Primary Open Angle Glaucoma Diagnosis Using Pattern Electroretinogram Parameters

Background

Glaucoma is the most typical cause of permanent blindness. POAG, or primary open angle glaucoma, is the most common type. The pattern electroretinogram (PERG) has become a promising technique for detecting glaucoma early-on. The goal of this study was to assess the ability of PERG to diagnose POAG, especially in early, difficult-to-diagnose cases in comparison with other already established diagnostic methods.

Methods

150 participants (300 eyes) were enrolled in a cross-sectional study at ophthalmology department at Menoufia University Hospital in August 2022 to February 2023. All recruited participants underwent comprehensive ophthalmological and PERG exams. The studied eyes were divided into three groups as 100 normal eyes (Group I), 100 eyes with preperimetric glaucoma (Group II), and 100 eyes with established perimetric glaucoma (Group III).

Results

OCT-RNFL average thickness had a significant positive correlation with P50 latency (r=0.289, p=0.041) or P50 amplitude (r=0.302, p=0.018) and N95 amplitude (r=0.640, p=0.001) among group (II). Also, RNFL thickness had negative correlation with P50 amplitude (r= -0.268, p=0.043) among group (III). RNFL thickness and P50 and N95 amplitude showed highest AUC values in detecting preperimetric glaucomatous eyes vs normal eyes (AUC=0.927, 0.952, 904), and for detecting established perimetric glaucomatous eyes vs normal eyes (AUC=1.00, 0.957, 0.983 respectively) compared with VF MD which showed AUC (0.458 and 0.901 respectively).

Conclusion

Glaucoma patients exhibit PERG alterations (comparable to RNFL thickness changes) so, it could be used as an accurate diagnostic method in POAG. Because PERG alterations occur before visual field abnormalities, it could be relied on as an early diagnostic tool in preperimetric glaucoma. We can use both RNFL thickness assessment by OCT with PERG parameters as complementary tests for accurate diagnosis of preperimetric glaucoma which represents the most difficult diagnostic challenge in glaucoma diagnosis.

Retinal Nerve Fiber Layer Imaging with Two Different Spectral Domain Optical Coherence Tomographs: Normative Data for Romanian Children

The purpose of this study is to analyze and compare pediatric normative data for the retinal nerve fiber layer of Romanian children using two different spectral domain optical coherence tomographs. Due to different scanning speeds and axial and transverse resolution, the results of the measurements of scans cannot be transposed. A total of 140 healthy children aged 4 to 18 were enrolled in the study. Overall, 140 eyes were scanned with a Spectralis SD-OCT (Heidelberg Technology), and the other 140 eyes were imaged with a Copernicus REVO SOCT (Optopol Technology (Zawiercie, Poland)). The mean global RNFL thickness and average RNFL thickness for the four quadrants were measured and compared. The average peripapillary RNFL thickness measured with the Spectralis was 104.03 ± 11.42 (range 81 to 126 µm), while the one measured with the Revo 80 was 127.05 ± 15.6 (range 111.43-158.28). The RNFL thickness measurements taken with the Spectralis in the superior, inferior, nasal, and temporal quadrants were 132 ±19.1, 133.5 ± 21.77, 74 ± 16.48, and 73 ± 11.95 µm, respectively, while those taken with the Revo 80 were 144.44 ± 9.25, 144.86 ±23.12, 96.49 ± 19.41, and 77 ± 11.4 µm, respectively. Multivariate analysis showed that the average RNFL thickness was not influenced by gender or eye laterality and was negatively correlated with age when we used the Spectralis device. This study provides normative data for SD-OCT peripapillary RNFL in healthy Romanian children for two different tomographs. These data help the clinician evaluate and interpret the results of optical coherence tomography for a child, taking into consideration all the technical and individual parameters.

Normative data for macular and retinal nerve fibre layer thickness in healthy German children and adolescents using optical coherence tomography

PURPOSE

To establish normative data for macular thickness, macular volume and peripapillary retinal nerve fibre layer (RNFL) thickness using Spectralis® spectral-domain optical coherence tomography (SD-OCT) in healthy German children and adolescents and investigate influencing factors.

METHODS

The cross-sectional study included the right eye of 695 children with at least one complete retinal OCT scan. As part of the LIFE Child study, the children underwent an ophthalmological examination including axial length (AL), spherical equivalent (SE) and OCT measurements. Various questionnaires were answered by the children or their parents to identify media use or outdoor time. Multiple linear regression models were used to investigate the potential influencing factors.

RESULTS

A total of 342 boys and 353 girls with an average age (SD) of 12.91 (3.29) years participated. The mean AL (SD) was 23.20 (0.86) mm. The mean macular thickness (SD) was 320.53 (12.29) μm and the mean RNFL thickness (SD) was 102.88 (8.79) μm. Statistical analysis revealed a significant correlation between average macular thickness and age (p < 0.001, β = 0.77) as well as AL (p < 0.001, β = -4.06). In addition, boys had thicker maculae (p < 0.001, β = 5.36). The RNFL thickness showed no significant correlation with children's age (p > 0.05), but with AL (p = 0.002, β = -2.15), birth weight (p = 0.02, β = 0.003) and a gender-specific effect of the body mass index standard deviation score for male participants (p = 0.02, β = 1.93).

