Central retina thickness measured with spectral-domain optical coherence tomography in Parkinson disease: A meta-analysis

BACKGROUND: Optical coherence tomography (OCT) can detect visual alterations associated with Parkinson disease, such as damage to the retinal nerve fiber layer or changes in retinal vasculature. Macula thinning in association with Parkinson disease (PD) remains controversial. Therefore, we conducted a meta-analysis to investigate the central retina thickness in PD measured using spectral-domain OCT (SD-OCT). METHODS: We searched PubMed and the Excerpta Medica database to identify studies that compared macular thickness between patients with PD and healthy controls published before July 31, 2021. A random-effects model was used to examine PD-associated changes in macular thickness. Meta-regression analysis was performed by assessing heterogeneity, publication bias, and study quality. RESULTS: Thirty-two studies with a cross-sectional design were selected, including 2118 patients with PD and 2338 controls. We identified significant differences in the thickness of the ganglion cell–inner plexiform layer (standardized mean difference [SMD], –0.41; 95% confidence interval [CI], –0.66 to –0.16; I(2) = 80%), ganglion cell complex (SMD, –0.33; 95% CI, –0.50 to –0.17; I(2) = 0%), and of all inner and outer sectors of the macula (SMD range, –0.21 to –0.56; all P < .05) between patients with PD and controls. DISCUSSION: These results corroborate the increased prevalence of changes in OCT measures in individuals with PD, highlighting the efficacy of SD-OCT–determined macular thickness as a biomarker for PD. Our findings may provide helpful guidelines for clinicians in rapidly evolving areas of PD diagnosis.