Tonicity of human tear fluid sampled from the cul-de-sac. Issue 8 (August 1989)

• Record Type: Journal Article
• Authors: Benjamin, W J; Hill, R M
• Is Part Of: British journal of ophthalmology. Volume 73:Issue 8(1989)
• Page Start: 624
• Page End: 627
• Publication Date: 1989-08
• Subjects: Ophthalmology -- Periodicals; 617.7
• DOI: 10.1136/bjo.73.8.624
• Languages: English
• ISSNs: 0007-1161

Abstract

Abstract : A 'freezing point' depression technique was used to determine the osmolality of 384 samples of tear fluid originating from the middle of the lower tear prism and the lower cul-de-sac of one eye of each of 12 young adults. Tear fluid from the cul-de-sac (mean 341.0 mosm/kg) was found overall to be significantly hypertonic (p less than 0.0001) relatively to fluid from the tear prism (mean 315.5 mosm/kg). However, the difference between the two sampling sites was highly variable between individuals, ranging from a maximum mean site difference of 64.5. mosm/kg for one of the six cul-de-sacs found to be significantly hypertonic, to a mean site difference of 25.0 mosm/kg for one of the two cul-de-sacs found to be significantly hypotonic. These results suggest that a unique localised tear environment exists inside the lower cul-de-sac, which has several clinical consequences--for example, for pharmaceutical absorption, ocular microbiology, and hydrophilic contact lens performance.