Optical coherence tomography and neurodegeneration: are eyes the windows to the brain?

Optical coherence tomography angiography findings of systemic lupus erythematosus patients and the effect of neuropsychiatric involvement on it

AIM

To investigate the radial peripapillary capillary plexus vessel density (RPCP-VD) and peripapillary retinal nerve fiber layer thickness (pRNFLT) of systemic lupus erythematosus (SLE) and neuropsychiatric SLE patients (NPSLE) using disc optical coherence tomography angiography (OCTA) and investigate the association between these parameters and SLE disease activity index (SLEDAI-2K).

METHODS

A total of 64 'right eyes (36 SLE patients, 28 healthy controls (HCs)) were included in this cross-sectional case-control study. Ten (27.7%) patients had neuropsychiatric involvement. RPCP-VD and pRNFLT of patients were evaluated in all peripapillary sectors. RPCP-VD and pRNFLT of NPSLE, non-NPSLE, and HCs were compared. The correlation between SLEDAI-2K and OCTA findings was evaluated.

RESULTS

SLE patients' RPCP-VDs were significantly lower compared with the HCs except for two sectors (p < .005). There was not a significant difference in pRNFLT of SLE patients and HCs. There was not a correlation between SLEDAI-2K and RPCP-VD in any subsectors but there was a significantly negative correlation between pRNFLT in tempo-inferior and inferior-temporal sectors. When compared with non-NPSLE-patients, NPSLE patients had significantly lower inferior-hemi (p = .001), inferior-nasal VDs (p = .003), and peripapillary (p = .012), superior-hemi (p = .038), inferior-hemi (p = .026), inferior-nasal (p = .002) and inferior-temporal (p = .012) pRNFLTs. A negative correlation was found between NPSLE and pRNFLT.

CONCLUSION

SLE patients may have early subclinical vascular involvement leading to decreased RPCP-VD. A negative correlation between the SLEDAI-2K and pRNFLT in the temporal subsectors of all SLE patients may show an association between the disease activity and temporal pRNFL thinning. The presence of neuropsychiatric involvement may also be associated with decreased RPCP-VD and pRNFLT.

Clinical Characteristics of Migraine and Their Association With the Retinal Nerve Fiber Layer Thickness

BACKGROUND

Migraine is characterized by recurrent episodes of unilateral, pulsating headaches. At the cerebral and ocular levels, it is recognized that the vascular narrowing and loss of blood flow are transient; however, the chronic nature of migraine may result in long-term functional and structural changes in these structures. It could result in axonal loss and an alteration in the thickness of the retinal nerve fiber layers (RNFL). This study aimed to measure the RNFL thickness, which provides a useful indication of the state of the axons and the loss of ganglion cells in migraine patients, and to find out if RNFL thickness and the clinical features of migraine are correlated.

MATERIALS AND METHODS

Sixty patients with migraine and 60 age-gender-matched controls were recruited. A complete neurological and ophthalmological examination was performed, and spectral-domain optical coherence tomography (SD-OCT) was done to measure RNFL.

RESULTS

All quadrants of the retina on both sides showed non-statistically significant differences in RNFL thickness between migraine patients and controls (p-value >0.05). Furthermore, in all retinal quadrants on both sides, there was no statistically significant difference in RNFL thickness between migraine patients with aura and those without aura (p-value >0.05). Significant correlations were found between the duration of migraine disease and the superior RNFL thickness of both eyes, as well as the inferior RNFL in the right eye. There was also a significant correlation between the headache attack duration and RNFL thickness of the superior retina (p<0.05), Conclusion: Our key finding was that when comparing migraine patients to controls, RNFL thickness did not significantly change; however, the duration of migraine disease did significantly affect RNFL thickness.

Using optical coherence tomography and optical coherence tomography angiography to delineate neurovascular homeostasis in migraine: a review

Migraine is one of the world's most debilitating disorders, and it has recently been shown that changes in the retina can be a potential biomarker for the disease. These changes can be detected by optical coherence tomography (OCT), which measures retinal thickness, and optical coherence tomography angiography (OCTA), which measures vessel density. We searched the databases Google Scholar, ProQuest, Scopus, and Web of Science for studies in English using OCT and OCTA in migraineurs, using the search terms "optical coherence tomography," "OCT," "optical coherence tomography angiography," "OCTA" and "migraine." We found 73 primary studies, 11 reviews, and 8 meta-analyses pertaining to OCT and OCTA findings in migraineurs. They showed that migraineurs had reduced retinal thickness (via OCT), retinal vessel density, and greater foveal avascular zone area (via OCTA) than controls. OCTA changes reflect a perfusion compromise occurring in migraineurs as opposed to in healthy controls. OCT and OCTA deficits were worse in migraine-with-aura and chronic migraine than in migraine-without-aura and episodic migraine. Certain areas of the eye, such as the fovea, may be more vulnerable to these perfusion changes than other parts. Direct comparison between study findings is difficult because of the heterogeneity between the studies in terms of both methodology and analysis. Moreover, as almost all case-control studies were cross-sectional, more longitudinal cohort studies are needed to determine cause and effect between migraine pathophysiology and OCT/OCTA findings. Current evidence suggests both OCT and OCTA may serve as retinal markers for migraineurs, and further research in this field will hopefully enable us to better understand the vascular changes associated with migraine, perhaps also providing a new diagnostic and therapeutic biomarker.

Deep learning predicts prevalent and incident Parkinson's disease from UK Biobank fundus imaging

Parkinson's disease is the world's fastest-growing neurological disorder. Research to elucidate the mechanisms of Parkinson's disease and automate diagnostics would greatly improve the treatment of patients with Parkinson's disease. Current diagnostic methods are expensive and have limited availability. Considering the insidious and preclinical onset and progression of the disease, a desirable screening should be diagnostically accurate even before the onset of symptoms to allow medical interventions. We highlight retinal fundus imaging, often termed a window to the brain, as a diagnostic screening modality for Parkinson's disease. We conducted a systematic evaluation of conventional machine learning and deep learning techniques to classify Parkinson's disease from UK Biobank fundus imaging. Our results suggest Parkinson's disease individuals can be differentiated from age and gender-matched healthy subjects with 68% accuracy. This accuracy is maintained when predicting either prevalent or incident Parkinson's disease. Explainability and trustworthiness are enhanced by visual attribution maps of localized biomarkers and quantified metrics of model robustness to data perturbations.

