Significant Retinal Nerve Fiber Layer Research Articles

Age-dependent regional retinal nerve fibre changes in SIX1/SIX6 polymorphism

SIX1/SIX6 polymorphism has been shown to be associated with glaucoma. Studies have also found that, in older adults, retinal nerve fibre layer (RNFL) thickness is significantly thinned with each copy of the risk allele in SIX1/SIX6. However, it is not known whether these genetic variants exert their effects in younger individuals. Comparing a healthy young adult with an older adult cohort (mean age 20 vs 63 years), both of Northern European descent, we found that there was no significant RNFL thinning in each copy of the risk alleles in SIX1/SIX6 in the eyes of younger individuals. The older cohort showed an unexpectedly thicker RNFL in the nasal sector with each copy of the risk allele for both the SIX1 (rs10483727) and SIX6 (rs33912345) variants. In the temporal sector, thinner RNFL was found with each copy of the risk allele in rs33912345 with a decrease trend observed in rs10483727. Our results suggest that SIX1/SIX6 gene variants exert their influence later in adult life.

Longitudinal outcomes of circumlimbal suture model-induced chronic ocular hypertension in Sprague-Dawley albino rats.

To characterise longitudinal structural and functional changes in albino Sprague-Dawley rats following circumlimbal suture ocular hypertension (OHT) induction. Ten-week-old rats (n = 24) underwent suture implantation around the limbal region in both eyes. On the next day, the suture was removed from one eye (control eyes) and left intact in the other eye (OHT eyes) of each animal. Intraocular pressure (IOP) was monitored weekly twice for the next 15weeks. Optical coherence tomography (OCT) and electroretinogram (ERG) were measured at baseline and weeks 4, 8, 12, and 15, and eyes were then collected for histological assessment. Sutured eyes (n = 12) developed IOP elevation of ~ 50% in the first 2 weeks that was sustained at ~ 25% above the control eye up to week 15 (p = 0.001). Animals with insufficient IOP elevation (n = 6), corneal changes (n = 3), and attrition (n = 3) were excluded from the analysis. OHT eyes developed significant retinal nerve fibre layer (RNFL) thinning (week 4: - 19 ± 14%, p = 0.10; week 8: - 17 ± 12%, p = 0.04; week 12: - 16 ± 10%, p = 0.04, relative to baseline) and reduction in retinal ganglion cell (RGC) density (- 32 ± 26%, p = 0.02). At week 15, both inner (9 ± 7%, p = 0.01) and outer retinal layer thicknesses (6.0 ± 5%, p = 0.001) showed a mild increase in thicknesses. The positive scotopic threshold response (- 28 ± 25%, p = 0.04) and a-wave were significantly reduced at week 12 (- 35 ± 21%; p = 0.04), whereas b-wave was not significantly affected (week 12: - 18 ± 27%, p = 0.24). The circumlimbal suture model produced a chronic, moderate IOP elevation in an albino strain that led to RNFL thinning and reduced RGC density along with the reductions in ganglion and photoreceptoral cell functions. There was a small thickening in both outer and inner retinal layers.

MS optic neuritis-induced long-term structural changes within the visual pathway.

BackgroundThe visual pathway is commonly involved in multiple sclerosis (MS), even in its early stages, including clinical episodes of optic neuritis (ON). The long-term structural damage within the visual compartment in patients with ON, however, is yet to be elucidated.ObjectiveOur aim was to characterize visual system structure abnormalities using MRI along with optical coherence tomography (OCT) and pattern-reversal visual evoked potentials (VEPs) depending on a single history of ON.MethodsTwenty-eight patients with clinically definitive MS, either with a history of a single ON (HON) or without such history and normal VEP findings (NON), were included. OCT measures comprised OCT-derived peripapillary retinal nerve fiber layer (RNFL) and macular ganglion cell/inner plexiform layer (GCIPL) thickness. Cortical and global gray and white matter, thalamic, and T2 lesion volumes were assessed using structural MRI. Diffusion-weighted MRI-derived measures included fractional anisotropy (FA), mean (MD), radial (RD), and axial (AD) diffusivity within the optic radiation (OR).ResultsMean (SD) duration after ON was 8.3 (3.7) years. Compared with the NON group, HON patients showed significant RNFL (p = 0.01) and GCIPL thinning (p = 0.002). OR FA (p = 0.014), MD (p = 0.005), RD (p = 0.007), and AD (p = 0.004) were altered compared with NON. Global gray and white as well as other regional gray matter structures did not differ between the 2 groups.ConclusionA single history of ON induces long-term structural damage within the retina and OR suggestive of both retrograde and anterograde neuroaxonal degeneration.

