The role of ethnicity versus environment in tear film stability: A pilot study

Purpose: Existing literatures suggest a difference in tear film stability between Caucasian and Asian ethnic groups. However, such a finding was compounded by the fact that the comparison was done on subjects living in different environments. Therefore, it is not clear whether such difference is due to ethnicity, environment, or both. The aim of this study is to clarify the roles of these two factors. Methods: A total of 88 asymptomatic subjects participated in this present study. For each subject, the tear film break-up time (TBUT), non-invasive TBUT (NITBUT) and tear meniscus height (TMH) were measured. To isolate the effect of ethnicity, the results of 12 American Asian young adults were compared against the results of 23 Caucasian adults. Both groups were recruited from Nova Southeastern University. To elucidate the effect of environment, the results from the same 12 American Asians were compared to that of the 53 Asian young adults recruited from the Tianjin Vocational Institute, China (Tianjin Asian). Results: The tear film stability did not show significant difference among American Asian subjects and Caucasian subjects in TBUT (10.49 +/- 2.86 s vs. 11.06 +/- 2.79 s,p = 0.57), NITBUT (11.19 +/- 4.89 s vs. 11.14 +/- 6.20 s, p = 0.98), and TMH (0.21 +/- 0.08 mm vs. 0.22 +/- 0.05 mm, p =0.59). However, the tear film stability was significantly better in the American Asian group than the Tianjin Asian group in TBUT (10.49 +/- 2.86 s vs. 7.60 +/- 3.26 s, p = 0.01), NITBUT (11.19 +/- 4.89 s vs. 8.03 +/- 3.56 s, p = 0.01), and TMH (0.21 +/- 0.08 mm vs. 0.14 +/- 0.03 mm, p < 0.01). Conclusions: The previously reported difference in Caucasian and Asian populations might be due to the fact that the studied subjects have different living environments.