A simple method for judging the desiccation of a hydrophilic lens, while on the eye, is described. This involves subjective determination of the loss in “crispness” and “regularity” of the keratometer mire reflected off the anterior lens surface in between blinks. The time interval between a complete blink and the moment of loss of regularity of the reflex was monitored over a 6 month period for subjects wearing a commercially available 67% water content contact lens. This time interval appears to remain constant, and is, on average, comparable with the normal interblink period.