Glaucomatous Nerve Research Articles

Earliest location of glaucomatous retinal nerve fibre layer damage is determined by intact baseline RNFL thickness profile

Background/aimsTo identify whether an intact retinal nerve fibre layer (RNFL) thickness profile could determine the location of the earliest RNFL defect in glaucoma.MethodsRetrospective longitudinal cohort study of patients with initial...

The Impact of Achieving Target Intraocular Pressure on Glaucomatous Retinal Nerve Fiber Layer Thinning in a Treated Clinical Population

To estimate the effect of being below and above the clinician-set target intraocular pressure (IOP) on rates of glaucomatous retinal nerve fiber layer (RNFL) thinning in a treated real-world clinical population. Retrospective cohort study. A total of 3256 eyes (1923 patients) with ≥5 reliable optical coherence tomography scans and 1 baseline visual field test were included. Linear mixed-effects modeling estimated the effects of the primary independent variables (mean target difference [measured IOP - target IOP] and mean IOP, mm Hg) on the primary dependent variable (RNFL slope, µm/y) while accounting for additional confounding variables (age, biological sex, race, baseline RNFL, baseline pachymetry, and disease severity). A spline term accounted for differential effects when above (target difference >0 mm Hg) and below (target difference ≤0 mm Hg) target pressure. Eyes below and above target had significantly different mean RNFL slopes (-0.44 vs -0.71 µm/y, P < .001). Each 1 mm Hg increase above target had a 0.143 µm/y faster rate of RNFL thinning (P < .001). Separating by disease severity, suspect, mild, moderate, and advanced glaucoma had 0.135 (P = .002), 0.116 (P = .009), 0.203 (P = .02), and 0.65 (P = .22) µm/y faster rates of RNFL thinning per 1 mm Hg increase, respectively. Being above the clinician-set target pressure is associated with more rapid RNFL thinning in suspect, mild, and moderate glaucoma. Faster rates of thinning were also present in advanced glaucoma, but statistical significance was limited by the lower sample size of eyes above target and the optical coherence tomography floor effect.

Astrocytes in the Optic Nerve Are Heterogeneous in Their Reactivity to Glaucomatous Injury.

The optic nerve head is thought to be the site of initial injury to retinal ganglion cell injury in glaucoma. In the initial segment of the optic nerve directly behind the globe, the ganglion cell axons are unmyelinated and come into direct contact to astrocytes, suggesting that astrocytes may play a role in the pathology of glaucoma. As in other parts of the CNS, optic nerve head astrocytes respond to injury by characteristic changes in cell morphology and gene expression profile. Using RNA-sequencing of glaucomatous optic nerve heads, single-cell PCR, and an in-vivo assay, we demonstrate that an up-regulation of astrocytic phagocytosis is an early event after the onset of increased intraocular pressure. We also show that astrocytes in the glial lamina of the optic nerve are apparently functionally heterogeneous. At any time, even in naïve nerves, some of the cells show signs of reactivity-process hypertrophy, high phagocytic activity, and expression of genetic markers of reactivity whereas neighboring cells apparently are inactive. A period of increased intraocular pressure moves more astrocytes towards the reactive phenotype; however, some cells remain unreactive even in glaucomatous nerves.

Rate of Retinal Nerve Fiber Layer Thinning in Glaucomatous Eyes with Optic Disc and Parapapillary Deep-Layer Microvasculature Loss.

