Nerve Fiber Layer Thickness Measurements Research Articles

Role of sex in retinal nerve fiber layer and macular thickness measurement by spectral domain optical coherence tomography

Purpose The aim of this study was to investigate the role of sex on retinal nerve fiber layer (RNFL) thickness and macular thickness measurement by spectral domain optical coherence tomography (SD-OCT). Patients and methods In this prospective observational study, 200 participants who fulfilled the inclusion and exclusion criteria were scanned three times as per predefined guidelines at 0, 30, and 60 min on the same day, by the same investigator using SD-OCT for measurement of RNFL and macular thickness. The observations were statistically analyzed and correlated. Results The RNFL thickness was greatest in the superior quadrant and thinnest in the temporal quadrant. The mean value of average RNFL thickness was 87.90±6.12 μm in females and 93.18±4.04 μm in males (range=74.33–99.67 μm). A statistically significant difference was found between males and females in all quadrants and in average RNFL thickness (P<0.0005). The macular thickness was thinnest at the central zone (innermost 1-mm ring), thickest within the inner 3-mm ring, and diminished peripherally. The mean macular thickness was 272.95±8.40 μm in females and 289.42±12.32 μm in males. A statistically significant difference was found between males and females in all macular zones and in the mean macular thickness (P<0.0005). Conclusion RNFL thickness and macular thickness were significantly thicker in males compared with females in healthy eyes. Sex should be used as an additional parameter in commercially available OCT machines, in addition to age, because of its potential in improving the existing RNFL thickness and macular thickness norms.

Fellow-eye asymmetry on optical coherence tomography angiography and thickness parameters in unilateral pseudoexfoliation syndrome.

To investigate inter-eye retinal vessel density and thickness asymmetry in unilateral pseudoexfoliation syndrome and understand its use for the early detection of glaucoma. Thirty patients with unilateral pseudoexfoliation syndrome were enrolled in our study. Optical coherence tomography angiography macular scans were used measure the retinal vessel density, and optical coherence tomography scans were used to assess the thickness parameters of the peripapillary retinal nerve fiber layer and the macular ganglion cell complex. Inter-eye asymmetry was determined by taking the absolute value of the difference in the vessel density and thickness parameters between the pseudoexfoliation syndrome eye and fellow eye. The mean patient age was 64.20 ± 7.05 y in the study group. Inter-eye asymmetry in the peripapillary retinal nerve fiber layer thickness and macular ganglion cell complex measurements were significant in the study group (p=0.03 and p=0.001, respectively). The vessel density of the macular superficial inner region was significantly lower in eyes with pseudoexfoliation syndrome than in fellow eyes (p=0.035). However, there was no inter-eye asymmetry in the central and full region macular superficial vessel density of eyes with pseudoexfoliation syndrome and fellow eyes (p>0.05). Retinal vessel density can be evaluated using optical coherence tomography angiography measurements. There was inter-eye asymmetry in the inner region macular superficial vessel density, peripapillary retinal nerve fiber layer, and macular ganglion cell complex thickness of the unilateral pseudoexfoliation syndrome eyes and fellow eyes. Further studies on a larger number of subjects might provide more clarity regarding the relationship between the inter-eye asymmetry of the retinal vessel density and thickness parameters with early detection of glaucomatous damage.

Combining OCT and OCTA for Focal Structure–Function Modeling in Early Primary Open-Angle Glaucoma

PurposeTo investigate modeling of the focal visual field (VF) loss by combining structural measurements and vascular measurements in eyes with early primary open-angle glaucoma (POAG).MethodsIn this cross-sectional study, subjects with early glaucoma (VF mean deviation, ≥−6 dB) underwent optical coherence tomography (OCT) imaging, optical coherence tomography angiography (OCTA) imaging, and Humphrey 24-2 VF tests. Capillary perfusion densities (CPDs) were calculated after the removal of large vessels in the OCTA images. Focal associations between VF losses at the individual VF test locations, circumpapillary retinal nerve fiber layer (RNFL) thickness measurements from OCT, and CPDs were determined using nerve fiber trajectory tracings. Linear mixed models were used to model focal VF losses at each VF test location.ResultsNinety-seven eyes with early POAG (VF mean deviation, −2.47 ± 1.64 dB) of 71 subjects were included. Focal VF modeling using a combined RNFL–CPD approach resulted in a median adjusted R2 value of 0.30 (interquartile range [IQR], 0.13–0.55), whereas the RNFL-only and CPD-only approaches resulted in median values of 0.22 (IQR, 0.10–0.51) and 0.26 (IQR, 0.10–0.52), respectively. Seventeen VF locations with the combined approach had an adjusted R2 value greater than 0.50. Likelihood testing at each VF test location showed that the combined approach performed significantly better at the superior nasal VF regions of the eyes compared with the univariate approaches.ConclusionsModeling of focal VF losses showed improvements when structural thickness and vascular parameters were included in tandem. Evaluation of VF defects in early glaucoma may benefit from considering both RNFL and OCTA characteristics.

