Retinal Nerve Fiber Layer Measurements Research Articles

Comparison of imaging parameters between OCT, GDx and HRT in the Northern Finland birth cohort eye study.

The purpose of the study was to assess and compare the optic nerve head (ONH) and retinal nerve fibre layer (RNFL) parameters and image quality parameters obtained by Cirrus HD-OCT, GDxECC and HRT3 in a population-based screening study. This analysis examined 2566 subjects taking part in the Northern Finland Birth Cohort Eye study. Images with spectral domain OCT (Cirrus HD-OCT 4000), scanning laser ophthalmoscopy (HRT3) and scanning laser polarimetry (GDxECC) were obtained from each subject. The correlation of average and regional parameters of RNFL and ONH between devices was evaluated. The RNFL thickness was 90.9 µm when measured with OCT, 24.6 µm with HRT and 48.1 µm with GDx. There was a high correlation between the disc and cup measurements with the HRT and OCT and the RNFL thickness of the OCT and GDx (r > 0.5). A statistically significant correlation was found between RNFL measurements of the HRT and OCT in the superior, temporal and inferior quadrants. Optical coherence tomography (OCT) signal strength correlated with the image quality parameters of the HRT and GDx. The percentage of good quality images was the lowest with the GDx. The RNFL thickness in Northern Finland birth cohort was at a lower level compared to other studies. The study confirms the difference in measuring ONH parameters between the imaging devices. However, significant correlations between devices were found in the cup volume and cup disc area ratio parameters of the OCT and HRT. The correlations between image quality parameters and glaucoma detection parameters were relatively low.

Retinal thinning in phenylketonuria and Gaucher disease type 3

PurposeRetinal alterations in inherited metabolic diseases associated with neurodegeneration are poorly studied. The objective was to study retinal thickness, specifically the components of the ganglion cell complex (GCC)—nerve fiber layer (NFL), ganglion cell layer (GCL), and inner plexiform layer (IPL)—using spectral-domain optical coherence tomography (SD-OCT) in two different diseases with potential dopaminergic depletion, phenylketonuria (PKU) and Gaucher disease type 3 (GD3).MethodsRetinal layers in 19 patients with PKU, 15 patients with GD3, and 93 healthy individuals were measured using peripapillary ring scan and macular SD-OCT. Linear mixed models were computed including an adjustment for age, sex, and spherical equivalent. We calculated Spearman’s rank correlations between retinal layer measurements and clinical and/or laboratory parameters.ResultsThinning of total retinal thickness was found in the macular inner ring (p = 0.002), and outer ring (p = 0.012), sparing the fovea (p = 0.12) in PKU, while in GD3, all subfields were thinned (fovea p < 0.001, inner ring p = 0.047, outer ring 0.07). In both conditions, thinning was most evident in the NFL, GCL, and IPL, while OPL (outer plexiform layer) was thickened. Peripapillary retinal nerve fiber layer measurements remained normal. GCL and IPL in PKU correlated with tyrosine serum concentration.ConclusionThinning of the NFL, GCL, and IPL, with thickened OPL, are both found in PKU and in GD3. Low dopamine concentrations in the retina might promote these effects. However, these data do not give evidence that retinal measurements can be used as a biomarker for disease severity in patients with GD3.

Evaluation of retinal nerve fiber layer thickness measured by (OCT) optical coherence tomography in patients with multiple sclerosis (MS)