Microvasculature dropout in the parapapillary choroidal layer was a more important biomarker of glaucomatous nerve fiber layer thinning when it presented with deep-layer microvasculature of the optic disc rather than when it presents by itself. To characterize open-angle glaucoma (OAG) eyes with optic nerve head (ONH) deep-layer microvasculature dropout (MvD-D) and parapapillary choroidal layer microvasculature dropout (MvD-P) and compare their retinal nerve fiber layer (RNFL) thinning rate. This study included 122 OAG eyes that underwent ≥5 serial spectral-domain optical coherence tomography (OCT) scans during a mean follow-up of 5.4 years. Swept-source OCT angiography (SS-OCTA) was used to evaluate MvD-P and MvD-D. Subjects were classified into three groups according to the presence of MvD-P and MvD-D: (1) no dropout (n=37); (2) solely MvD-P (n=40), and (3) both MvD-P and MvD-D (n=45). The RNFL thinning rate was compared among the three groups, and the associated factors were assessed by Cox proportional hazard analysis. RNFL thinning rates were highest in the group with both MvD-P and MvD-D, followed by the group with solely MvD-P and finally by the no dropout group (-0.24 vs. -0.65 vs. -1.20μm/year, P<0.001). Thinner central corneal thickness (hazard ratio [HR]=0.990, P=0.003), presence of disc hemorrhage (HR=1.802, P=0.035), and coexistence of MvD-P and MvD-D (HR=2.941, P<0.001) were the factors associated with RNFL thinning. The coexistence of MvD-P and MvD-D was associated with faster RNFL thinning than MvD-P alone or no dropout, which suggested that observing the optic disc deep microvasculature along with parapapillary choroidal layer using SS-OCTA may be clinically relevant in monitoring glaucoma progression.

Development of a deep learning system to detect glaucoma using macular vertical optical coherence tomography scans of myopic eyes

Myopia is one of the risk factors for glaucoma, making accurate diagnosis of glaucoma in myopic eyes particularly important. However, diagnosis of glaucoma in myopic eyes is challenging due to the frequent associations of distorted optic disc and distorted parapapillary and macular structures. Macular vertical scan has been suggested as a useful tool to detect glaucomatous retinal nerve fiber layer loss even in highly myopic eyes. The present study was performed to develop and validate a deep learning (DL) system to detect glaucoma in myopic eyes using macular vertical optical coherence tomography (OCT) scans and compare its diagnostic power with that of circumpapillary OCT scans. The study included a training set of 1416 eyes, a validation set of 471 eyes, a test set of 471 eyes, and an external test set of 249 eyes. The ability to diagnose glaucoma in eyes with large myopic parapapillary atrophy was greater with the vertical than the circumpapillary OCT scans, with areas under the receiver operating characteristic curves of 0.976 and 0.914, respectively. These findings suggest that DL artificial intelligence based on macular vertical scans may be a promising tool for diagnosis of glaucoma in myopic eyes.

Multicolor imaging compared with red-free fundus photography in the detection of glaucomatous retinal nerve fiber layer thinning

BackgroundTo compare the ability of multicolor imaging (MCI) with red-free fundus photography (RFP) to detect glaucomatous retinal nerve fiber layer (RNFL) thinning. MethodsA total of 127 eyes of 79 patients with glaucoma underwent MCI using blue light, RFP, and circumpapillary optical coherence tomography (OCT) scanning on the same day. Angular location and width of the RNFL defects (RNFLDs) identified on the MCI and RFP were independently measured, and compared with those of RNFL thinning indicated by abnormal color codes on OCT. ResultsThe angular location and width of the RNFLDs determined by both MCI and RFP were well correlated with those of RNFL thinning determined by OCT (all P ≤ 0.013). The correlation of angular width with OCT was significantly stronger for MCI than for RFP (R = 0.708 vs. R = 0.616, P = 0.009). The superiority of MCI to RFP in the detection of OCT-determined RNFL thinning was significant in the inferior (P = 0.025) and marginally significant in the superior (P = 0.084) hemisectors. Thinner RNFL and longer axial length were significantly associated with better visualization of RNFLD by MCI than by RFP, respectively in the superior (OR = 0.948, P = 0.048) and inferior (OR = 1.490, P = 0.012) hemisectors. ConclusionsRNFLD on MCI correlated well with OCT measurement of RNFL thinning in eyes with glaucoma. MCI performed better than conventional RFP in the detection of OCT-determined RNFL thinning, specifically in eyes with thinner RNFL and those with myopia. MCI may be more useful than conventional RFP in evaluating glaucomatous RNFL thinning.

Elevated intraocular pressure and microvascular retinal injury identified by overhead mounted optical coherence tomography in two infants with glaucoma

OCT imaging (tabletop and handheld/overhead-mounted methodology) aids in evaluating the optic nerve and retina in children. Glaucomatous optic nerve damage can be described on OCT as an isolated loss of ganglion cells in the macula. Using supine imaging with overhead-mounted OCT, we examined the macula in children with glaucoma, hoping to characterize the pattern of glaucomatous nerve damage.

