Clinical Research On The Relationship Between Visual Dysfunction And Cognitive Impairment In Parkinson Disease

Objective To observe the inherent correlation and changes of retinal nerve fiber layer thickness,total macular volume,visual field change,colour vision in Parkinson disease and the internal correlation of visual dysfunction,disease severity and cognitive function.So that providing clinical evidence for early identification of visual dysfunction and cognitive impairment in Parkinson’s disease.Method 23 patients with Parkinson’s disease and 9 healthy subjects who were matched with age and sex were selected randomly.Mo CA,MMSE,UPDRS,HoehnYahr stagement were conducted in all subjects.Divided the PD patients into three groups according to the score of Mo CA:PD without cognitive impairment(PD-NCI)(n = 8),PD with mild cognitive dysfunction(PD-MCI(n = 9)and Parkinson’s disease dementia(PDD)(n = 6).Examed and analysised the retinal nerve fiber layer thickness,macular volume and thickness which were correted with body mass index(BMI)by optical coherence tomography(OCT)imaging.Examed the visual field using Humphrey Ⅱtype-750 analyzer and recorded the average visual field defect(MD),pattern standard deviation(PSD).The Farnsworth-Munsell 100 Hue test(FM-100)was performed to evaluate the patients’ colour vision.Then calculated the total number of errors by computer software.All the data were analyzed by SPSS software.All the drawings were drawed by Graphpad Prism 6.0 software.Result(1)The average thickness of RNFL and the thickness of each quadrant were thinning along with cognitive impairment.There were statistically significances between PDD and HC(P=0.003),PDD and PD-NCI(P=0.000),PDD and PD-MCI(P=0.003)in the average thickness of RNFL.Statistically significances were found between PDD and HC(P=0.008),PDD and PD-NCI(P=0.000),PDD and PD-MCI(P=0.004)in the superior quadrant RNFL thickness.There were statistically significances between PDD and HC(P=0.006),PDD and PD-NCI(P=0.003),PDD and PD-MCI(P=0.017)in the inferior quadrant RNFL thickness.Statistically significances were found between PDD and HC(P=0.025),PDD and PD-NCI(P=0.006),PDD and PD-MCI(P=0.020)in the nasal quadrant RNFL thickness.The temporal quadrant RNFL thickness were thinning along with cognitive impairment,but there was no significance among groups.There was significant positive correlation between the average thickness of RNFL and Mo CA score(r=0.697,P<0.0001).(2)The total macular volume in the Parkinson disease group was smaller than the health control group,but it has no statistically significance.The total macular volume was smalling along with cognitive impairment.There were statistical significances of the total macular volume between PDD and HC(P=0.005),PDD and PD-NCI(P=0.025),PD-MCI and HC(P=0.031).There was significantly positive correlation between the total macular volume and Mo CA score(r=0.459,P=0.001).(3)The macular thickness of each quadrant in Parkinson disease was thiner than health control,but it has no statistically significance.The macular thickness of each quadrant in Parkinson disease was thining along with cognitive impairment.Except for the fovea,infer-outer quadrant,nasal-outer quadrant,the macular thickness(um/BMI)in PD-MCI in super-outer quadrant,infer-inner quadrant,nasal-inner quadrant,temp-outer quadrant,temp-inner quadrant were respectly:8.60±1.19,10.0±1.54,8.94±1.06,9.76±1.44,8.24±1.29,9.48±1.12.Compared with the healthy control group,the differences of the macular thickness in quadrants above in PD-MCI had statistically significances.Except for the fovea,the macular thickness(um/BMI)in PDD in super-outer quadrant,super-inner quadrant,infer-outer quadrant,infer-inner quadrant,nasal-inner quadrant,nasal-outer quadrant,temp-outer quadrant,temp-inner quadrant were respectly:7.94±1.64,9.18±1.75,7.83±1.76,9.01± 1.66,8.71±1.89,9.08±1.63,7.50±1.70,8.60±1.70.Compared with the healthy control group,the differences of the macular thickness in quadrants above in PDD had statistically significances.(4)The total error score of FM100 hue test was significantly higher in Parkinson disease compared to healthy controls(194.60±136.17 v.s 59.56±13.92,P=0.000).The TES score was significantly higher in subgroups of Parkinson disease than that in healthy controls.The differences of TES score between PD-MCI and HC、PDD and HC were statistically significant(P=0.02、0.001).There were significantly negative correlations between TES and Mo CA score(r = 0.597,P = 0.006),TES and MMSE score(r = 0.578,P = 0.578),TES and the visual space and executive function(r = 0.600,P = 0.600),TES and concentration(r = 0.669,P = 0.669).But there were no clear correlations with disease severity and stage.It showed positive correlation between TES and the average RNFL thickness(r=0.410,P=0.010).But it had no clear correlation between TES and the macular volume(r=0.300,P=0.063).(5)The mean visual field defect(MD)in PD and HC were:(-4.26±3.92)d B,(-0.76±1.10)d B.Compared with each other,there was statistical significance(P=0.000).The pattern standard deviation of visual field(PSD)in PD and HC were:(4.12±2.43)d B and(2.27±1.10)d B.Compared with each other,there was statistically significance(P=0.001).The MD in PD,PD-MCI and PDD group were:(-3.47±2.36)d B,(-3.07±2.81)d B,(-8.50±5.81)d B.There were statisticallly significances compared to the healthy controls(-0.76±1.10)d B.The PSD in PD,PD-MCI and PDD group were:(3.81±2.05)d B,(3.26±1.59)d B,(6.69±3.22)d B.There were statistically significances compared to the healthy controls(2.27±1.10)d B.All of the above hint us that the visual field was obviously defected in Parkinson disease.There was significantly positive correlation between MD and Mo CA(r=0.540,P=0.002).It showed positive correlation between MD and the average RNFL thickness(r=0.591,P=0.0005).But it had no clear correlation between MD and the macular volume(r=0.291,P=0.112).Conclusion 1.The retina nerve fiber layer thickness(except for the temporal quadrant)and the macular thickness(except for the fovea,nasal-outer quadrant)in infer-outer quadrant and nasal-outer quadrant changes may predict PDD.2.The visual field is Significantly impaired in Parkinson disease.3.The colour vision is Significantly impaired in Parkinson disease.But it has no correlation with disease sevirity and stage.The colour vision impairment in PD correlate with cognitive impairment,especially with visual space and executive function,attentiveness.The colour vision impairment in PD may predict the degree of cognitive impairment.4.Changes in RNFL thickness in PD are significantly correlated with the retinal function changes,such as the visual field defect,the colour vision impairment.But change of macular volume has no correlation with the retinal function changes.5.The RNFL thickness,macular volume and visual field changes along with cognitive impairment.