Fractal Phototherapy in Maximizing Retina and Brain Plasticity

The neuroplasticity potential is reduced with aging and impairs during neurodegenerative diseases and brain and visual system injuries. This limits the brain's capacity to repair the structure and dynamics of its activity after lesions. Maximization of neuroplasticity is necessary to provide the maximal CNS response to therapeutic intervention and adaptive reorganization of neuronal networks in patients with degenerative pathology and traumatic injury to restore the functional activity of the brain and retina.Considering the fractal geometry and dynamics of the healthy brain and the loss of fractality in neurodegenerative pathology, we suggest that the application of self-similar visual signals with a fractal temporal structure in the stimulation therapy can reactivate the adaptive neuroplasticity and enhance the effectiveness of neurorehabilitation. This proposition was tested in the recent studies. Patients with glaucoma had a statistically significant positive effect of fractal photic therapy on light sensitivity and the perimetric MD index, which shows that methods of fractal stimulation can be a novel nonpharmacological approach to neuroprotective therapy and neurorehabilitation. In healthy rabbits, it was demonstrated that a long-term course of photostimulation with fractal signals does not harm the electroretinogram (ERG) and retina structure. Rabbits with modeled retinal atrophy showed better dynamics of the ERG restoration during daily stimulation therapy for a week in comparison with the controls. Positive changes in the retinal function can indirectly suggest the activation of its adaptive plasticity and the high potential of stimulation therapy with fractal visual stimuli in a nonpharmacological neurorehabilitation, which requires further study.

Optical coherence tomography (OCT) measurements and cognitive performance in multiple sclerosis: a systematic review and meta-analysis

BACKGROUND

Several studies report mixed associations between the retinal nerve fiber layer (RNFL) thickness with cognitive and physical disability in persons with multiple sclerosis (PwMS). Systematic synthesis of these findings is crucial in deriving credible conclusions.

METHODS

Five databases were searched from their inception to March 2022. The inclusion criteria for studies were MS-specific and required RNFL and cognitive performance data in order to be analyzed. The selection processes followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.

RESULTS

The systematic review yielded 31 studies that investigated the association between RNFL thickness and cognitive performance. Twenty-two studies reported positive associations, and nine did not. The meta-analysis included 11 studies with a total of 782 PwMS with mean age of 40.5 years, mean Expanded Disability Status Scale (EDSS) of 2.7, and disease duration of 11.3 years. RNFL thickness was significantly associated Symbol Digit Modalities Test (pooled r = 0.306, p < 0.001), Paced Auditory Serial Addition Test (pooled r = 0.374, p < 0.001) and Word List Generation (WLG, pooled r = 0.177, p < 0.001). RNFL was also significantly correlated with visuospatial learning and memory tests (pooled r = 0.148, p = 0.042) and verbal learning and memory tests (pooled r = 0.245, p = 0.005). Within three eligible studies, no significant association between ganglion cell inner-plexiform layer and SDMT 0.083 (95% CI - 0.186, 0.352) was noted. The heterogeneity was high in all correlation studies (I² > 63% and p < 0.008) except for the WLG and visuospatial memory findings.

CONCLUSION

RNFL thickness is associated with cognitive processing speed, verbal learning and memory, visual learning and memory, as well as verbal fluency in PwMS. The number of studies included in the meta-analyses were limited due to non-standardized reporting.

Deterioration of visual quality and acuity as the first sign of ceroid lipofuscinosis type 3 (CLN3), a rare neurometabolic disease

Ceroid lipofuscinosis type 3 (CLN3) is an autosomal recessive, neurodegenerative metabolic disease. Typical clinical symptoms include progressive visual loss, epilepsy of unknown etiology and dementia. Presence of lipofuscin deposits with typical pattern of 'fingerprints' and vacuolized lymphocytes suggest the diagnosis of CLN3. Cause of CLN3 are mutations in the CLN3 gene, among which the most frequently found is the large deletion 1.02 kb spreading on exons 7 and 8. We present 4 patients from 2 families, in whom the deterioration of visual quality and acuity was observed as first clinical sign, when they were a few years old and it was successively accompanied by symptoms of neurologic deterioration (like generalized convulsions with consciousness impairment). In all patients the 1.02 kb deletion in the CLN3 gene was detected in homo- or heterozygosity with other CLN3 pathogenic variant. Ultrastructural studies revealed abnormal structures corresponding to 'fingerprint' profiles (FPPs) in conjunctival endothelial cells. It should be emphasized that in patients with blindness of unknown cause the diagnosis of ceroid lipofuscinosis should be considered and in older children-especially CLN3. The facility of the analysis for the presence of 1.02 kb deletion and economic costs are a solid argument for intensive use of this test in the diagnostic procedure of CLN3.

Review: Emerging Eye-Based Diagnostic Technologies for Traumatic Brain Injury

The study of ocular manifestations of neurodegenerative disorders, Oculomics, is a growing field of investigation for early diagnostics, enabling structural and chemical biomarkers to be monitored overtime to predict prognosis. Traumatic brain injury (TBI) triggers a cascade of events harmful to the brain, which can lead to neurodegeneration. TBI, termed the "silent epidemic" is becoming a leading cause of death and disability worldwide. There is currently no effective diagnostic tool for TBI, and yet, early-intervention is known to considerably shorten hospital stays, improve outcomes, fasten neurological recovery and lower mortality rates, highlighting the unmet need for techniques capable of rapid and accurate point-of-care diagnostics, implemented in the earliest stages. This review focuses on the latest advances in the main neuropathophysiological responses and the achievements and shortfalls of TBI diagnostic methods. Validated and emerging TBI-indicative biomarkers are outlined and linked to ocular neuro-disorders. Methods detecting structural and chemical ocular responses to TBI are categorised along with prospective chemical and physical sensing techniques. Particular attention is drawn to the potential of Raman spectroscopy as a non-invasive sensing of neurological molecular signatures in the ocular projections of the brain, laying the platform for the first tangible path towards alternative point-of-care diagnostic technologies for TBI.