CONCLUSION

This study provides normative data and correlations between macular and RNFL thickness in healthy German children. Especially age, gender and AL must be taken into account when evaluating quantitative OCT measurements to classify them as normal.

Two Year Functional and Structural Changes-A Comparison between Trabeculectomy and XEN Microstent Implantation Using Spectral Domain Optical Coherence Tomography

The aim of this study was to analyze retinal nerve fiber layer (RNFL) thickness after trabeculectomy (TE) versus XEN microstent implantation (XEN) in primary open-angle glaucoma (POAG) cases naïve to prior incisional glaucoma surgery. We examined 119 consecutive glaucoma patients retrospectively, who received a TE or XEN for medically uncontrolled POAG. Intraocular pressure (IOP), amount of IOP-lowering medication, mean deviation of standard automated perimetry and peripapillary RNFL thickness were evaluated during the first 24 months after surgery. Fifty eyes were treated with TE and 69 eyes with XEN. Mean IOP decreased from 25.1 ± 0.8 to 13.3 ± 0.6 mm Hg (p < 0.01) and mean number of IOP-lowering eye drops from 3.2 ± 0.2 to 0.4 ± 0.1 (p < 0.01) 24 months after TE. In 69 eyes undergoing XEN, mean IOP dropped from 24.8 ± 0.6 to 15.0 ± 0.4 mm Hg (p < 0.01) and medication from 3.0 ± 0.1 to 0.6 ± 0.1 (p < 0.01) during the 24 months follow-up. Mean deviation of standard automated perimetry remained stable in TE (8.5 ± 0.7 to 8.1 ± 0.8 dB; p = 0.54) and XEN group (11,0 ± 0.5 to 11.5 ± 0.5 dB; p = 0.12) after 24 months, while mean RNFL thickness further deteriorated in the TE (−2.28 ± 0.65 µm/year) and XEN (−0.68 ± 0.34 µm/year) group. Postoperative RNFL loss develops after TE and XEN despite effective and significant lowering of IOP and amount of IOP-lowering medication. RNFL loss was more pronounced in the first year after glaucoma surgery.

OCT Results in Myopia: Diagnostic Difficulties in Clinical Practice?

Background: Optical coherence tomography (OCT) is a modern, non-invasive technique for examining the posterior segment of the eye in vivo. The quality of images is crucial for the diagnostic process. Despite good image quality and high signal strength, we still obtain images with less relevant diagnostic data, especially in relation to RNFL and GCL thickness in myopic and hyperopic eyes. Aim: To evaluate the change of RNFL, GCL thickness and rim and disk areas in myopic eyes that underwent OCT examination before and after refractive correction with contact lenses or glasses. Method: A prospective cross-sectional pilot study included 43 eyes in 22 patients with myopia and hyperopia, with or without astigmatism. Patients were examined using OCT with and without contact lenses or glasses. Results: RNFL thickness, GCL thickness, rim area and disk area average and minimum values were significantly changed after correction with glasses or contact lenses. Conclusion: Myopic patients with greater than −2.50 D have to be examined using OCT with their contact lens or glasses corrections in the case of borderline data. Uncorrected myopic eyes show a thinner RNFL and GCL and smaller disk areas, which may mislead ophthalmologists.

Changes in and the association of retinal blood perfusion and retinal nerves in diabetic patients without retinopathy

OBJECTIVE

To explore intraretinal blood flow perfusion and nerve changes, as well as the correlation between them, in diabetic patients without diabetic retinopathy (NDR).

METHOD

Eighty-six NDR patients (86 eyes) who attended the ophthalmology clinic between December 2019 and December 2021 were included. Sixty-four eyes of 64 healthy examined controls in the same period were selected as the control group. The patients underwent routine ophthalmological examination, optical coherence tomography (OCT) and OCT angiography.

RESULTS

The average thickness, minimum thickness and thickness of each quadrant except for the superior temporal quadrant of the ganglion cell-inner plexiform layer (GCIPL) in the macular area of the affected eyes in the NDR group were lower than that of the tested eyes in the control group (P < 0.05). The average retinal nerve fibre layer (RNFL) thickness of the NDR group and the superior, inferior and nasal quadrants around the optic disc of the affected eyes in the NDR group were lower compared with the tested eyes in the control group (P < 0.001, P = 0.003, P = 0.001, P = 0.009). The mean vessel length density in the parafoveal and perifoveal areas in the NDR group was positively associated with the mean GCIPL thickness in the macular area (ρ = 0.265, ρ = 0.257 and P < 0.001). No blood flow perfusion parameters in the NDR group were correlated with the RNFL thickness of the corresponding quadrant around the optic disc (P > 0.05).

CONCLUSION

In diabetic patients without diabetic retinopathy, the superficial retinal vessel density in the macular area positively correlated with GCIPL thickness, and the superficial retinal vessel density around the optic disc was not correlated with RNFL thickness.

Role of spectral domain optical coherence tomography in the diagnosis and prognosis of papilledema

Purpose:

The study of papilledema with a novel noninvasive technique such as spectral domain-optical coherence tomography (SD-OCT) provides minute and detailed cross-sectional changes thus giving an insight into the application of biomechanical principles and pathophysiology of disc edema.