Sustained Intraocular Pressure Rise after the Treat and Extend Regimen at 3 Years: Aflibercept versus Ranibizumab.

Purpose To determine the risk factors associated with sustained intraocular pressure (IOP) rise in patients enrolled in the treat and extend (T&E) protocol receiving aflibercept/ranibizumab therapy for 3 years. Design Retrospective, observational chart review. Setting. Multicentric. Patients. 789 patients (1021 eyes; 602 males) enrolled in T&E using aflibercept/ranibizumab for diabetic macular edema (DME), wet age-related macular degeneration (AMD), or macular edema in retinal vein occlusion (RVO). Intervention. The history, examination (clinical and special investigations), and treatment records were thoroughly scrutinized. Sustained IOP rise was defined as a rise in IOP above baseline by ≥6 mmHg and/or >24 mmHg on 2 or more consecutive visits. The Wilk–Shapiro test was used for confirming normality of data. The Mantel–Haenszel test and generalized estimating equations were used to analyse multicentric data as well as to analyse data from both eyes of the same patients in the event that both eyes were under therapy. The relative risk, chi-square test (with and without Yates' correction), and univariate and multivariate analysis were used wherever appropriate. Statistical significance was set at P < 0.05. The primary outcome measure was the determination of risk factors for sustained IOP rise with ranibizumab/aflibercept therapy. Secondary outcome measures included determining the incidence of IOP rise (short term and sustained), visual field, and retinal nerve fibre layer (RNFL) changes. Results The mean follow-up was 42.4 months. Male gender, South Asian ethnicity, older age, presence of AMD and vein occlusion, use of ranibizumab, higher number of injections, narrow angles, switch to bevacizumab/ranibizumab, and preexisting glaucoma were associated with sustained IOP rise. No significant visual field and RNFL changes were seen. The overall incidence was 8.91%. No patient required filtering surgery. No patient with IOP rise returned to baseline. Conclusion IOP rise is an important consideration as the chronicity of the condition can eventually lead to glaucomatous changes in eyes with already compromised vision. Follow-ups and use of appropriate therapy can be determined correspondingly.

Retinal Nerve Fiber Layer Thickness Progression after Robotic-Assisted Laparoscopic Radical Prostatectomy in Glaucoma Patients

Purpose To investigate the effect of the steep Trendelenburg position surgical procedure on the retinal structure and function during robotic-assisted laparoscopic radical prostatectomy (RALP) in glaucoma patients. Methods At 1 month and 1 day before and at 1 and 2 months after the RALP operation, 10 glaucoma patients underwent standard automated perimetry and optical coherence tomography. After placing patients in a supine position, intraocular pressure (IOP) was measured at 5 min after intubation under general anesthesia (T1), at 5 discrete time points (5, 30, 60, 120, and 180 min; T2-6) and at 5 min after returning to a horizontal supine position (T7). The Guided Progression Analysis software program was used to assess serial retinal nerve fiber layer (RNFL) thicknesses and visual field progression. Results Eight additional patients were newly diagnosed in addition to the two previous glaucoma patients. Average IOP (mmHg) at each time point was as follows: T1 = 11.2 ± 3.8, T2 = 19.0 ± 4.4, T3 = 23.3 ± 6.3, T4 = 25.1 ± 4.3, T5 = 25.5 ± 5.1, T6 = 28.3 ± 4.8, and T7 = 22.6 ± 5.4. IOP significantly increased during RALP. RNFL thickness progressed in two eyes of two patients after the surgery, even though there was no progression of the visual field. Conclusions Two eyes of two patients exhibited significant RNFL thickness progression. Since an increased IOP during the surgery was the probable cause of the changes, ophthalmologic examinations should be performed before and after RALP, especially in glaucoma patients.