Objective: The aim of this study is to evaluate the retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT) in Syrian patients with MS and diseases- free controls and to assess this thickness in MS-ON and MS-NON, and assess the relationship between RNFL thickness Expanded Disability Status Scale (EDSS) score. Although there are many similar studies to evaluate role of OCT at MS patients in different countries and many races,but this study is the first one of using OCT at MS patients in our country. Methods: This study (cross sectional ,case- control) was carried out at Tishreen University Hospital in Latakia. A total of 112 eyes from 56 individuals with an age range from 22 to 43 years were studied. twenty -six patients with definite MS, Diagnosis of MS was based on the MacDonald criteria.The disease-free controls were matched for age and gender (n=30; 60eyes). Retinal nerve fiber layer thickness was measured using optical coherence tomography (Spectralis OCT - Heidelberg Engineering), and gathering information about past ON history since more than 6 months and EDSS. Results: There were statistically Significant differences (p=0.0001) between both groups (case- control) were observed in OCT parameters (average, and all sectors especially temporal and superior sector) with lower RNFL thickness in the MS group (MS-ON,MS-NON).There were statistically significant differences (p=0.0001) between MS-ON (n = 20 eyes) and MS-NON (n = 32eyes) for all RNFL parameters measured by OCT, with lower RNFL thickness in (MS-ON).There were statistically significant inverse correlations was observed between average RNFL thickness and neurologic impairment (Expanded Disability Status Scale) (r=- 0.6، P=0.0001) and all sectors especially in temporal and superior quadrants (r=-7 , P=0.0001). Conclusions: OCT seems to be a reproducible test to detect axonal loss of ganglion cells in MS (RNFL). Further and larger longitudinal prospective studies would be valuable to assess the evolution over time of the RNFL measurements in Syrian MS patients.

Evaluation of Retinal Nerve Fiber Layer Thickness and Macular Thickness in Amblyopic Children

Objective: To compare central macular and retinal nerve fiber layer (RNFL) thickness using Spectral Domain Optical Coherence Tomography (SD-OCT) among patients with hyperopic anisometropic, strabismic and mixed amblyopia and healthy controls. Method: This prospective, cross-sectional study included 39 amblyopic children, their fellow eyes and 20 healthy individuals. Central macular and RNFL (superior, nasal, inferior and temporal quadrants and mean RNFL) thicknesses were measured with SD-OCT. Results: Difference was not statistically significant in the central macular thickness when the anisometropic, strabismic and mixed amblyopia groups were compared among themselves, fellow eyes and healthy control group. In the anisometropic amblyopic group, the inferior RNFL and nasal RNFL values were significantly thicker compared to the fellow eyes (p=0.009, p=0.028, respectively). Mean RNFL measurements were significantly thicker in anisometropic and mixed groups in the amblyopic eyes compared to the fellow eyes (p=0.009, p=0.031, respectively). In the temporal quadrant, the RNFL was found to be statistically significantly thinner in the anisometropic and mixed amblyopic groups compared to the fellow eyes (p=0.049, p=0.010, respectively). Conclusions: There was no considerably difference in the central macular thickness among the amblyopia groups, fellow eyes and healthy controls. However, significant changes were found in the mean RNFL and certain quadrants of the RNFL thicknesses in the anisometropic and mixed amblyopic groups.

Evaluation of choroidal thickness, retinal nerve fiber layer thickness, macular thickness and retinal vessel diameter by optical coherence tomography in patients with peripheral arterial disease

Aim: To evaluate retinal nerve fiber layer thickness, macular thickness and retinal vessel diameter by optical coherence tomography in patients with peripheral artery disease.&#x0D; Materials and Methods: 35 patients with a diagnosis of peripheral arterial disease (PAD) and 32 healthy individuals (control group) were included in the study. Retinal thickness (RT), choroidal thickness (CT) in enhanced depth imaging (EDI) mode, retinal nerve fiber layer (RNFL) thickness, retinal artery and vein diameters were measured with optical coherence tomography (OCT) device.&#x0D; Results: The mean age of the PAH group included in the study was 59.4±11.9 and the mean age of the control group was 55.5±5.3 years. A statistically significant difference was observed between the two groups in the values obtained from the CT in the subfoveal region of the EDI measured from three different regions and the nasal quadrant of the RNFL measured from 7 quadrants (p=0.03 and p=0.03, respectively). On the contrary, no statistically significant difference was observed in EDI and other measurements of RNFL, RT values, artery and vein diameters (p values were between 0.08-1.00).&#x0D; Conclusion: In patients with PAD, it is important to determine the RNFL and CT to be thinner. It can be a guide in more comprehensive studies in the future.