Methods:

We measured average retinal nerve fiber layer (RNFL) thickness and the retinal pigment epithelium/Bruch’s membrane (RPE/BM) angle at the temporal and nasal borders of the neural canal opening (NCO) in 30 eyes with papilledema, 30 eyes with papillitis, and 80 control eyes. The inward angulation was considered as positive and the outward as negative. Follow-up was done at 1, 2, 3, and 6 months. The main outcome measures are the average RNFL thickness and the RPE/BM angle.

Results:

29 eyes (96.6%) with papilledema had a positive RPE/BM angle (+8.11 ± 3.13). 29 eyes (96.6%) with papillitis had a negative RPE/BM angle (−1.04 ± 3.27). On follow-up at 1 month, both RNFL thickness (P = 0.01) and RPE-BM angle (P = 0.001) reduced significantly in eyes with papilledema; in eyes with papillitis, there was a significant reduction in the RNFL thickness (P = 0.02), but not in the RPE-BM angle (P > 0.05). RNFL thickness in papilledema cases normalized at 3 months whereas RPE/BM normalized at 6 months of follow-up. To detect papilledema, OCT has a sensitivity of 96.66% and specificity of 99.09% on both nasal and temporal sides.

Conclusion:

After appropriate treatment, the RPE/BM angle in papilledema decreased much later than the RNFL thickness. Hence, the RPE/BM angle in papilledema (positive) can be used to differentiate it from papillitis (negative) and also to monitor the activity of the disease.

Correlation of axial length and peripapillary retinal nerve fiber layer thickness measured by Cirrus HD optical coherence tomography in myopes

Purpose:

To evaluate the RNFL thickness by optical coherence tomography (OCT) and correlate it with the axial length and refractive error in myopes.

Methods:

Patients with myopia −1D to −10D attending ophthalmology OPD at a tertiary hospital from October 2013 to April 2015 for evaluation underwent ophthalmic examination including refraction, axial length, and OCT RNFL thickness measurements. The patients were divided into two groups; group A included patients with AL ≤24 mm and group B AL >24 mm.

Results:

The study included 100 eyes with myopia ranging from −1D to −10D. The mean (±SD) age was 26.87 (±5.93) years with a range of 21–48 years and male: female ratio of 2:3. There was a statistically significant difference in the average peripapillary RNFL thickness between the two axial length groups (P = 0.01); RNFL thickness in group A being 91.40 (±10.17) and group B 86.06 (±10.09); and in the average RNFL thickness between the 3 degrees of myopia groups, with higher myopic group having thinner RNFL (P = 0.001).

Conclusion:

There is a significant decrease in RNFL thickness with an increase in the grade of myopia and axial length. This polar RNFL thinning could be wrongly attributed to glaucomatous change. We recommend careful interpretation of RNFL data in myopes with axial length >24 mm, when applying the current OCT nomograms.

Correlations between Retinal Arterial Morphometric Parameters and Neurodegeneration in Patients with Type 2 Diabetes Mellitus with No or Mild Diabetic Retinopathy

Background and Objectives: In patients with diabetes mellitus (DM), the neural retina is starting to degenerate before the development of vascular lesions. Our purpose was to investigate the correlation between the retinal arterial morphometric parameters and structural neurodegeneration in patients with type 2 DM with no or mild diabetic retinopathy (DR). Materials and Methods: This is a prospective study including 53 eyes of patients with type 2 DM and 32 eyes of healthy controls. Based on SD-OCT (spectral domain—optical coherence tomography) images, using a micro-densitometry method, we measured the outer and luminal diameter of retinal arteries and calculated the AWT (arterial wall thickness), WLR (wall-to-lumen ratio), and WCSA (wall cross-sectional area). GCL (ganglion cell layer) and RNFL (retinal nerve fiber layer) thickness were analyzed in correlation with the retinal arterial morphometric parameters mentioned above. Results: GCL was thinner in the inner quadrants in the NDR (no DR) group compared to controls (p < 0.05). RAOD (retinal artery outer diameter), RALD (retinal artery lumen diameter), AWT, WLR, and WCSA were similar between groups. A regression model considering age, gender, duration of DM, and HbA1C was carried out. Central GCL thickness was correlated positively with RAOD (coefficient 0.360 per µm, p = 0.011), RALD (coefficient 0.283 per µm, p = 0.050), AWT (coefficient 0.304 per µm, p = 0.029), and WCSA (coefficient 3.90 per µm, p = 0.005). Duration of DM was positively correlated with WCSA (coefficient 0.311 per one year duration of diabetes, p = 0.043). Conclusions: Significant GCL thinning in the inner quadrants preceded the morphological retinal arterial morphometric changes, supporting the neurodegeneration as primary pathogenic mechanism in DR.

Correlation between retrobulbar blood flow parameters and retinal nerve fiber, ganglion cell and inner plexus layer thickness in myopia

PURPOSE

To assess the thickness of the retinal nerve fiber layer (RNFL), ganglion cell and inner plexus layer (GCIPL) and blood flow parameters in retrobulbar vessels, and to analyze correlations between these parameters in myopes.

