Superior Retinal Nerve Fiber Layer Research Articles

Relationship between optic nerve head topography and nerve fiber layer thickness with central corneal thickness in patients with primary open-angle glaucoma

Introduction/Objective. In patients with primary open-angle glaucoma (POAG) we explored the relationship between the optic nerve head (ONH) topography parameters and the retinal nerve fiber layer (RNFL) thickness with the central corneal thickness (CCT). Methods. This retrospective study included 97 patients (97 eyes) with primary open-angle glaucoma. Patients were divided into a thin CCT < 540 ?m (45 eyes) and a thick CCT ? 540 ?m (52 eyes) group, using ultrasonic pachymeter. Topographic measurements of the ONH parameters and RNFL thickness was performed using optical coherence tomography (OCT). The outcomes were compared with the thin and thick CCT and correlated with the thin CCT of the subjects. Results. There were significantly lower mean intraocular pressure (p < 0.0001) and CCT (p < 0.0001) in patients with thin CCT compared to patients with thick CCT. Statistically significant differences of ONH parameters were found in thin cornea group compared to thick cornea group in: cup/disc area ratio (p < 0.03), vertical cup/disc ratio (p < 0.01) and rim volume (p < 0.01). Statistically significant differences of RNFL thickness were found in thin cornea group compared to thick cornea group in: average (p < 0.001), superior (p < 0.03), inferior (p < 0.03) and nasal (p < 0.01). Significant positive correlation was found between thin CCT and OCT parameters in: optic disc area (r = 0.429, p = 0.003), cup/disc area ratio (r = 0.287, p = 0.05), horizontal cup/disc ratio (r = 0.472, p < 0.001), vertical cup/disc ratio (r = 0.578, p < 0.001), average RNFL (r = 0.796, p < 0.001), superior RNFL (r = 0.665, p < 0.001), inferior RNFL (r = 0.650, p < 0.001), nasal RNFL (r = 0.611, p < 0.001) and temporal RNFL thickness (r = 0.601, p < 0.001). Conclusion. POAG patients with thin cornea will probably develop larger glaucoma changes than those with a thicker cornea. Ultrasonic pachymetry measurements of CCT and OCT analysis of ONH topography parameters and RNFL thickness provide significant information in early diagnosis and monitoring progression of POAG.

Sensitivity of optical coherence tomography and visual evoked potential in demyelinating optic neuritis

Aim The aim of this study is to analyze the structural and functional abnormalities of the optic nerve in multiple sclerosis (MS) patients utilizing optical coherence tomography (OCT) and visual evoked potential (VEP). We compare between eyes with and without a history of neuritis. Patients and methods A cross-sectional study which compared 60 eyes of MS patients with 20 eyes of the healthy control group. MS patients were classified into MS with optic neuritis (MS-ON, n=44) and MS without optic neuritis (MS-NON, n=16). Both VEP and OCT were done. Results Both groups showed thinning in the retinal nerve fiber layer (RNFL), ganglion cell complex, and prolongation in latency (P100). The decrement in RNFL was more in the MS-ON group in superior RNFL, temporal RNFL, and average RNFL (P=0.002, 0.002, 0.03), respectively. In the MS-ON group, the average, temporal, and nasal RNFL showed significant negative correlation with latency of P100 (P=0.0001, 0.0001, 0.001), respectively. Latency of P100 showed higher sensitivity (52.3%) over temporal RNFL (43.2%) in detecting ON. Conclusion Both VEP and OCT have been proven to be sensitive tools in the detection of optic neuropathy in MS. Latency showed the highest sensitivity followed by the temporal RNFL. Temporal RNFL and average ganglion cell complex can be a biomarker for both axonal and neuronal loss in eyes with and without neuritis. This loss can precede the demyelination process.