Optical Coherence Tomography and Optical Coherence Tomography Angiography Findings in Amblyopic Patients

Abstract Background: Amblyopia is a unilateral or bilateral decrease of visual acuity caused by deprivation of pattern vision or abnormal binocular interaction, for which no cause can be detected by physical examination of the eye and which in some cases, can be reversed by therapeutic measures. Aim of Study: To examine amblyopic eyes in a comparative study with age matched controls to detect possible changes in macular, Ganglion cell layer (GCL), choroid, peripapillary retinal nerve fiber layer (RNFL) measurements using optical coherence tomography (OCT), and foveal avascular zone (FAZ) area using optical coherence tomography angiography (OCTA). Patients and Methods: A case control observational study. Forty eyes of forty participants divided into 4 groups. 30 patients with unilateral amblyopia due to strabismus, ani-sometropia and sensory deprivation (each group included 10 patients) compared with 10 controls. OCT & OCTA were done using (Heidelberg Engineering, OCT spectralis, Germany). Results: As regard mean GCL thickness and FAZ area in superficial capillary plexus (SCP) and deep capillary plexus (DCP), there was no statistically significant difference between patients' groups and control group. Also there was no statisti-cally significant difference in RNFL thickness between am-blyopic groups and control group except nasal quadrant in strabismic and sensory deprivative groups, there was statisti-cally significant difference. For sub-foveal thickness there was statistically significant difference in strabismic, anisome-tropic groups, but no significant difference in sensory depriv-ative group. Conclusion: Patients with unilateral amblyopia were prone to have a higher central macular thickness in sensory depriv-ative group only, with no difference in thickness regarding other groups, and thinner nasal quadrant RNFL thickness in strabismic and sensory deprivative groups only, when compared to control eyes.

Bruch Membrane Opening Minimum Rim Width and Retinal Nerve Fiber Layer Helps Differentiate Compressive Optic Neuropathy From Glaucoma

To compare optical coherence tomography-measured Bruch membrane opening minimum rim width (MRW), peripapillary retinal nerve fiber layer (pRNFL) measurements, and MRW:pRNFL ratios in eyes with compressive optic neuropathy (CON) and glaucoma and controls, and evaluate the ability of these parameters to differentiate CON from glaucoma. Prospective, cross-sectional study. Setting: Single-center tertiary hospital and outpatient clinic. One hundred fifteen eyes of 77 participants, 34 with CON from chiasmal lesions, 21 with glaucoma, and 22 healthy controls. Optical coherence tomography-measured MRW, pRNFL, and MRW:pRNFL ratios for each optic disc sector and global average. MRW, pRNFL, and MRW:pRNFL ratios compared using generalized estimated equations. Area under the receiver operating characteristic curve and positive and negative likelihood ratios were calculated. MRW and pRNFL measurements were significantly reduced in CON and glaucoma compared with controls. In glaucoma, MRW was thinner than in CON in the global, inferotemporal, superonasal, inferonasal, and vertical average measurements, but a significant overlap was observed in many parameters. MRW:pRNFL ratios increased the ability to discriminate between CON and glaucoma, as shown by the high area under the receiver operating characteristic curve, high positive likelihood ratios, and low negative likelihood ratios, especially in the nasal disc sector and the nasal and temporal average. MRW measurements alone cannot reliably distinguish CON from glaucoma, but the combination of MRW, pRNFL, and MRW:pRNFL ratios significantly improves accuracy. When comparing the 2 conditions, MRW:pRNFL ratios yielded higher area under the receiver operating characteristic curve and positive and negative likelihood ratios, suggesting this parameter may be helpful in clinical practice.

Estimating the Severity of Visual Field Damage From Retinal Nerve Fiber Layer Thickness Measurements With Artificial Intelligence.