Decrease Retinal Thickness in Patients with Chronic Migraine Evaluated by Optical Coherence Tomography

The purpose of this study is to determine the possible alterations that may occur in the thickness of the retinal nerve fibre layer (RNFL), ganglion cell layer (GCL), and macular thickness in patients with chronic migraines compared with healthy controls. Hence, we examined some of the possibilities that are offered by optical coherence tomography (OCT) in order to study different neurological diseases and to study its application, in this case, how it may be applied to patients with chronic migraines. This was an observational cross-sectional study in adults aged 18-65 years. The study group consisted of 90 patients (90 eyes) with chronic migraines who met the inclusion criteria, and 90 healthy controls (90 eyes) matched for age and sex. Retinal thickness was measured by spectral domain OCT (SD-OCT). The thickness of the superior quadrant of the peripapillary RNFL, as well as the mean thickness in the macula, RNFL macular, and GCL was significantly thinner in chronic migraine patients than in healthy controls (p ≤ 0.05). Chronic migraines are associated with a decrease in retinal thickness which is detectable by an OCT diagnostic technique. The quantification of the axonal damage could be used as a biomarker to help in the diagnosis and monitoring of this pathology. Further studies will be needed to confirm these findings.

Total retinal thickness: a neglected factor in the evaluation of inner retinal thickness

AIM

To determine whether macular retinal nerve fibre layer (mRNFL) and ganglion cell-inner plexiform layer (GC-IPL) thicknesses vary by ethnicity after accounting for total retinal thickness.

METHODS

We included healthy participants from the UK Biobank cohort who underwent macula-centred spectral domain-optical coherence tomography scans. mRNFL and GC-IPL thicknesses were determined for groups from different self-reported ethnic backgrounds. Multivariable regression models adjusting for covariables including age, gender, ethnicity and refractive error were built, with and without adjusting for total retinal thickness.

RESULTS

20237 participants were analysed. Prior to accounting for total retinal thickness, mRNFL thickness was on average 0.9 μm (-1.2, -0.6; p<0.001) lower among Asians and 1.5 μm (-2.3, -0.6; p<0.001) lower among black participants compared with white participants. Prior to accounting for total retinal thickness, the average GC-IPL thickness was 1.9 μm (-2.5, -1.4; p<0.001) lower among Asians compared with white participants, and 2.4 μm (-3.9, -1.0; p=0.001) lower among black participants compared with white participants. After accounting for total retinal thickness, the layer thicknesses were not significantly different among ethnic groups. When considered as a proportion of total retinal thickness, mRNFL thickness was ~0.1 and GC-IPL thickness was ~0.2 across age, gender and ethnic groups.

CONCLUSIONS

The previously reported ethnic differences in layer thickness among groups are likely driven by differences in total retinal thickness. Our results suggest using layer thickness ratio (retinal layer thicknesses/total retinal thickness) rather than absolute thickness values when comparing retinal layer thicknesses across groups.

Amyotrophic lateral sclerosis and retinal changes in optical coherence tomography: A systematic review and meta-analysis

INTRODUCTION

Increasing evidence suggests Amyotrophic Lateral Sclerosis (ALS) as a widespread pathological process comprising nonmotor features like fatigue, mild sensory symptoms, cognitive decline, and visual impairment. Measurements of retinal nerve fiber layer (RNFL) thickness using Optical Coherence Tomography (OCT) may correlate with the neurodegeneration associated with ALS. In addition to RNFL thickness, other OCT parameters have been explored in the context of diagnosing ALS and predicting disease severity. In this study, we explore the possibility that OCT parameters of patients with ALS may differ significantly from those of healthy controls and thus serve as biomarkers for the disease and its progression.

MATERIALS AND METHODS

Between 2010 and 2021, the PubMed and EMBASE databases were examined for English language literature. ALS severity was assessed using the revised ALS functional rating scale (ALSFRS-R). The pooled mean differences in RNFL thickness between ALS patients and controls were calculated using the Standard Mean Difference (Hedges's g) with a 95% confidence interval (CI) in STATA software version 16.

RESULTS

Eleven studies were reviewed for data collection. RNFL thickness was not statistically significantly different between ALS patients (n = 412) and controls (n = 376) (Hedges's g = -0.22; 95% CI: -0.51 to 0.07, I² = 73.04%, p = .14). However, the thickness of inner nuclear layer was significantly different between ALS patients and controls (Hedges's g = -0.38; 95% CI: -0.61 to 0.14, I² = 14.85%, p = .00).

CONCLUSION

Our meta-analysis found that RNFL thickness as a whole or by individual quadrants was not significantly different between ALS patients and controls while the inner nuclear layer (INL) was substantially thinner.

The macular inner plexiform layer thickness as an early diagnostic indicator for Parkinson's disease

Whether structural alterations of intraretinal layers are indicators for the early diagnosis of Parkinson’s disease (PD) remains unclear. We assessed the retinal layer thickness in different stages of PD and explored whether it can be an early diagnostic indicator for PD. In total, 397 [131, 146, and 120 with Hoehn-Yahr I (H-Y I), H-Y II, and H-Y III stages, respectively] patients with PD and 427 healthy controls (HCs) were enrolled. The peripapillary retinal nerve fiber layer (pRNFL), total macular retinal thickness (MRT), and macular volume (TMV) were measured by high-definition optical coherence tomography, and the macular intraretinal thickness was analyzed by the Iowa Reference Algorithms. As a result, the PD group had a significantly lower average, temporal quadrant pRNFL, MRT, and TMV than the HCs group (all p < 0.001). Moreover, the ganglion cell layer (GCL), inner plexiform layer (IPL), and outer nuclear layer were thinner in patients with PD with H-Y I, and significantly decreased as the H-Y stage increased. In addition, we observed that GCL and IPL thicknesses were both correlated with Movement Disorder Society-Unified Parkinson’s Disease Rating Scale III (MDS-UPDRS III) scores and non-motor symptoms assessment scores. Furthermore, macular IPL thickness in the superior inner (SI) quadrant (IPL-SI) had the best diagnostic performance in patients with PD with H-Y I versus HCs, with a sensitivity and specificity of 75.06% and 81.67%, respectively. In conclusion, we confirmed the retinal structure was significantly altered in patients with PD in different clinical stages, and that GCL and IPL changes occurred during early PD disease and were correlated with MDS-UPDRS III scores and non-motor symptoms assessment scores. Furthermore, macular IPL-SI thickness might be performed as an early diagnostic indicator for PD.