Physiological changes in retinal layers thicknesses measured with swept source optical coherence tomograph

AbstractPurposeTo evaluate the physiological changes of the different layers of the retina measured by the standard protocol and the grid points of the swept source optical coherence tomography (SS‐OCT).MethodsA total of 463 eyes divided into four groups will be analyzed: Group 1 (71 eyes of subjects of 20 and 34 years); Group 2 (65 subjects from 35 to 49 years), Group 3 (with 230 subjects from 50 to 64 years) and Group 4 (97 subjects from 65 to 79 years). Wide protocol of Triton SS‐OCT (Topcon Corporation, Japan) was used to measure thickness of different layers of the retina, retinal nerve fiber layer (RNFL), ganglion cell layer, and choroid.ResultsTransition from group 2 to group 3 showed the most significant thinning of all the retinal layers, especially in the superior‐temporal quadrant of RNFL, ganglion cell and retinal layers (p &lt; 0.001), and temporal sectors in the choroid layer (p &lt; 0.001). A significant RNFL thickening was found in group 2 compared with group 1 in the superior temporal quadrant (p = 0.001), inferior half (p &lt; 0.001) and temporal half (p = 0.001), and also in the choroid layer (p = 0.001).ConclusionThere is a progressive and physiological thinning of all the layers of the retina from the third decade of life.

Relationship between preoperative high intraocular pressure and retinal nerve fibre layer thinning after glaucoma surgery

Recent reports show varying results regarding peripapillary retinal nerve fibre layer (RNFL) thickness after intraocular pressure (IOP)-lowering glaucoma surgery. We hypothesised that different levels of the preoperative IOP influence RNFL thickness. A total of 60 patients (60 eyes) with glaucoma, who underwent glaucoma surgery and had a stable postoperative mean IOP < 22 mmHg, were enrolled. The RNFL thickness was measured using spectral domain optical coherence tomography, before and at 3–6 months after surgery. The preoperative peak IOP, 37.4 ± 10.8 mmHg, decreased to a postoperative mean IOP of 14.8 ± 3.5 mmHg (p < 0.001). The average RNFL thickness was significantly reduced from 75.6 ± 17.7 μm to 70.2 ± 15.8 μm (p < 0.001). In subgroup analyses, only patients with a preoperative peak IOP ≥ median value (37 mmHg) exhibited significant RNFL thinning (9.7 ± 6.6 μm, p < 0.001) associated with a higher preoperative peak IOP (r = 0.475, p = 0.008). The RNFL thinning was evident for a few months after glaucoma surgery in patients with a higher preoperative peak IOP, although the postoperative IOP was stable.

Glial proliferation and atrophy: Two poles of optic disc in patients with retinitis pigmentosa

PurposeTo clarify the difference of retinal nerve fiber layer (RNFL) thicknesses between patients with retinitis pigmentosa (RP) and normal subjects. MethodsThe study included right eyes of 30 patients with non-late-stage RP, which had a waxy pallor in OD, attenuation in retinal arterioles, and midperipheral bone spicule pigmentary changes. To compare the RNFL analysis with normal subjects, the right eyes of 30 age- and gender-matched healthy subjects were included as a control group. ResultsThere were no differences between the RP and control groups in terms of demographic and baseline characteristics (P > 0.05, for all). The mean temporal quadrant RNFL thickness was 102.9 ± 31.7 μm (43–222) in the RP group and 72.4 ± 11.8 μm (51–90) in the control group (P < 0.001). The mean nasal quadrant RNFL thickness was 57.6 ± 33.7 μm (21–140) in the RP and 75.0 ± 14.1 μm (56–132) in the control group (P < 0.001). There were no significant RNFL thickness differences between the groups in other sectors and globally (P > 0.05, for all). There was no significant correlation between temporal RNFL thickening and ageing (r = −0.136, P = 0.196) while there was a significant correlation between nasal RNFL thinning and ageing (r = −0.274, P = 0.047). ConclusionsRNFL is thicker in temporal quadrants and thinner in nasal quadrants in non-late stage RP. Age-related decreases in RNFL thickness occurred earlier in the nasal quadrant and RNFL thickening in the temporal quadrant occurred earlier than this global thinning.