PurposeThe purpose of this study was to assess the accuracy of artificial neural networks (ANN) in estimating the severity of mean deviation (MD) from peripapillary retinal nerve fiber layer (RNFL) thickness measurements derived from optical coherence tomography (OCT).MethodsModels were trained using 1796 pairs of visual field and OCT measurements from 1796 eyes to estimate visual field MD from RNFL data. Multivariable linear regression, random forest regressor, support vector regressor, and 1D convolutional neural network (CNN) models with sectoral RNFL thickness measurements were examined. Three independent subsets consisting of 698, 256, and 691 pairs of visual field and OCT measurements were used to validate the models. Estimation errors were visualized to assess model performance subjectively. Mean absolute error (MAE), root mean square error (RMSE), median absolute error, Pearson correlation, and R-squared metrics were used to assess model performance objectively.ResultsThe MAE and RMSE of the ANN model based on the testing dataset were 4.0 dB (95% confidence interval = 3.8–4.2) and 5.2 dB (95% confidence interval = 5.1–5.4), respectively. The ranges of MAE and RMSE of the ANN model on independent datasets were 3.3–5.9 dB and 4.4–8.4 dB, respectively.ConclusionsThe proposed ANN model estimated MD from RNFL measurements better than multivariable linear regression model, random forest, support vector regressor, and 1-D CNN models. The model was generalizable to independent data from different centers and varying races.Translational RelevanceSuccessful development of ANN models may assist clinicians in assessing visual function in glaucoma based on objective OCT measures with less dependence on subjective visual field tests.

Evaluation of the effect of unilateral late blindness on the retina, optic nerve and choroid parameters in the sighted eye

To investigate whether unilateral late blindness alters the peripapillary retinal nerve fiber layer (RNFL), ganglion cell complex (GCC), central macular thickness (CMT) and choroidal thickness (CT). The 17 healthy eyes of 17 monocular patients with late blindness due to isolated eye trauma in one eye and the 19 eyes of 19 healthy individuals were evaluated in this retrospective study. Patients with at least 10years of monocular blindness, a refractive error between + 1.5 and -1.5 D in the sighted eye, a best-corrected visual acuity of at least 20/20 and an axial length (AL) < 25mm were included in the study. Following ophthalmologic examination, the RNFL, GCC, CMT and CT values were measured with spectral domain optic tomography (SD-OCT). Those with ocular, systemic or neurological disease that could influence the measured parameters were excluded from the study. A total of 17 (14 males, 3 females) monocular patients [mean age 41.00 ± 11.95 (24-64)] and 19 (16 males, 3 females) healthy individuals [mean age 39.79 ± 6.74 (30-56)], similar in age and gender (p = 0.949 and p = 0.881), were included in the study. The mean duration of being monocular was 22.76 ± 11.76 (10-49) years. No difference was present between the RNFL, GCC, CMT and CT measurements of the monocular patients and the healthy individuals (p = 0.692, p = 0.294, p = 0.113, p = 0.623, respectively). No significant correlation was found between the duration of monocularity and the retinal and optic nerve parameters. The results of our study indicate no difference in the optic nerve, retina and choroid OCT findings in the sighted eyes of subjects with long-term monocular blindness compared to subjects with bilateral normal eyes. Although functional and volumetric neuroimaging studies suggest the possibility of compensation in these patients, our findings indicate that this is not at the ocular level.

Reproducibility of Retinal Nerve Fiber Layer and Macular Ganglion Cell Layer Thickness Measurements by Optical Coherence Tomography in Myopic Eyes.

In myopic eyes, reproducibility of circumpapillary retinal nerve fiber layer (RNFL) and macular ganglion cell-inner plexiform layer thickness measurement by optical coherence tomography (OCT) showed excellent reproducibility except for the temporal quadrant RNFL thickness measurement. The aim of this study was to evaluate the long-term reproducibility of circumpapillary RNFL and macular ganglion cell-inner plexiform layer (GCIPL) thickness measurements using OCT in myopic eyes. Sixty-five eyes with moderate-to-high myopia (spherical equivalent <-3.0 D, myopia group) and 53 eyes with low-to-no myopia (spherical equivalent ≥-3.0 D, control group) without ocular disorders, such as glaucoma or retinal diseases, were included. Three serial OCT scans recorded at 1-year intervals were analyzed. Reproducibility was evaluated using within-subject SD (Sw), coefficient of variation (CVw), and intraclass correlation coefficient (ICC). Mean±SD refractive error was -0.30±0.80 and -6.26±2.45 D for control and myopia groups, respectively. The myopia group had thinner superior, inferior, and nasal quadrant RNFL, thicker temporal quadrant RNFL, and thinner GCIPL than the control group (P<0.05), except for the minimum and superotemporal GCIPL thicknesses (P>0.05). The myopia group had lower reproducibility in temporal quadrant RNFL thickness (Sw, 2.57 μm; CVw 3.27%; ICC, 0.979) than the control group (Sw, 1.80 μm; CVw 2.59%; ICC, 0.989), whereas in other sectors of RNFL and all GCIPL parameters, comparable reproducibility was observed between the 2 groups. Long-term reproducibility of RNFL and GCIPL thickness measurements in moderate-to-high myopia was comparable to that of low-to-no myopia, except RNFL thickness in the temporal quadrant. These findings should be considered when detecting RNFL and GCIPL changes.

