Abstract
Purpose: :
Dry eye disease is significantly more prevalent in presbyopes than non presbyopes and in the latter group more marked in women than men. The increase in dry eyes in presbyopes is traditionally thought to be associated with a decrease in tear production enhanced by hormonal changes. Clinical evidence of an abnormal lipid production system in presbyopes, in particular women is established. It therefore postulated that the greater prevalence of dry eye problems in presbyopes than non presbyopes is at least in part of evaporative nature. The hypothesis tested was that the rate of the evaporation was greater in presbyopes than non presbyopes and in that older group greater in women than men.
Methods: :
Tear film evaporation was measured with the Oregon Health Sciences University Evaporimeter at low (30%) and normal (40%) hygrometry.
Results: :
A total of 160 non-presbyopes (NPresb) aged 28.1±7.3 years (Range 18 to 44 years) and 57 presbyopes (Presb) aged 53.7±7.8 years (Range 45 to 83 years) form the two test populations. ANOVA revealed, a significant effect of both Age (p<0.001) and Gender (p<0.001) and of their interaction (p<0.001); SNK comparisons between subgroups revealed significant differences of clinical relevance: i) The rate of evaporation was higher for Presb than NPresb, by 31% at 30%RH (20.1±10.3 vs. 15.3±7.2 10 -7 g/cm2/s) and by 55% at 40%RH (18.5±11.7 vs. 11.9±7.1 10 -7g/cm2/s); ii). The rate of evaporation was higher for females than males by 24% at 30%RH (18.3±9.7 vs. 14.7 ± 6.3 10 -7 g/cm2/s) and by 47% at 40%RH (16.2 ± 10.2 vs. 11.0± 6.6 10 -7 g/cm2/s); iii) The synergic effect of age and gender was very marked: the rate of evaporation of presbyopic females was 34% higher at 30% hygrometry and 80% higher at 40% hygrometry than that of presbyopic males and 36% higher at 30% hygrometry and 69% at 40 % hygrometry than non-presbyopic females.
Conclusions: :
Aging of the tear film includes a significant evaporative component, characterized by higher tear film evaporation compared to non presbyopes for the population overall and a significant greater tear film evaporation for female than male presbyopes. The findings have significant implications for the management of presbyopic dry eye sufferers.
Keywords: cornea: tears/tear film/dry eye