Retinal Nerve Fiber Layer Thickness Loss Research Articles

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

To develop an objective glaucoma damage severity classification system based on OCT-derived retinal nerve fiber layer (RNFL) thickness measurements. Algorithm development for RNFL damage severity classification based on multicenter OCT data. 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. 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. Accuracy, area under the receiver operating characteristic curve, and confusion matrix. 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 , 86 to 95 , 70 to 85 and < 70 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. Unsupervised machine learning discovered that the optimal RNFL thresholds for separating normal eyes and eyes with early, moderate, and advanced RNFL loss were 95 , 85 μm, and 70 , 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. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Structural measurements and vessel density of spectral-domain optic coherence tomography in early, moderate, and severe primary angle-closure glaucoma.

To compare the macular ganglion cell-inner plexiform layer (GCIPL) thickness, retinal nerve fiber layer (RNFL) thickness, optic nerve head (ONH) parameters, and retinal vessel density (VD) measured by spectral-domain optical coherence tomography (SD-OCT) and analyze the correlations between them in the early, moderate, severe primary angle-closure glaucoma (PACG) and normal eyes. Totally 70 PACG eyes and 20 normal eyes were recruited for this retrospective analysis. PACG eyes were further separated into early, moderate, or severe PACG eyes using the Enhanced Glaucoma Staging System (GSS2). The GCIPL thickness, RNFL thickness, ONH parameters, and retinal VD were measured by SD-OCT, differences among the groups and correlations within the same group were calculated. The inferior and superotemporal sectors of the GCIPL thickness, rim area of ONH, average and inferior sector of the retinal VD were significantly reduced (all P<0.05) in the early PACG eyes compared to the normal and the optic disc area, cup to disc ratio (C/D), and cup volume were significantly higher (all P<0.05); but the RNFL was not significant changes in early and moderate PACG. In severe group, the GCIPL and RNFL thickness were obvious thinning with retinal VD were decreasing as well as C/D and cup volume increasing than other three groups (all P<0.01). In the early PACG subgroup, there were significant positive correlations between retinal VD and GCIPL thickness (except superonasal and inferonasal sectors, r=0.573 to 0.641, all P<0.05), superior sectors of RNFL thickness (r=0.055, P=0.049). More obvious significant positive correlations were existed in moderate PACG eyes between retinal VD and superior sectors of RNFL thickness (r=0.650, P=0.022), and temporal sectors of RNFL thickness (r=0.740, P=0.006). In the severe PACG eyes, neither GCIPL nor RNFL thickness was associated with retinal VD. The ONH damage and retinal VD loss appears earlier than RNFL thickness loss in PACG eyes. As the PACG disease progressed from the early to the moderate stage, the correlations between the retinal VD and RNFL thickness increases.

Optic disc blood perfusion and oxygenation in glaucoma

PurposeTo investigate the haemoglobin concentration and oxygenation in the optic disc in glaucoma patients vs. controls.MethodsThirty-one eyes of primary open angle glaucoma patients (mean age: 64.9 ± 2.1 years) and 31 eyes of 31 healthy controls (65.5 ± 2.0 years) were included. Perimetry, optical coherence tomography (OCT), and OCT angiography were performed. Multispectral imaging was used to record the optic disc reflectance at wavelengths 522 nm, 548 nm, 555 nm, 586 nm, and 610 nm, and haemoglobin concentration and oxygenation (SO2) were calculated from these measures. This was done in the rest and under stimulation of neuronal activity by flicker light.ResultsThe haemoglobin concentration was significantly lower (p < 0.001) in the rim (40.0 ± 6.3) and the excavation (35.7 ± 8.0) of the glaucoma patients’ discs than in controls (45.7 ± 7.5). SO2 was not different in general, but lower in a subgroup of 18 glaucoma patients with ischaemic disc rims than in non-ischaemic ones (median 26.8%, interquartile range (IQR): 29.5% vs. 51.9%, IQR 32.0%, p = 0.02) as well as in controls (41.0%, IQR 30.6%, p = 0.01). Flicker light stimulation significantly increased the haemoglobin concentration in the controls (+ 1.3 ± 3.6, p = 0.048) as well as in the rim of glaucoma discs (+ 2.6 ± 5.0, p = 0.006) and SO2 in the controls only (+ 15.4 ± 23.6%, p = 0.001). The haemoglobin concentration was significantly correlated with the perimetric mean defect, retinal nerve fibre layer (RNFL) thickness and para-papillary perfusion density.ConclusionsThe optic disc haemoglobin concentration and oxygenation are quantifiable from multispectral imaging and reduced in glaucoma. The correlation of haemoglobin concentration with perfusion density, RNFL thickness and visual field loss indicates its implication in glaucoma pathology.

