Premium
Compartmental factors influencing tear film osmolarity
Author(s) -
BRON AJ,
TIFFANY JM,
GAFFNEY EA
Publication year - 2008
Publication title -
acta ophthalmologica
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.534
H-Index - 87
eISSN - 1755-3768
pISSN - 1755-375X
DOI - 10.1111/j.1755-3768.2008.4333.x
Subject(s) - osmotic concentration , ophthalmology , relative humidity , population , chemistry , medicine , physics , biochemistry , meteorology , environmental health
Purpose To illustrate how compartmental factors could influence the distribution of tear osmolarity at the ocular surface in normals and dry eye. Methods Mathematical modelling using parameters in the literature. Results Tear film hyperosmolarity is a final common pathway causing ocular surface damage in dry eye. Modelling predicts that tear osmolarity is higher in the tear film than the meniscus, which may influence the distribution of ocular surface damage and the initiation of symptoms caused by hyperosmolarity. Once tear film break up occurs within the blink interval it is likely that this differential is amplified locally. The model allows the effect of compartmental factors on tear osmolarity to be addressed, including: regional differences in air flow and surface temperature, variations in ambient temperature and humidity, imperfect tear mixing, differential corneal and conjunctival exposure and individual differences in reflex tear flow, evaporation rate and blink interval. We hypothesise that interactions between these factors determine the dry eye phenotype in an individual. Additional considerations suggest that events at the ocular surface differ in aqueous‐deficient and evaporative dry eye. Conclusion Hyperosmolarity at the ocular surface is affected by multiple factors, each of which may make different contributions to distribution and severity of surface damage in a given individual. This may determine the phenotype, frequency and severity of dry eye in a population.