Can the long term using of pregabalin in fibromyalgia affect the choroid and retinal nerve fiber layer?

In this study, the effects of long-term pregabalin use on the choroid and retinal nerve fiber layer were investigated in the fibromyalgia disease. The patient group consisted of 41 fibromyalgia patients using pregabalin. The control group consisted of 41 newly diagnosed fibromyalgia patients who had not received any treatment yet. Choroidal and retinal nerve fiber layer thickness measurements were performed with Cirrus HD-OCT (Carl Zeiss Meditec Inc., Dublin, CA, USA) 30 minutes after pupil dilation with 1% tropicamide. There was no difference in subfoveal choroidal thickness, nasal choroidal thickness and temporal choroidal thickness between the patient and control groups (p > 0.05). Increasing the duration of drug use within the patient group was found to thin the retinal nerve fiber layer (p < 0.05). We found that pregabalin had no effect on the choroid, while it had a thinning effect for retinal nerve fiber layer. It is recommended not to be preferred pregabalin in fibromyalgia patients with retinal nerve fiber layer damage such as diabetic retinopathy and glaucoma. Patients treated with pregabalin should have regular control in the ophthalmology clinic.

Deep Learning Image Analysis of Optical Coherence Tomography Angiography Measured Vessel Density Improves Classification of Healthy and Glaucoma Eyes

To compare convolutional neural network (CNN) analysis of en face vessel density images to gradient boosting classifier (GBC) analysis of instrument-provided, feature-based optical coherence tomography angiography (OCTA) vessel density measurements and OCT retinal nerve fiber layer (RNFL) thickness measurements for classifying healthy and glaucomatous eyes. Comparison of diagnostic approaches. A total of 130 eyes of 80 healthy individuals and 275 eyes of 185 glaucoma patients with optic nerve head (ONH) OCTA and OCT imaging were included. Classification performance of a VGG16 CNN trained and tested on entire en face 4.5×4.5-mm radial peripapillary capillary OCTA ONH images was compared to the performance of separate GBC models trained and tested on standard OCTA and OCT measurements. Five-fold cross-validation was used to test predictions for CNNs and GBCs. Areas under the precision recall curves (AUPRC) were calculated to control for training/test set size imbalance and were compared. Adjusted AUPRCs for GBC models were 0.89 (95% CI=0.82, 0.92) for whole image vessel density GBC, 0.89 (0.83, 0.92) for whole image capillary density GBC, 0.91 (0.88, 0.93) for combined whole image vessel and whole image capillary density GBC, and 0.93 (0.91, 095) for RNFL thickness GBC. The adjusted AUPRC using CNN analysis of en face vessel density images was 0.97 (0.95, 0.99) resulting in significantly improved classification compared to GBC OCTA-based results and GBC OCT-based results (P ≤ 0.01 for all comparisons). Deep learning en face image analysis improves on feature-based GBC models for classifying healthy and glaucoma eyes.

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.

Does the ISNT rule apply to the radial peripapillary capillary vessel density in OCT angiography?