Clinical correlation of retinal nerve fiber layer thickness in multiple sclerosis patients- A North Indian study

Background: Axonal loss is thought to occur early in the course multiple sclerosis (MS) and is supposed to be associated with, and predictive of, neurologic deficits progressing to permanent disability.Axonal loss in the retinal nerve fiber layer (RNFL) is measured by optical coherence tomography (OCT). Material and Methods: A longitudinal observational study, conducted on 30 MS patients. All subjects underwent neurological examination, including expanded disability status scale (EDSS) scoring and OCT on two visits, minimum 2 months apart. Results: Total of 60 eyes of 30 patients were subdivided into 21 eyes having optic neuritis (ON) [‘MS – ON’] and 39 eyes without ON. The RNFL thickness (RNFLt) was found to be significantly reduced in all parameters except in temporal quadrant, as the duration of disease increases. Average RNFLt were found to have negative correlation (r = -0.450) with disease duration. Negative correlation (r=-0.657) was also found between EDSS score change and average RNFLt change. The eyes having ON showed statistically significant RNFL thinning as compared to the non – ON fellow eyes. The baseline EDSS score was found to be negatively correlated (moderate degree, r = -0.348) with baseline average RNFL thickness, with p-value of 0.006. Conclusions: The RNFLt is not only significantly thinner in those with history of ON, but it is also affected remarkably even in absence of prior ON, suggesting subclinical ongoing axonal loss in patients with MS. The EDSS score is inversely correlated with RNFL thickness.

Diagnostic Performance of Macular Ganglion Cell/Inner Plexiform Layer Thickness to Discriminate Normal Eye from Eye with Early Glaucoma Using Cirrus Spectral-Domain Optical Coherence Tomography

&#x0D; &#x0D; &#x0D; Background: Glaucoma is a progressive optic neuropathy characterized by a progressive loss of retinal ganglion cells (RGC). In glaucomatous optic neuropathy, structural optic nerve changes may occur before detectable functional loss, which can be diagnosed early by detecting loss of RGC. This review was conducted to see the diagnostic performance of macular ganglion cell/inner plexiform layer (GC-IPL) thickness parameters to discriminate normal eye from early glaucoma eye using Cirrus Spectral-domain OCT compared to peri-papilarry Retinal Nerve Fiber Layer (RNFL) thickness parameters. &#x0D; Methods: Literature search was conducted from MEDLINE database using Pubmed, Clinical Key, and ScienceDirect. No publication date was set, and only articles published in English were included. Reference list from the included studies were also checked for potentially relevant articles. Results: Twenty articles were found related to search term. Seven articles met the inclusion criteria. Fourteen others were excluded. All studies revealed significant thinner GC-IPL and RNFL average thickness in glaucoma patients compared to normal patients. GC-IPL Average was inferior to GC-IPL Minimum and RNFL inferior in determining normal eye from early glaucomatous eyes. Studies evaluating the diagnostic performance of Ganglion Cells Complex (GCC) thickness also found low sensitivity values, ranging between 61.0% and 78.6% for average GCC. &#x0D; Conclusion: Diagnostic performance of GC-IPL is comparable to RNFL parameters measurement in detecting early glaucoma eyes. Best performance in detecting early glaucoma were showed by GC-IPL minimum and RNFL inferior. &#x0D; &#x0D; &#x0D;

Three dimensional neuro-retinal rim thickness and retinal nerve fiber layer thickness using high-definition optical coherence tomography for open-angle glaucoma.

To compare the diagnostic capability of three-dimensional (3D) neuro-retinal rim thickness (NRR) with existing optic nerve head and retinal nerve fiber layer (RNFL) scan parameters using high-definition optical coherence tomography (HD-OCT). Retrospective study. Based on the mean deviation (MD) of the Humphrey Field Analyzer (HFA), the 152 subjects were categorized into mild (MD > - 6dB, 100), moderate (MD - 6 to - 12dB, 26), and severe (MD < - 12dB, 26) glaucoma. The HD-OCT values of NRR, RNFL and ganglion cell inner plexiform layer (GCIPL) thicknesses, along with those of other parameters (rim area, disc area) were obtained, and the average NRR thickness was calculated. For all of the HD-OCT parameters, RNFL thickness showed a higher area under the ROC (AUROC) curve (range: 0.937-1.000) than did NRR thickness (range: 0.827-1.000). There were significant RNFL, NRR, and GCIPL AUROC curve differences among the mild, moderate and severe glaucoma groups. RNFL thickness for mild glaucoma showed a significantly larger area than did NRR thickness [area difference: 0.110 (± 0.025); p value < 0.0001). Furthermore, RNFL relative to NRR thickness yielded higher sensitivity (85-100% vs. 72-100%) and specificity (89-100% vs. 84-100%) for diagnosis of glaucoma. RNFL thickness remains significantly better than 3D NRR thickness in terms of glaucoma-diagnostic capability in HD-OCT.

