Measures of tear exchange under rigid contact lenses: Part III. Influence of base curve on post-lens tear exchange

Abstract Observations of net tear exchange associated with steeper than K and flatter than K fits of rigid lenses to each of six human corneas revealed within this sample that tear exchange was always reduced in steeper than K cases and always increased in flatter than K cases. Fits within ±0. 05 mm of the K case did not manifest tear-exchange performances significantly different from the K case. Although the net volume of the postlens reservoir exchange associated with on-K cases commonly averaged 5% per blink, exchanges of up to 16.57% were found possible, but rarely practical, with fits of 0.15 mm flatter than K.