The cotton thread test on chinese eyes:effect of age and gender

Tear volume, measured using a cotton thread test (CTT), was assessed in 91 Hong Kong (HK)-Chinese (46 females,45 males aged from 8 to 70 years) and 35 Singapore (S)-Chinese (21 females, 14 males aged from 7 to 65 years). The mean (±SD) CTT value of HK-Chinese and S-Chinese was 17.5 (±8.1) mm/min and 19.6 (±12.0) mm/min respectively. No significant difference in the CTT values between the two groups of Chinese was found, so their data were pooled. The mean (±SD) CTT value of the pooled data was 18.1 (±9.3) mm/min; 18.4 (±9.0) mm/min for female subjects and 17.8 (±9.7) mm/min for male subjects. Regression statistics of the pooled CTT values on age showed a correlation of −0.59 (p<0.01), suggesting that tear volume decreases with increasing age. No gender effect on tear volume for either group of Chinese was found.