A Novel Tree Shrew (Tupaia belangeri) Model of Glaucoma.

PurposePrimates and rodents are used widely as animal models of glaucoma, but each has significant limitations. Researchers need additional animal models that closely resemble the relevant anatomy and pathologic features of the human disease to more quickly advance research. We validate a novel glaucoma animal model in tree shrews (Tupaia belangeri).MethodsExperimental glaucoma was induced in adult tree shrews (n = 8) by injecting 50 μL of a 25 mg/mL ferromagnetic bead solution into the anterior chamber. Beads were directed into the iridocorneal angle with a magnet to impede aqueous outflow. Animals were followed for 3 months with weekly IOP measurements and biweekly spectral domain optical coherence tomography (SD-OCT) images of the optic nerve head. Histopathology of the optic nerve and optic nerve axon counts were completed at the end of the study.ResultsThe 12-week average mean IOP was 22.7 ± 3.6 and 8.6 ± 2.9 mm Hg in the treated and control eyes, respectively. Longitudinal analysis showed significant retinal nerve fiber layer (RNFL) thinning throughout the study. Axon counts were significantly reduced (59.7%) in treated versus control eyes. SD-OCT imaging showed cupping and posterior displacement of the lamina cribrosa in glaucomatous eyes. RNFL thickness and optic nerve axon counts were reduced consistent with IOP elevation. Optic nerves demonstrated histopathology consistent with glaucomatous optic neuropathy.ConclusionsTree shrews with experimental glaucoma show key pathologic characteristics of the human disease. The tree shrew model of glaucoma has the potential to help researchers accelerate our understanding of glaucoma pathophysiology.

Evaluating displacement of lamina cribrosa following glaucoma surgery

PurposeThe purpose of the study is to assess the displacement of lamina cribrosa (LC) and prelaminar tissue area (PTA) changes following trabeculectomy and non-penetrating deep sclerectomy (NPDS) using spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging technology.MethodsA total of 30 patients underwent glaucoma surgery. Sixteen patients underwent trabeculectomy, and 14 patients undertook NPDS. Serial horizontal B-scan images of optic nerve head (ONH) were obtained using SD-OCT preoperatively, and at 2-week, 1-, 3-, and 6-month postoperative visit (6 pv). LC displacement magnitude and PTA changes were determined from selected B-scan images. Correspondingly, OCT retinal nerve fiber layer (RNFL) parameters were measured.ResultsIntraocular pressure (IOP) decreased from 27.4 ± 10.3 mmHg (mean ± standard deviation) to 10.2 ± 4.0 mmHg (P = 0.011) and from 19.9 ± 4.0 mmHg to 11.9 ± 3.6 mmHg (P = 0.012) at 6 pv, for trabeculectomy and NPDS, respectively. There was a significant decrease in the LC depth from a baseline glaucomatous LC displacement of 468.0 ± 142.4 to 397.6 ± 125.2 μm in the trabeculectomy group (P = 0.001) and from 465.2 ± 129.6 to 412.0 ± 122.4 μm in the NPDS group (P = 0.029) at 6 pv. The PTA differed between the procedures at baseline (P = 0.002), but was not statistically significant postoperatively. Multivariate analysis for all patients including age, magnitude of IOP reduction, baseline glaucomatous LC displacement, magnitude of LC displacement, and the type of surgery revealed that only the magnitude of LC displacement was associated with significant RNFL thinning on average (r2 = 0.162, P = 0.027) and in the following sectors: temporal superior (r2 = 0.197, P = 0.014), temporal (r2 = 0.150, P = 0.034), and nasal superior (r2 = 0.162, P = 0.027).ConclusionsDecrease in the LC depth after NPDS surgery can be observed at 6 pv. Regardless of the performed procedure, magnitude of LC displacement is associated with significant, focal RNFL thinning.

Retinal sensitivity changes associated with diabetic neuropathy in the absence of diabetic retinopathy

PurposeTo explore any relationship between the markers of early retinal neuronal damage and peripheral diabetic neuropathy in subjects with no diabetic retinopathy (DR).MethodsA cross-sectional study in which type 2 diabetic...