To investigate the applicability of ISNT (inferior ≥ superior ≥ nasal ≥ temporal), IST (inferior ≥ superior ≥ temporal), and T min (temporal quadrant with the minimum value) rules to the peripapillary nerve fiber layer (NFL) thickness and radial peripapillary capillary (RPC) vessel density (VD) using Optical Coherence Tomography (OCT) and OCT angiography (OCT-A). This cross-sectional study included 134 eyes of 74 healthy individuals. NFL thickness and RPC VD were measured in all four quadrants using OCT and OCT-A in order to determine the number of eyes that obey the ISNT, IST, and T min rules. Mean age was 48.8 ± 15.5 (range 25-82) years. The ISNT rule was valid in 52 eyes (38.81%) on OCT and only 12 eyes (8.95%) on OCT-A scans. The IST rule was followed by 83 (61.94%) and 37 (27.61%) eyes on OCT and OCT-A scans respectively. The T min rule was valid in 86 eyes (64.18%) in OCT scans and in 26 eyes (19.4%) in OCT-A scans. The topography of the RPC network does not obey the ISNT rule in healthy eyes. The ISNT rule and its variants were found to be more relevant in OCT NFL thickness measurements compared to OCT-A RPC VD measurements.

Deep Learning-Based Retinal Nerve Fiber Layer Thickness Measurement of Murine Eyes.

PurposeTo design a robust and automated estimation method for measuring the retinal nerve fiber layer (RNFL) thickness using spectral domain optical coherence tomography (SD-OCT).MethodsWe developed a deep learning–based image segmentation network for automated segmentation of the RNFL in SD-OCT B-scans of mouse eyes. In total, 5500 SD-OCT B-scans (5200 B-scans were used as training data with the remaining 300 B-scans used as testing data) were used to develop this segmentation network. Postprocessing operations were then applied on the segmentation results to fill any discontinuities or remove any speckles in the RNFL. Subsequently, a three-dimensional retina thickness map was generated by z-stacking 100 segmentation processed thickness B-scan images together. Finally, the average absolute difference between algorithm predicted RNFL thickness compared to the ground truth manual human segmentation was calculated.ResultsThe proposed method achieves an average dice similarity coefficient of 0.929 in the SD-OCT segmentation task and an average absolute difference of 0.0009 mm in thickness estimation task on the basis of the testing dataset. We also evaluated our segmentation algorithm on another biological dataset with SD-OCT volumes for RNFL thickness after the optic nerve crush injury. Results were shown to be comparable between the predicted and manually measured retina thickness values.ConclusionsExperimental results demonstrate that our automated segmentation algorithm reliably predicts the RNFL thickness in SD-OCT volumes of mouse eyes compared to laborious and more subjective manual SD-OCT RNFL segmentation.Translational RelevanceAutomated segmentation using a deep learning–based algorithm for murine eye OCT effectively and rapidly produced nerve fiber layer thicknesses comparable to manual segmentation.

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.

Retinal nerve fibre layer thickness measurements in childhood glaucoma: the role of scanning laser polarimetry and optical coherence tomography

PurposeA central diagnostic tool in adult glaucoma is the peripapillary retinal nerve fibre layer (pRNFL) thickness. It can be assessed by scanning laser polarimetry (SLP) or optical coherence tomography (OCT). However, studies investigating the relevance of pRNFL measurements in children are rare. This study aims to compare the glaucoma diagnosing ability of SLP and OCT pRNFL thickness measurements in a paediatric population.MethodsThis retrospective study included 105 children (glaucoma: 22 (21.0%); healthy glaucoma suspects: 83 (79.0%)) aged 4–18 years, examined with SLP (GDxPro/ECC, Carl Zeiss Meditec) and spectral-domain OCT (SPECTRALIS®, Heidelberg Engineering). The thickness of pRNFL sectors was compared between diseased and healthy participants. Areas under the receiver-operating characteristic curves (AUC) and logistic regression results were used to compare the glaucoma discriminative capacity between SLP and OCT measurements.ResultsUsing OCT, pRNFL thickness was decreased in the superior, nasal, and inferior quadrants of glaucoma patients compared to healthy controls (P < 0.001, each). With SLP, such a difference was only observed in the inferior quadrant (P = 0.011). A correlation between glaucoma diagnosis and OCT-measured pRNFL thickness was found in all quadrants (P < 0.001) other than the temporal. With SLP, a correlation was found for the total average thickness (P = 0.037) and inferior quadrant (P = 0.0019). Finally, the AUCs of OCT measurements were markedly higher than those of SLP (e.g., inferior quadrant: OCT 0.83, SLP 0.68).ConclusionpRNFL thickness measurements using both OCT and SLP, correlate notably with the presence of glaucoma. In general, the diagnostic performance of pRNFL thickness measurements seems higher for OCT than for SLP. Thus, pRNFL thickness measurements could provide important information, complementing conventional clinical and functional parameters in the diagnostic process of paediatric glaucoma.