The Pattern of Retinal Ganglion Cell Loss in Wolfram Syndrome is Distinct From Mitochondrial Optic Neuropathies

To describe the clinical phenotype of a cohort of patients with Wolfram syndrome (WS), focusing on the pattern of optic atrophy correlated with brain magnetic resonance imaging (MRI) measurements, as compared with patients with OPA1-related dominant optic atrophy (DOA). Retrospective, comparative cohort study. We reviewed 25 patients with WS and 33 age-matched patients affected by OPA1-related DOA. Ophthalmologic, neurologic, endocrinologic, and MRI data from patients with WS were retrospectively retrieved. Ophthalmologic data were compared with data from patients with OPA1-related DOA and further analyzed for age dependency dividing patients in age quartiles. In a subgroup of patients with WS, we correlated the structural damage assessed by optical coherence tomography (OCT) with brain MRI morphologic measurements. Visual acuity (VA), visual field mean defect (MD), retinal nerve fiber layer (RNFL), and ganglion cell layer (GCL) thickness were assessed by OCT and MRI morphologic measurements of anterior and posterior visual pathways. Optic atrophy was present in 100% of patients with WS. VA, MD, and RNFL thickness loss were worse in patients with WS with a faster decline since early age as compared with patients with DOA, who displayed a more stable visual function over the years. Conversely, GCL sectors were overall thinner in patients with DOA since early age compared to patients with WS, in which GCL thickness started to decline later in life. The neuroradiologic subanalysis on 11 patients with WS exhibited bilateral thinning of the anterior optic pathway, especially the prechiasmatic optic nerves and optic tracts. Optic tract thinning was significantly correlated with GCL thickness but not with RNFL parameters. Our results showed a generally more severe and diffuse degeneration of both anterior and posterior visual pathways in patients with WS, with fast deterioration of visual function and structural OCT parameters since early age. The pattern observed with OCT suggests that retinal ganglion cell axonal degeneration (ie, RNFL) precedes cellular body atrophy (ie, GCL) by about a decade. This differs substantially from DOA, in which a more stable visual function is evident with predominant early loss of GCL, indirectly supporting the lack of a primary mitochondrial dysfunction in patients with WS.

Influence of sex on neuroretinal degeneration: 6 month follow‐up in rats with chronic glaucoma

AbstractPurposeTo evaluate differences by sex in the neuroretina of rats with chronic glaucoma (CG) induced by two different methods of increased ocular hypertension (OHT) vs healthy animals (HA).MethodsForty‐six Long Evans rats (18 males, 28 females) with CG and paired HA were analyzed. Glaucoma was achieved by sclerosing the episcleral veins or by injecting microspheres into the anterior chamber. Intraocular pressure was measured every week by Tonolab® tonometer, neuroretinal function was recorded by dark/light‐adapted RETIanimal® electroretinography (ERG) at 0, 12 and 24 weeks; and structure was analyzed by Spectralis high definition Heidelberg® optical coherence tomography (OCT), using the Retina, Retinal Nerve Fiber Layer (RNFL) and Ganglion Cell Layer (GCL) protocols at 0, 8, 12, 18 and 24 weeks.ResultsMales showed statistically significant higher IOP in both CG models and HA (p &lt; 0.05). Greater differences were found in the episcleral model at early stages. Males with episclerally induced glaucoma showed higher increase (p &lt; 0.05) in retinal thickness in OCT recordings than its females, microspheres model and HA. CG rats showed bigger thickness loss of RNFL and GCL (p &lt; 0.05) comparing HA. Males showed a higher percentage of RNFL thickness loss (p &lt; 0.05) in both models and HA. No differences by sex were observed in GCL thickness in the episcleral model, but comparison in microspheres model and HA showed differences. Males exhibited worse dark/light‐adapted functionality in CG models (p &lt; 0.05), with worsened in the episcleral model at 12 weeks, than paired females and HA.ConclusionsMale rats experienced higher IOP, structural loss and worse neurorretinal functionality than females under physiological and glaucomatous conditions. Sex and the OHT‐inducing method influenced neuroretinal degeneration.