Effect of Obstructive Sleep Apnea Syndrome on Retinal Nerve Fiber Layer and Ganglion Cell Complex

In this study, we aimed to identify the effect of oxygen desaturation due to comparing ganglion cell complex (GCC), retinal nerve fiber layer (RNFL) between patients with obstructive sleep apnea syndrome (OSAS), simple snoring and healthy individuals.132 total patients with OSAS and simple snoring who were diagnosed with polysomnography between 2016 -2018 and 88 healthy individuals were included in the prospective-case control study. The patients were grouped according to the Apnea Hypopnea Index (AHI). Healthy volunteers and the patients with simple snoring (the AHI index value lower than 5) were grouped as respectively Group 1(G1) and Group 2 (G2). Groups 3 to 5 were separated according to the AHI index as mild OSAS (Group 3 (G3); AHI=5-15), moderate OSAS (Group 4(G4);AHI=16-30), and severe OSAS (Group 5(G5); AHI>30). All study participants underwent an examination of both eyes including corrected visual acuity, intraocular pressure measurement, dilated-pupil fundus examination, with RNFL and GCC thickness which were measured with optical coherence tomography (OCT). Of the 132 patients included in the study, 29 had simple snoring, 22 mild, 22 moderate, and 57 severe OSAS. When bilateral mean, superior, inferior, temporal, and nasal RNFL thickness and mean, superior and inferior GCC values were compared among the study groups; no statistically significant difference was found (p>0.005). No significant difference was evaluated between mean RNFL thickness, four quadrants RNFL thicknesses, mean GCC thickness, two quadrants GCC thickness with OCT in the study patients. Indeed, because the patients with diagnosed OSAS could more likely to develop glaucoma, it would be appropriate for these patients to have a regular optic examination.

Evaluation of Retinal Nerve Fiber Layer Thickness, Electroretinogram and Visual Evoked Potential in Patients with Alzheimer's Disease.

Objective To study the retinal nerve fibre layer (RNFL) thickness and visual electrophysiology testing in patients with Alzheimer's disease (AD). Methods A cross-sectional, hospital-based study: 25 AD subjects and 25 controls were recruited. Candidates who fulfil the criteria with normal ocular examinations were made to proceed with scanning laser polarimetry, pattern electroretinogram (PERG), and pattern visual evoked potential (PVEP) examinations of the right eye. RNFL thickness, PERG, and PVEP readings were evaluated. Results In AD, the mean of average RNFL thickness was 45.28 μm, SD = 3.61, P < 0.001 (P < 0.05), while the superior RNFL thickness was 54.44 μm, SD = 2.85, P < 0.001 (P < 0.05) and inferior RNFL thickness was 47.11 μm, SD = 4.52, P < 0.001 (P < 0.05). For PERG, the mean P50 latency was 63.88 ms, SD = 7.94, P < 0.001 (P < 0.05) and the mean amplitudes of P50 waves were 1.79 μV, SD = 0.64, P < 0.001 (P < 0.05) and N95 waves were 2.43 μV, SD = 0.90, P < 0.001 (P < 0.05). For PVEP, the mean latency of P100 was 119.00 ms, SD = 9.07, P < 0.001 (P < 0.05), while the mean latency of N135 was 145.20 ms, SD = 8.53, P < 0.001 (P < 0.05). The mean amplitude of P100 waves was 3.71 μV, SD = 1.60, P < 0.001 (P < 0.05), whereas the mean amplitude of N135 waves was 3.67 μV, SD = 2.02, P < 0.001 (P < 0.05). RNFL thickness strongly correlates with PERG readings, with P50 latency R = 0.582, R2 = 0.339, P=0.002 (P < 0.05), amplitude of P50 wave at R = 0.749, R2 = 0.561, P ≤ 0.001 (P < 0.05), and amplitude of N95 wave at R = 0.500, R2 = 0.250, P=0.011 (P < 0.05). No significant difference and correlation were observed on PVEP readings. Conclusion The mean of the average, superior and inferior RNFL thickness were significantly lower in the AD group compared with control. There is also significant difference of PERG and PVEP parameters between AD and controls. Regression analysis showed average RNFL thickness having significantly linear relationship with the PERG parameters.

Structure-function relationship in a series of glaucoma cases

To map retinal sensitivity and peripapillary retinal nerve fiber layer (RNFL) thickness, as measured by standard automated perimetry (SAP) and optical coherence tomography (OCT) respectively, in patients with various stages of primary open-angle glaucoma (POAG). Ninety patients with POAG were prospectively selected for SAP and for OCT RNFL thickness measurements. Factorial analysis performed independently for each hemifield was used to identify groups of related SAP visual field points. Pearson correlation coefficients were determined between visual field regions and peripapillary RNFL sectors and these data used to construct structure-function correlation maps for the various disease stages. Factorial analysis identified 4 factors or visual field regions for the inferior hemifield and 5 for the superior hemifield. For all patients and the subset of patients with advanced POAG, the strongest correlation was detected between the superior hemifield and the inferior RNFL sectors, while higher correlations for incipient and moderate disease stages were observed between the inferior hemifield and the superior RNFL sectors. In these patients, functional and structural damage can be mapped such that each zone of related SAP points correlates with one or several peripapillary RNFL zones. Such maps could improve our understanding of structure-function relationships in glaucoma.