TrkB Receptor Agonist 7,8 Dihydroxyflavone is Protective Against the Inner Retinal Deficits Induced by Experimental Glaucoma

Glaucoma is an age-related neurodegenerative disorder characterized by retinal ganglion cell (RGC) degeneration and excavation of the optic nerve head (ONH). It is associated with an increase in intraocular pressure (IOP) and progressive decline in the visual field. Reduction in the retrograde axonal transport of neurotrophic factors such as brain-derived neurotrophic factor (BDNF) from the brain to the neuronal cell bodies in retina, has been suggested as one of the key mechanisms underlying selective degeneration of ganglion cells and optic nerve in glaucoma. Multiple studies have indicated that BDNF and its high affinity receptor Tropomyosin receptor kinase B (TrkB) play crucial roles in survival of RGCs and that upregulating BDNF/TrkB signalling using gene therapy can protect the ganglion cells against degeneration. This study corroborates previous findings and demonstrates that glaucoma is associated with downregulation of TrkB downstream signalling and enhanced levels of amyloid β (Aβ 1–42) accumulation in the retina. 7,8 dihydroxyflavone (7,8 DHF) is a TrkB agonist and regular administration of this compound imparted significant protection against loss of GCL density and preserved inner retinal function in experimental glaucoma models. 7,8 DHF treatment stimulated activation of TrkB intracellular signalling as well as ameliorated the increase in the levels of soluble Aβ (1–42) in the retinas of rats and mice exposed to high IOP. The protective effects of 7,8 DHF were also evident in BDNF+/− mice indicating that TrkB agonist mediated activation of TrkB signalling was not altered upon BDNF allelic impairment. These data support BDNF/TrkB axis as a promising therapeutic target in glaucoma and highlight that the detrimental effects of high IOP exposure can be compensated by the exogenous administration of a TrkB agonist.

Prevalence of pre-perimetric primary open angle glaucoma in hypertensives of North India.

Systemic hypertension is alleged to increase the risk of glaucoma. As clinically Primary Open angle Glaucoma (POAG) is diagnosed only after approximately 40% of ganglion cell loss has occurred, therefore this study was commenced with an aim to determine the prevalence of pre-perimetric glaucomatous damage and its association with systemic hypertension using optical coherence tomography (OCT). A total of 680 study participants were enrolled in this cross-sectional study. Among them 340 patients were of systemic hypertension (Group 1) and 340 patients without hypertension (Group 2). All patients underwent detailed history, ocular and systemic examination including slit lamp examination, fundus examination by +90 D lens, Humphrey field analyser for field charting and OCT for nerve fiber analysis. For glaucomatous nerve damage. Group 1 and Group 2 had Male: Female ratio of 1:8 and 1:9, respectively (P = 0.809). Maximum participants 48.8% and 54.4% in Group 1 and Group 2, respectively, were in age group 50-59 years. Statistically significant difference was seen in the percentage of pre-perimetric glaucomatous patients between the two groups (P < 0.001). On OCT analysis between pre-perimetric glaucomatous eyes and healthy eyes significant difference in thickness was seen in temporal inner macula, inferior outer macula, temporal outer macula, superior outer macula and nasal outer macula. Significant difference in volume was seen for inferior temporal and nasal outer macula (P < 0.001). In hypertensives, glaucomatous optic nerve damage starts much earlier before the obvious clinical signs of POAG appear, as compared to normotensive individuals.