Retinal nerve fibre layer thickness measured with SD-OCT in a population-based study: the Handan Eye Study

PURPOSE

To examine the normative profile of retinal nerve fibre layer (RNFL) thickness and ocular parameters based on spectral-domain optical coherence tomography (SD-OCT) and its associations with related parameters among the Chinese population.

METHODS

This population-based cohort Handan Eye Study (HES) recruited participants aged≥30 years. All subjects underwent a standardised ophthalmic examination. Peripapillary RNFL thickness was obtained using SD-OCT. Mixed linear models were adopted to evaluate the correlation of RNFL thickness with ocular parameters as well as systemic factors. R V.3.6.1 software was used for statistical analysis.

RESULTS

3509 subjects (7024 eyes) with the average age of 55.54±10.37 were collected in this analysis. Overall mean RNFL thickness measured was 113.46±10.90 µm, and the thickest quadrant of parapapillary RNFL was the inferior quadrant, followed by the superior quadrant, the nasal quadrant and the temporal quadrant. In the multivariate linear regression model, thinner RNFL thickness was remarkable association with male (p<0.001), older age (p<0.001), increased body mass index (>30, p=0.018), absence of diabetes (p=0.009), history of cataract surgery (p=0.001), higher intraocular pressure (p=0.007), lower spherical equivalent (p<0.001) and increased axial length (p=0.048).

CONCLUSIONS

In non-glaucoma individuals, this difference of RNFL thickness in Chinese population should be noted in making disease diagnoses. Meanwhile, multiple ocular and systemic factors are closely related to the thickness of RNFL. Our findings further emphasise the need to demonstrate ethnic differences in RNFL thickness and the specificity of associated ocular and systemic factors, as well as to develop better normative databases worldwide.

TRIAL REGISTRATION NUMBER

HES was registered in Chinese Clinical Trial Registry website, and the registry number was ChiCTR-EOC-17013214.

The Value of Optical Coherence Tomography Angiography (OCT-A) in Neurological Diseases

Optical coherence tomography angiography (OCT-A) was commercially introduced in 2014. OCT-A allows a fast, non-invasive, three-dimensional analysis of the retinal vasculature from the vitreoretinal interface to the choriocapillaris. The results can be evaluated separately in automated or custom-defined retinal layers. Since its introduction, OCT-A has also been used in patients with neurological diseases in order to find and characterize retinal biomarkers. Many neurological diseases have retinal manifestations, often preceding the key symptoms of the neurological disease. Anatomically and developmentally, the retina is a part of the brain. In contrast to the brain, the retina is easily accessible for imaging methods; moreover, retinal imaging is more cost-effective than brain imaging. In this review, the current knowledge about OCT-A findings and possible OCT-A biomarkers in neurological diseases is summarized and discussed regarding the value of OCT-A as a diagnostic tool in neurological diseases.

Retinal and circumpapillary nerve fiber layer thickness and associated factors in children

OBJECTIVE

To evaluate the distribution of macula and circumpapillary retina nerve fiber layer (cpRNFL) thickness and other associated factors among grade-1 primary school children in Lhasa using spectral-domain optical coherence tomography (SD-OCT).

METHODOLOGY

OCT assessment was conducted on 1856 grade-1 students from 7 primary schools in Lhasa, Tibet following a successful random stratified sampling of the students. Each child underwent comprehensive general and ocular examinations as well as an SD-OCT detection (12 × 9 mm, 3D wide scan mode, Topcon 3D OCT-1) to assess the thickness of the macula, ganglion cell-inner plexiform layer (GCIPL), ganglion cell complex (GCC), and cpRNFL. Multivariate and correlation analyses were performed to evaluate the association of the demographic and ocular variables.

RESULTS

The average age of the 1762 (94.43%) students who underwent OCT assessment was 6.83 ± 0.46 years. Among them, 984 (53.02%) were boys. The number of students who had macular, cpRNFL, and optic disc scans completed and with adequate image quality were 1412 (82.2%), 1277 (74.4%), and 1243 (72.4%), respectively. The average macula full retinal thickness (FRT), GCIPL, GCC, and cpRNFL thickness of the students was 279.19 ± 10.61 μm, 76.41 ± 4.70 μm, 108.15 ± 6.15  μm, and 112.33 ± 13.5 μm, respectively. Multivariate regression and correlation analysis further revealed that boys and girls had significant differences in their average cpRNFL thickness. Moreover, GCC and GCIPL thickness was negatively correlated with IOP but positively correlated with the body mass index. The thickness of all the layers of the macula and cpRNFL were positively correlated with spherical equivalent. Further to this, the average macular FRT, GCIPL, and GCC thicknesses were positively correlated with cpRNFL global thickness.

CONCLUSION

This study describes the normal distribution of macular retina, cpRNFL, and optic disc parameters in grade-1 Tibetan children in Lhasa. It contributes to the establishment of a normative ophthalmology database of Tibetan children, and advances the ability of OCT in ophthalmic disorder diagnosis during long-term monitoring in plateau.

Ocular Neurodegenerative Diseases: Interconnection between Retina and Cortical Areas

The possible interconnection between the eye and central nervous system (CNS) has been a topic of discussion for several years just based on fact that the eye is properly considered an extension of the brain. Both organs consist of neurons and derived from a neural tube. The visual process involves photoreceptors that receive light stimulus from the external environment and send it to retinal ganglionic cells (RGC), one of the cell types of which the retina is composed. The retina, the internal visual membrane of the eye, processes the visual stimuli in electric stimuli to transfer it to the brain, through the optic nerve. Retinal chronic progressive neurodegeneration, which may occur among the elderly, can lead to different disorders of the eye such as glaucoma, age-related macular degeneration (AMD), and diabetic retinopathy (DR). Mainly in the elderly population, but also among younger people, such ocular pathologies are the cause of irreversible blindness or impaired, reduced vision. Typical neurodegenerative diseases of the CSN are a group of pathologies with common characteristics and etiology not fully understood; some risk factors have been identified, but they are not enough to justify all the cases observed. Furthermore, several studies have shown that also ocular disorders present characteristics of neurodegenerative diseases and, on the other hand, CNS pathologies, i.e., Alzheimer disease (AD) and Parkinson disease (PD), which are causes of morbidity and mortality worldwide, show peculiar alterations at the ocular level. The knowledge of possible correlations could help to understand the mechanisms of onset. Moreover, the underlying mechanisms of these heterogeneous disorders are still debated. This review discusses the characteristics of the ocular illnesses, focusing on the relationship between the eye and the brain. A better comprehension could help in future new therapies, thus reducing or avoiding loss of vision and improve quality of life.

