cornée traditionnelle. Dans les yeux à haut risque d'échec de greffe, la kératoprothèse de Boston de type 1 (KPro) peut rétablir la vision et est la cornée artificielle la plus utilisée au monde. Cependant, le glaucome est une complication importante de la KPro (papier I). Cette maladie chronique est influencée par une pression intraoculaire (PIO) élevée et endommage le nerf optique, menant à une perte de vision. Chez les patients avec KPro, le glaucome est fréquent et difficile à contrôler, mais sa cause exacte demeure inconnue. L'objectif principal de cette thèse est de découvrir les mécanismes et d'optimiser la prise en charge du glaucome après l'implantation de la KPro. Pour ce faire, nous avons investigué l'une des plus grandes cohortes de patients KPro en Amérique du Nord avec un total de 157 patients, ainsi qu'un groupe de souris ayant reçu une implantation de kératoprothèse. Le premier but était d'identifier les facteurs de risque pour le développement et la progression du glaucome après la KPro (papier II). Par régression logistique multivariée, nous avons démontré qu'une PIO préopératoire élevée mène à un plus grand risque de développement et de progression du glaucome. Les maladies cornéennes stromales ou endothéliales sont moins associées à une progression, alors que les maladies autoimmunes ou de la surface oculaire précipitent le développement du glaucome. Deuxièmement, il n'existe aucune donnée objective pour indiquer le meilleur ordre des chirurgies de glaucome et de KPro. En comparant les traitements médicaux et chirurgicaux des yeux KPro avec glaucome (papier III), nous avons démontré que les chirurgies de glaucome peuvent limiter la progression en étant effectuées avant ou pendant l'implantation de KPro dans les yeux avec glaucome préexistant, sans augmenter les complications. Dans le glaucome de novo, les chirurgies de glaucome n'augmentent pas les complications en comparaison aux médicaments. Troisièmement, les deux implants de glaucome les plus communs ont été étudiés chez les patients KPro (papier IV). Comparé à la valve Ahmed, l'implant Baerveldt est associé à des taux d'échec plus bas, sans augmentation des complications. Quatrièmement, même avec une prise en charge agressive, plusieurs patients KPro souffrent de glaucome qui progresse, parfois sans PIO élevée. Les cytokines inflammatoires jouent un rôle dans la pathophysiologie du glaucome, mais leur rôle dans le glaucome associé à la KPro est inconnu. En analysant les larmes de patients KPro (papier V), nous avons identifié que les cytokines TNF-a, IL-1b, FGF-basic et IFN-g sont élevées chez les patients KPro avec glaucome comparé à ceux sans glaucome. Ces cytokines corrèlent avec l'excavation du nerf optique et la PIO. Pour la première fois chez les humains, ces résultats concordent avec les niveaux élevés de TNF-a et IL-1b documentés dans le modèle murin de KPro. L'inflammation de la surface oculaire pourrait donc refléter les processus inflammatoires qui perpétuent le dommage glaucomateux. Cinquièmement, nous avons déterminé que l'implantation de la KPro miniature chez la souris requiert beaucoup de pratique pour être utilisé comme modèle de glaucome post-KPro (papier VI). Des modèles animaux avec des yeux plus larges et une excision cornéenne de pleine épaisseur sur 360 degrés devraient être priorisés pour valider les résultats chez l'humain. En conclusion, le glaucome associé à la KPro est un processus multifactoriel qui persiste à long terme. Les mécanismes probables combinent l'inflammation médiée par TNF-a et IL-1b et une fermeture de l'angle qui augmente la PIO. Nos résultats contribuent à établir les facteurs de risque de glaucome pour les receveurs de KPro, à améliorer leur prise en charge et à développer des thérapies ciblées. Ce travail a le potentiel de préserver la vision de milliers de patients recevant une KPro chaque année dans le monde et d'aider à mieux comprendre le rôle de l'inflammation dans d'autres maladies avec atteinte neuronale.

