Effect of meibomian oils on Schirmer tear test

The detrimental effect of meibomian oils expressed onto the lid margins on the value of the Schirmer test was investigated in two studies (N = 12 per study): without and with topical anaesthesia. In the 12 subjects studied there was no evidence of external ocular disease. The studies were conducted in a double masked randomised cross-over fashion. It was found that neither expression of meibomian oils nor topical anaesthesia showed any statistically significant (P greater than 0.05) reduction in final tear secretion rates. Thus, the notions that lid manipulation may impede tear flow into the Schirmer strip and that topical anaesthesia reduces apparent tear flow, are not supported.