METHODS

The study included forty myopic and 20 healthy eyes. Standard eye examination was supplemented with OCT of the optic nerve and macula (GCIPL, RNFL, RNFL in each quadrant and rim area of the optic nerve) and color Doppler imaging of retrobulbar arteries [peak systolic and end-diastolic velocities, pulsatile index and resistance index (RI) in the ophthalmic (OA), central retinal (CRA), nasal posterior ciliary and temporal posterior ciliary arteries].

RESULTS

Significant correlations were found between blood flow parameters in the CRA, RNFL and GCIPL thickness, and axial length (AL) and spherical equivalent (SE). There were significant positive correlations between RNFL with PSV and EDV in the CRA and negative correlations between RNFL and RI in the CRA. GCIPL was positively correlated with PSV and EDV in the CRA. The decrease in RA was associated with reduced blood flow velocities in the CRA, TPCA and NPCA.

CONCLUSION

The reduced retrobulbar blood flow in healthy young myopes is correlated with increasing AL and refractive value, and thinning of the RNFL and GCIPL. Reduction of the rim-area of the optic disc is associated with vascular and retinal circulatory disorders. These phenomena indicate the vascular basis of the described changes. To the best of our knowledge, this is the first study which correlates ocular circulation with retinal structure.

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

PURPOSE

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.

METHODS

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.

RESULTS

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).

CONCLUSION

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.

Repeatability and Reproducibility of Axial and Lateral Measurements on Handheld Optical Coherence Tomography Systems Compared with Tabletop System

Purpose

To compare the repeatability and reproducibility of axial and lateral retinal measurements using handheld optical coherence tomography (OCT) systems and a tabletop OCT system.

Methods

Graders measured central foveal thickness (CFT), optic nerve-to-fovea distance (OFD), and retinal nerve fiber layer (RNFL) thickness on OCT scans of the right eye of 10 healthy adults. Three OCT systems were used: handheld Leica Envisu, investigational handheld swept-source OCT (UC3), and Heidelberg Spectralis tabletop system. All eyes were imaged five times with each OCT system by each of two imagers. A components of variance analysis provided estimates of repeatability (variation due to random error) and reproducibility (variation due to imager, grader, and random error) expressed as standard deviation and (coefficient of variation %).

Results

Repeatability of CFT (µm) for Envisu, UC3, and Spectralis was 5.9 (2.6%), 6.9 (2.9%), and 4.7 (2.1%), and the reproducibility was 6.1 (2.7%), 7.3 (3.1%), and 4.7 (2.1%), respectively. The repeatability of OFD (mm) was 0.13 (2.9%), 0.10 (2.3%), and 0.07 (1.6%), and the reproducibility was 0.13 (3.0%), 0.10 (2.3%), and 0.07 (1.6%,) respectively. The repeatability for RNFL thickness (µm) for Envisu, UC3, and Spectralis was 4.3 (7.8%), 2.7 (5.4%), and 2.9 (4.9%), and the reproducibility was 4.5 (8.3%), 2.9 (5.8%), and 2.9 (4.9%), respectively.

Conclusions

All three OCT systems had good repeatability and reproducibility with coefficients of variation of less than 3.5% for CFT and OFD measurements, and less than 8.5% for RNFL thickness.

Translational Relevance

Our findings inform the repeatability and reproducibility of retinal axial and lateral measurements on handheld OCT and are useful for both clinical research and patient care.

Analysis of macular, foveal, and retinal nerve fiber layer thickness in children with unilateral anisometropic amblyopia and their changes following occlusion therapy

Purpose:

To analyze macular thickness (MT), foveal thickness (FT), and retinal nerve fibre layer thickness (RNFLT) in children with unilateral anisometropic amblyopia and their changes following occlusion therapy.

Methods:

A prospective, longitudinal, and comparative study of 60 children aged between 5 and 18 years consisted of two groups, group 1: 30 children with unilateral anisometropic amblyopia; group 2: 30 normal children. Best corrected visual acuity (BCVA), a detailed ocular examination, spectral domain optical coherence tomography for MT, FT, and RNFLT in both eyes were done at visit one (baseline) and every 3 months for a year following occlusion therapy (initiated one month after first visit) in group 1.

Results:

Mean BCVA, MT, FT, and RNFLT in amblyopic eyes at first visit were 0.63 ± 0.405, 286.9 ± 6.522 μm, 195.90 ± 8.462 μm, and 100.87 ± 6.240 μm, respectively and at last visit after occlusion therapy were 0.50 ± 0.318, 248.9 ± 11.681 μm, 169.47 ± 10.941 μm, and 99.43 ± 5.722 μm, respectively. At first visit, mean BCVA, MT, FT, and RNFLT in nonamblyopic eyes (group 1) were 0 ± 0, 240 ± 10.447 μm, 159.27 ± 9.285 μm, 98.63 ± 4.723 μm and in normal eyes (group 2: average of right and left eyes) were 0 ± 0, 239.8 ± 4.294 μm, 143.6 ± 4.61 μm, 100.5 ± 2.895 μm, respectively.