Peripapillary changes after vitrectomy and silicone oil tamponade for rhegmatogenous retinal detachment.

Purpose:To evaluate the peripapillary changes after vitrectomy and silicone oil (SO) tamponade in eyes with rhegmatogenous retinal detachment (RRD).Methods:In this study, 25-gauge vitrectomy with SO tamponade was performed in 22 eyes with RRD. The radial peripapillary capillary (RPC) vessel density (VD) and retinal nerve fiber layer thickness (RNFLT) were assessed by optical coherence tomography angiography at 2, 4, 8, and 12 weeks postoperatively. The values of healthy fellow eyes were used as controls.Results:The global RPC VDs were significantly lower in the eyes with RRD than in fellow healthy eyes at 2 weeks (P < 0.001), and increased at 4 weeks, then decreased over time after surgery (F = 1.046, P = 0.377). The RPC VDs in the superior-hemifield were lower than those in the inferior-hemifield at 12 weeks postoperatively (t = −2.844, P = 0.010). The global RNFLTs decreased gradually after vitrectomy in the eyes with RRD (F = 1.312, P = 0.276). The RNFLTs in the superior-hemifield were thinner than those in the inferior-hemifield at 12 weeks postoperatively (t = −2.222, P = 0.037). The global, superior, and inferior RNFLTs were correlated with corresponding RPC VDs in the eyes with RRD at all time-points postoperatively (P < 0.05).Conclusion:RRD resulted in the decrease of RPC VDs. The RPC VDs recovered in the early postoperative period but were still lower than the normal level. Long-term application of SO tamponade resulted in the reduction of peripapillary VDs secondary to loss of RNFLTs.

Measurements of OCT Angiography Complement OCT for Diagnosing Early Primary Open-Angle Glaucoma

To compare measurements of global and regional circumpapillary capillary density (cpCD) with retinal nerve fiber layer (RNFL) thickness and characterize their relationship with visual function in early primary open-angle glaucoma (POAG). Cross-sectional study. Eighty healthy eyes, 64 preperimetric eyes, and 184 mild POAG eyes from the Diagnostic Innovations in Glaucoma Study. Global and regional RNFL thickness and cpCD measurements were obtained using OCT and OCT angiography (OCTA). For direct comparison at the individual and diagnostic group level, RNFL thickness and capillary density values were converted to a normalized relative loss scale. Retinal nerve fiber layer thickness and cpCD normalized loss at the individual level and diagnostic group. Global and regional areas under the receiver operating characteristic curve (AUROC) for RNFL thickness and cpCD to detect preperimetric glaucoma and glaucoma, R2 for the strength of associations between RNFL thickness function and capillary density function in diagnostic groups. Both global and regional RNFL thickness and cpCD decreased progressively with increasing glaucoma severity (P < 0.05, except for temporal RNFL thickness). Global and regional cpCD relative loss values were higher than those of RNFL thickness (P < 0.05) in preperimetric glaucoma (except for the superonasal region) and glaucoma (except for the inferonasal and superonasal regions) eyes. Race, intraocular pressure (IOP), and cpCD were associated with greater cpCD than RNFL thickness loss in early glaucoma at the individual level (P < 0.05). Global measurements of capillary density (whole image capillary density and cpCD) had higher diagnostic accuracies than RNFL thickness in detecting preperimetric glaucoma and glaucoma (P < 0.05; except for cpCD/RNFL thickness comparison in glaucoma [P= 0.059]). Visual function was significantly associated with RNFL thickness and cpCD globally and in all regions (P < 0.05, except for temporal RNFL thickness-function association [P= 0.070]). Associations between capillary density and visual function were found in the regions known to be at highest risk for damage in preperimetric glaucoma eyes and all regions of mild glaucoma eyes. In early glaucoma, capillary density loss was more pronounced than RNFL thickness loss. Individual characteristics influence the relative magnitudes of capillary density loss compared with RNFL thickness loss. Retinal nerve fiber layer thickness and microvascular assessments are complementary and yield valuable information for the detection of early damages seen in POAG.

