Purchase this article with an account.
N. Hanna, S. Athawale, P. Hsu, A. Dhinojwala, D. P. Edward; Does the Surface Tension of Tears Change With Age?. Invest. Ophthalmol. Vis. Sci. 2010;51(13):4190.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Tear film stability is dependent on several factors including its surface tension (ST). Normal tear ST measurements range from 41-53 mN/m (milli-Newton/meter). The effect of age and gender on ST of tears has not been reported although tear production and its components change with age. The purpose of this study was to measure the tear film ST of subjects in different age groups and investigate the variability in measurements.
After sample size determination, stimulated tears were collected from 45 normal subjects divided into the age groups(yrs) 18-34, 35-54 and 55-84. Criteria for enrollment included absence of ocular disease and medication use that might alter tears. Tears were collected using a 25µl glass capillary tube. ST was measured using the Pendant drop technique and DROPimage software. Ten ST readings were obtained from each sample and averaged. The differences in ST among the 3 age groups were compared using a one-way ANOVA, and a t-test was used to compare any differences between gender.
The ST in the 18-34 age group was 45.92 mN/m ± 5.53 (31.35-56.19 mN/m)(n=15); in the 35-54 age group the ST was 46.72 mN/m ± 4.23 (40.80-54.24 mN/m) (n=16); and in the 55-84 age group the ST was 46.57 mN/m ± 3.7(41.50-52.92 mN/m)(n=14). There was no significant difference in the ST values between the different age groups (p=0.879). The ST in males (n=14) was 45.88 mN/m ± 3.55 (41.01-56.19 mN/m ) and in females (n=31) the ST was 46.64 mN/m ± 4.87 (31.35-52.72 mN/m). Again there was no difference seen (p = 0.604). Linear regression analysis also showed no relationship between age, gender and ST results.
The ST values of tears in our study were comparable to those previously reported in normal subjects. Our results did not demonstrate age or gender related differences in ST. It is possible that the wide range of ST within age groups may account for the lack of difference. Although the literature suggests expected changes in ST because of decreased protein production with aging, our study did not demonstrate this. The lack of change in our study may be secondary to other tear film components that might cause variability in ST values. This information provides a good baseline to study other factors that affect ST of tears, its stability in the normal state, dry eyes and the effect that topical ocular medications may have on tear ST.
This PDF is available to Subscribers Only