Conclusion:

MT and FT, which were more in amblyopic eyes as compared to normal fellow eyes and group 2, decreased with improvement in BCVA after occlusion therapy. However, there was no difference in RNFLT between amblyopic eyes and normal fellow eyes and group 2 before and after occlusion therapy.

The application of RNFL thickness detection in early differential diagnosis among various types of idiopathic optic neuritis

In this study, we attempted to investigate the application of RNFL thickness detection in the early differential diagnosis among various types of idiopathic optic neuritis (ION). In comparison with 19 healthy controls (HC), retrospective analysis of quadrant RNFL thickness in 83 patients with ION was performed, including eighteen multiple sclerosis (MS), forty-five neuromyelitis optica spectrum disorder (NMOSD), twenty patients with other idiopathic optic neuritis (O-ION). Our results showed that mean and every quadrant RNFL thickness of MS, NMOSD and O-ION were thinner than those of HC (P < 0.05). In comparison with MS and O-ION, NMOSD group had thinner RNFL thickness in nasal quadrant (P < 0.05). No significant difference in each quadrant RNFL thickness between MS-ON and O-ION was suggested (P > 0.05). Mean and every quadrant RNFL thickness of unaffected eyes of MS-ON were not different from those of HC (P > 0.05). We concluded that for patients only with simple optic neuritis, NMOSD has a significantly thinner RNFL thickness in nasal quadrant than MS and O-ION, which may contribute to the clinical differentiation and therapy among various types of idiopathic optic neuritis.

Alterations in retinal nerve fiber layer thickness in early stages of diabetic retinopathy and potential risk factors

AIMS

To investigate the loss of retinal nerve fiber layer (RNFL) in type-2 diabetic patients with early-stage diabetic retinopathy (DR) and to identify potential risk factors accounting for these alterations.

METHODS

In this cross-sectional study, 158 type-2 diabetic patients were divided into three groups based on their DR status. RNFL thickness and other optic disc parameters were obtained by optical coherence tomography (OCT) and then compared among different groups. We investigated the potential association between RNFL loss and systemic risk factors for DR, including diabetes duration, body mass index (BMI), serum lipids, hemoglobin A1c (HbA1c) and albumin-creatinine ratio (ACR). One-way ANOVA was carried out to compare RNFL thickness among different groups, Pearson correlation and multivariate linear regression analysis were performed to determine potential risk factors related to RNFL thickness in these patients.

RESULTS

There were significant differences in the average (F = 8.872, P = 0.003), superior (F = 8.769, P = 0.004), and inferior (F = 8.857, P = 0.003) RNFL thickness of both eyes among the groups, but no obvious difference in optic disc parameters was found. Diabetic duration, BMI, TG, High density lipoprotein cholesterol (HDL), HbA1c, and ACR were found negatively related to the RNFL thickness in both or single eye according to Pearson correlation analysis. After controlling for age, gender, and axis length (AL) in multivariate linear regression analysis, the diabetic duration was associated significantly with RNFL thickness of superior in both eye (right eye: p = 0.016, left eye: p = 0.024), BMI was related to the nasal quadrant of the right eye (p = 0.034), and TG was related to the inferior of the right eye (p = 0.037), HbA1c (p = 0.026) was associated significantly with the average RNFL thickness of the right eye. In addition, ACR was found negatively related to average (p = 0.042) and inferior quadrant (p = 0.014) of the left eye, respectively.

CONCLUSIONS

RNFL loss might be the earliest structural change of retina in diabetic patients, and associated with diabetic duration, BMI, TG, HbA1c, and ACR. The conclusions of this study need to be proved by other well-matched and large-scale prospective clinical trials in the future, because the correlations discovered in our study were weak.

Comparative analysis of mean retinal thickness measured using SD-OCT in normal young or old age and glaucomatous eyes

PURPOSE

To evaluate changes in macular thickness, ganglion cell layer/inner plexiform layer (GCL/IPL) thickness, and retinal nerve fiber layer (RNFL) thickness in normal eyes and glaucomatous eyes using spectral domain optical coherence tomography (SD-OCT).

METHODS

We enrolled 89 eyes (all left eyes), including 45 (of 45 patients) eyes with glaucoma and 44 (of 44 patients) normal eyes. The data from macular measurements using spectral domain optical coherence tomography were analyzed according to groups divided by age and glaucoma status. The macular thickness analysis, GCL/IPL thickness, and RNFL thickness values determined by SD-OCT scans were compared among the groups.

RESULTS

Mean macular thickness decreased significantly with age or glaucoma. Mean GCL/IPL thickness decreased significantly in glaucomatous eyes in all sectors but did not decrease with age. Mean RNFL thickness, which was divided into four quadrants (superior, nasal, inferior, and temporal), decreased significantly in glaucomatous eyes at all quadrants and decreased in the temporal quadrant with age in non-glaucomatous eyes. No significant differences were detected between eyes with normal tension glaucoma (NTG) and primary open angle glaucoma (POAG) in all sectors of mean GCL/IPL thickness, RNFL thickness, and macular thickness.

CONCLUSIONS

No significant difference in mean thickness was detected between eyes with NTG and POAG. Some of the sectors of RNFL thickness decreased with age or glaucoma. GCL/IPL thickness, however, decreased in glaucomatous eyes but not with age. Therefore, GCL/IPL thickness is less influenced by age when monitoring patients with glaucoma or suspect glaucoma.