Corneal Endothelial Cell Density and Retinal Nerve Fiber Layer in Primary Open Angle Glaucoma, Normal Tension Glaucoma and Ocular Hypertension

Purpose: To compare the corneal endothelial cell density (CED) and retinal nerve fiber layer thickness (RNFL) in primary open angle glaucoma (POAG), normal tension glaucoma (NTG) and ocular hypertension (OHT).&#x0D; Study Design: Cross sectional Observational study.&#x0D; Place and Duration of Study: Khyber Teaching Hospital, Peshawar, from April 2016 to March 2018.&#x0D; Methods: Patients having a single IOP reading of 21 mm Hg or more with glaucomatous cupping, visual field defect and open angle were labeled as POAG. Patients with IOP less than 21 mm Hg with same findings were labeled as NTG. Those eyes with raised IOP (more than 21 mm Hg), normal visual field and optic disc were labeled as OHT. Corneal endothelial cell count, central corneal thickness and retinal nerve fiber layer (RNFL) thickness were measured in patients of POAG, NTG and OHT. These were compared with normal age matched values.&#x0D; Results: Thirty eyes with POAG, 10 with OHT and 10 with NTG were included in the study. In patients with POAG there was 13.33% CED and 27.7% mean RNFL thickness loss. In patients with NTG there was 3.06% CED and 34.04% mean RNFL thickness loss. In patients with OHT there was 7.17% CED and 5.5% mean RNFL thickness loss.&#x0D; Conclusion: The loss of both RNFL thickness and CED occurs in POAG, OHT and NTG. Severe loss of RNFL thickness occurs in POAG and NTG while severe loss of CED occurs in POAG and OHT. Mild loss of RNFL thickness occurs in OHT while mild loss of CED occurs in NTG.&#x0D; Key Words: Specular Microscopy, Optical Coherence Tomography, Nerve Fiber Layer, Open Angle Glaucoma, Ocular Hypertension.

Effect of Diabetes Control on Rates of Structural and Functional Loss in Patients with Glaucoma

To investigate the association between levels of diabetes mellitus (DM) control and rates of visual field and retinal nerve fiber layer (RNFL) loss over time in glaucoma. Retrospective cohort study. A total of 351 eyes of 222 patients with type 2 DM with concomitant primary open-angle glaucoma (POAG) or suspected glaucoma extracted from the Duke Glaucoma Registry. All patients had at least 2 reliable standard automated perimetry (SAP) tests, 2 spectral domain OCT (SD-OCT) tests, and 2 glycated hemoglobin (HbA1c) measures over time with a minimum follow-up of 6 months. Values of HbA1c were summarized for each patient as mean, peak, and fluctuation across time. Multivariable linear mixed models were used to estimate the effect of HbA1c on rates of change in SAP mean deviation (MD) and OCT RNFL thickness loss over time while adjusting for various confounding factors. Rates of change in MD and RNFL thickness over time. Subjects had a mean baseline age of 62.5 ± 10.2 years and follow-up time of 6.9 ± 5.1 years. Subjects had an average of 4.8 SAP tests (range, 2-28), 3.6 SD-OCT tests (range, 2-10), and 8.3 HbA1c tests (range, 2-21). Average HbA1c mean was 7.1% ± 1.1% (range, 5.4-11.7), peak HbA1c over time was 8.1% ± 2% (range, 5.5-15.6), and HbA1c fluctuation was 0.6% ± 0.6% (range, 0-4.4). Mean rate of SAP MD changewas-0.09 ± 0.20 decibel/year(median -0.06 decibel/year; interquartile range -0.15 to 0.01 decibel/year), and mean rate of RNFL change was-0.83 ± 0.51 μm/year(median -0.76 μm/year; interquartile range -1.06 to 0.56 μm/year). After adjustment for confounding factors, mean, peak, and fluctuation in HbA1c levels were not significantly associated with rates of MD change over time (P= 0.994, P= 0.689, P= 0.920, respectively), nor were rates of change in RNFL loss over time (P= 0.805, P= 0.575, P= 0.770). We did not find a significant association between diabetes control, as measured by levels of HbA1c, and rates of visual field or RNFL loss over time in individuals with glaucoma or suspected glaucoma.

An Artificial Intelligence Approach to Assess Spatial Patterns of Retinal Nerve Fiber Layer Thickness Maps in Glaucoma.