Minimum Rim Width and Lamina Cribrosa Depth in Non-Glaucomatous and Glaucomatous U.S. Veterans

Purpose: Assess the utility of the MRW and lamina cribrosa depth measurements for detecting differences between non-glaucomatous and glaucomatous U.S. Veterans. Compare inter-eye differences of individuals with glaucoma. Method: 38 subjects were recruited per group: Group 1 included one eye of non-glaucomatous participants, and Group 2 included each qualifying eye of participants with glaucoma. Analysis compared Group 1 with the more affected eye only of Group 2 participants, and separately between the more and less affected eyes of group 2 participants. MRW measurements were obtained with Heidelberg Eye Explorer© (HEYEX). Average lamina cribrosa depths were measured manually utilizing HEYEX. Results: 26 subjects from Group 1 and 33 subjects from Group 2 were included. A significantly thinner MRW was found in glaucomatous eyes vs. non-glaucomatous eyes (210 µm vs. 309 µm; P &lt; .001). The normative database in HEYEX had an 85% sensitivity and 92% specificity to detect glaucomatous nerves. Among the 27 participants in Group 2 who had both eyes tested, eyes with more advanced visual field loss showed significantly thinner global MRW compared to fellow eyes (203 µm vs. 224 µm P = .03). Lamina cribrosa depths were non-significantly deeper in glaucomatous vs. non-glaucomatous eyes (476 µm vs. 429 µm P = .17). Conclusions: The MRW parameter differentiates between glaucomatous and non-glaucomatous optic nerves. Lamina cribrosa depths were non-significantly deeper in glaucomatous vs. non-glaucomatous participants. Post-hoc inter-eye data analysis suggested that inter-eye differences in gMRW values of glaucomatous eyes reflect asymmetric damage as correlated with the visual field

English

BACKGROUND Myopia is a complex trait including both genetic and environmental factors as well as gene-environment interactions. It has been recognized as a risk factor for development of glaucoma. Both Myopia and raised IOP are known to increase mechanical stress at optic nerve head leading to glaucomatous nerve damage. This study intends to evaluate the clinical profile of myopic subjects and its correlation with Primary open angle glaucoma (POAG). METHODS A prospective observational study done from November 2019 to December 2020 after taking proper informed consent and ethical clearance. 164 eyes of 96 patients studied were divided into three groups, Group 1: low myopia (&lt; -3.00D), Group 2: moderate myopia (-3.00 D to -5.75 D), Group 3: high myopia (≥ -6.00 D). A complete ocular examination was performed. Intraocular pressure was measured using Goldmann applanation tonometer. Visual field analysis using Humphrey automated perimetry was done in patients with suspected primary open angle glaucoma (POAG). Angle parameters and central corneal thickness (CCT) were measured using anterior segment optical coherence tomography (AS-OCT). RESULTS 164 eyes of 96 Myopic subjects were studied with no dropout during study period. Mean age was 46.05 yr. (range: 25-75 yr.). The refraction ranged from -0.50 DS to -17.00 DS. There was no statistically significant difference between Intraocular pressure (IOP), Central corneal thickness (CCT), corrected IOP and Nasal and Temporal Trabecular-iris Angle (TIA) between male and female of same age group. Mean IOP and mean CCT were found to vary significantly with age and with higher degree of myopia. Corrected IOP, Nasal and Temporal TIA increase significantly with higher degree of myopia. Cup-disc ratio (CDR) was found to be significantly higher in patients with moderate to high degree of Myopia. CONCLUSIONS Myopia is an important risk factor for development of primary open angle glaucoma, with its incidence increasing in patients with moderate to high myopia. KEYWORDS Myopia, Primary Open Angle Glaucoma, Intraocular Pressure, Central Corneal Thickness, Trabecular Iris Angle

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

Race-adjusted interpretation of data from Cirrus high-definition OCT (HD-OCT) devices is not standard practice. The aim of this study is to evaluate differences in peripapillary retinal nerve fiber layer (RNFL) thickness between healthy Black Americans and the Cirrus HD-OCT normative database. This is a cross-sectional observational study using control patients recruited from the greater Philadelphia, Pennsylvania, area. A total of 466 eyes were included in this study. Subjects were retrospectively identified from the control cohort of the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study. Using an age-stratified or linear regression method, we reclassified white-green-yellow-red color probability codes for RNFL thicknesses by quadrant. The distribution of reclassified color codes was compared with the expected 5%-90%-4%-1% percentiles and to the original color codes by the Cirrus machine. Average RNFL thickness in the POAAGG control cohort was thinner than in the Cirrus normative database in all except the nasal quadrant. The original color codes of the POAAGG cohort did not fall into the expected distributions, with more RNFL measurements assigned as white and red codes than expected (9.5% and 1.7%) and fewer measurements assigned as green and yellow codes than expected (85.3% and 3.5%) (P < 0.001). Compared with the original Cirrus machine, reclassification using linear regression produced color codes closest to the expected distributions (P= 0.09). The proportion of abnormal results shifted closer to the expected 5% in the nasal (1.3%, P < 0.001 vs. 3.0%, P= 0.048) and temporal (8.2%, P= 0.002 vs. 3.6%, P= 0.18) quadrants. Results further establish the presence of structural differences in the RNFL of Black American patients. Color code reclassification suggests that the existing Cirrus database may not be accurately evaluating glaucomatous nerves in patients of African descent. This study addresses an unmet need to assess Cirrus HD-OCT color probability codes in a Black American population.