Evaluation of Cerebrospinal Fluid Pressure by a Formula and Its Role in the Pathogenesis of Glaucoma.

Purpose To investigate potential associations between intraocular pressure (IOP) and cerebrospinal fluid pressure (CSFP) in patients with primary open-angle glaucoma (POAG) and healthy subjects. Methods Forty-three subjects were recruited. Weight and height were measured to calculate body mass index (BMI), along with blood pressure, heart rate, visual acuity, and IOP. Biometrics exam, corneal pachymetry, peripapillary retinal nerve fiber layer (RNFL) thickness, and macular thickness were assessed. The visual field exam was performed on all patients, and both pattern standard deviation (PSD) and mean deviation (MD) were considered. CSFP was estimated indirectly by using the mathematical formula CSFP = 0.44 × BMI + 0.16 × diastolic pressure − 0.18 × age − 1.91, based on the previous scientific studies. The TLCPD was calculated as follows: IOP−CSFP. Results A significant (p < 0.05) difference was found between the two groups for several parameters. Specifically, the CSFP was lower in patients with POAG than in healthy subjects (8.14 ± 4.52 and 7.43 ± 2.06, p < 0.001, respectively). Anamnestic TLCPD was found to be significantly (p < 0.001) higher in patients with POAG compared to healthy subjects. A significant (p < 0.05) correlation was found between anamnestic TLCPD and MD (r = −0.31), inferior RNFL thickness (r = −0.29), superior RNFL thickness (r = −0.27), IOP (r = 0.22), and CSFP (r = −0.46). Conclusion The CSFP was lower in glaucomatous patients compared to healthy subjects, whereas the TLCPD was higher in glaucomatous patients compared to healthy subjects, even though this difference was not statistically significant. A higher TLCPD may damage the RNFL, resulting in functional visual field impairment.

Comparison of the retinal nerve fiber layer and ganglion cell complex thickness in Korean patients with unilateral exfoliation syndrome and healthy subjects.

PurposeTo compare retinal nerve fiber layer (RNFL) and ganglion cell complex (GCC) thickness in patients with unilateral exfoliation syndrome (XFS) and age-matched controls using spectral domain-optical coherence tomography (SD-OCT).Materials and methodsThis prospective case–control study included 54 eyes (the XFS-affected and the fellow eyes) of 27 unilateral XFS patients and 27 eyes of 27 age-matched control subjects. The RNFL and GCC thicknesses were measured using SD-OCT (RT-Vue 100, Optovue, Fremont, CA) after pupillary dilation. RNFL and GCC thicknesses were compared between case and control groups.ResultsThe mean age of XFS patients was 73.3 years and that of age-matched controls was 74.3 years. Both groups demonstrated a male preponderance. Superior RNFL thickness of XFS-affected eyes were significantly thinner than those of the healthy age-matched controls (P = 0.002 by ANOVA). There were no statistically significant differences in the RNFL thickness between both eyes of unilateral XFS patients. Moreover, superior GCC thickness of both eyes in unilateral XFS patients were thinner than those in controls (P = 0.002 by ANOVA).ConclusionsThinner RNFL and GCC thicknesses were observed in unilateral XFS patients without visual field defects. These findings imply that XFS itself might be a risk factor for development of glaucomatous optic disc and RNFL damage.

Decreased retinal thickness in patients with Alzheimer's disease is correlated with disease severity.