The volume of peripapillary vessels within the retinal nerve fibre layer: an optical coherence tomography angiography study of normal subjects

BACKGROUND/AIMS

To investigate the contribution of vascular volume calculated by optical coherence tomography angiography (OCTA) to the measurement of peripapillary retinal nerve fibre layer (RNFL) thickness.

METHODS

We used OCTA scans to build volumetric maps of the RNFL angiograms by thresholding the decorrelation images and summing the number of white pixels along the z-axis at each location. We used these maps to calculate the contribution of the vascular tissue to the RNFL thickness.

RESULTS

We analysed 51 eyes from 36 subjects. The mean RNFL volume calculated on the peripapillary region was 0.607±0.045 mm³ and the mean vessel volume was 0.217±0.035 mm³, with a mean vessel/total RNFL ratio of 35.627%±3.942%. When evaluated in the peripapillary circular section, the total contribution of the vascular tissue to the global RNFL thickness was 29.071%±3.945%. The superior and inferior sectors showed the highest percentage of vascular tissue within the RNFL circular profile (31.369% and 34.788% respectively).

CONCLUSIONS

We found that the vascular contribution to the RNFL thickness is 29.07±3.945%. This is much higher than what has been reported from calculations made on the structural OCT alone (13% reported by Hood et al and 11.3%±1.6% for the Cirrus OCT and 11.8%±1.4% for the Spectralis OCT reported by Patel et al). We conclude that evaluation of the vascular tissue contribution to the RNFL thickness with OCTA might be useful when performing precise quantification of the neuronal tissue.

Evaluation of Optic Nerve Head Parameters and Retinal Nerve Fiber Layer Thickness in Axial Myopia Using SD OCT

Introduction

The purpose of this research was to study the effect of increased axial myopia, in non-glaucomatous eyes, and its correlation with ONH parameters, and RNFL thickness, using Cirrus HD 4000 SD-OCT.

Methods

The myopia group included 86 eyes of 86 patients, while the control group involved 92 eyes of 92 patients, attending the Ophthalmology Outpatient Clinic in Minia University Hospital, between November 2013 and March 2015. ONH parameters and peripapillary RNFL thickness measurement were evaluated by using SD-OCT, selecting the standard optic disc cube 200 × 200.

Results

The mean age of the myopia group was (36.55 ± 9.44), the mean spherical equivalent was (−12.70 ± 3.87 D), and the mean axial length was (27.88 ± 1.92 mm). The control group had mean age of (34.82 ± 8.87), mean spherical equivalent of −0.65 ± 0.41 D, and mean AL of (22.16 ± 0.82). A significant difference was reported between the two groups, regarding disc area (p = 0.01), rim area (p = 0.001), vertical C/D (p = 0.01), average C/D ratio (p = 0.001), average and temporal RNFL thickness (p = 0.0001, p = 0.001, respectively).

Conclusion

A significant difference was found between highly myopic non-glaucomatous eyes and the control group, regarding ONH parameters and RNFL thickness as measured by SD-OCT. As OCT magnification adjusted ONH parameters were larger, global and the temporal RNEL were thicker in the myopia group, those magnification adjusted parameters helped in an accurate evaluation of ONH and RNFL in highly myopic eyes, in order to avoid misdiagnosis of glaucoma in such eyes.

Assessing posterior ocular structures in β-thalassemia minor

PURPOSE

The aim of this study was to investigate the effect of β-thalassemia minor on choroidal, macular, and peripapillary retinal nerve fiber layer thickness.

METHODS

To form the sample, we recruited 40 patients with β-thalassemia minor and 44 healthy participants. We used spectral-domain optical coherence tomography to take all measurements of ocular thickness, as well as measured intraocular pressure, axial length, and central corneal thickness. We later analyzed correlations of hemoglobin levels with ocular parameters.

RESULTS

A statistically significant difference emerged between patients with β-thalassemia minor and the healthy controls in terms of mean values of subfoveal, nasal, and temporal choroidal thickness (p = 0.001, p = 0.016, and p = 0.010, respectively). Except for central macular thickness, differences in paracentral macular thicknesses between the groups were also significant (superior: p < 0.001, inferior: p = 0.007, temporal: p = 0.001, and nasal: p = 0.005). Also, no statistically significant differences were noted for retinal nerve fiber layer thickness between two groups.

CONCLUSION

Mean values of subfoveal, nasal, temporal choroidal, and macular thickness for the four quadrants were significantly lower in patients with β-thalassemia minor than in healthy controls.

Evaluation of the acute effect of haemodialysis on retina and optic nerve with optical coherence tomography

Purpose

The primary objective of haemodialysis (HD) was to correct the composition and volume of body fluids. The aim of this study was to evaluate the acute effect of HD on mean arterial pressure changes and on retina and optic nerve with optical coherence tomography (OCT).

Methods

Fifty-three eyes of 28 patients were enrolled in this study. The patients’ retinal and RNFL thicknesses were measured by OCT and mean arterial pressure alterations were recorded before and immediately after HD session.

