Comparison of optic coherence tomography results in patients with diagnosed epilepsy: Findings in favor of neurodegeneration

The thickness of the retinal nerve fiber layer, macula, and ganglion cell-inner plexiform layer in people with drug-resistant epilepsy

OBJECTIVE

Using Optical coherence tomography (OCT), we evaluated the association between peripapillary retinal nerve fiber, macular thickness, macular ganglion cell-inner plexiform layer, and drug resistance.

METHODS

In this cross-sectional study, we recruited people diagnosed with epilepsy and healthy controls. People with epilepsy were further stratified as drug-resistant or non-drug-resistant based on their response to anti-seizure medications. OCT measurements were conducted, and findings in right eye were analyzed.

RESULTS

Fifty-one drug-resistant participants, 37 non-drug-resistant, and 45 controls were enrolled. The average peripapillary retinal nerve fiber layer, ganglion cell-inner plexiform layer, and macular thickness were thinner in the epilepsy groups than in controls. The drug-resistant group had significantly lower average ganglion cell-inner plexiform layer thickness (p = 0.004) and a higher proportion of abnormal/borderline GC/IPL thickness (p = 5.40E-04) than the non-drug-resistant group. Nevertheless, no significant differences were seen between the average thickness of peripapillary retinal nerve fiber and macular thickness. The temporal sectors of these three parameters were also significantly thinner in the drug-resistant group than in the non-drug-resistant. In a multivariate regression model, drug resistance was an independent predictor of reduced ganglion cell-inner plexiform thickness (Odds ratios OR = 10.25, 95% CI 2.82 to 37.28). Increased seizure frequency (r = -0.23, p = 0.039) and a higher number of anti-seizure medications ever used (r = -0.27, p = 0.013) were negatively associated with ganglion cell-inner plexiform layer thickness.

SIGNIFICANCE

Individuals with drug-resistant epilepsy had a consistent reduction in average ganglion cell-inner plexiform layer thickness and the temporal sector of peripapillary retinal nerve fiber layer and macular thickness. This suggests that ganglion cell-inner plexiform layer thickness could potentially serve as an indicator of the burden of drug resistance, as it correlated with reduced thickness in individuals having more frequent seizures and greater exposure to ASMs.

PLAIN LANGUAGE SUMMARY

In our study, we used a special tool called OCT to measure how thick the retina is in people with epilepsy and in healthy control. We found that the retina was consistently thinner in all areas for those with epilepsy compared to healthy control. Particularly, a specific layer called the ganglion cell-inner plexiform layer was a lot thinner in the group that didn't respond to medications, and this thinning was related to how often seizures occurred and how much medications were taken. Also, certain parts of the retina were thinner in the drug-resistant group.

The effect of epilepsy and anti-epileptic drugs on the anterior and posterior segment of the eye

CLINICAL RELEVANCE

Understanding the causes of visual symptoms in epilepsy patients is important for early diagnosis and taking precautions.

BACKGROUND

The aim of this study is to evaluate the anterior and posterior segment parameters in patients with generalized tonic-clonic epilepsy (GTCE).

METHODS

This retrospective study included 50 eyes of 50 patients with GTCE and 55 eyes of 55 healthy controls. For all participants, detailed ophthalmic examinations were obtained from the files of patients. Anterior segment parameters were measured using corneal topography and non-contact specular microscopy, and posterior segment parameters were measured using swept-source optical coherence tomography.

RESULTS

The mean age of the patients with GTCE was 43.3 ± 13.2 years, and in the healthy controls it was 47.6 ± 10.7 years (p = 0.405). In GTCE patients, 34 patients were treated with monotherapy (MT) and 16 patients with polytherapy (PT). Central macular thickness (CMT) was statistically significantly thin in GTCE patients (p = 0.001). The average and four quadrants (superior, inferior, nasal, temporal) retinal nerve fibre layer (RNFL) were thinner in GTCE patients than in the healthy controls, but there was no statistically significant difference (p > 0.05, all). The central corneal thickness was statistically significantly thin in GTCE patients (p = 0.04). Endothelial cell density (ECD), endothelial cell number (ECN), and average cell area (ACA) were statistically significantly lower in GTCE patients than in the healthy controls (p < 0.05, all). Although the CMT, average, and four-quadrants RNFL were thinner in the PT group compared to the MT group, no statistically significant difference was observed (p > 0.05, all). Total high-order aberrations (HOAs) were 0.6 ± 0.4 in the MT group and 0.4 ± 0.1 in the PT group (p = 0.01). ECD, ECN, and ACA measurements were observed to be lower in the PT group compared to the MT group, but no statistically significant difference was detected (p > 0.05, all).