PurposeThe purpose of this study was to classify the spatial patterns of retinal nerve fiber layer thickness (RNFLT) and assess their associations with visual field (VF) loss in glaucoma.MethodsWe used paired reliable 24-2 VFs and optical coherence tomography scans of 691 eyes from 691 patients. The RNFLT maps were used to determine the RNFLT patterns (RPs) by non-negative matrix factorization (NMF). The RPs were correlated with mean deviation (MD), spherical equivalent (SE), and major blood vessel locations. The RPs were further used to predict the 52 total deviation (TD) values by linear regression compared with models using 24 15-degree sectors. Last, we associated the RPs with average TDs of the central upper two locations (C2-TD). Stepwise regression was applied to remove redundant features.ResultsNMF highlighted 16 distinct RPs. Twelve RPs had arcuate-like informative zones (iZones): six with superior iZones, five with inferior iZones, and one RP with a bi-hemifield iZone, and four with non-arcuate-like temporal or nasal iZones. Twelve, nine, nine, and nine RPs were significantly (P < 0.05) correlated to MD, SE, and superior and inferior artery locations, respectively. Using RPs significantly (P < 0.05) improved the prediction of 52 TDs compared with using 24 15-degree sectors. Using RPs significantly (P < 0.001) improved the C2-TD prediction related to thinning in the inferior vulnerability zone compared with using the 24 sectoral RNFLTs.ConclusionsUsing RPs improved the VF prediction compared with using sectoral RNFLTs.Translational RelevanceThe RPs characterizing both pathological and anatomical variations can potentially assist clinicians better assess RNFLT loss.

Randomized control trial of evaluation of Clemastine effects on visual evoked potential, nerve fiber layer and ganglion cell layer complex in patients with optic neuritis

ObjectivesOptic neuritis (ON) is the most common cause of optic neuropathy; typically presenting with a unilateral visual loss in young adults, with incidence of 1–5 in 100,000 per year. We evaluated the effect of Clemastine, a first-generation and CNS (central nervous system)-penetrant H1 receptor antagonist on visual evoked potential (VEP), retinal nerve fibre layer (RNFL) and ganglion cell layer (GCL) complex in patients with optic neuritis. Patients and methodsThis is a prospective comparative interventional case series in 25 patients with acute optic neuritis. Patients were randomly assigned to group 1 (treated with Clemastine 1 mg orally twice a day for 90 days; 16 patients) or group 2 (received placebo for 90 days; 9 patients) and both groups received standard treatment of optic neuritis. We recorded VEP and peripapillary OCT (optical coherence tomography) of patients before and after three months of treatment. ResultsIn contrast to patients treated with Clemastine, RNFL thickness loss between base line phase and after three months follow up in control group were statistically significant in temporal, supra temporal, Infrotemporal and almost global sections of RNFL map. The reduction in GCL thickness between base line phase and after three months follow up in control group were significant, while it did not reach significance in treatment group except in inferior region. ConclusionIn contrast to treatment group, RNFL and GCL thickness of most quadrants are decreased significantly after three months in patients with ON in control group. In contrast to control group, p100 wave’s amplitude recovered in a significant manner in treatment group.

Effect of hemodialysis on Intraocular Pressure

Background: Hemodialysis (HD) is an important and by far the commonest treatment for end stage renal failure (ESRF). Changes in intraocular pressure (IOP) are one of the eye problems among hemodialysis patients. Objective: To evaluate changes in intraocular pressure (IOP) before, during and after single dialysis session. To detect changes in retinal fiber thickness measured by Optical Coherence Tomography (OCT) 6 months after basic examination. Patients and methods: This prospective study was carried out on 80 eyes of 80 patients undergoing regular hemodialysis (HD), both males and females. The study was conducted in Aswan University Hospital. Results: There was statically significant (but clinically not significant) decrease in IOP during HD, but there was no significant decrease when measured six month later. No significant difference in the mean IOP as regarding group’s age, sex and duration of dialysis was found. Significant decrease in mean average RNFL thickness during the six months was noted as well as between age groups. There was no significance decrease in retinal nerve fiber layer (RNFL) thickness regarding sex and duration. Conclusion: As there was loss of RNFL thickness in hemodialysis patients, visual field changes is recommended to be investigated on such patients. Also the effect of hemodialysis on patients with high IOP or glaucoma should be investigated as well.

