Retinal nerve fiber layer thinning: a window into rapid eye movement sleep behavior disorders in Parkinson's disease.
OBJECTIVE
Retinal nerve fiber layer (RNFL) thinning occurs in Parkinson's disease (PD) and other neurodegenerative diseases. Idiopathic RBD (iRBD) is a well-established prodromal hallmark of synucleinopathies and occurs secondary to many neurodegenerative diseases, including PD. The aim of this study is to determine whether or not retinal structures are altered with the onset of rapid eye movement (REM) sleep behavior disorders (RBD).


METHODS
In all, a total of 63 patients with PD, 14 patients with idiopathic RBD, and 26 sex- and age-matched healthy controls were enrolled and underwent optical coherence tomography measurements (HD-OCT (Zeiss) ) for the average and every quadrant of RNFL thickness. The REM Sleep Behavior Disorder Screening Questionnaire (RBDSQ) was used to classify PD patients with clinically probable RBD (PD + pRBD) or without probable RBD (PD - pRBD). Patients with iRBD were identified by polysomnography.


RESULTS
For patients with RBD (idiopathic or secondary to PD), we found a significant decrease in RNFL thickness compared with groups without RBD (PD - pRBD and healthy controls) (all p < 0.05). Average RNFL thickness in patients with iRBD is significantly thinner than in healthy controls (p < 0.05). In PD, the average RNFL thickness was dramatically thinner in the PD + pRBD group than the PD - pRBD group (p < 0.005). Compared with healthy controls, RNFL thickness was slightly thinner in the drug-naive PD group but not the PD group with drug treatment. Multiple linear regression analysis showed that RBDSQ score was negatively associated with average and inferior RNFL variation in PD (all p < 0.005).


CONCLUSIONS
The findings show that RNFL was slightly but significantly thinner in idiopathic RBD. In PD, RNFL thickness may vary depending on the presence of RBD.
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
Zi-Jiao
ZJ
Yang
Department of Ophthalmology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China.
Jing
J
Wei
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
Cheng-Jie
CJ
Mao
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
Jin-Ru
JR
Zhang
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
Jing
J
Chen
Department of Ophthalmology, The Second Affiliated Hospital of Soochow University, Suzhou, 215004, China.
Xiao-Yan
XY
Ji
Institute of Neuroscience, Soochow University, Suzhou, 2151123, China.
Jun-Yi
JY
Liu
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
Yun
Y
Shen
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
Kang-Ping
KP
Xiong
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.
Jun-Ying
JY
Huang
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China.|Institute of Neuroscience, Soochow University, Suzhou, 2151123, China.
Ya-Ping
YP
Yang
Department of Neurology and Sleep Center, The Second Affiliated Hospital of Soochow University, Soochow University, 1055 Sanxiang Road, Suzhou, 215004, China. liuchunfeng@suda.edu.cn.|Institute of Neuroscience, Soochow University, Suzhou, 2151123, China. liuchunfeng@suda.edu.cn.|Beijing Key Laboratory for Parkinson's Disease, Beijing, 100053, China. liuchunfeng@suda.edu.cn.
Chun-Feng
CF
Liu
D000368:Aged; D016022:Case-Control Studies; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009412:Nerve Fibers / Q000473:pathology*; D019636:Neurodegenerative Diseases / Q000473:pathology*; D010300:Parkinson Disease / Q000473:pathology*; D017286:Polysomnography; D020187:REM Sleep Behavior Disorder / Q000473:pathology*; D012016:Reference Values; D012160:Retina / Q000473:pathology*; D012895:Sleep, REM / Q000502:physiology*; D011795:Surveys and Questionnaires; D041623:Tomography, Optical Coherence
Idiopathic rapid eye movement sleep behavior disorders; Optical coherence tomography measurement; Parkinson’s disease; Rapid eye movement sleep behavior disorders; Retinal nerve fiber layer thickness