Soft contact lens wear in Hong Kong-Chinese: predicting success

The tear stability and tear volume of 55 asymptomatic Hong Kong-Chinese wer e assessed before soft contact lens (Hydron Zero 6) wear and repeated on th ree visits over 28 weeks of lens wear. Soft lens wear caused a significant initial transient decrease in the non-invasive tear break-up time (NITBUT), but no change in tear volume as assessed by the self-prepared cotton threa d test (SP-CTT) and phenol red thread (PRT) test. After 28 weeks, the subje cts were classified according to the length of time they could wear their l enses without dry eye related signs and symptoms. The NITBUT and PRT tests were unable to predict the success of soft contact lens wear. However, the SP-CTT gave a sensitivity and specificity of 88.5 and 52.4%, respectively, in the prediction of subjects most likely to be successful wearers. The pos itive and negative predictive values at the chosen cut-off point were 69.7 and 78.6%, respectively. Wetting values, that is, combinations of NITBUT an d SP-CTT values or NITBUT and PRT values, did not predict success in soft c ontact lens wear. (C) 2000 The College of Optometrists. Published by Elsevi er Science Ltd. All rights reserved.