Genetic background modifies vulnerability to glaucoma-related phenotypes in Lmx1b mutant mice.

ABSTRACTVariants in the LIM homeobox transcription factor 1-beta (LMX1B) gene predispose individuals to elevated intraocular pressure (IOP), a key risk factor for glaucoma. However, the effect of LMX1B mutations varies widely between individuals. To better understand the mechanisms underlying LMX1B-related phenotypes and individual differences, we backcrossed the Lmx1bV265D (also known as Lmx1bIcst) allele onto the C57BL/6J (B6), 129/Sj (129), C3A/BLiA-Pde6b+/J (C3H) and DBA/2J-Gpnmb+ (D2-G) mouse strain backgrounds. Strain background had a significant effect on the onset and severity of ocular phenotypes in Lmx1bV265D/+ mutant mice. Mice of the B6 background were the most susceptible to developing abnormal IOP distribution, severe anterior segment developmental anomalies (including malformed eccentric pupils, iridocorneal strands and corneal abnormalities) and glaucomatous nerve damage. By contrast, Lmx1bV265D mice of the 129 background were the most resistant to developing anterior segment abnormalities, had less severe IOP elevation than B6 mutants at young ages and showed no detectable nerve damage. To identify genetic modifiers of susceptibility to Lmx1bV265D-induced glaucoma-associated phenotypes, we performed a mapping cross between mice of the B6 (susceptible) and 129 (resistant) backgrounds. We identified a modifier locus on Chromosome 18, with the 129 allele(s) substantially lessening severity of ocular phenotypes, as confirmed by congenic analysis. By demonstrating a clear effect of genetic background in modulating Lmx1b-induced phenotypes, providing a panel of strains with different phenotypic severities and identifying a modifier locus, this study lays a foundation for better understanding the roles of LMX1B in glaucoma with the goal of developing new treatments.

The Effect of Age on Increasing Susceptibility to Retinal Nerve Fiber Layer Loss in Glaucoma.

PurposeTo determine whether aging modifies the effect of intraocular pressure (IOP) on progressive glaucomatous retinal nerve fiber layer (RNFL) thinning over time.MethodsThis was a retrospective cohort study involving patients with glaucoma or suspected of having glaucoma who were followed over time from the Duke Glaucoma Registry. Rates of RNFL loss from spectral-domain optical coherence tomography (SD-OCT) were used to assess disease progression. Generalized estimating equations with robust sandwich variance estimators were used to investigate the effects of the interaction of age at baseline and mean IOP on rates of RNFL loss over time. Models were adjusted for gender, race, diagnosis, central corneal thickness, follow-up time, and baseline disease severity.ResultsThe study included 85,475 IOP measurements and 60,026 SD-OCT tests of 14,739 eyes of 7814 patients. Eyes had a mean follow-up time of 3.5 ± 1.9 years. The average rate of change in RNFL thickness was –0.70 µm/year (95% confidence interval, –0.72 to –0.67). There was a significant interaction between age and mean IOP and the rate of RNFL loss (P = 0.001), with older eyes having significantly faster rates of RNFL loss than younger ones for the same level of IOP. The effect of IOP on rates of change was greater in the inferior and superior regions of the optic disc.ConclusionsAge is a significant modifier of the relationship between IOP and glaucomatous loss in RNFL thickness over time. Older patients may be more susceptible to glaucomatous progression than younger patients at the same level of IOP.