Assessment of central retinal thickness, choroidal thickness, and retinal nerve fiber layer in psoriasis: a spectral-domain optical coherence tomography study

Background

This study aims to evaluate choroidal thickness (CT), retinal thickness, ganglion cell-inner plexiform layer (GCIPL), and retinal nerve fiber layer (RNFL) structures in psoriasis patients using optical coherence tomography (OCT).

Methods

This study included 33 psoriasis patients and 33 healthy individuals. Moreover, psoriasis patients who did not use any systemic anti-inflammatory treatment were evaluated. Retinal and choroidal images of the participants were obtained with spectral-domain OCT. Furthermore, CT was measured in the subfoveal, temporal, and nasal positions at 500-µm intervals to a distance of 1,500 μm from the foveal center.

Results

The mean psoriasis area and severity index (PASI) score was 5.70 (range, 2.40–9.00). No significant differences were found in subfoveal (p = 0.659), temporal, and nasal CT values in psoriasis patients compared with the control group (p > 0.05). Similarly, no statistically significant differences were found between the groups in terms of central retinal thickness, macular GCIPL, and RNFL (p > 0.05). Moreover, no significant correlation exists between the duration of psoriasis disease and PASI scores and OCT parameters (p > 0.05).

Conclusions

No significant changes in CT, ganglion cell layer, RNFL, and retinal thickness values were noted in psoriasis patients with mild to moderate mean PASI score.

Evaluating Retinal and Choroidal Perfusion Changes after Isometric and Dynamic Activity Using Optical Coherence Tomography Angiography

Optical coherence tomography angiography (OCTA) is a non-invasive tool for imaging and quantifying the retinal and choroidal perfusion state in vivo. This study aimed to evaluate the acute effects of isometric and dynamic exercise on retinal and choroidal sublayer perfusion using OCTA. A pilot study was conducted on young, healthy participants, each of whom performed a specific isometric exercise on the first day and a dynamic exercise the day after. At baseline and immediately after the exercise, heart rate (HR), mean arterial pressure (MAP), superficial capillary plexus perfusion (SCPP), deep capillary plexus perfusion (DCPP), choriocapillaris perfusion (CCP), Sattlers’s layer perfusion (SLP), and Haller’s layer perfusion (HLP) were recorded. A total of 34 eyes of 34 subjects with a mean age of 32.35 ± 7.87 years were included. HR as well as MAP increased significantly after both types of exercise. Both SCPP and DCPP did not show any significant alteration due to isometric or dynamic exercise. After performing dynamic exercise, CCP, SLP, as well as HLP significantly increased. Changes in MAP correlated significantly with changes in HLP after the dynamic activity. OCTA-based analysis in healthy adults following physical activity demonstrated a constant retinal perfusion, supporting the theory of autoregulatory mechanisms. Dynamic exercise, as opposed to isometric activity, significantly changed choroidal perfusion. OCTA imaging may represent a novel and sensitive tool to expand the diagnostic spectrum in the field of sports medicine.

Applicability of optical coherence tomography angiography (OCTA) imaging in Parkinson's disease

To evaluate the significance of motion artifacts in optical coherence tomography angiography (OCTA) images of patients with Parkinson’s disease (PD) and healthy controls. In this prospective, cross-sectional study subjects with medicated PD (ON) and healthy, age- and gender-matched volunteers were recruited. Participants underwent specific ophthalmological examinations, including OCTA. Angiograms of the superficial retinal capillary plexus were evaluated for the type and frequency of artifacts using a validated motion artifact score (MAS). A total of 30 PD patients (60 eyes), average disease duration of 9.61 ± 5.55 years, and 30 matched, healthy controls (60 eyes) were recruited. Twenty percent of all eyes had an eye disease, unknown to the participant, with a significant impact on OCTA results. After cleansing the dataset by excluding subjects with confounding ocular comorbidities 42 eyes of 28 PD patients and 53 eyes of 29 healthy controls were further evaluated. Overall MAS and all five subtypes of motion artifacts were comparable without significant differences between groups. OCTA can be used in treated PD patients (ON) without a significant increase in motion artifacts. Nevertheless, special attention should be paid to image quality during the acquisition of OCTA data, for which an experienced OCTA operator is useful.

Optic Nerve Head Parameters and Peripapillary Retinal Nerve Fiber Layer Thickness in Patients with Coronavirus Disease 2019

Purpose: To quantify the optic nerve head (ONH) and peripapillary retinal nerve fiber layer (pRNFL) thickness in patients with Coronavirus Disease-2019 (COVID-19) and compare the measurements with a healthy control group.Methods: In a comparative cross-sectional observational study, ONH and pRNFL thickness were evaluated in patients with a history of COVID-19, at least 2 weeks after recovery from the systemic disease, and compared with an age-matched, normal control group.Results: Thirty COVID-19 patients along with 60 age- and gender-matched healthy controls were studied. Mean average pRNFL thickness was 105.0 ± 16.3 µm in the COVID-19 patients, compared to 99.0 ± 9.0 µm in the controls (p = .31). The pRNFL thicknesses in all sectors was higher in patients with a history of COVID-19; however, this did not reach statistical significance. Similarly, ONH parameters were not significantly different between the groups.Conclusion: Patients recovered from COVID-19 had unremarkable alterations in the peripapillary RNFL thickness.Abbreviations: ONH: Optic Nerve HeadRNFL: Retinal Nerve Fiber LayerSD-OCT: Spectral-Domain Optical Coherence TomographyCOVID-19: Coronavirus Disease 2019SARS-CoV-2: Severe Acute Respiratory Syndrome Coronavirus 2CNS: Central Nervous SystemACE: Angiotensin-Converting EnzymeRT-PCR: Reverse Transcription-Polymerase Chain Reaction.

Visual deficits and cognitive assessment of multiple sclerosis: confounder, correlate, or both?