CONCLUSION

There could be statistically significant differences between GTCE patients and healthy controls in anterior and posterior segment parameters. This situation may be due to the epilepsy itself or to the antiepileptic drugs.

Ocular hemodynamics in epileptic children treated with antiepileptic drugs

PURPOSE

To evaluate the quantitative measurements obtained for vessel density (VD) of the optic nerve head, macula, peripapillary retinal nerve fibre layer (p-RNFL) and total retinal thicknesses (Trt) by optical coherence tomography angiography (OCT-A) and the choroidal vascular structure using an image binarization method in children with epilepsy using three different antiepileptic drugs (AEDs) and to compare these measurements with healthy participants.

METHODS

This observational, cross-sectional study included 124 patients divided into 4 groups: Group-1: patients receiving carbamazepine(n = 30), group-2: patients receiving levetiracetam (n = 31), group-3: patients receiving valproic acid (n = 32), and group 4: healthy controls (n = 31).A fully automated microstructural analysis of the VD of the retinal superficial capillary plexus (SCP), deep capillary plexus (DCP), and the choriocapillaris (CC) layers and radial peripapillary capillary, and Trt, p-RNFL thickness were analyzed by using OCT-A. Enhanced depth imaging (EDI)-OCT scans of the macula were obtained and the images were binarized using the ImageJ software.

RESULTS

The mean age, gender distribution and the duration of epilepsy were similar in all groups. Evaluation of the p-RNFL thickness and perifoveal Trt between the groups showed a statistically significant difference in all quadrants.The p-RNFL thickness was lower in patients receiving carbamazepine and valproic acid. The lowest values of the luminal area and choroidal vascular index (CVI) were found in patients receiving valproic acid; comparison with matched healthy controls showed statistically significant differences.

CONCLUSION

Valproic acid and carbamazepine are associated with thinning of the p-RNFL in epilepsy patients, but the macular and radial peripapillary VD were not affected.However, a reduction of choroidal vascular blood flow was found in epilepsy patients taking valproic acid.

Association between retinal thickness and disease characteristics in adult epilepsy: A cross-sectional OCT evaluation

OBJECTIVE

Thinning of the peripapillary retinal nerve fiber layer (p-RNFL), as measured by optical coherence tomography (OCT), was recently introduced as a promising marker for cerebral neuronal loss in people with epilepsy (PwE). However, its clinical implication remains to be elucidated. We thus aimed to (1) systematically characterize the extent of the retinal neuroaxonal loss in a broad spectrum of unselected PwE and (2) to evaluate the main clinical determinants.

METHODS

In this prospective study, a spectral-domain OCT evaluation was performed on 98 well-characterized PwE and 85 healthy controls (HCs) (18-55 years of age). All inner retinal layers and the total macula volume were assessed. Group comparisons and linear regression analyses with stepwise backward selection were performed to identify relevant clinical and demographic modulators of the retinal neuroaxonal integrity.

RESULTS

PwE (age: 33.7 ± 10.6 years; 58.2% female) revealed a significant neuroaxonal loss across all assessed retinal layers (global pRNFL, P = 0.001, Δ = 4.24 μm; macular RNFL, P < 0.001, Δ = 0.05 mm3 ; ganglion cell inner plexiform layer, P < 0.001, Δ = 0.11 mm3 ; inner nuclear layer, INL, P = 0.03, Δ = 0.02 mm3 ) as well as significantly reduced total macula volumes (TMV, P < 0.001, Δ = 0.18 mm3 ) compared to HCs (age: 31.2 ± 9.0 years; 57.6% female). The extent of retinal neuroaxonal loss was associated with the occurrence and frequency of tonic-clonic seizures and the number of antiseizure medications, and was most pronounced in male patients.