Reproducibility of SD-OCT inner macular layer thickness measurements in children with primary congenital glaucoma

To examine the reproducibility of spectral domain optical coherence tomography (SD-OCT) segmented ganglion cell complex and circumpapillary retinal nerve fiber layer (cpRNFL) measurements in children with primary congenital glaucoma (PCG) in comparison with healthy children. 12 children with PCG (G1) and 24 healthy children (G2) were recruited. The following SD-OCT measurements (Spectralis, Heidelberg Engineering) were made in one eye per child: total macular thickness (MT), thicknesses in several subfields and volumes of the three inner macular layers, macular retinal nerve fiber layer (mRNFL), ganglion cell layer (GCL), and inner plexiform layer (IPL) and cpRNFL thickness. In a single day, an expert operator obtained 3 circumpapillary and 3 macular measurements in each participant to determine intraoperator variability. Intraoperator repeatability was defined by the coefficient of variation (CoV) and intraclass correlation (ICC). ICC was excellent in both groups for cpRNFL measurements (G1 ICC=0.950 and G2 ICC=0.995) and for MT was excellent in G1 (ICC=0.957) and moderate in G2 (ICC=552). For the inner macular layer measurements, all ICCs were better in PCG group (mRNFL-ICC: 0.915 vs. 0.765; ICC-GCL: 0.584 vs. 0.263 and ICC-IPL: 0.979 vs. 0.742; G1 and G2 respectively). Greater CoV were recorded for macular measurements (from 0.71% to 9.82%) compared to cpRNFL measurements (from 0.52% to 1.50%). In children with PCG, Spectralis SD-OCT showed excellent intrasession repeatability for cpRNFL, MT, mRNFL and IPL measurements and moderated for GCL measurements. For all macular measurements, ICC were higher in children with PCG than healthy children.

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

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

Segregation of neuronal-vascular components in a retinal nerve fiber layer for thickness measurement using OCT and OCT angiography.

Assessment of the circumpapillary retinal nerve fiber layer (RNFL) provides crucial knowledge on the status of the optic nerve. Current circumpapillary RNFL measurements consider only thickness, but an accurate evaluation should also consider blood vessel contribution. Previous studies considered the presence of major vessels in RNFL thickness measurements from optical coherence tomography (OCT). However, such quantitative measurements do not account for smaller vessels, which could also affect circumpapillary RNFL measurements. We present an approach to automatically segregate the neuronal and vascular components in circumpapillary RNFL by combining vascular information from OCT angiography (OCTA) and structural data from OCT. Automated segmentation of the circumpapillary RNFL using a state-of-the-art deep learning network is first performed and followed by the lateral and depth-resolved localization of the vascular component by vertically projecting the vessels along the circular scan from OCTA vessels map onto the segmented RNFL. Using this proposed approach, we compare the correlations of circumpapillary RNFL thicknesses with age at different levels of vessel exclusion (exclusion of major vessels only vs both major- and micro-vessels) and also evaluate the thickness variability in 75 healthy eyes. Our results show that the ratio of major- and micro-vessels to circumpapillary RNFL achieved a stronger correlation with aging (r = 0.478, P < .001) than the ratio with only major vessels to circumpapillary RNFL (r = 0.027, P = .820). Exclusion of blood vessels from circumpapillary RNFL thickness using OCTA imaging provides a better measure of the neuronal components and could potentially improve the diagnostic performance for disease detection.

