Clinical Research Of Retina And Vision Changes In Early Parkinson’ S Disease Patients

Background: Parkinson’s disease(PD) is a common neurodegenerative disorder of multiple systems. Beside the typical motor symptoms, visual dysfunction is also common in PD patients. A number of observations found that PD patients exhibit retinal dysmorphology and deficits in visual function, the pathological mechanism about the visual impairment is still not clear, and the domestic research about the retina and vision change of early PD patients is very little, furthermore, there have been few analyses of possible correlations between the visual impairment and PD motor symptoms. We explore, in this study, the change of retinal and visual field defect in early PD patients and the relationship with PD clinical characteristics.Objective : To investigate the clinical characteristics of the changes of retinal morphological structure and visual field mean defects(MD) in early Parkinson’s disease(PD) and the related influceing clinical factors.Methods:From July 2013 to February 2014, 42 early PD patients in our Department of Neurology were enrolled to this study, PD patients were evaluated by unified Parkinson’s disease rating scale(UPDRS) and Hoehn-Yahr(H-Y) stage in “off” period. Patients were classified into two groups(left-dominant or right-dominant) depending on the predominant side of their motor symptoms, according to the score of UPDRS motor item. All eye examinations of PD patients were conducted in “on” period. 33 age, gender matched healthy controls were assessed in this study. Subjects of two groups undertook retina of retinal nerve fiber layer(RNFL) and macular examinations by Optical Coherence Tomography(OCT). The MD was measured by automatic visual field analyzer. Using SPSS16.0 software packages, Differences between PD and control eyes and between left and right eyes of same patient were tested using independent sample t test. Pearson’s correlations were used to analyze the correlations of retina and vision damage and clinical characteristics.Results:In 42 patients with PD, 5 patients were ruled out due to high myopia, macular degeneration and cataract. At last, 37 cases enrolled.PD patients often exhibit asymmetric motor symptoms, so PD patients were classified into two groups(left-dominant or right-dominant) depending on the predominant side of their motor symptoms, which according to the scores of UPDRS motor item values. For all patients, there was a ≥2-point difference between the UPDRS motor item with the highest score on the more affected body side and the same item on the contralateral side. Among of PD patients, 19 were L-PD patients and 18 were R-PD patients.(1) For OCT, RNFL near the optic disc of PD patients and normal subjects is similar: thicker in superior and inferior quadrant, thinner in temporal and nasal quadrant. The average thicknesses of RNFL in early PD group were(94.73±7.35) μm,while in the control group they were(102.61±4.99) μm. Compared to healthy controls,the RNFL thicknesses of PD patients were obviously thinner(P=0.000). The instrument software permitted mapping of RNFL thickness based on both quadrant-by-quadrant and clock-hour analyses, the superior, inferior, nasal, and temporal quadrants and each 12-o’clock hour position were examined. We discovered that there were significant differences between groups in the superior and inferior quadrants and the 5-, 7-, 10- and 11-o’clock positions. PD patients had a thinner average thickness of macular and smaller macular volume compared with controls(276.00±12.30 vs 285.82±12.58, P=0.002; 9.95±0.44 vs 10.30±0.42, P=0.001), but there was no significant difference between groups in foveal thickness.(2) For MD, PD patients had significantly worse MD scores than control individuals(1.02±2.74 vs-0.18±1.41,P=0.023). It showed that there has been a loss of vision sensitivity in early PD patients.(3) For PD subgroups,differences between left and right eyes of same patient were tested,The results showed that the RNFL, macula, and fovea retinal thickness were thinner and macular volume was smaller in the eye contralateral to the most affected side, but these differences did not reach statistical significance.(4) Pearson’s correlation analysis showed that H-Y stage was negatively correlated with average RNFL thickness, average macular thickness and macular volume in PD patients(r=﹣0.560、﹣0.489 and﹣0.453,all P <0.01). and positively correlated with MD score(r=0.466, P=0.004). PD duration was negatively correlated with average RNFL thickness and positively correlated with MD score. UPDRS-III motor score was negatively correlated with macular thickness and volume.Conclusions:Early PD patients have thinner retinal thicknesses of RNFL and macular,smaller macular volume,more obvious visual field defect than those in normal controls, and the damage in the eye contralateral to the most affected side in PD patients is more obvious. The retina and visual field damage of PD patients was associated with duration and severity of disease. These findings are compatible with the hypothesis that retina and visual field damage may be early marker of the presence of PD.