Effect of hemodialysis on Intraocular Pressure

Background: Hemodialysis (HD) is an important and by far the commonest treatment for end stage renal failure (ESRF). Changes in intraocular pressure (IOP) are one of the eye problems among hemodialysis patients. Objective: To evaluate changes in intraocular pressure (IOP) before, during and after single dialysis session. To detect changes in retinal fiber thickness measured by Optical Coherence Tomography (OCT) 6 months after basic examination. Patients and methods: This prospective study was carried out on 80 eyes of 80 patients undergoing regular hemodialysis (HD), both males and females. The study was conducted in Aswan University Hospital. Results: There was statically significant (but clinically not significant) decrease in IOP during HD, but there was no significant decrease when measured six month later. No significant difference in the mean IOP as regarding group’s age, sex and duration of dialysis was found. Significant decrease in mean average RNFL thickness during the six months was noted as well as between age groups. There was no significance decrease in retinal nerve fiber layer (RNFL) thickness regarding sex and duration. Conclusion: As there was loss of RNFL thickness in hemodialysis patients, visual field changes is recommended to be investigated on such patients. Also the effect of hemodialysis on patients with high IOP or glaucoma should be investigated as well.

Differential Effects of Aging in the Macular Retinal Layers, Neuroretinal Rim, and Peripapillary Retinal Nerve Fiber Layer

We determined the differential aging effects of the inner 6 layers of the macula in contrast to the minimum neuroretinal rim width (MRW) and peripapillary retinal nerve fiber layer (RNFL) thickness. Cross-sectional, multicenter study. An approximately equal number of white subjects with a normal ocular and visual field examination in each decade group from 20 to 90 years. OCT of the macula, optic nerve head, and peripapillary retina. Sectoral measurements of the inner 6 layers of the macula; age-related decline of each of these layers; strength of the associations with age of the macular parameters, MRW, and peripapillary RNFL thickness; and association between ganglion cell layer (GCL) thickness and MRW and peripapillary RNFL thickness. The study sample comprised 1 eye of 246 subjects with a median (range) age of 52.9 (19.8-87.3) years. Of the 6 layers, there was a statistically significant decline with age of only the GCL, inner plexiform layer, and inner nuclear layer thickness with rates of-0.11 μm/year,-0.07 μm/year, and-0.03 μm/year, respectively. These rates corresponded to 2.82%, 2.10%, and 0.78% loss per decade, respectively, and were generally uniform across sectors. The rate of loss of MRW and peripapillary RNFL thickness was-1.22 μm/year and-0.20 μm/year, corresponding to 3.75% and 2.03% loss per decade. However, the association of GCL thickness change with age (R2 = 0.28) was approximately twice that of MRW and RNFL thickness (R2 = 0.14 for each). In concordance with histopathologic studies showing age-related loss of retinal ganglion cell axons, we showed a significant decline in GCL thickness, as well as MRW and peripapillary RNFL thickness. The stronger relationship between aging and GCL thickness compared with the rim or peripapillary RNFL may indicate that GCL thickness could be better suited to measure progression of structural glaucomatous loss.

Relationship between intraocular pressure and retinal nerve fibre thickness loss in a monkey model of chronic ocular hypertension

Chronic ocular hypertension (COHT) monkey models were established by destroying the trabecular meshwork, for investigating the relationship between intraocular pressure (IOP) and retinal nerve fibre layer (RNFL) thickness loss. IOP and RNFL thickness were measured before laser injury and weekly thereafter for 27 weeks using Tono Vet and Stratus optical coherence tomography (OCT). The quantitative relationship was as follows: (1) at 32-47 mmHg, the average damage rate was -3.08 ± 0.28 μm/week; (2) at 25-30 mmHg, it was -1.45 ± 0.19 μm/week. The inferior RNFL and superior RNFL turned out to be the most IOP-sensitive quadrants with the rate of RNFL change almost in parallel with IOP levels. The superior sector seemed to be resistant to high IOP conditions until a RNFL loss of ~20 μm was detected in the inferior sector. The rate of RNFL thickness loss was slowed with obvious turning points at RNFL thicknesses of ~75 μm, 65 μm, and 50 μm. The experimental results have achieved research significance. The COHT Monkey was an ideal animal model that can be used for evaluating the relationship between IOP and RNFL damage. Higher IOP was associated with faster RNFL thickness loss. The level of IOP was a vital factor for RNFL damage rate, and baseline/residual RNFL thickness was also important for subsequent RNFL damage. OCT was suitable for measuring RNFL thickness change in COHT monkey models.

