Structural And Functional Retinal Changes In Parkinson's Disease With Visual Hallucinations

Background:Parkinson's Disease(PD)is one of the common neurodegenerative diseases which mostly affects the elderly.It is associated with the degeneration and deficiency of dopaminergic neurons in the substantia nigra.In addition to the cardinal motor symptoms,visual hallucinations(VH)is one of the common nonmotor symptoms of the disease and the incidence of visual hallucinations in PD patients was 22%.VH is seriously affecting the quality of life of patients and caregivers.In recent years some scholars have used optical imaging and visual electrophysiology to reveal the abnormalities of retinal structure and function in PD patients.It is suggested that abnormal visual function may be related to degeneration and loss of dopaminergic neurons in retina.However,there are few domestic and abroad studies on retinal changes in PD patients with VH,we use the technique of optical coherence tomography(OCT)and multifocal electroretinogram(mfERG)to explore the correlation between the characteristics of retinal changes in PD patients with VH and its with clinical parameters on the structure and function of retina.Objective: To study the changes of retinal structure and function in PD patients with VH and its correlation with disease duration,stage and severity of motor symptoms.Methods:From July 2015 to July 2016,17 PD patients(34 eyes)with VH(PDVH),30 PD patients(34 eyes)without VH(PDnonVH)and 15 gender-age-matched healthy control(HC)(30 eyes).After collecting disease duration,Hoehn-Yahr(HY)stage,UPDRS,MMSE,HRSD,HAMA score and other clinical data,completing routine eye examination,visual field analyser was used to measure the mean defect(MD),OCT was used to measure the thickness of the macular and optic fibers(RNFL),mfERG was used to detect the amplitude and latency of 1-5-ring P1 wave and N1 wave.Variance analysis and Kruskal-Wallis H test was used to tell the difference between the three groups,Pearson analysis to assess the correlation between retinal structure,functional changes and disease duration,staging of disease,severity of motor symptom and hallucinations.Result:(1)In PDnon VH group 5 eyes were ruled out due to high myopia,macular degeneration and cataract.At last,55 eyes were enrolled.There was significant difference in the scores of H-Y stage,HRSD and HAMA between PDVH group and PDnonVH group,(P <0.05),but there was no significant difference in the scores of the UPDRS-III and MMSE.(2)Retinal structure: PD groups' upper and lower,nasal quadrant and mean RNFL thickness were thinner than HC group(P <0.05),but there was no significant difference between two PD groups.Compared with PDnon VH group and HC group,PDVH group's mean RNFL thickness decreased(P <0.01).Retinal function:the MD value of the two PD groups was deeper than HC group's,but there were no significant differences in between the two PD groups.Compared with the HC group,the amplitudes density of P1 in PDVH and PDnon VH group was decreased in ring1-5(P <0.01);Compared with the PDnonVH group,tthe amplitudes density of P1 in PVDH group was decreased in ring 3,and there were no significant differences in the amplitudes density of P1 in 1,2,4,5 between the two PD groups.The latency of P1 in PDVH group was longer than PDnon VH and HC group(P <0.05),there were no significant differences between PDnonVH and HC group;The amplitudes density of N1 in PDVH group and PdnonVH group was decreased than HC group in ring4,5(P<0.01),there was no significant difference between the two PD group.There was no significant difference between the three groups in the amplitudes density of N1 in ring 1-5(3)In PDVH group the H-Y stage was negatively correlated with mean,lower and nasal quadrant RNFL thickness(r =-0.443,-0.414,-0.421,P <0.05)and MMSE motor score was negatively correlated with mean and lower quadrant RNFL thickness(r = 0.356,0.386);MD value was positively correlated with H-Y stage(r = 0.417),UPDRS-III scores(r = 0.363)and HRSD scores(r = 0.473).MD value was negatively correlated with MMSE scores(r =-0.364).Macular and mfERG parameters have no correlation with clinical parameters.Conclusion:PD patients have thinner retinal thickness,more obvious visual field defect and macular visual acuity decreased.PDVH patients have particularly evident changes in macular thickness and visual acuity,so the retinal structural and functional changes may related to the mechanism of visual hallucinations.The retinal changes of PDVH patients are associated with stage of disease,severity of motor symptoms,cognitive function and emotional disorders.