Matching Misaligned Spectralis OCTs to a Reference Scan in Pediatric Glaucoma with Poor Fixation and Nystagmus.

PurposePoor fixation or nystagmus in children causes misalignment errors when measuring circumpapillary retinal nerve fiber layer (cpRNFL) thickness by simultaneous scanning laser ophthalmoscope imaging/optical coherence tomography (SLO/OCT). We investigated a method to assess cpRNFL from misaligned SLO/OCT scans.MethodsHeidelberg Spectralis SLO/OCT scans from a single clinical examination were retrospectively analyzed when automated eye tracking was unreliable. Retinal layer thickness was measured at overlapping match locations between a reference and misaligned scans based on the position data from simultaneously acquired SLO images. Three layers were segmented: cpRNFL, internal limiting membrane to outer nuclear layer (ILM-ONL), and total retinal thickness (TR). Accuracy was defined as the difference in thickness between the reference and misaligned scans at their match locations after correction for scan angle.ResultsThirty-five subjects, evaluated for glaucomatous nerve loss, met inclusion criteria. Group-averaged accuracy was −2.7, 1.4, and 0.3 µm for cpRNFL, ILM-ONL, and TR thickness, respectively. Across all layers, interobserver intraclass correlation coefficients ranged from 0.97 to 0.63 and the maximum Bland-Altman 95% limits of agreement were −21.6 to 20.7 µm. Variability was greatest for cpRNFL thickness and least for TR thickness. Increased variability was associated with lower signal-to-noise ratio but not with image-motion indices of shear, rotation, and scale.ConclusionsRetinal layer thickness can be compared to a reference cpRNFL OCT scan when poor fixation and nystagmus causes misalignment errors. The analysis can be performed post hoc using multiple misaligned scans from standard SLO/OCT protocols.Translational RelevanceOur method allows for assessment of cpRNFL in children who fail eye tracking.

Adaptive Immunity: New Aspects of Pathogenesis Underlying Neurodegeneration in Glaucoma and Optic Neuropathy.

Glaucoma is a globally unmet medical challenge and the most prevalent neurodegenerative disease, which permanently damages the optic nerve and retinal ganglion cells (RGCs), leading to irreversible blindness. Present therapies target solely at lowering intraocular ocular pressure (IOP), a major risk factor of the disease; however, elevated IOP is neither necessary nor sufficient to cause glaucoma. Glaucomatous RGC and nerve fiber loss also occur in individuals with normal IOP. Recent studies have provided evidence indicating a link between elevated IOP and T cell-mediated autoimmune responses, particularly that are specific to heat shock proteins (HSPs), underlying the pathogenesis of neurodegeneration in glaucoma. Reactive glial responses and low-grade inflammation may initially represent an adaptive reaction of the retina to primary stress stimuli; whereas, sustained and excessive glial reactions lead to expanded immune responses, including adaptive immunity, that contribute to progressive neural damage in glaucoma. Emerging data suggest a similar mechanism in play in causing neurodegeneration of other forms of optic neuropathy, such as that resulted from acute ischemia and traumatic injuries. These studies may lead to the paradigm shift and offer a new basis for the development of novel mechanism-based diagnosis, therapy, and preventive interventions for glaucoma. As HSPs are induced under various conditions of neural stress and damage in the brain and spinal cord, these findings may have broader implications for our elucidating of the etiology of other neurodegenerative disorders in the central nervous system.

Benzoic acid derivative-modified chitosan-g-poly(N-isopropylacrylamide): Methoxylation effects and pharmacological treatments of Glaucoma-related neurodegeneration

