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Parkinson's disease (PD)-associated inner retinal abnormalities, particularly the retinal ganglion cells (RGC) layer, on optical coherence tomography (OCT) have recently gained importance as a biomarker of non-motor involvement of the disease but functional RGC evaluation using photopic negative response (PhNR) has not yet been determined. This study aims to compare structural and functional findings of the retina and optic nerve in PD with healthy controls (CT) including PhNR and OCT.Forty-one eyes of 21 PD patients and 38 eyes of 19 CT underwent ophthalmic examination including visual contrast sensitivity test (CS), OCT, light-adapted full-field electroretinography (ffERG), and PhNR. OCT was used to measure the peripapillary retinal nerve fiber layer, the segmented macular layers, and the choroid. For functional parameters, CS, ffERG (oscillatory potentials, photopic response, 30 Hz-flicker), and PhNR waves were used. Measurements were compared using generalized estimating equation and significance was set at P ≤ 0.05.The PD group presented a significantly lower mono- and binocular CS, oscillatory potentials amplitude, b-wave amplitude on ffERG (152.3[45.4] vs 187.1[32.7]μV; P = 0.002), and PhNR amplitude (135.0[35.0] vs 156.3[34.1]μV; P = 0.025). There was no statistically significant difference in OCT measurements between groups. No correlation was found between statistically significant measurements and clinical data.Functional abnormalities on CS, ffERG, and PhNR can be detected in PD even when structural damages are not observed on OCT. PhNR represents a new potential biomarker in PD. Our findings indicate dysfunction of bipolar, amacrine, and retinal ganglion cells in PD, probably with a cellular dysfunction overcoming morphological damage.

Background Pupil dilation and mydriasis maintenance throughout vitreoretinal surgeries are important to allow satisfactory fundus visualization and reduce risk of complications. The purpose of this study is to evaluate the role of subconjunctival epinephrine 0.1% injection in mydriasis maintenance during vitrectomy. Methods Ninety-nine consecutive patients undergoing vitrectomy were enrolled. All subjects were preoperatively dilated with tropicamide 1%. Each patient was randomly allocated either in the epinephrine or placebo group. In epinephrine group, patients were submitted to a 0.2 cc subconjunctival injection of a 0.1% epinephrine solution just before first incisions. In placebo group, the same procedure was performed with 0.2 cc of saline 0.9%. Horizontal pupil diameter was measured with calipers before and in the end of the procedure. Results Patients in the epinephrine group showed a significantly larger mean pupil diameter in the end of the surgery compared to placebo. There was a significant increase of mean pupil diameter from the beginning to the end of the surgery in such patients. Blood pressure was significantly higher in the epinephrine group than in placebo group. No other adverse effects were noted. Conclusion Subconjunctival epinephrine is effective for maintaining and increasing pupil size during vitrectomy, compared to placebo. Caution should be taken regarding intraoperative blood pressure levels. Trial registration RBR; RBR-3qzhvg; Registered 8 May 2018—Retrospectively registered, http://www.ensaiosclinicos.gov.br/rg/RBR-3qzhvg/.