Retinal Morphology and Sensitivity Are Primarily Impaired in Eyes with Neuromyelitis Optica Spectrum Disorder (NMOSD).

BackgroundPrevious studies of neuromyelitis optica spectrum disorder (NMOSD) using spectral domain optical coherence tomography (SD-OCT) showed that the outer nuclear layer (ONL) in eyes without a history of optic neuritis (ON) was thinner than that of healthy controls. It remains unclear whether the ONL thinning is caused by a direct attack on the retina by an autoantibody or a retrograde degeneration.ObjectiveTo determine the mechanisms involved in the retinal damage in eyes with NMOSD without ON.MethodsSD-OCT was used to determine the thicknesses of the different retinal layers of 21 eyes of 12 NMOSD patients without prior ON and 19 eyes of 10 healthy controls. Eyes with peripapillary retinal nerve fiber layer (RNFL) thinning were excluded to eliminate the confounding effects of retrograde degeneration. Microperimetry was used to determine the central retinal sensitivity. The data of the two groups were compared using generalized estimated equation models to account for inter-eye dependencies.ResultsThe ganglion cell plus inner plexiform layer and the inner nuclear layer plus outer plexiform layer thicknesses of the NMOSD eyes were not significantly different from that of the control eyes (P = 0.28, P = 0.78). However, the ONL and average macular thickness (AMT) in the NMOSD eyes were significantly thinner than that of the control eyes (P = 0.022, P = 0.036). The retinal sensitivity in the central 10°, 10° to 2°, and 2° sectors were significantly lower in the NMOSD eyes than in the control eyes (P = 0.013, P = 0.022, P = 0.002).ConclusionsThe ONL thinning, AMT thinning, and reduced retinal sensitivity in eyes with NMOSD without significant peripapillary RNFL thinning are most likely due to direct retinal pathology.

Effect of chronic alcohol and tobacco use on retinal nerve fibre layer thickness: a case–control study

ObjectiveTo identify the effects of chronic alcohol and/or tobacco use on retinal nerve fibre layer (RNFL) thickness and to find the association between severity of addiction with RNFL thinning.MethodologyA case–control...

Retinal nerve fiber layer thickness changes in obstructive sleep apnea syndrome: a systematic review and Meta-analysis.

To evaluate the retinal nerve fiber layer (RNFL) thickness changes in patients with obstructive sleep apnoea syndrome (OSAS), and detect possible prevalence of glaucoma in this population. Comprehensive studies were conducted on the Cochrane Library, PubMed and Embase through March, 2015. Only studies that fit the selection criteria about RNFL and OSAS would be included. For the measures, we calculated the 95% confidence interval (CI) and weighted mean differences (WMD). The systematic review and Meta-analysis was performed by RevMan 5.2 software. Nine case-control studies were analyzed containing a total of 1086 cases and 580 controls. Average RNFL thickness in OSAS was reduced significantly compared with healthy controls in random effects model (WMD=-2.56, 95% CI: -4.82 to -0.31, P =0.003, I2=57%). A significant RNFL thickness reduction were found between the two groups in inferior quadrant (WMD=-3.11, 95% CI: -5.53 to -0.69, P=0.01), superior quadrant (WMD=-2.37, 95%CI: -4.7 to 0.04, P=0.05). In nasal quadrant (WMD=-2.54, 95% CI: -6.53 to 1.45, P=0.21) and temporal quadrant (WMD=-1.26, 95% CI: -2.19 to 0.47, P=0.15) there was no difference of RNFL thickness between the two groups. The results show that RNFL thickness is lower in patients with moderate or severe OSAS than in normal subjects or patients with mild OSAS according to the nine homogeneity studies.

Patterns of Retinal Nerve Fiber Layer Loss in Different Subtypes of Open Angle Glaucoma Using Spectral Domain Optical Coherence Tomography.