Long-acting drug delivery systems with advanced functionalities are critically important to pharmacologically treat glaucomatous optic neuropathy, a chronic and multifactorial neurodegenerative disease. Here, a novel strategy based on the methoxylation effects of benzoic acid derivatives was exploited to rationally design a biodegradable and injectable thermogel, which possesses potent antioxidant activities and sustained drug delivery abilities for treating glaucomatous nerve damage. In particular, 4-hydroxy-3,5-dimethoxybenzoic acid, consisting of two methoxyl groups and one hydroxyl group at the position para to the carboxylic group, was demonstrated to contribute to the strong antioxidant activities of a chitosan-g-poly(N-isopropylacrylamide) biomaterial while maintaining the drug encapsulation/release efficiencies of the thermogel. The pharmacological treatment relies on the intracameral injection of the thermogel coloaded with pilocarpine and RGFP966 and exhibits significant improvement in the attenuation of neurodegeneration via suppressing oxidative stress, lowering ocular hypertension, reducing retinal ganglion cell loss and enhancing myelin growth and neuron regeneration. These findings on the development of long-acting drug delivery systems with extended functions show great promise for the management of glaucoma-related neurodegeneration.

Association of Retinal Nerve Fiber Layer Thickness and Degree of Myopia Using Spectral Domain Optical Coherence Tomography

Background: High myopia is defined as refractive error above -6.0 D and axial length above 26 mm. High myopia and its complications are considered to be one of the most significant causes of blindness and visual impairment in young people. Objective: To evaluate the effect of the degree of myopia on the peripapillary retinal nerve fiber layer (RNFL) thickness by spectral-domain optical coherence tomography (OCT). Patients and Methods: The study had been carried out in Embaba Ophthalmic Hospital during the period of June 2018 to February 2019. The study included 60 eyes, divided equally into 3 groups: Group A: Mild myopia (spherical equivalent between −0.5 and −3.0 D). Group B: Moderate myopia (spherical equivalent between −3.1 and −5.99 D). Group C: High myopia (spherical equivalent more than −6.0 D). Results: This study showed that RNFL thickness was lower in the high and moderate myopic eyes compared with low myopic eyes in all quadrants except in temporal quadrant. A highly significant positive correlation was evident between spherical equivalent and RNFL thickness in each quadrant. A highly significant negative correlation between axial length and RNFL thickness was found in each quadrant. Conclusion: High myopia should be considered in the interpretation of OCT data because of thinning of RNFL thickness and normative database corrected for refractive error and axial length should be incorporated. It is difficult for OCT to discriminate between high myopes with and without glaucoma. Therefore, clinical signs of glaucomatous nerve fiber damage are very important.

Comparison of retinal ganglion cell-related layer asymmetry between early glaucoma eyes with superior and inferior hemiretina damage

AimTo compare retinal ganglion cell (RGC)-related layer thickness asymmetry between early open-angle glaucoma (EG) eyes with superior and inferior hemiretina damage.MethodsThis was a retrospective study including 95 EG eyes (mean...

Systemic Determinants of Peripapillary Vessel Density in Healthy African Americans: The African American Eye Disease Study

To determine the relationship between systemic factors and radial peripapillary capillary (RPC) vessel density (VD) in healthy African American (AA) participants of the African American Eye Disease Study. A population-based, cross-sectional study. A total of 4135 eyes from 2127 AA participants aged 40 years and older in Inglewood, California, were imaged for 6×6-mm optic disc scans on a spectral-domain optical coherence tomography angiography (OCTA) device. Of these, 1029 eyes from 1029 participants who met the inclusion and exclusion criteria were analyzed, including only 1 eye per participant. Custom software was used to quantify RPC VD. Multivariate linear regression was used to identify systemic factors associated with RPC VD with a significance level set at 0.05. The contribution of each variable to the final model was estimated with the magnitude of standardized regression coefficients (SRCs). The fit of the final model was measured by R2. The average RPC VD was 0.346±0.045. Controlling for signal strength, the systemic variables in the final multivariate model associated with reduced RPC VD were older age (β= -0.0123 per decade; SRC= -0.2733; P < .0001), male sex (β=-0.0067; SRC= -0.0716; P= .0060), and longer diabetes duration (β= -0.0022 per 5 years; SRC=-0.0527; P= .0427). The model R2 was 0.3689. Age, sex, and systemic influences, such as diabetes duration, need to be considered when assessing changes in RPC VD in glaucoma and other ocular diseases. Longitudinal studies are needed to investigate whether reduced RPC VD and the factors that affect it are associated with an increased risk of developing glaucomatous nerve damage.