Background and purposeThe loss of retinal ganglion cells observed in Alzheimer’s disease (AD) may be attributable to a neurodegeneration of the neuro-retinal structure. Amnestic mild cognitive impairment (aMCI) has been considered a prodromal stage of AD. We evaluated retinal thicknesses in patients with aMCI and AD compared to healthy controls using spectral-domain optical coherence tomography (OCT) to investigate whether changes in retinal thickness are correlated with the clinical severity of dementia.MethodsPatients with aMCI (n = 14), mild to moderate AD (n = 7), severe AD (n = 9), and age-matched controls (n = 17) underwent neuro-ophthalmologic examinations. Global deterioration scale (GDS), clinical dementia rating (CDR), and mini-mental status examination (MMSE) were used to evaluate the clinical overall severity of dementia. The thicknesses of the peripapillary retinal nerve fiber layer (RNFL), total macula, and macular ganglion cell-inner plexiform layer (GC-IPL) were measured using Cirrus HD-OCT.ResultsThe severe AD group had overall significantly thinner GC-IPL, total macula, and peripapillary RNFL compared to the controls (p<0.05). In the mild to moderate AD group, the total macula, average RNFL, and superior RNFL thickness were each significantly reduced compared to controls (p<0.05). The aMCI group had reduced total macula, average RNFL, and inferior RNFL thickness, but there were no significant differences compared to the controls. The GDS and CDR scores had a negative correlation with the thickness of the GC-IPL and the total macula. The MMSE scores had a positive correlation with both the total macular and average RNFL thickness, when adjusted for age (p<0.05).ConclusionsThis study confirmed that retinal thickness is decreased in AD patients. There is a correlation between reduced retinal thickness and the clinical severity of dementia.

Early retinal neurodegeneration in preclinical diabetic retinopathy: a multifactorial investigation.

To investigate effects of microalbuminuria (MA), diabetes duration, glycosylated haemoglobin (HbA1c) level, hypertension (HT) and/or hyperlipidaemia (HL) coexistence on retinal layers in diabetic patients without diabetic retinopathy (DR) using spectral-domain optical coherence tomography (SD-OCT). This cross-sectional study involved 95 (45 had MA and 50 had no MA) patients with type 2 diabetes mellitus (DM) without DR and 91 age- and gender-matched non-diabetic controls. Macular and peripapillary SD-OCT measurements (Heidelberg Engineering GmbH, Heidelberg, Germany), DM duration, HbA1c levels and presence of HT and/or HL were used for statistical analyses. The MA (+), MA (-) and control groups had similar age and gender distribution (p > 0.05). The differences in SD-OCT measurements among the MA (+), MA (-) and control groups were insignificant (p > 0.05). However, diabetic patients (n = 95) had significantly thinner inferior-temporal peripapillary retinal nerve fibre layer (RNFL) (p = 0.042) than in the controls (n = 91). Superior peripapillary RNFL was significantly thinner in patients with an HbA1c level > 7% (p = 0.049). However, 3 mm-nasal, temporal and superior perifoveal thicknesses were significantly lower in patients with DM duration over 10 years (p < 0.05). HT and/or HL coexistence did not lead a significant difference in SD-OCT parameters among the groups. In diabetic patients without DR, peripapillary inferior-temporal RNFL thinning might be an early sign of neuroretinal degeneration and it seems to be independent from vascular endothelial damage (MA). Poor metabolic control appears to lead superior peripapillary RNFL thinning, while perifoveal thicknesses tend to decrease with longer DM duration.

Influence of Choroidal Microvasculature Dropout on the Rate of Glaucomatous Progression: A Prospective Study

To determine the prognostic significance of choroidal microvasculature dropout (MvD) to predict the future rate of progressive retinal nerve fiber layer (RNFL) thinning in eyes with primary open-angle glaucoma (POAG). Prospective, longitudinal case series. This study enrolled 101 eyes of 101 patients with POAG who underwent OCT angiography (OCTA) imaging of the optic nerve head at baseline and were followed up for at least 2 years thereafter, during which RNFL thickness was measured by serial spectral-domain OCT. The peripapillary microvasculature was evaluated by examining en face OCTA images. Choroidal MvD was defined as a focal sectoral capillary dropout with no visible microvascular network in the choroidal layer. The rate of RNFL thinning was determined by linear regression of serial OCT RNFL thickness measurements. Influence of the presence of an MvD on the rate of subsequent RNFL thinning. Microvasculature dropout was identified in 48 eyes (47.5%). The rate of global RNFL thinning was significantly faster in eyes with MvD than eyes without MvD (-1.6±0.8 vs.-1.2±0.9 μm/year, P= 0.018). Eyes with MvD in the inferior hemisphere (n= 41) showed a faster rate of inferior RNFL thinning than eyes without MvD (P= 0.036). Eyes with MvD in both the superior and inferior hemispheres (n= 5) showed faster rates of superior (P= 0.027) and inferior (P= 0.016) RNFL thinning than eyes without MvD. Multivariate regression analysis showed that MvD at baseline (P= 0.003) and the presence of disc hemorrhage during follow-up (P= 0.001) were independently associated with a faster rate of global RNFL thinning. Microvasculature dropout was an independent predictor of a faster rate of progressive RNFL thinning in patients with POAG. Microvasculature dropout location was topographically associated with the location of faster RNFL thinning.