Comparison of Quadrantic Retinal Nerve Fiber Layer Thickness between Glaucoma Patients and Age Matched Controls

Purpose: To compare the quadrantic retinal nerve fiber layer thickness between the glaucoma patients and age-matched controls.&#x0D; Study Design: Descriptive observational study.&#x0D; Place and Duration of study: Eye Department of Civil Hospital Karachi, from January 2018 to December 2020.&#x0D; Methods: Two hundred and fifty eyes were included in this study. There were 128 eyes of the glaucoma patients and 122 eyes were age-matched controls. After complete ocular examination, all participants underwent optical coherence tomography and retinal nerve fiber layer thickness measurement in four quadrants. Prior quadrants were subsequently analyzed. Heidelberg 3-D optical coherence tomography 2017, Spec- TR- 04859 was used. Readings were saved on Excel sheet and analyzed on SPSS version 25. For descriptive statistics the mean and standard deviations were calculated for each quadrant and for inferential statistics the data was first checked for the normality. Comparison of the quadrants was done using non-parametric Paired Sample t-test (Wilcoxon signed rank test).&#x0D; Results: Out of 250. Form which 128 (51%) eyes were those of glaucoma patients and 122 (49%) eyes were of non-glaucoma patients. The mean difference between the Glaucomatous and non-Glaucomatous eyes were statistically significant in all four quadrants (p &gt; 0.05).&#x0D; Conclusion: Glaucomatous eyes had reduced RNFL thickness in all quadrants. The thickness of the inferior quadrant was more as compared to the other quadrants in both glaucoma and control groups. Whereas the least thickness was that of the temporal quadrant.&#x0D; Key Words: Retinal nerve fiber layer, Optical coherence tomography, Glaucoma.

Quantitative assessment of retinal changes in COVID-19 patients

ABSTRACT Clinical relevance The SARS-COV 2 virus, which is responsible for the COVID-19 pandemic, acts on the angiotensin converting enzyme 2 (ACE-2) receptor in the host cell. Ocular effects may occur because of the ACE-2 receptor in the retina. Background To investigate the impact of COVID-19 on the retinal layers and optic disc parameters in previously confirmed COVID-19 patients using spectral domain optical coherence tomography (SD-OCT). Methods This study included 60 eyes of 60 subjects; 35 of them were in the COVID-19 group and the remaining 25 were in the control group. Patients with the diagnosis of COVID-19 that had a negative result after treatment were included in the study. Macular and peripapillary retinal nerve fiber layer (RNFL) thickness measurements, each retinal layer thickness of all participants were done 14–30 days after COVID-19 symptom onset, following the negative result of real time reverse transcriptase-polymerase chain reaction test using SD-OCT. Results The mean value of central macular thickness was significantly higher in the COVID-19 group than the control group (p = 0.02). The mean values of the ganglion cell layer and inner nuclear layer thickness in the COVID-19 group were significantly thinner than control group (p = 0.04 and p = 0.04, respectively). Even though mean RNFL thickness measurements in all sections in the COVID-19 group was thinner than controls, there were no significant differences between groups (p > 0.05 for all). Conclusion In the early recovery phase, changes in the macula, ganglion cell layer and inner nuclear layer could be seen. These patients should be followed up closely for the recognition of new pathologies that could be seen in the late recovery phase.

Repeatability of Spectral Domain Optical Coherence Tomography Measurements of Bruch's Membrane Opening-Minimum Rim Width in Epiretinal Membrane Patients with Peripapillary Involvement.