SIGNIFICANCE

PwE presented an extensive retinal neuroaxonal loss, affecting not only the peripapillary but also macular structures. The noninvasive and economic measurement via OCT bears the potential to establish as a practical tool to inform patient management, as the extent of the retinal neuroaxonal loss reflects aspects of disease severity and sex-specific vulnerability.

PLAIN LANGUAGE SUMMARY

The retina is an extension of the brain and closely connected to it. Thus, cerebral alterations like atrophy reflect also on the retinal level. This is advantageous, as the retina is easily accessible and measureable with help of the optical coherence tomography. Here we report that adults with epilepsy have a significantly thinner retina than healthy persons. Especially people with many big seizures and a lot of medications have a thinner retina. We propose that measurement of the retina can be useful as a marker of disease severity and to inform patient management.

Phenome- and genome-wide analyses of retinal optical coherence tomography images identify links between ocular and systemic health

The human retina is a multilayered tissue that offers a unique window into systemic health. Optical coherence tomography (OCT) is widely used in eye care and allows the noninvasive, rapid capture of retinal anatomy in exquisite detail. We conducted genotypic and phenotypic analyses of retinal layer thicknesses using macular OCT images from 44,823 UK Biobank participants. We performed OCT layer cross-phenotype association analyses (OCT-XWAS), associating retinal thicknesses with 1866 incident conditions (median 10-year follow-up) and 88 quantitative traits and blood biomarkers. We performed genome-wide association studies (GWASs), identifying inherited genetic markers that influence retinal layer thicknesses and replicated our associations among the LIFE-Adult Study (N = 6313). Last, we performed a comparative analysis of phenome- and genome-wide associations to identify putative causal links between retinal layer thicknesses and both ocular and systemic conditions. Independent associations with incident mortality were detected for thinner photoreceptor segments (PSs) and, separately, ganglion cell complex layers. Phenotypic associations were detected between thinner retinal layers and ocular, neuropsychiatric, cardiometabolic, and pulmonary conditions. A GWAS of retinal layer thicknesses yielded 259 unique loci. Consistency between epidemiologic and genetic associations suggested links between a thinner retinal nerve fiber layer with glaucoma, thinner PS with age-related macular degeneration, and poor cardiometabolic and pulmonary function with a thinner PS. In conclusion, we identified multiple inherited genetic loci and acquired systemic cardio-metabolic-pulmonary conditions associated with thinner retinal layers and identify retinal layers wherein thinning is predictive of future ocular and systemic conditions.

Evaluation of ganglion cell complex and retinal nerve fiber layer thinning in epilepsy patients

Purpose

This study aimed to compare the perimacular ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (RNFL) thickness measurements of epileptic and healthy individuals.

Methods

The right eyes of 38 epileptic and 38 healthy individuals who had been using antiepileptic drugs (AEDs) for at least 1 year were included in the study. Central macular thickness, perimacular GCC thickness and volume, and peripapillary retinal nerve fiber layers were measured by optical coherence tomography (OCT) device. Perimacular 1, 3, and 6 mm circle diameters of Early Treatment of Diabetic Retinopathy Study (ETDRS.

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were selected for GCC measurements.

Results

In epilepsy patients, GCC was significantly lower in the 3 mm superior quadrant and 6 mm in all quadrants compared to the control group (P < 0.05). RNFL was significantly thinner in epilepsy patients only in the temporal-inferior quadrant (P < 0.05). There was no significant difference between the patients who received AEDs as monotherapy and polytherapy (P > 0.05).

Conclusion

We found that epilepsy patients had significant thinning in the GCC layers and temporal-inferior quadrant of RNFL compared to the control group. Our findings from the study show that early retinal changes in epilepsy patients, especially perimacular GCC layers, can be followed up with OCT.