Results

The results show that while there was a reduction at central foveal thickness and ganglion cell layer thickness, central subfield and RNFL thickness were increased with HD session. But none of them were statistically significant (p = 0.320, p = 0.792, p = 0.744, p = 0.390). The mean arterial pressure of the patients decreased significantly (p < 0.05) but it was not correlated with retinal and RNFL values.

Conclusion

The changes in retinal and RNFL findings were not significant. But these alterations may effect the long term follow-up of the patients with retinal and optic nerve disease. Therefore it is important to pay attention HD session time for these patients’ measurements.

Determinants of peripapillary retinal nerve fiber layer thickness regarding ocular and systemic parameters - the MIPH Eye&Health Study

BACKGROUND

Optical coherence tomography (OCT) allows quantitative image analysis of retinal tissue in vivo. Peripapillary retinal nerve fiber layer (pRNFL) thickness is widely used for evaluation of retinal nerve fiber rarefaction in several optic neuropathies. This study evaluates associations of pRNFL thickness in healthy adult subjects in order to evaluate influencing factors.

METHODS

A cross-sectional study was performed in a working-age population. Only eyes without detectable ocular pathologies were included in the analysis. Among analyzed systemic cardiovascular parameters were age, gender, body-mass index, mean arterial blood pressure, HbA1c, high- and low-density-lipoproteins, and triglycerides. A comprehensive ophthalmological examination including refraction, tonometry, keratometry, and central corneal thickness measurmentwas performed. In addition, pRNFL thickness was imaged by spectral-domain OCT. Univariable and multivariable associations of pRNFL thickness in all four quadrants and on average with systemic and ocular parameters were calculated using a generalized estimating equation model.

RESULTS

Three hundred and six subjects were included. pRNFL thickness measurements showed a significant association with spherical equivalent: pRNFL thickness decreased with increasing myopia in all quadrants (multivariable regression coefficients Beta: superior: 1.16, 95 % CI [0.62;1.71], p < 0.001; temporal: 0.87, [0.33;1.41], p = 0.001; inferior: 1.80, [1.18;2.42], p < 0.001; nasal: 2.60, [2.01;3.20], p < 0.001) and on average (1.51, [1.20;1.82], p < 0.001). A thicker central cornea thickness was related to lower pRNFL in the superior (-0.05, [-0.10; -0.01], p = 0.01), the inferior quadrant (-0.05, [-0.10;0.00], p = 0.03) and on average (-0.04, [-0.07; -0.01], p = 0.02). All other parameters were not  associated.

CONCLUSION

Our findings highlight the importance of refraction when evaluating pRNFL thickness and its independence from other systemic parameters.

The Effect of Pseudoexfoliation Syndrome on the Retinal Nerve Fiber Layer and Choroid Thickness

PURPOSE

To investigate thickness of the retinal nerve fiber layer (RNFL) and choroid thickness in patients with pseudoexfoliation syndrome (PEX) and pseudoexfoliation glaucoma (PXG) compared to healthy volunteers.

METHODS

This cross-sectional, prospective study included 43 patients with PXG, 45 patients with PEX syndrome, and 48 healthy volunteers. The RNFL and macular thickness were analyzed with standard OCT protocol while choroidal thickness was analyzed with EDI protocol in all subjects.

RESULTS

The RNFL thickness was higher in the PEX and control groups compared to the PXG group (p<0.001). The choroid thickness was significantly higher in the control group compared to the PXG and PEX groups (p<0.05). No significant difference was detected between the both groups.

CONCLUSIONS

PEX might weaken choroid circulation by accumulating in choroid vessels. The thinner choroid in the PXG group suggests that ischemia affects the duration of PEX and has a role in the development of glaucoma.

Scanning laser polarimetry and spectral domain optical coherence tomography for the detection of retinal changes in Parkinson's disease

PURPOSE

Whether retinal degeneration is part of the degenerative processes in patients with Parkinson's disease (PD) is still unclear. This cross-sectional study was undertaken to compare the retinal morphology of patients with PD and healthy controls using spectral domain optical coherence tomography (SD-OCT) and scanning laser polarimetry (SLP).

METHODS

Both eyes of patients with PD (n = 108) and healthy controls (n = 165) were examined using SD-OCT and SLP on the same day. Data on the thickness of the retinal nerve fibre layer (RNFL) of all quadrants and the macular area were acquired by OCT (Cirrus, Zeiss). The SLP device (Glaucoma diagnostics (GDx), Zeiss) measured the RNFL and calculated the nerve fibre index (NFI). All patients and probands were checked for concomitant ocular disorders by an ophthalmologist. Visual acuity, intraocular pressure (IOP), objective refraction and the anterior and posterior segment were assessed.

RESULTS

Patients with PD showed a reduced macular volume and a reduced central subfield thickness in OCT examinations. The RNFL in the different quadrants did not differ significantly from that of controls. SLP data showed a reduced average RNFL thickness, a decreased thickness of the inferior quadrant and an increase of the NFI in patients with PD.

CONCLUSION

PD may be associated with reduced thickness and volume of the macula and a reduced thickness of the RNFL in the inferior quadrant of the retina. Investigations using SD-OCT and SLP revealed distinct but significant differences between patients with PD and healthy controls.