Macular evaluation of the retinal and choroidal vasculature changes in anterior ischemic optic neuropathy-a case control study

BackgroundThis study aimes to characterize the fundus structural changes in patients with nonarteritic anterior ischemic optic neuropathy (NAION) and the correlation between macular vessel density, retinal nerve fibre layer (RNFL) parameters and visual field sensitivity (VFS) in NAION patients.MethodsA retrospective case control study was performed using 37 eyes with NAION, 30 uninvolved contralateral eyes, and 27 eyes of healthy age-matched subjects. Data on the retinas and choroidal vessel densities and VFS were compared among the three groups.ResultsThe NAION group exhibited significantly lower RNFL thicknesses, lower ganglion cell complexes (GCC), larger global loss volume (GLV) values and focal loss volume (FLV) values when compared with both uninvolved eyes and healthy eyes (p < 0.01 for all comparisons). The superficial vessel density (SVD) valus (whole, parafovea, superior-hemi and inferior-hemi) were significantly lower in NAION eyes, followed by uninvolved eyes and healthy eyes (p < 0.01; LSD, p < 0.05 for all comparisons). The deep vessel density (DVD) values (parafovea, superior-hemi and inferior-hemi) were the lowest by a significant value in NAION eyes, followed by uninvolved eyes and healthy eyes (p < 0.01; LSD, p < 0.05 for all comparisons). However, DVD value measurements (whole and fovea) of healthy and uninvolved eyes were not significantly different. The average threshold deviation (TD) was − 11.02 ± 3.75 dB for the overall field region, − 6.01 ± 2.21 dB for the affected superior field region and − 9.98 ± 3.34 dB for the affected inferior field region in NAION eyes. A statistically significant correlation was found between the RNFL thickness and visual field(VF) loss (r = − 0.788, p < 0.001).ConclusionIn addition to peripapillary vascular changes occurring in NAION eyes, macular vessel density is also involved. Furthermore, NAION-uninvolved eyes exhibited abnormalities compared with healthy eyes. This indicates that vascular changes may occur before changes in retinal thickness at the early stages of NAION.

Ophthalmic Findings in Patients After Renal Transplantation

The aim of the study was to perform complete ophthalmic examinations in patients after renal transplantation to determine ocular alterations and condition of the eyes. Moreover, ophthalmic findings were correlated with certain clinical characteristics related to transplantation such as post-operative renal functions and immunosuppressive regimen. The study was performed on 84 eyes of 42 patients who had received a renal transplant at least 6 months earlier. All patients underwent a complete ophthalmologic examination. In addition, in 33 (78.6%) patients peripapillary retinal nerve fiber layer (RNFL) thickness was determined using optical coherence tomography (Stratus OCT, Zeiss, Germany), which is a unique finding among renal transplantation patients. Recipients received immunosuppressive therapy consisting of tacrolimus, mycophenolate mofetil, and corticosteroid. Of 42 patients, 19 (45%) were women and 23 (55%) were men. The age of the patients ranged from 26 to 74 years, the mean age was 53.4 years. At least one ocular abnormality could be detected in 37 patients (88%), including impaired visual acuity (n = 31, 74%), keratoconjunctivitis sicca (n = 6, 14.3%), pinguecula (n = 3, 7.1%), arcus lipoides (n = 1, 2.4%), cataracts (n = 24, 57.1%), glaucoma (n = 2, 5%), retinal drusen (n = 6, 14.3%), and hypertensive or atherosclerotic retinopathy (n = 22, 52.4%). Twenty-five patients (75.8%) have reduced RNFL thickness. Cataract formation was positively correlated with age and usage of methylprednisolone. Moreover, RNFL thickness loss was correlated with transplantation duration and postoperative infections. Our study suggests that ocular disorders are frequent among renal transplantation patients. Besides immunosuppression and postoperative infection, aging is a high-risk factor in such cases.