BACKGROUND

The relationship between visual impairment and cognitive performance in multiple sclerosis (MS) remains poorly understood.

OBJECTIVE

To determine associations between visual acuity and optical coherence tomography (OCT) measures with cognitive performance of MS patients and healthy controls (HCs).

METHODS

141 MS patients (with and without MS optic neuritis; MSON) and 50 HCs underwent neuropsychological, visual, and OCT testing. California Verbal Learning Test (CVLT-II), Brief Visuospatial Memory Test (BVMT-R), and Symbol Digit Modalities Test (SDMT) were used. Patients with test performance below - 1.5 standard deviations of the mean HCs scores were labeled as cognitive impairment. Visual ability was assessed with 100%, 2.5%, and 1.25% low-contrast letter acuity (LCLA) charts. OCT-derived peripapillary retinal nerve fiber layer (pRNFL) thickness, macular volume (MV), macular ganglion cell inner plexiform (mGCIP) thickness (as a sum of GC and IP layers), and macular inner nuclear layer (mINL) were computed.

RESULTS

100% and 2.5% LCLA associated with SDMT in MS and HCs (p < 0.001; and p < 0.012, respectively). In MSON patients, visually demanding tests were explained by pRNFL and macular volume for SDMT (β = 0.172, p = 0.039 and β = 0.27, p = 0.001) and MV for BVMT-R (β = 0.21, p = 0.012). In non-MSON, only mINL was predictor of CVLT-II. pRNFL and MV predicted cognitive impairment with an accuracy of 72.2% (Negelkerke R² = 0.234). These findings were driven by associations within the progressive MS subgroup. HC's SDMT performance was explained by mGCIP (β = 0.316, p = 0.001).

CONCLUSIONS

Both LCLA and OCT-based measures (pRNFL and macular volume) were associated with MS cognitive performance. OCT-based measures were also significant predictors of cognitive status in MS patients. mGCIP associated with cognitive performance in HCs.

Morphological Outer Retina Findings in Multiple Sclerosis Patients With or Without Optic Neuritis

Purpose: To investigate on the morphology of the macular inner (IR) and outer (OR) layers in multiple sclerosis (MS) patients with and without history of optic neuritis (ON), followed by good or poor recovery of best corrected visual acuity (BCVA). Methods: Thirty-five normal control subjects and 93 relapsing remitting MS patients were enrolled. Of this, 40 MS patients without ON (MS-noON, 40 eyes), 27 with history of ON and good BCVA recovery (MS-ON-G, 27 eyes), and 26 with history of ON and poor BCVA recovery (MS-ON-P, 26 eyes) were studied. Controls and MS patients underwent an extensive ophthalmological examination including spectral-domain optical coherence tomography evaluating in 3 localized macular areas (0-1 mm, Area 1; 1-3 mm, Area 2; 3- 6 mm, Area 3), volumes (MV), and thicknesses (MT) of the whole retina (WR), further segmented in IR and OR. The differences of MV and MT between the groups were tested by ANOVA. In the MS-ON-P group, the correlations between MV and MT and BCVA were evaluated by Pearson's test. Results: When compared to controls, the MS-noON group showed not significantly (p > 0.01) different MVs, whereas MTs were significantly (p < 0.01) reduced in the evaluation of WR and IR. In the MS-ON-G group, a significant (p < 0.01) reduction of WR and IR MVs and MTs was found in Areas 2 and 3; OR MVs and MTs were similar (p > 0.01) to controls. In the MS-ON-P group a significant (p < 0.01) reduction of WR, IR, and OR MVs and MTs was detected in all areas; the BCVA reduction was significantly (p < 0.01) correlated with WR and IR MVs and MTs. Conclusions: In MS without history of ON or when ON is followed by a good BCVA recovery, the neurodegenerative process is limited to IR macular layers; in the presence of ON, with a poor BCVA recovery, a morphological impairment of both IR and OR macular layers occurs.

Evaluation of neurodegenerative and inflammatory processes in temporomandibular joint disorders using optical coherence tomography

INTRODUCTION

Temporomandibular joint disorders (TMD) is a process with systemic effects rather than local effects. The purpose of this study is to examine the retinal layer structure using optical coherence tomography (OCT) method in order to detect possible degenerative and inflammatory process in patients with TMD.

MATERIAL AND METHODS

Thirty-five healthy controls and 34TMD patients were evaluated bilaterally in this study. The retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL) and choroidal thickness were analyzed using OCT.

RESULTS

When TMD patients were compared with healthy controls, GCL and IPL volumes and RNFL thickness decreased; while choroidal thickness increased. In the unilateral TMD patients, there was no statistically significant difference in GCL, IPL, RNFL and choroidal thickness between the affected and the unaffected regions.

DISCUSSION

OCT findings showed GCL and IPL volumes and RNFL thickness were decreased while choroidal thickness was increased in TMD patients. These findings suggest that TMD may cause neurodegeneration and inflammation.

Serum neurofilament light chain and optical coherence tomography measures in MS: A longitudinal study

OBJECTIVE

To study the association between serum neurofilament light chain (sNfL) and multiple optical coherence tomography (OCT) measures in patients with MS and healthy controls (HCs).

METHODS

In this prospective study, 110 patients with MS were recruited, together with 52 age- and sex-matched HCs. Clinical evaluation and spectral domain OCT and sNfL were obtained at baseline and after 5.5 years of follow-up. Nested linear mixed models were used to assess differences between MS vs HC and associations between sNfL and OCT measures. Partial correlation coefficients are reported, and p values were adjusted for the false discovery rate.

RESULTS

At baseline, peripapillary retinal nerve fiber layer thickness (pRNFLT) and macular ganglion cell and inner plexiform layer thickness (mGCIP) were significantly lower in MS than HC both in MS-associated optic neuritis (MSON) (p = 0.007, p = 0.001) and nonaffected MSON (n-MSON) eyes (p = 0.003, p = 0.018), along with total macular volume (TMV) in n-MSON eyes (p = 0.011). At follow-up, MS showed significantly lower pRNFLT, mGCIP, and TMV both in MSON and n-MSON eyes (p < 0.001) compared with HC. In MS n-MSON eyes, sNfL was significantly associated with baseline pRNFLT and mGCIP (q = 0.019). No significant associations were found in MSON eyes.