The Relationship Between the Thickness of cpRNFL in Segments and Intraocular Pressure

Purpose

The aim of this study was to investigate whether the retinal nerve fibre layer (RNFL) in some segments of the optic nerve disc in pathological intraocular pressure is more damaged in eyes without antiglaucoma treatment.

Patients and Methods

The cohort consisted of 69 subjects (122 eyes), 32 males (6x one, 26x both eyes) aged 21 to 76 years and 37 females (4x one and 30x both eyes) aged 22 to 75 years, who were measured to have IOP greater than 21 mmHg (21–36) in routine ambulatory care. Measurements were performed using the Ocular Response Analyser, taking into account corneal hysteresis. RNFL thickness was measured using the Avanti RTVue XR and was assessed in 8 segments (1-IT, 2-TI, 3-TS, 4-ST, 5-SN, 6-NS, 7-NI, 8-IN). The visual field was examined with a fast threshold glaucoma program using the Medmont M700. The overall defect (OD) was evaluated. Pearson’s correlation coefficient r was used to assess the dependence between the selected parameters.

Results

The largest peripapillary changes in RNFL were observed in segments 1, 4, 5 and 8. It should be emphasized that segments 1 and 4 have been temporarily shifted. Segments 5 and 8 then corresponded to the upper (at no. 12) and lower (at no. 6) sectors.

Conclusion

The most important result of this study is the finding that the greatest changes in the RNFL layer were observed in pathological IOP at segment 5 (r=−0.3) and 8 (r=−0.28), at the point where the fibres of the magnocellular retinal ganglion cells enter the retina.

Interplay between aging and other factors of the pathogenesis of age-related macular degeneration

Age-related macular degeneration (AMD) is a complex eye disease with the retina as the target tissue and aging as per definition the most serious risk factor. However, the retina contains over 60 kinds of cells that form different structures, including the neuroretina and retinal pigment epithelium (RPE) which can age at different rates. Other established or putative AMD risk factors can differentially affect the neuroretina and RPE and can differently interplay with aging of these structures. The occurrence of β-amyloid plaques and increased levels of cholesterol in AMD retinas suggest that AMD may be a syndrome of accelerated brain aging. Therefore, the question about the real meaning of age in AMD is justified. In this review we present and update information on how aging may interplay with some aspects of AMD pathogenesis, such as oxidative stress, amyloid beta formation, circadian rhythm, metabolic aging and cellular senescence. Also, we show how this interplay can be specific for photoreceptors, microglia cells and RPE cells as well as in Bruch's membrane and the choroid. Therefore, the process of aging may differentially affect different retinal structures. As an accurate quantification of biological aging is important for risk stratification and early intervention for age-related diseases, the determination how photoreceptors, microglial and RPE cells age in AMD may be helpful for a precise diagnosis and treatment of this largely untreatable disease.

Bioengineering Human Pluripotent Stem Cell-Derived Retinal Organoids and Optic Vesicle-Containing Brain Organoids for Ocular Diseases

Retinal organoids are three-dimensional (3D) structures derived from human pluripotent stem cells (hPSCs) that mimic the retina's spatial and temporal differentiation, making them useful as in vitro retinal development models. Retinal organoids can be assembled with brain organoids, the 3D self-assembled aggregates derived from hPSCs containing different cell types and cytoarchitectures that resemble the human embryonic brain. Recent studies have shown the development of optic cups in brain organoids. The cellular components of a developing optic vesicle-containing organoids include primitive corneal epithelial and lens-like cells, retinal pigment epithelia, retinal progenitor cells, axon-like projections, and electrically active neuronal networks. The importance of retinal organoids in ocular diseases such as age-related macular degeneration, Stargardt disease, retinitis pigmentosa, and diabetic retinopathy are described in this review. This review highlights current developments in retinal organoid techniques, and their applications in ocular conditions such as disease modeling, gene therapy, drug screening and development. In addition, recent advancements in utilizing extracellular vesicles secreted by retinal organoids for ocular disease treatments are summarized.