Noninvasive retinal imaging may be able to identify structural changes in the eye that are associated with Parkinson disease, according to a new study published in JAMA Ophthalmology

Researchers at the Duke Neurological Disorders Clinic in Durham, North Carolina, carried out a cross-sectional study that looked at alterations in the structure and microvasculature of the retina and choroid in eyes of patients with Parkinson disease, and compared them with those of healthy control participants using optical coherence tomography (OCT) and OCT angiography (OCT-A). 

They found that patients with the disease had decreased retinal vessel density and perfusion density, as well as choroidal structural changes, when compared with control participants of a similar age or the same gender.


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In the past 10 years, scientists have studied structural and functional changes in the retina as replacement biomarkers for neurodegenerative changes in the brain. Patients with Parkinson disease often experience visual symptoms, including hallucinations and decreased contrast sensitivity, as well as impaired circadian rhythms. 

For this study, researchers used OCT and OCT-A to explore how changes in the eye might suggest a Parkinson diagnosis. Patients with Parkinson disease who were aged 50 years or older were eligible. Control participants were also aged 50 years or older and did not have subjective cognitive dysfunction, a history of tremors, or evidence of motor dysfunction that suggested Parkinson disease. People with a history of diabetes, glaucoma, or retinal pathology were excluded.

Researchers analyzed 124 eyes of 69 participants with Parkinson disease (30 female; mean [SD] age, 71.7 [7.0] years) and 248 eyes of 137 control participants (60 women and 77 men; mean [SD] age, 70.9 [6.7] years). Vessel density and perfusion density were measured in an Early Treatment Diabetic Retinopathy Study [ETDRS] grid overlay. 

Individuals with Parkinson disease had lower superficial capillary plexus vessel density (β coefficient = 0.37; 95% CI, 0.04-0.71; P =.03) and perfusion density (β coefficient = 0.009; 95% CI, 0.0003-0.018; P =.04) in the 6 × 6-mm ETDRS circle. They also had lower superficial capillary plexus vessel density (β coefficient = 0.61; 95% CI, 0.20-1.02; P =.003) and perfusion density (β coefficient = 0.015; 95% CI, 0.005-0.026; P =.004) in the inner ring of the 6 × 6-mm ETDRS circle.

Objective retinal and choroidal structural changes may exist in people with a clinical diagnosis of Parkinson disease. However, analysis suggests that individual retinal parameters may not be specific enough to serve as independent biomarkers of the disease. Nevertheless, when combined with clinical history and other existing tests, these imaging findings may improve doctors’ confidence in diagnosing Parkinson disease.

Disclosures: One author reported a financial relationship with industry. See the original article for more details. 

Reference

Robbins CB, Thompson AC, Bhullar PK, et al. Characterization of retinal microvascular and choroidal structural changes in Parkinson disease. JAMA Ophthalmol. Published online December 23, 2020. doi:10.1001/jamaophthalmol.2020.5730