OCT Variability Prevents Their Use as Robust Biomarkers in Multiple Sclerosis.

ObjectiveTo evaluate the agreement between the peripapillary retinal nerve fiber layer (pRNFL) and foveal thickness (FT) measurements among three different spectral domain-optical coherence tomography (SD-OCT) instruments in a sample of multiple sclerosis (MS) patients and a healthy age-matched control group.MethodsAn observational cross-sectional study with three groups: healthy subjects and MS patients w/w a previous clinical diagnosis of optic neuritis (ON) was conducted. The pRNFL and FT were measured using three different SD-OCT instruments (OCT PRIMUS 200 and OCT CIRRUS 500 SD-OCT [Carl Zeiss Meditec] and OCT 3D 2000 [Topcon]).ResultsTwenty eyes from 10 healthy subjects matched in age with MS patients without a previous history of eye disease and 62 MS eyes from 31 MS patients (29 eyes without history of ON and 33 eyes with history of ON) were enrolled. Healthy subjects and MS patients without ON did not show differences between the pRNFL and FT thickness (P>0.99) with any of the instruments. However, MS eyes with a previous episode of ON showed thinner pRNFL and FT (P<0.01). PRIMUS and CIRRUS OCT showed better agreement of the pRNLF and FT in both healthy and MS eyes. However, 3D OCT showed less agreement in the pRNFL measurement with CIRRUS in both healthy and MS eyes.InterpretationAlthough OCT is a valuable technology to improve MS patient assessment, differences between devices must be taken into account. It is necessary to create an international group that standardizes the measurement conditions and above all that provides reference bases for normal subjects.

Neuroretinal Biomarkers for Schizophrenia Spectrum Disorders.

PurposeWe evaluated the patient-control differences and predictive value of the retina as potential biomarkers for schizophrenia.MethodsThe institutional study included both eyes of 58 schizophrenia spectrum disorder (SSD) patients (age 37.2 ± 12.3 years) and 35 controls (age 41.1 ± 15.2 years). Retinal nerve fiber layer (RNFL), ganglion cell–inner plexiform layer, outer retinal photoreceptor complex, and total macula thicknesses were measured by optical coherence tomography (OCT). Anterior segment parameters including central corneal thickness, anterior chamber depth, and axial length were measured to rule out confounds on the retinal measures.ResultsThe peripapillary RNFL was overall significantly thinner in SSD relative to controls (F = 3.97, P = 0.049), most pronounced in the temporal (5.2 µm difference, F = 6.95, P = 0.010) and inferior quadrants (12.1 µm difference, F = 7.32, P = 0.009). There were no significant group differences in thickness for the macular RNFL, ganglion, or photoreceptor cell related measures (P > 0.05). Peripapillary RNFL, central macula, and outer photoreceptor complex thicknesses were together able to classify SSD patients with 80% sensitivity and 71% specificity; area under the curve = 0.82 (95% confidence interval, 0.75–0.88).ConclusionsSSD patients exhibited significant RNFL thinning relative to controls. Notably, retinal thickness measures including both peripapillary and macular data exhibited improved diagnostic accuracy for SSD as compared to these regions alone.Translational RelevanceThis is the first study to evaluate the predictive value of both the inner and outer retina in SSD. OCT retinal thickness measures including peripapillary data in conjunction with macular data may provide an informative, noninvasive in vivo ocular biomarker for schizophrenia.

Evaluation of the retinal nerve fiber layer with optic coherence tomography in patients with alcohol use disorder

This study aims to evaluate the retinal nerve fiber layer (RNFL) with optical coherence tomography (OCT) among patients with alcohol and tobacco use disorder. This study included 29 patients and 29 age and gender-matched healthy participants without alcohol dependency. The patients underwent full ophthalmologic examination including visual acuity, intraocular pressure, anterior segment and fundus examinations, and RNFL measurements taken with spectral-domain OCT. The RNFL values of the two groups were compared with each other. In comparison to the control group, the RNFL was found to be thinner in all quadrants in the group with alcohol and tobacco dependency. The RNFL thinning in the superotemporal, temporal, and inferotemporal quadrants was found to be statistically significant (P-values 0.012, 0.040 and 0.005, respectively). Chronic alcohol and tobacco use may cause RNFL thinning. Assessment of RNFL thinning by OCT among patients with alcohol and tobacco dependency might be used to identify visual morbidity.