To Evaluate the Effect of Chronic Obstructive Pulmonary Disease on Retinal and Choroidal Thicknesses Measured by Optical Coherence Tomography.

Purpose To evaluate the retinal and choroidal thicknesses in patients with chronic obstructive pulmonary disease using optical coherence tomography. Methods The study included 26 patients with chronic obstructive pulmonary disease (COPD) and 26 age-matched healthy control groups. Detailed ocular examinations were performed on all participants. Cirrus EDI-OCT (enhanced depth imaging-optical coherence tomography) was used for choroidal thickness measurements with frame enhancement software. The subfoveal area was used for choroidal thickness measurements. Results The patients with the chronic obstructive pulmonary disease had an average 239.13 ± 57.77 μm subfoveal choroidal thickness, and the control group had an average 285.02 ± 25 μm subfoveal choroidal thickness. The subfoveal choroidal thickness measurements revealed a statistically significant difference between patients and the control group (p < 0.05). There were no statistically significant differences between patients and control group regarding mean macular thickness, central macular thickness, and GCIPL (ganglion cell-inner plexiform layer) thickness. Also, there was no statistically significant difference between patients and control group regarding mean, superior, nasal, inferior, and temporal RNFL (retinal nerve fiber layer) thicknesses. Conclusion Chronic hypoxemia seems to cause decreased choroidal thickness in patients with chronic obstructive pulmonary disease.

Evaluation of the Macula, Retinal Nerve Fiber Layer and Choroid Thickness in Women Using Oral Contraceptive Pills

AbstractBackground: Oral Contraceptive Pills (OCP) have some risks and side effects with regard to several organs, one of which is the eye. Estrogen & progesterone receptors have been shown to be present in various eye structures, such as the choroid, retina, conjunctiva, cornea, Meibomian glands, and lens.Aim of Study: The purpose of this study is to assess the macula, Retinal Nerve Fiber Layer (RNFL), and choroid thickness, in addition to evaluation of macular Ganglion Cell Complex (GCC) by using spectral-domain OCT system (3D OCT-2000 FA; Topcon Crop., Tokyo, Japan) in 20 women using Oral Contraceptive Pills (OCP) for more than one year and to compare them with 20 healthy reproductive age women volunteers.Patients and Methods: This is cross sectional study in-cluded 20 women using oral contraceptive pills in comparison to 20 normal females between April 2018 till July 2018 at Giza memorial Institute of Ophthalmic Research. Optical Coherence Tomography (OCT) is used to evaluate the posterior ocular segments, and measurements have been taken in the follicular phase (day 3) of the cycle in all women.Results: The mean age of the OCP group was 31.7±3.76 years and the mean age of the control group was 31.3±5.031 years. Both groups are homogenous in terms of age (p=0.7773). Most of the macular layer thickness and the foveal center are significantly thinner in OCP group. The macular volume is thinner in OCP study group. Retinal nerve fiber layers are thicker in OCP study group a part from Superior RNFL which is thinner in OCP study group, while temporal RNFL zone is with no significant changes. Choroid thickness values, is thicker in OCP study group. Ganglion cell complex is with no significant difference.Conclusion: We found that women who had received combined oral contraceptive pills more than one year have changes in posterior ocular segment.