More sensitive correlation of afferent pupillary defect with ganglion cell complex

PurposeThis study investigated the correlation between the relative afferent pupillary defect (RAPD) and retinal nerve fiber layer thickness (RNFLT) in optic neuropathy. MethodsRAPD assessment was performed using a log unit neutral density filter bar. Spectral domain optical coherence tomography RTVue-100 (Optovue) was used to examine the subjects. The optic nerve head pattern (ONH) was subdivided and identified for the purpose of the study into circumpapillary RNFLT (cpRNFLT) and peripheral circumpapillary RNFLT (pcpRNFLT). The cpRNFLT, pcpRNFLT and ganglion cell complex (GCC) parameters were analyzed. ResultsEighteen females and twenty three males with asymmetric optic neuropathy and a RAPD participated. Thirty-three subjects had glaucoma and eight had optic neuropathy other than glaucoma. Significant correlations (p<0.02) were obtained for the RAPD and the percentage difference loss of the GCC and RNFLT parameters. The grouped mean percentage difference loss for RNFLT was significantly different from that of the GCC (p<0.001). At a 0.6log unit RAPD, the average mean percentage difference loss was 23% for the CRNFLT, 15% for the GCC, 12% for the global loss volume percentage and 6% for the focal loss volume percentage (FLV%). ConclusionsSignificant correlations between RNFLT loss for cpRNFLT, pcpRNFLT and GCC parameters with RAPD were observed. Approximately a 35% higher sensitivity was obtained using GCC compared to CRNFL parameters. The expected change in GCC average for every 0.3log unit increment was approximately 8.49μm. The FLV% corresponded more sensitively to a RAPD but appeared to be influenced by disease severity.

Comparing the Rates of Retinal Nerve Fiber Layer and Ganglion Cell–Inner Plexiform Layer Loss in Healthy Eyes and in Glaucoma Eyes

To compare the rates of circumpapillary retinal nerve fiber layer (RNFL) and macular retinal ganglion cell-inner plexiform layer (GCIPL) change over time in healthy and glaucoma eyes. Cohort study. The rates of circumpapillary RNFL and macular GCIPL loss in 28 healthy subjects and 97 glaucoma subjects from the Diagnostic Innovations in Glaucoma Study (DIGS) were compared using mixed-effects models. The median follow-up time and number of visits were 1.7 years and 6 visits and 3.2 years and 7 visits for healthy and glaucoma eyes, respectively. Significant rates of loss of both global circumpapillary RNFL and average macular GCIPL thickness were detectable in early and moderate glaucoma eyes; in severe glaucoma eyes, rates of average macular GCIPL loss were significant, but rates of global circumpapillary RNFL loss were not. In glaucoma eyes, mean rates of global circumpapillary RNFL thickness change (-0.98μm/year [95% confidence interval (CI),-1.20 to-0.76]) and normalized global circumpapillary RNFL change (-1.7%/year [95% CI,-2.1 to-1.3]) were significantly faster than average macular GCIPL change (-0.57μm/year [(95% CI,-0.73 to-0.41]) and normalized macular GCIPL change (-1.3%/year [95% CI,-1.7 to-0.9]). The rates of global and inferior RNFL change were weakly correlated with global and inferior macular GCIPL change (r ranges from 0.16 to 0.23, all P < .05). In this cohort, the rate of circumpapillary RNFL thickness change was faster than macular GCIPL change for glaucoma eyes. Global circumpapillary RNFL thickness loss was detectable in early and moderate glaucoma, and average macular GCIPL thickness loss was detectable in early, moderate, and severe glaucoma, suggesting that structural changes can be detected in severe glaucoma.

Retinal Nerve Fiber Loss in Anti-VEGF Therapy for Age-Related Macular Degeneration Can Be Decreased by Anterior Chamber Paracentesis

Purpose: To analyze peripapillary retinal nerve fiber layer thickness (RNFLT) change after long-term intravitreal anti-VEGF therapy. Patients with regular anterior chamber paracentesis (ACP) prior to intravitreal injections (IVIs) were compared to those without ACP. Methods: Neovascular age-related macular degeneration (nAMD) was treated in a pro re nata regimen with a minimum of 9 IVIs. RNFLT change was determined in spectral domain optical coherence tomography. Results: In 32 patients without ACP, mean RNFLT loss (-2.16 ± 3.60 µm) was significantly higher than in 44 patients with regular ACP (0.16 ± 3.60; p = 0.029). Both groups were comparable in age (75.0 vs. 76.8 years; p = 0.35), number of IVIs (16.2 vs. 16.6; p = 0.98), and observational time (30.0 vs. 32.3 months; p = 0.32). In patients without ACP, RNFLT loss was higher compared to IVI-naive fellow eyes (p = 0.005), whereas in ACP patients, no difference was detected (p = 0.5). Conclusions: A moderate RNFLT loss is found in nonglaucomatous patients after injection therapy for nAMD. As it is decreased with regular ACP, tight management of intraocular pressure seems advisable.