Pediatric normative Retinal nerve fiber layer thickness in south Indian population

To study the retinal nerve fiber layer (RNFL) thickness in pediatric age group and its correlation with age, gender, refractive error and axial length Prospective observational study of 200 eyes of 100 children aged between 5-18 years presenting to the ophthalmic department. All children underwent detailed ophthalmic evaluation and SD OCT examination for RNFL thickness, Standard RNFL assessment protocol was used. Mean RNFL thickness in micrometers along the whole circle circumference, four quadrants, 12’o clock hours were obtained. RNFL measurements included average/full circle thickness — RNFL-FC (360ºmeasure), temporal quadrant thickness, RNFL-T, superior quadrant thickness, RNFL-S, nasal quadrant thickness, RNFL-N, inferior quadrant thickness, RNFL-I. Mean age was 13.3 ± 2.4 years. The refractive error in spherical equivalent was -0.28 ± 0.91 dioptre (SE). The mean axial length was 23.1 ± 0.7mm. The mean global RNFL thickness (RNFL-FC) was 97.0 ± 8.8mm (range 79.4 -114.6). RNFL thickness was maximum in the inferior quadrant (RNFL-I) 126 ± 13.7mm followed in order by superior (RNFL-S) 126 ± 16.3mm, nasal (RNFL-N) 70.5 ± 12.3mm and temporal (RNFL-T) 63.4 ± 9.2mm, in both the sexes. For every increase in one diopter of spherical equivalent of refractive error the mean RNFL increased by 3.77 microns and there was a reduction in mean RNFL thickness by 4.86 micron for every 1mm increase in axial length. RNFL varied minimally with gender. Positive correlation was seen with refractive error while inverse or negative correlation was seen with axial length and age. RNFL measurements could serve as reference for further studies on pediatric glaucoma or other optic nerve head pathologies.

An Evaluation of the Relationship between Retinal Nerve Fiber Thickness, Cochlear Nerve Thickness, the Level of Tinnitus, and Hearing Loss in Unilateral Tinnitus Patients

Background: In this study, optic coherence tomography (OCT) examination was performed to check whether there was any interaction between ophthalmic axonal structures in unilateral tinnitus patients, and the relationship between optic nerve thickness and cochlear nerve thickness was evaluated. Objective: The aim of the study was to evaluate the relatioship between hearing loss, tinnitus, and nerve thicknesses. Study Design: Prospective study. Setting: Tertiary referral university hospital. Patients: The study included 88 patients with unilateral tinnitus, for which no organic cause could be found in physical examination, psychiatric evaluation, or with imaging methods. Study groups were formed of the tinnitus side and control groups were formed of the healthy side as follows: Group 1 (Non-tinnitus side normal hearing values – n = 30), Group 2 (non-tinnitus side minimal hearing loss – n = 27), Group 3 (non-tinnitus side moderate hearing loss – n = 31), Group 4 (tinnitus side normal hearing values – n = 25), Group 5 (tinnitus side minimal hearing loss – n = 25), and Group 6 (tinnitus side moderate hearing loss – n = 38). Intervention: Retinal nerve fiber layer (RNFL) thickness was evaluated with OCT, and the cochlear nerve cross-sectional area was evaluated with MRI. Main Outcome Measures: RNFL measurements were taken with OCT from the subfoveal area (RNFL-SF) and 1.5 mm temporal to the fovea (RNFL-T µm) and nasal (RNFL-N µm) sectors. On MRI, 3 measurements were taken along the nerve from the cerebellopontine angle as far as the internal auditory canal, and the mean value of these 3 measurements was calculated. Results: When the groups were evaluated in respect of cochlear nerve thickness, a significant difference was seen between Group 1 and both the groups with hearing loss and the tinnitus groups. In the subgroup analysis, a statistically significant difference was determined between Group 1 and Groups 3, 4, 5, and 6 (p = 0.013, p = 0.003, p < 0.001, and p < 0.001, respectively). When the groups were evaluated in respect of the RNFL-SF (µm), RNFL-T (µm), and RNFL-N (µm) values, the differences were determined to be statistically significant (p < 0.001 for all). In the correlation analysis, a negative correlation was determined between hearing loss and cochlear nerve diameter (r: −0.184, p = 0.014), and RNFL-N (r: −0.272, p < 0.001) and between tinnitus and cochlear nerve diameter (r: −0.536, p < 0.001), and RNFL-T (r: −0.222, p < 0.009). Conclusion: The study results clearly showed a relationship between cochlear nerve fiber thickness and hearing loss and the severity of tinnitus in cases with unilateral tinnitus and that there could be neurodegenerative factors in the disease etiology. A similar relationship seen with the RNFL supports the study hypothesis.