Şizofreni Hastalarında Gözün Arka Segment Yapılarının Değerlendirilmesi

Purpose: We aimed to evaluate the effects of schizophrenia on posterior ocular structures including the retinal nerve fiber layer (RNFL), central macular thickness (CMT), choroidal thickness (CT) and lamina cribrosa (LC) measurements.Methods: A total of 35 patients with schizophrenia and 35 healthy individuals were enrolled. Only the right eye of each participant was tested. RNFL thickness in all quadrants, CT, CMT, LC thickness, and LC depth (LCD) measurements were performed using Fourier domain optic coherence tomography (OCT), and each variable was compared between groups.Results: The mean age and sex distributions were similar between groups (p=0.528 and p=0.299, respectively). The average, superior, inferior, nasal, and temporal RNFL thicknesses were significantly lower in schizophrenia patients than in controls (p&amp;lt;0.001, p&amp;lt;0.001, p=0.001, p=0.002 and p&amp;lt;0.001, respectively). The mean subfoveal and perifoveal CT were not significantly different between the groups (subfoveal; p=0.676, 1.5 mm nasal; p=0.632, 3 mm nasal; p=1.000, 1.5 mm temporal; p=0.811, 3 mm temporal; p=0.145). The mean CMT was similar among the groups (p=0.678). LC thickness and LCD were not statistically significant between groups (p=0.816 and p=0.161).Conclusions: We demonstrated that RNFL thicknesses in all quadrants were significantly lower in schizophrenia patients than in control subjects. However, there were no significant differences in the CMT, perifoveal and subfoveal CT, LC thickness, and LCD between the groups. These results suggest that OCT can be used to image neuronal loss by evaluating the RNFL in patients with schizophrenia. Keywords: Schizophrenia; retinal nerve fiber layer; choroidal thickness; lamina cribrosa thickness; macular thickness

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

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

The HD-OCT Study May Be Useful in Searching for Markers of Preclinical Stage of Diabetic Retinopathy in Patients with Type 1 Diabetes.

The aim of the study was to analyze the thickness of individual retinal layers in patients with type 1 diabetes (T1D) in comparison to the control group and in relation to markers of diabetes metabolic control. The study group consisted of 111 patients with an average of 6-years of T1D duration. The control group included 36 gender- and age-matched individuals. In all patients optical coherence tomography (OCT) study was performed using HD-OCT Cirrus 5000 with evaluation of optic nerve head (ONH) parameters, thickness of retinal nerve fiber layer (RNFL) with its quadrants, macular full-thickness parameters, ganglion cells with inner plexus layer (GCIPL) and choroidal thickness (CT). Lower disc area value was observed in the study group as compared to controls (p = 0.0215). Negative correlations were found both between age at examination and rim area (R = −0.28, p = 0.0007) and between superior RNFL thickness and duration of diabetes (R = −0.20, p = 0.0336). Positive correlation between center thickness and SD for average glycemia (R = 0.30, p = 0.0071) was noted. Temporal CT correlated positively with age at examination (R = 0.21, p = 0.0127). The selected parameters the HD-OCT study may in the future serve as potential markers of preclinical phase of DR in patients with T1D.

Assessment of Retinal Nerve Fiber Layer Thickness Using Optical Coherence Tomography in Patients with Type 2 Diabetes Mellitus

Background: Diabetic retinopathy (DR) is the most common ocular complication of diabetes mellitus (DM) and considered one of the leading causes of blindness in developed countries. Diabetic retinopathy is predominantly a microangiopathy in which high glucose levels can make small blood vessels particularly, vulnerable to damage. Objective: The aim of this work was to assess the thickness of peripapillary retinal nerve fiber layer (RNFL) measured by Swept Source optical coherence tomography (SS-OCT) in patients with Type 2 Diabetes Mellitus (DM). Patients and Methods: The study was an observational cross-sectional study. The study was conducted on 40 eyes of diabetic patients from the outpatient clinic in ophthalmology department of Al-Azhar University Hospitals. All patients were subjected to a complete ophthalmic examination including OCT. Results: The current study showed a negative correlation between parameters related to DM (duration of DM, and state of glycemic control measured by HbA1C) and all the parameters related to RNFL, and RGCL thickness but this correlation was statistically insignificant, and there was statistically significant decrease in superior RNFL thickness in patients with mild DR than patients with no DR, however, this difference was statistically insignificant in all parameters related to RGCL thickness in the two groups. Conclusion: Optical coherence tomography (OCT) provides non-invasive, quantitative and objective measurement of RNFL thickness, optic nerve head, and RGCL thickness with high resolution and accuracy. This could be the method of choice for monitoring the neurodegenerative changes in DR.

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.

Evaluation of Optic Nerve Head Parameters, Retinal Nerve Fiber Layer Thickness, and Ocular Perfusion Pressure in Migraine Patients.

