Retina thickness in atypical parkinsonism: a systematic review and meta-analysis

Retinal Thinning as a Marker of Disease Severity in Progressive Supranuclear Palsy

OBJECTIVE

Progressive supranuclear palsy (PSP) involves a variety of visual symptoms that are thought to be partially caused by structural abnormalities of the retina. However, the relationship between retinal structural changes, disease severity, and intracranial alterations remains unknown. We investigated distinct retinal thinning patterns and their relationship with clinical severity and intracranial alterations in a PSP cohort.

METHODS

We enrolled 19 patients with PSP (38 eyes) and 20 age-matched healthy controls (40 eyes). All of the participants underwent peripapillary and macular optical coherence tomography. Brain 11C-2β-carbomethoxy-3β-(4-fluorophenyl) tropane (11C-CFT) and 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography imaging were also performed in patients with PSP. We investigated the association between retinal thickness changes and clinical features, striatal dopamine transporter availability, and cerebral glucose metabolism.

RESULTS

The peripapillary retinal nerve fiber layer (pRNFL) and macula were significantly thinner in patients with PSP than in controls. The thickness of the superior sector of the pRNFL demonstrated a significant negative relationship with the Movement Disorder Society-Unified Parkinson's Disease Rating Scale part III and Hoehn and Yahr staging scale scores. A significant negative correlation was found between outer inferior macular thickness and disease duration. Outer temporal macular thickness was positively correlated with Montreal Cognitive Assessment scores. In PSP, lower outer temporal macular thickness was also positively correlated with decreased dopamine transporter binding in the caudate.

CONCLUSION

The pRNFL and macular thinning may be candidate markers for monitoring disease severity. Additionally, macular thinning may be an in vivo indicator of nigrostriatal dopaminergic cell degeneration in PSP patients.

Retinal Structure Abnormalities in Parkinson's Disease and Atypical Parkinsonism

We investigated retinal structure changes in patients with Parkinson's disease (PD), multiple system atrophy (MSA), progressive supranuclear palsy (PSP), and controls, and explored the value of this method in differential diagnosis. Spectral domain optical coherence tomography (SD-OCT) was used to measure peripapillary retinal nerve fiber layer (pRNFL) thickness, and macular thickness and volume. PSP patients showed higher temporal pRNFL thickness than PD and MSA patients. Peripapillary RNFL thickness could be used for discriminating PSP from MSA and PD. PD and MSA patients showed retinal thinning in the foveal center circle and nasal inner sectors compared to controls. Macular thickness and volume could be used for discriminating MSA from PD. There were negative correlations between disease duration and OCT parameters in PD, MSA, and PSP, independent of age, sex ratio, and the side of the eye. PD and atypical parkinsonism correlate with specific patterns of retina alterations. OCT could be a biomarker for differential diagnosis and progression evaluation of parkinsonian syndrome.

Evaluation of the visual system with visual evoked potential and optical coherence tomography in patients with idiopathic Parkinson's disease and with multiple system atrophy

BACKGROUND

In addition to motor findings, non-motor findings including alterations in visual acuity, decrease in blink reflex, and pupil reactivity cause the impaired quality of life in idiopathic Parkinson's disease (PD) and multiple system atrophy (MSA). Our study aimed to examine possible latency and amplitude changes in pattern visual evoked potentials (pVEP) along with retinal and macular changes in optical coherence tomography (OCT) in PD and MSA groups. We also intended to investigate whether any OCT parameters could be a biomarker for Parkinson's or MSA.

METHODS

Our study included 50 patients with PD, 15 with MSA, and 50 healthy control subjects. All patients in the study underwent neurological and ophthalmological examination and investigations of OCT to measure the retinal and macular thickness and pVEP to assess visual pathways.

RESULTS

When PD, MSA, and control groups were compared, a significant difference was found in all retinal thickness values in average, nasal, and superior retinal nerve fiber thickness (pRNFL), and in all macular thickness values except nasal outer and inferior outer quadrants and in ganglion cell complex (GCC) thicknesses (p < 0.05). Moreover, a significant difference was found in N75, P100, and N145 latencies and N75-P100 amplitude (p < 0.05). The thickness of both pRNFL, inner and outer macular quadrants, was thinner in the MSA group than in PD but GCC thickness was thinner in PD group.

CONCLUSIONS

The present study compared pVEP and OCT parameters in PD and MSA groups. It was concluded that pVEP and OCT examinations were of importance in that they were easily accessible, affordable, noninvasive biomarkers that might be used in early periods and progression of the disease and in follow-up.