Impact of optical coherence tomography scan direction on the reliability of peripapillary retinal nerve fiber layer measurements.

PurposeTo evaluate the intradevice repeatability and agreement for peripapillary retinal nerve fiber layer (pRNFL) measurements in healthy eyes with two different scan directions and two different number of B scans.MethodspRNFL was measured with a spectral domain optical coherence tomography on 54 healthy participants. Three-dimensional optic disc scans (6 mm x 6 mm) were performed on the right eye of the participants. Two repeated scans were performed in four different settings: H1: Horizontal scan with 512 A-scans x 96 B-scans; H2: Horizontal scan with 512 A-scans x 128 B-scans; V1: Vertical scan with 512 A-scans x 96 B-scans; V2: Vertical scan with 512 A-scans x 128 B-scans. The pRNFL thickness was evaluated in twelve clock-hour sector in a circle of 3.45 mm diameter centred at the optic disc. Repeatability and agreement were assessed with within subject standard deviation (Sw) and Bland-Altman test respectively.ResultsThe repeatability of pRNFL measurements varied depending on the scan direction and sectors. The repeatability for the horizontal sectors were better with H1 and H2, with sector 9 having the best Sw (< 3 μm). The repeatability for the vertical sectors were better with V1 and V2 with sector 5 and 9 having the best Sw (< 4 μm). The repeatability with vertical scan was more symmetric among the sectors than with horizontal scans. The repeatability metrics of the sectors did not vary much between H1 and H2 (difference < 2 μm) and between V1 and V2 (difference < 3.2 μm). Comparing horizontal and vertical scans, the vertical sectors had larger limits of agreement of about 45 μm.ConclusionThe reliability of the pRNFL thickness measurements is dependent on the direction of the scan and independent on the numbers of B-scans. Vertical scans for pRNFL gives more homogeneous repeatability across the different sectors.

Functional Prognostic value of optical coherence tomography in optic chiasmal decompression: A preliminary study

To assess the predictive value for functional recovery of Ganglion Cell Complex Layer (GCC) and Retinal Nerve Fiber Layer (RNFL) measurements obtained by Optical Coherence Tomography (OCT) in patients undergoing chiasmal decompression and to define potential OCT thresholds for visual recovery. We measured preoperative GCC and RNFL thickness in patients with a sellar and/or perisellar tumor compressing the optic chiasm. Visual recovery was defined as recovery of mean deviation (MD) and pattern standard deviation (PSD) using Humphrey visual field testing after 12 successful decompressions (24 eyes). Receiver operating characteristic curve (ROC) analysis was used to identify the best thresholds. Robust global and focal OCT thresholds were found. Superior GCC≥63μm had the best functional prognostic value (AUC=1) for visual improvement. Mean GCC ≥ 67μm and mean RNFL≥75μm also had excellent predictive values (AUC>0.9). In this preliminary study, significant preoperative OCT thresholds for early visual recovery after chiasmal decompression were identified, mainly regarding GCC measurements. Further studies on larger cohorts with closely scheduled follow-up could refine our results.