BackgroundNeurovascular changes occur during the migraine is believed to cause alteration in cerebral and retinal circulation that possible result in damage to the brain and even retina or optic nerve. Retinal nerve fiber layer (RNFL) thickness measurement can be used as an index to assess ganglion cell and retinal nerve fiber damages. The aim of this study was to evaluate the optic nerve head (ONH) parameters, RNFL thickness, and ocular perfusion pressure (OPP) in migraine patients.MethodsThis was a cross-sectional study, conducted in Hospital Universiti Sains Malaysia, Kelantan from July 2016 to November 2018, involving patients with a confirmed diagnosis of migraine and controls. Ninety-four eyes of 47 migraine patients and 94 eyes of 47 healthy subjects were included in this study. Blood pressure and intraocular pressure were measured and OPP was calculated. ONH parameters and RNFL thickness were measured using optical coherence tomography (OCT) after pupillary dilatation. Statistical analysis was done using Statistical Package for the Social Science (SPSS Inc Version 24).ResultsWith respect to all means values of ONH parameters, there was no statistically significant difference between migraine patients and controls. For RNFL, there were significant reductions in average and superior RNFL thickness on both eyes with adjustment of age and gender (P-value: right eye (RE) average = 0.027; RE superior = 0.034; left eye (LE) average = 0.037; LE superior = 0.031). In view of OPP, there was no significant difference between migraine patients and controls (P-value = 0.172). Weak correlations were found between the ONH parameters and RNFL thickness with OPP, respectively, in migraine patients.ConclusionThis study showed no difference in ONH parameters between migraine patients and healthy subjects. There was significant thinning in average and superior RNFL for migraine patients. No difference found in OPP between both groups. ONH parameters and RNFL thickness had a weak correlation with OPP in migraine patients.

Effects of chronic elevated intraocular pressure on parameters of optical coherence tomography in rhesus monkeys.

To determine the progression of parameters from optical coherence tomography (OCT) in chronic elevated intraocular pressure (IOP) monkeys. A chronic elevated IOP model of rhesus monkeys was induced by laser photocoagulation. Representative OCT parameters, including the average and four-quadrant retinal nerve fiber layer (RNFL) thickness, and parameters from optic nerve head (ONH) analysis were collected before and after laser treatments biweekly for up to 28wk. The performance of each parameter for early progression detection was analyzed. The progressive trends toward elevated IOP were analyzed using a linear mixed-effects model. There were 10 successfully maintained high IOP eyes in 7 monkeys. The follow-up time was 24±5.37wk. With cumulative IOP elevation, the cup area, rim area and C/D area ratio were statistically significantly changed as early as 2wk after elevated IOP induction (P<0.05). The quadrant RNFL thickness changed at 6wk after high IOP induction, and the superior and inferior RNFL thicknesses exhibited more obvious reductions than other quadrants. The average RNFL thickness was the last one to show a significant decrease at 8wk. The parameters of ONH are most sensitive to elevated IOP in a primate glaucomatous model. These findings suggest that we should focus on those parameters instead of RNFL thickness in patients with elevated IOP, as they might present with earlier glaucomatous changes.

Sex-Specific Effect of BDNF Val66Met Genotypes on the Progression of Open-Angle Glaucoma.

To investigate whether the brain-derived neurotrophic factor (BDNF) Val66Met genotype is associated with the rate of progression of open-angle glaucoma (OAG). In this retrospective cohort study, 148 OAG patients (292 eyes) were enrolled with a median follow-up period of 5.3 (range, 1.1-8.6) years. All participants had undergone regular clinical examinations by using spectral-domain optical coherence tomography (SD-OCT) scans and Humphrey (SITA) visual field tests. BDNF Val66Met polymorphisms were genotyped in all participants. Longitudinal visual field and retinal nerve fiber layer (RNFL) changes were compared between Met carriers (n = 68, 135 eyes) and Val homozygotes (n = 80, 157 eyes) by using the generalized estimating equations (GEE) model and Kaplan-Meier survival analysis. There was no significant difference in mean rates of progression for the two genotypes. However, there was a significant association between the Val66Met genotypes and slower OAG progression, as suggested by a higher rate of global RNFL loss in Val/Val homozygotes (P = 0.008) in the long-term survival analysis. The effect demonstrated a degree of sex specificity, with the significant difference present only in females (P = 0.016) but not males. Similar sexual dimorphism was presented in superior (P = 0.005 in females, P = 0.38 in males) and inferior (P = 0.004 in females, P = 0.41 in males) RNFL loss. No significant difference was observed in visual field parameters. Our results suggested that carriage of Met allele reduces the rate of long-term OAG progression. However, the fact that this effect is observed only in females indicates BDNF Val66Met influences the progression rate of OAG in a sex-specific manner.