CONCLUSIONS

This study confirms the ability of sNfL to detect neurodegeneration in MS and advocates for the inclusion of sNfL and OCT measures in clinical trials.

CLASSIFICATION OF EVIDENCE

This study provides Class III evidence that sNfL levels were associated with MS neurodegeneration measured by OCT.

Examination of retinal vascular trajectory in schizophrenia and bipolar disorder

AIM

Evidence suggests microvascular dysfunction (wider retinal venules and narrower arterioles) in schizophrenia (SCZ) and bipolar disorder (BD). The vascular development is synchronous with neuronal development in the retina and brain. The retinal vessel trajectory is related to retinal nerve fiber layer thinning and cerebrovascular abnormalities in SCZ and BD and has not yet been examined. Hence, in this study we examined the retinal vascular trajectory in SCZ and BD in comparison with healthy volunteers (HV).

METHODS

Retinal images were acquired from 100 HV, SCZ patients, and BD patients, respectively, with a non-mydriatic fundus camera. Images were quantified to obtain the retinal arterial and venous trajectories using a validated, semiautomated algorithm. Analysis of covariance and regression analyses were conducted to examine group differences. A supervised machine-learning ensemble of bagged-trees method was used for automated classification of trajectory values.

RESULTS

There was a significant difference among groups in both the retinal venous trajectory (HV: 0.17 ± 0.08; SCZ: 0.25 ± 0.17; BD: 0.27 ± 0.20; P < 0.001) and the arterial trajectory (HV: 0.34 ± 0.15; SCZ: 0.29 ± 0.10; BD: 0.29 ± 0.11; P = 0.003) even after adjusting for age and sex (P < 0.001). On post-hoc analysis, the SCZ and BD groups differed from the HV on retinal venous and arterial trajectories, but there was no difference between SCZ and BD patients. The machine learning showed an accuracy of 86% and 73% for classifying HV versus SCZ and BD, respectively.

CONCLUSION

Smaller trajectories of retinal arteries indicate wider and flatter curves in SCZ and BD. Considering the relation between retinal/cerebral vasculatures and retinal nerve fiber layer thinness, the retinal vascular trajectory is a potential marker for SCZ and BD. As a relatively affordable investigation, retinal fundus photography should be further explored in SCZ and BD as a potential screening measure.

Retinal nerve fibre layer thickness in a normal black South African population

BACKGROUND

The measurement of retinal nerve fibre layer (RNFL) thickness on spectral domain OCT (SD-OCT) are compared with built-in age- and gender-matched European normative databases and this difference is used to assist with glaucoma diagnosis. However, there are differences in RNFL thickness between population groups. Therefore, using the built in European normative database as a comparison across all population groups could lead to erroneous results, due to the basic assumption that the normative values for non-European populations are the same as their European counterparts.

METHODS

Cross-sectional study of RNFL thickness in normal black South African patients.

RESULTS

One hundred and thirty-two eyes of 132 patients were enroled in this study. The mean (SD) age of patients in this study was 41.3 (12.5) years. Males comprised 40.9% (n = 54; p = 0.0367). All RNFL sectors except the temporal sector were significantly thicker than the reference database. The RNFL sectors measured as follows: global (108.7 µm, p < 0.001), superotemporal (152.4 µm, p < 0.001), superonasal (132.6 µm, p < 0.001), inferotemporal (150.1 µm, p < 0.001), inferonasal (129.2 µm, p < 0.001), nasal (77.7 µm, p < 0.001), temporal 74.8 µm, p = 0.9534).

CONCLUSION

The RNFL thickness of normal black South Africans is significantly thicker than that of the European database on the Spectralis SD-OCT. This needs to be taken into account when performing RNFL thickness measurements on black patients.

Neurofilament light chain in the assessment of patients with multiple sclerosis

Multiple sclerosis (MS) is an autoimmune, inflammatory, and degenerative disease of the central nervous system. Axonal degeneration is triggered by inflammation and is the pathological substrate of progressive disability in patients with MS. Therapeutic interventions can reduce inflammatory activity, thus delaying neurodegeneration and the progression of disability. Disease activity and neurodegeneration are assessed mainly through clinical evaluation and magnetic resonance imaging. These measures lack sensitivity and accuracy, so new biomarkers are necessary. Several markers have been studied and to date the most promising is neurofilament light (NfL), a component of the axonal cytoskeleton, which is released into cerebrospinal fluid (CSF) following axonal damage. In the present study, we review the current knowledge about CSF NfL determination in MS, clinically isolated syndrome, and radiologically isolated syndrome, and critically discuss how CSF NfL measurement may contribute to therapeutic decision-making in these patients.

Retinal layers in Parkinson's disease: A meta-analysis of spectral-domain optical coherence tomography studies

BACKGROUND

Patients with Parkinson's disease experience visual symptoms, partially originating from retinal changes. Since 2011, multiple case-control studies using spectral-domain OCT, which allows for studying individual retinal layers, have been published. The aim of this study was to substantiate the occurrence, extent, and location of retinal degeneration in Parkinson's by meta-analysis.

METHODS

Spectral-domain OCT case-control data were collected by performing a search in PubMed and Embase with terms: "optical coherence tomography" and "parkinson", up to November 5th, 2018. Studies with fewer than 10 patients or controls were excluded. We performed a random effects meta-analysis. Heterogeneity was evaluated with I² statistics; publication bias with Egger's and Begg's tests.

RESULTS

Out of 77 identified studies, 36 were included, totaling 1916 patients and 2006 controls. A significant thinning of the peripapillary retinal nerve fiber layer (d = -0.42; 95% confidence interval -0.54 to -0.29) and the combined ganglion cell and inner plexiform layers (d = -0.40; -0.72, to -0.07) was found. The inner nuclear layer and outer plexiform layer did not show significant changes. Heterogeneity ranged from 3 to 92%; no publication bias was found.

CONCLUSIONS

Parkinson's patients show significant thinning of the inner retinal layers, resembling changes found in glaucoma and other neurodegenerative diseases like Alzheimer's. Study of different cell layers in-vivo is possible by moving from time-to spectral domain OCT. Retinal degeneration may be affiliated with neurodegenerative pathology overall, and could serve as a biomarker in neurodegenerative disorders. Longitudinal research including clinical correlations is needed to determine usefulness in Parkinson's disease.