The Bruch’s membrane opening-minimum rim width (BMO-MRW) is a recently introduced parameter of the neuroretinal rim. We analyzed the repeatability of spectral-domain optical coherence tomography (SD-OCT) measurements of BMO-MRW in epiretinal membrane (ERM) patients with peripapillary involvement, since the surface around the optic disc is distorted in such patients. BMO-MRW and retinal nerve fiber layer (RNFL) thickness measurements were performed using SD-OCT in prospectively enrolled ERM patients and age-matched healthy control individuals. After two consecutive measurements with a 5 min interval, repeatability was analyzed using the intraclass correlation coefficient (ICC), repeatability coefficient (RC), and coefficient of variation (CV). Fifty-two eyes of 52 ERM patients and 62 eyes of 62 healthy controls were included in the study. The ICCs of the mean BMO-MRW/RNFL thickness measurements were 0.999/0.985 in ERM eyes and 0.999/0.999 in normal eyes, respectively. The RC values of mean BMO-MRW/RNFL thickness measurements were 9.0/6.25 μm in ERM eyes and 4.61/0.92 μm in normal eyes, respectively. The CV values were 0.91% and 1.45% for BMO-MRW and RNFL thickness in ERM eyes, and 0.63% and 0.33% in normal eyes, respectively. In ERM eyes, the RC, CV of average BMO-MRW were 1.9 and 1.4 times greater than those of normal eyes, but 6.8 and 4.4 times greater for average RNFL thickness. BMO-MRW and RNFL thickness showed good repeatability in the diseased eyes with peripapillary involvement and healthy control eyes. Based on the ICC, RC, and CV values, the repeatability of BMO-MRW measurements in peripapillary membrane patients was better than that of RNFL thickness.

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.

Ophthalmologic manifestations of adult patients with cystic fibrosis.

Cystic fibrosis (CF) is the most common life-shortening recessive genetic disease in Caucasians, affecting primarily the lungs. The objective of our study was to investigate potential ophthalmologic involvement in adult patients with CF. Fifty adult patients with cystic fibrosis and 60 age- and sex-matched controls underwent complete ophthalmologic examination including tear-film Break-Up Time (BUT), Macular Thickness, and peripapillary Retinal Nerve Fiber Layer (pRNFL) thickness measurements using Spectral Domain-OCT. CF patients had significantly lower nasal-inferior pRNFL thickness (median 82 IQR 67-102 vs 92.5 IQR 82-107, p = 0.005) and lower percentage of normal tear Break-Up Time (56.0% vs 96.7%, p = 0.001) than healthy controls. All CF patients with BUT <10 s were diagnosed with blepharitis at the time of our assessement. The subgroup of patients homozygous for the most common CF mutation, F508del, had lower nasal-inferior pRNFL thickness (p = 0.014) and lower percentage of normal tear Break-Up Time (p = 0.001) compared to the control group. Additional findings, present in the CF group only, were punctuate retinal hemorrhages (four patients), vessel tortuosity (four patients), snail-track degeneration, and retinal tufts (two patients without refractive error). There were no significant differences in visual acuity, refractive errors, gonioscopic findings, or intraocular pressure between the groups. Our study is, to the best of our knowledge, the largest ophthalmologic study of patients with cystic fibrosis. We found that CF patients had significantly decreased inferior-quadrant peripapillary retinal nerve fiber layer thickness and decreased tear-film break-up time compared to controls. We highlight the importance of careful regular ophthalmologic assessment and follow-up of these patients.

Temporal patterns of visual recovery following pituitary tumor resection: A prospective cohort study

Significant restoration of visual function can occur following pituitary tumor resection, although the time course of visual recovery remains poorly understood. This single-centre, two-year, prospective cohort study investigated the temporal patterns of visual recovery in consecutive patients undergoing pituitary tumor resection, between 2009 and 2018. Eyes were stratified based on pre-operative optical coherence tomography (OCT) retinal nerve fibre layer (RNFL) thickness measurements, with thin RNFL being defined as those within the fifth-percentile of age-matched normative values, and normal RNFL as those above the fifth-percentile. Visual function and OCT parameters were assessed pre-operatively, and at 6 weeks, 6 months, and 2 years post-operatively. 456 eyes of 228 patients (mean ± SD age, 53 ± 15 years) were included, of which 114 (25%) eyes had thin RNFL pre-operatively. Visual field recovery was observed in both groups during the first 6 weeks post-operatively (all Q ≤ 0.02), although improvements in visual field parameters between 6 weeks to 6 months were limited to eyes with thin RNFL (both Q < 0.05). No further improvements in visual function were detected beyond 6 months in both groups (both Q > 0.50). Similar trends were observed in linear regression analysis according to baseline visual function in both groups. In summary, eyes with normal RNFL thickness at baseline experienced most of their recovery within the first six weeks following surgery, while eyes with thin RNFL exhibited gradual improvements during the first six months. These findings have important implications when providing patient counselling and prognostication in the pre-operative setting.