Insights into human health from phenome- and genome-wide analyses of UK Biobank retinal optical coherence tomography phenotypes

The human retina is a complex multi-layered tissue which offers a unique window into systemic health and disease. Optical coherence tomography (OCT) is widely used in eye care and allows the non-invasive, rapid capture of retinal measurements in exquisite detail. We conducted genome- and phenome-wide analyses of retinal layer thicknesses using macular OCT images from 44,823 UK Biobank participants. We performed phenome-wide association analyses, associating retinal thicknesses with 1,866 incident ICD-based conditions (median 10-year follow-up) and 88 quantitative traits and blood biomarkers. We performed genome-wide association analyses, identifying inherited genetic markers which influence the retina, and replicated our associations among 6,313 individuals from the LIFE-Adult Study. And lastly, we performed comparative association of phenome- and genome- wide associations to identify putative causal links between systemic conditions, retinal layer thicknesses, and ocular disease. Independent associations with incident mortality were detected for photoreceptor thinning and ganglion cell complex thinning. Significant phenotypic associations were detected between retinal layer thinning and ocular, neuropsychiatric, cardiometabolic and pulmonary conditions. Genome-wide association of retinal layer thicknesses yielded 259 loci. Consistency between epidemiologic and genetic associations suggested putative causal links between thinning of the retinal nerve fiber layer with glaucoma, photoreceptor segment with AMD, as well as poor cardiometabolic and pulmonary function with PS thinning, among other findings. In conclusion, retinal layer thinning predicts risk of future ocular and systemic disease. Furthermore, systemic cardio-metabolic-pulmonary conditions promote retinal thinning. Retinal imaging biomarkers, integrated into electronic health records, may inform risk prediction and potential therapeutic strategies.

Evaluation of optical coherence tomography findings in adolescents with genetic generalized epilepsy

OBJECTIVE

To evaluate retinal nerve fiber layer (RNFL) thickness, central macular thickness (CMT), and subfoveal choroid thickness (CT) by using optical coherence tomography (OCT) in adolescents with newly diagnosed epilepsy and patients who had been using Na valproate (VPA) for at least 1 year.

METHODS

We examined 60 patients with genetic generalized epilepsy (GGE) aged 8-17 years. Thirty patients with newly diagnosed GGE who were evaluated before the beginning of the therapy and another 30 patients who were chosen from among adolescents with epilepsy using VPA for at least 1 year were included in the study.

RESULTS

Nasal quadrant RNFL thickness and CMT measurements were significantly lower in the monotherapy group compared with the newly diagnosed group (p = 0.044 and p = 0.032, respectively). CT measurements were not significantly different between the groups (p = 0.413). There was a negative correlation in regression analysis between the duration of drug use and RNFL thickness in all quadrants.

CONCLUSION

According to our study, we observed thinning of the nasal RNFL and macular thickness in adolescents with epilepsy who were using Na valproate for at least 1 year and that as the duration of use increased, the thinning occurred in all RNFL quadrants. Further studies with larger series are needed to better understand the effects of both epilepsy and VPA on the eye.

Peripapillary retinal nerve fibre layer thinning in genetic generalized epilepsy

PURPOSE

The purpose of this study was to compare the peripapillary retinal nerve fibre layer (RNFL) between patients with genetic generalized epilepsy (GGE) and healthy controls.

METHODS

This prospective observational study was conducted on adults aged 18-60 years. The study group comprised 26 consecutive patients who met the inclusion criteria and 26 healthy age- and sex-matched healthy adults. Peripapillary RNFL thickness was measured by spectral domain optical coherence tomography.

RESULTS

The average peripapillary RNFL thickness was significantly thinner for GGE patients (98.61 μm) than for healthy controls (104.77 μm) (p = 0.016). Similar results were obtained for the left eye. The peripapillary RFNL thickness of all quadrants was lower for GGE patients than for healthy controls, but it was significant only in the superior (p = 0.009) and inferior (p = 0.024) quadrants for both eyes.

CONCLUSIONS

Our results suggest that the peripapillary RNFL is significantly thinner in GGE patients than in healthy participants. We concluded that this microstructural feature might be an intrinsic feature of GGE.