 PNR assessments will be conducted in patients with Unresponsive Wakefulness Syndrome UWS diagnosed by the Coma recovery scale-revised CRS-R.An objective index,the ratio of pupillary constriction pupil diameter change after a stimulus presentation divided by the resting state pupil diameter will be used as the measure of PNRs presence positive results indicate the presence of PNR,whereas negative results indicate the absence of PNR.According to the presence of PNR,patients will be divided into 2 groups,one includes patients who show PNR during the PNR assessment PNR,the other includes patients who fail to show PNR during the PNR assessmentPNR-.3 months later,a follow-up will be conducted to obtain their prognosis in the form of another CRS-R assessment.Patients diagnosed as Minimally Conscious State MCS will be considered as favourable prognosis,patients diagnosed as UWS will be considered as unfavourable prognosis.Their prognosis difference will then be compared to see PNRs effect on their prognosis consciousness recovery. And for they couldnt show conscious visual behaviors visual behaviors in CRS-R which indicate MCS in the first CRS-R,their difference between visual prognosis difference between each groups proportion of patients showing conscious visual behavior diagnosed by CRS-R in the follow up will be compared to see PNRs capability to predict prognosis in patients without voluntary eye movements conscious visual behaviors in CRS-R require voluntary eye movements. 