A simplified combined index of structure and function for detecting and staging glaucomatous damage

Glaucomatous damage results in characteristics structural and functional changes on optical coherence tomography (OCT) imaging and standard automated perimetry (SAP) testing. The clinical utility of these measures differs based on disease severity, as they are evaluated along different measurement scales. This study therefore sought to examine if a simplified combined structure–function index (sCSFI) could improve the detection and staging of glaucomatous damage, compared to the use of average retinal nerve fiber layer thickness (RNFL) measurements from OCT and mean deviation (MD) values from SAP alone, and also an estimated retinal ganglion cell counts (eRGC) measure derived using empirical formulas described previously. Examining 577 eyes from 354 participants with perimetric glaucoma and 241 normal eyes from 138 healthy participants, we found that the sCSFI performed significantly better than average RNFL, MD and eRGC count for discriminating between glaucoma and healthy eyes (P ≤ 0.008 for all). The sCSFI also performed significantly better than RNFL and eRGC count at discriminating between different levels of visual field damage in glaucoma eyes (P < 0.001 for both). These findings highlight the clinical utility of combining structural and functional information for detecting and staging glaucomatous damage using the simplified index developed in this study.

The effects of ocular surface disease on optical coherence tomography test results in patients with glaucoma.

To evaluate the effects of current ocular surface disease (OSD) on OCT signal quality and peripapillary retinal nerve fiber layer (RNFL) thickness measurements in patients treated with antiglaucomatous medications and the changes in these test results by dry eye treatment. Fifty-five patients, diagnosed with primary open-angle glaucoma (POAG) and OSD, who were treated for glaucoma with topical medications for at least 6 months were included in this study. Patients were treated with topical preservative free polyvinyl alcohol + povidone artificial tear drops four times a day for at least 20 days and topical loteprednol etabonate drops four times a day for 1 week. Patients were divided into groups according to the number of active substances in their glaucoma drops, daily drop numbers, and duration of drug utilizations. OCT signal quality and mean RNFL thickness measurements were evaluated within these groups before and after OSD treatment. Pre-treatment mean OCT signal quality was 19.15 ± 3.739 and mean RNFL thickness was 93.07 ± 13.931µ; post-treatment mean OCT signal quality was 23.93 ± 3.839 and mean RNFL thickness was 98.27 ± 14.863 µ (p < 0.05). Post-treatment measurements were significantly improved compared to pre-treatment measurements in our patients, but the differences among subgroups were not statistically significant. There was a strong positive correlation between pre-treatment signal quality measurements and Schirmer II test values (p < 0.0001). Treatment of OSD in glaucoma patients being treated with long-term anti-glaucoma medications, seem to improve the quality and reliability of OCT test results.

Relationship between Retinal Nerve Fiber Layer Thickness and Cognitive Measures in Mild Cognitive Impairment Patients

Relationship between Retinal Nerve Fiber Layer Thickness and Cognitive Measures in Mild Cognitive Impairment Patients

Evaluation of the external validity of a joint structure\u2013function model for monitoring glaucoma progression

The dynamic structure–function (DSF) model was previously shown to have better prediction accuracy than ordinary least square linear regression (OLSLR) for short series of visits. The current study assessed the external validity of the DSF model by testing its performance in an independent dataset (Ocular Hypertension Treatment Study–Confocal Scanning Laser Ophthalmoscopy [OHTS–CSLO] ancillary study; N = 178 eyes), and also on different test parameters in a sample selected from the Diagnostic Innovations in Glaucoma Study or the African Descent and Glaucoma Evaluation Study (DIGS/ADAGES). Each model was used to predict structure–function paired data at visits 4–7. The resulting prediction errors for both models were compared using the Wilcoxon signed-rank test. In the independent dataset, the DSF model predicted rim area and mean sensitivity paired measurements more accurately than OLSLR by 1.8–5.5% (p ≤ 0.004) from visits 4–6. Using the DIGS/ADAGES dataset, the DSF model predicted retinal nerve fiber layer thickness and mean deviation paired measurements more accurately than OLSLR by 1.2–2.5% (p ≤ 0. 007). These results demonstrate the external validity of the DSF model and provide a strong basis to develop it into a useful clinical tool.