Retinal nerve fibre layer thickness measured with SD-OCT in a population-based study of French elderly subjects: the Alienor study

PURPOSE

To establish normative data of retinal nerve fibre layer (RNFL) thickness in the elderly and to determine the factors influencing its thickness.

METHODS

Peripapillary RNFL thickness was measured with spectral domain OCT (SD-OCT) in 210 elderly participants from the Alienor population-based study who were aged 75 years or older. The measure was assessed in six segments (the superotemporal, temporal, inferotemporal, inferonasal, nasal and superonasal segments). RNFL data were analysed across age and sex strata in non-glaucoma participants. Mixed linear models were used to evaluate the associations of RNFL thickness with age, sex, ocular parameters and vascular risk factors.

RESULTS

The mean global RNFL thickness was 91.4 μm (SD: 12.6), ranging from 55 to 122; the highest values were found in the inferotemporal and superotemporal segments. After adjustment for sex and ocular parameters, including axial length, increasing age was significantly associated with lower thickness globally (mean thinning per decade = 5.6 μm, p = 0.003), in the superotemporal (-12.7 μm per decade, p < 0.0001) and inferotemporal (-8.1 μm per decade, p = 0.022) segments. RNFL thickness tended to be higher in women than in men, but this trend was significant only in the inferotemporal segment (+6.6 μm for women, p = 0.012). The axial length was associated with RNFL thickness globally and in most segments. RNFL thickness did not differ according to cataract extraction. There were no associations between vascular factors and RNFL thickness.

CONCLUSION

Retinal nerve fibre layer thickness decreased with age globally and in the supero- and inferotemporal segments, even after 75 years; it also tended to be higher in women, particularly in the inferotemporal segment. Normative data on RNFL thickness should consider these characteristics as well as ocular parameters, particularly axial length.

Peripapillary retinal nerve fiber layer and foveal thickness in hypermetropic anisometropic amblyopia

Purpose

To evaluate whether there was a difference in peripapillary retinal nerve fiber layer (RNFL) and foveal thickness between amblyopic and normal individuals with optical coherence tomography.

Materials and methods

Sixty patients, 30 patients with hypermetropic anisometropic amblyopia and 30 normal emmetropic subjects, were enrolled in this study. The eyes of the participants were divided into three groups: 30 eyes of 30 patients with amblyopia (A), 30 fellow eyes of the amblyopic patients (B), and 30 eyes of 30 normal subjects (C). Emmetropic normal subjects included cases with normal visual acuity and unremarkable ocular examinations. After routine ophthalmic examination, peripapillary retinal nerve fiber layer and foveal thickness measurements were measured by time-domain optical coherence tomography and compared among the three groups.

Results

The difference in RNFL thickness between amblyopic eyes, fellow eyes of the amblyopic patients, and normal eyes of the emmetropic subjects was not clinically significant. However, the mean foveal thickness was significantly thicker in amblyopic eyes versus the fellow eyes and normal subjects’ eyes.

Conclusion

Our results suggest that amblyopia seems to have an effect on the foveal thickness, but not on the RNFL thickness.

Comparative studies of RNFL thickness measured by OCT with global index of visual fields in patients with ocular hypertension and early open angle glaucoma

PURPOSE

To compare the functional changes in visual fields with optical coherence tomography (OCT) findings in patients with ocular hypertension, open angle glaucoma, and suspected glaucoma. In addition, our purpose is to evaluate the correlation of global indices with the structural glaucomatous defect, to assess their statistical importance in all the groups of our study, and to estimate their validity to the clinical practice.

METHODS

One hundred sixty nine eyes (140 patients) were enrolled. The patients were classified in three groups. Group 1 consisted of 54 eyes with ocular hypertension, group 2 of 42 eyes with preperimetric glaucoma, and group 3 of 73 eyes with chronic open angle glaucoma. All of them underwent ophthalmic examination according to a prefixed protocol, OCT exam (Stratus 3000) for retinal nerve fiber layer (RNFL) thickness measurement with fast RNFL thickness protocol and visual fields (VF) examination with Octopus perimeter (G2 program, central 30-2 threshold strategy). Pearson correlation was calculated between RNFL thickness and global index of VF.

RESULTS

A moderate correlation between RNFL thickness and indices mean sensitivity (MS), mean defect (MD) and loss variance (LV) of VF (0.547, -0.582, -0.527, respectively; P <0.001) was observed for all patients. Correlations of the ocular hypertension and preperimetric groups are weak. Correlation of RNFL thickness with global indices becomes stronger as the structural alterations become deeper in OCT exam. Correlation of RNFL thickness with the global index of VF, in respective segments around optic disk was also calculated and was found significant in the nasal, inferior, superior, and temporal segments.

CONCLUSION

RNFL average thickness is not a reliable index for early diagnosis of glaucoma and for the follow-up of patients with ocular hypertension. Segmental RNFL thickness seems to be a more reliable index. Deep structural alterations with OCT examination constitute an important indication of early functional changes, even if they are not still detected with achromatic perimetry. The MD index of VF seems to be more sensitive for the follow-up of patients with ocular hypertension.