The alteration of retinal nerve fibre layer thickness with repetitive transcranial magnetic stimulation in patients with treatment resistant major depression

OBJECTIVE

The nerves and axons of the retinal nerve fibre layer (RNFL) are similar to those in the brain and therefore retina is considered as the extension of the brain. We aimed to evaluate the RNFL thickness in the treatment-resistant major depressive patients before and after repetitive transcranial magnetic stimulation (rTMS) treatment and at least 6 months later after rTMS treatment using optical coherence tomography (OCT).

METHODS

Thirty patients with treatment resistant major depression and 24 healthy controls were included in the study. rTMS was applied to the left dorsolateral prefrontal cortex (DLPFC) of the patients.

RESULTS

rTMS was initiated in 28 patients. OCT assessments were performed in 24 patients at baseline and after rTMS treatment and in 19 patients at least sixth months after the rTMS treatment. We found significant increase in RNFL thickness compared with controls at the baseline and further increase in RNFL thickness after rTMS treatment. Although there was a decreasing trend in RNFL thickness 6 months after rTMS treatment, 6 months later RNFL thickness was still higher compared with controls.

CONCLUSIONS

RNFL thickness is increased in treatment resistant major depression and rTMS over the left DLPFC further increases RNFL thickness in treatment resistant major depressive patients.

The Effect of Glatiramer Acetate on Retinal Nerve Fiber Layer Thickness in Patients with Relapsing-Remitting Multiple Sclerosis: A Longitudinal Optical Coherence Tomography Study

BACKGROUND

Optical coherence tomography (OCT) is a technique that allows for the assessment of retinal nerve fiber layer thickness (RNFLT) and total macular volume (TMV), which reflect neuroaxonal integrity within the retina. As such it has been used in multiple sclerosis (MS) to study neurodegeneration. Glatiramer acetate (GA) is a widely used treatment for MS, which is suggested to have a possible neuroprotective role.

OBJECTIVE

The aim of this study was to assess RFNLT and TMV changes in relapsing-remitting MS (RRMS) patients who started treatment with GA and were followed for a 24-month period.

METHODS

A cohort of 60 RRMS patients and 40 healthy controls (HCs) were imaged with OCT at baseline and follow-up. All subjects also underwent clinical and neurological examination. Measurements were compared between the RRMS patients and HCs as well as between optic neuritis (ON)-affected and ON-unaffected eyes.

RESULTS

At baseline, MS patients showed lower average RNFLT (p = 0.046) and TMV (p = 0.013) when compared with HCs. No significant differences in the evolution of OCT measures were detected over the follow-up between MS patients and HCs. MS patients with both affected and unaffected eyes showed significantly lower average RNFLT, temporal inferior RNFLT, and TMV at baseline, compared with HCs. No significant differences between ON-affected and ON-unaffected eyes in MS patients were detected over the follow-up, except for the nasal superior RNFLT (p = 0.019).

CONCLUSIONS

This study suggests a beneficial role of GA on retinal axonal degeneration in MS, and further confirms the utility of OCT to monitor the neuroprotective effect of disease-modifying treatment.

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.

Optical Coherence Tomography in Patients with Chronic Migraine: Literature Review and Update

Migraine is a chronic disease characterized by unilateral, pulsating, and often moderate-to-severe recurrent episodes of headache with nausea and vomiting. It affects approximately 15% of the general population, yet the underlying pathophysiological mechanisms are not fully understood. Optical coherence tomography (OCT) is a safe and reproducible diagnostic technique that utilizes infrared wavelengths and has a sensitivity of 8–10 μm. It can be used to measure thinning of the retinal nerve fiber layer (RNFL) in some neurological disorders. Although ophthalmologists are often the first specialists to examine patients with migraine, few studies have addressed the involvement of the optic nerve and retino-choroidal structures in this group. We reviewed the literature on the etiological and pathological mechanisms of migraine and the relationship between recurrent constriction of cerebral and retrobulbar vessels and ischemic damage to the optic nerve, retina, and choroid. We also assessed the role of OCT for measuring peripapillary RNFL thickness and macular and choroidal changes in migraine patients. There is considerable evidence of cerebral and retrobulbar vascular involvement in the etiology of migraine. Transitory and recurrent constriction of the retinal and ciliary arteries may cause ischemic damage to the optic nerve, retina, and choroid in patients with migraine. OCT to assess the thickness of the peripapillary RNFL, macula, and choroid might increase our understanding of the pathophysiology of migraine and facilitate diagnosis of retino-choroidal compromise and follow-up of therapy in migraine patients. Future studies should determine the usefulness of OCT findings as a biomarker of migraine.

Evaluation of Retinal Vessel Morphology in Patients with Parkinson's Disease Using Optical Coherence Tomography

PURPOSE

The retina has been found affected in Parkinson's disease (PD). It is unclear if this is due to neurodegeneration of local dopamine-dependent retinal cells, a result of central nervous degeneration including the optic nerve or retinal small vessel disease. This study aimed to detect changes of the retinal vasculature in PD patients compared to controls.

METHODS

We examined 49 PD patients and 49 age- and sex-matched healthy controls by spectral domain optical coherence tomography (SD-OCT) with a circular scan centred at the optic disc. Vessels within the retinal nerve fibre layer were identified by an automated algorithm and thereafter manually labelled as artery or vein. Layer segmentation, vessel lumen and direct surrounding tissue were marked automatically with a grey value and the contrast between both values in relation to the surrounding tissue was calculated. The differences in these grey value ratios among subjects were determined and used as an indicator for differences in vessel morphology. Furthermore, the diameters of the veins and arteries were measured and then compared between the groups.

RESULTS

The contrast of retinal veins was significantly lower in PD patients compared to controls, which indicates changes in vessel morphology in PD. The contrast of arteries was not significantly different. Disease duration, disease stage according to Hoehn and Yahr or age did not influence the grey value ratios in PD patients. Vessel diameter in either veins or arteries did not differ between subject groups. The contrast of retinal veins contralateral to the clinically predominant and first affected side was significantly lower compared to the ipsilateral side.

CONCLUSION

Our data show a potential difference of the retinal vasculature in PD patients compared to controls. Vascular changes in the retina of PD patients might contribute to vision-related complaints in PD.