The purpose of the study was to determine whether there are different patterns of retinal nerve fiber layer (RNFL) thinning as measured by spectral domain optical coherence tomography (SD-OCT) for 4 subtypes of open angle glaucoma (OAG): primary OAG (POAG), normal tension glaucoma (NTG), pseudoexfoliation glaucoma (PXG), and pigmentary glaucoma (PDG) and to compare them with normal controls. SD-OCT RNFL thickness values were measured for 4 quadrants and for 4 sectors (ie, superior-nasal, superior-temporal, inferior-nasal, and inferior-temporal). Differences in RNFL thickness values between groups were analyzed using analysis of variance. Paired t tests were used for quadrant comparisons. Two hundred eighty-five participants (102 POAG patients, 33 with NTG, 48 with PXG, 13 with PDG, and 89 normal patients) were included in this study. All 4 subtypes of OAG showed significant RNFL thinning in the superior, inferior, and nasal quadrants as well as the superior-temporal and inferior-temporal sectors (all P-values <0.0001) compared with normals. POAG and NTG patients had greater RNFL thinning inferiorly and inferior-temporally than superiorly (P-values: 0.002 to 0.018 and 0.006, respectively) compared with PXG patients. In contrast, PDG patients had greater RNFL thinning superiorly and superior-nasally than inferiorly compared with other OAG subtypes (ie, POAG, NTG, PXG groups, with P-values: 0.009, 0.003, 0.009, respectively). Of the 4 OAG subtypes, PXG patients exhibited the greatest degree of inter-eye RNFL asymmetry. This study suggests that SD-OCT may be able to detect significant differences in patterns of RNFL thinning for different subtypes of OAG.

Modeling the Chronic Loss of Optic Nerve Axons and the Effects on the Retinal Nerve Fiber Layer Structure in Primary Disorder of Myelin.

PurposeWe determined whether the chronic lack of optic nerve myelination and subsequent axon loss is associated with optical coherence tomography (OCT) changes in the retinal nerve fiber layer (RNFL), and whether this models what occurs in multiple sclerosis (MS) and confers its use as a surrogate marker for axon degeneration.MethodsUsing an animal model of Pelizaeus-Merzbacher disease (shp) bilateral longitudinal measurements of the peripapillary RNFL (spectral-domain OCT), electroretinograms (ERG), and visual evoked potentials (VEP) were performed in affected and control animals from 5 months to 2 years and in individual animals at single time points. Light and electron microscopy of the optic nerve and retina and histomorphometric measurements of the RNFL were compared to OCT data.ResultsOf the shp animals, 17% had an average reduction of OCT RNFL thickness on the superior retinal quadrant compared to controls (P < 0.05). Electroretinograms showed normal photopic A- and B-waves but flash VEPs were disorganized in shp animals. Morphologically, the shp retinas and optic nerves revealed significant RNFL thinning (P < 0.001) without retinal ganglion cell (RGC) loss, decrease total and relative retinal axonal area, and loss of optic nerve axons. There was strong positive correlation between OCT and morphometric RNFL thickness measurements (r = 0.878, P = 0.004).ConclusionThe loss of optic nerve axons demonstrated in the shp model resulted in moderate thinning of the RNFL confirmed by OCT and histology. These results indicate that OCT-derived RNFL measurement can be a useful surrogate biomarker of optic nerve axon loss and potentially disease progression in demyelinating diseases.

Dyschromatopsia in Multiple Sclerosis Patients: A Marker of Subclinical Involvement?

In multiple sclerosis (MS), even in the absence of a clinical episode of optic neuritis (ON), the optic nerve and retinal nerve fiber layer (RNFL) may be damaged leading to dyschromatopsia. Subclinical dyschromatopsia has been described in MS associated with lower motor and cognitive performances. To set the prevalence of dyschromatopsia in eyes of MS patients without a history of ON, to compare its prevalence in patients with and without ON history, and to explore the association between dyschromatopsia and disease duration, average peripapillary RNFL thickness, macular volume, and cognitive and motor performances. An observational cross-sectional study was conducted at multiple medical centers. Data were collected after single neurological and ophthalmological evaluations. Dyschromatopsia was defined by the presence of at least 1 error using Hardy-Rand-Rittler plates. In our population of 125 patients, 79 patients (63.2%) never had ON and 35 (28.8%) had unilateral ON. The prevalence of dyschromatopsia in eyes of patients without ON was 25.7%. Patients with dyschromatopsia had a statistically significant lower RNFL thickness (P = 0.004 and P = 0.040, right and left eyes, respectively) and worse performance in symbol digit modalities test (P = 0.012). No differences were found in macular volume or motor function tasks. Dyschromatopsia occurs frequently in MS patients. It may be associated with a worse disease status and possibly serve as a marker for the detection of subclinical disease progression since it was detected even in the absence of ON. It correlated with thinner peripapillary RNFL thickness and inferior cognitive performance.