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Tear break-up time in eyes with pterygia and pingueculae in Ibadan.

BACKGROUND
Ultraviolet (UV) rays and chronic irritation to dust have been implicated in the pathogenesis of degenerative conditions of the cornea and conjunctiva like pterygium and pinguecula. It has been postulated that exposure to these environmental factors cause corneal and conjunctival drying by disruption of the tear film. While some researchers have found tear film dysfunction in eyes with pterygia and pingueculae, others have found no such abnormalities. The differences in findings may be due to different methods of investigation, or differences based on geography and climate.


STUDY DESIGN
The tear film has been studied using tear break-up time (TBUT) in adults with pterygia and pingueculae disorders, TBUT was measured in 73 eyes with pterygia and 74 eyes with pinguecula and were compared to TBUT in 74 eyes of age and sex matched normal controls. Abnormal TBUT was defined as TBUT less than 15 secs. Unstable tear film was defined as TBUT less than 10 secs.


RESULTS
The mean TBUT was lower in eyes with pterygia (17.90 secs) than in control eyes (19.86 secs), although the mean difference was not statistically significant. Abnormal TBUT, defined as TBUT less than 15 secs, was found in 29 eyes out of 73 eyes with pterygia (39.7%), compared with 13 eyes out of 74 eyes with pingueculae (17.6%) and in 17(23.0%) of 74 control eyes (X2 = 10.01, df = 2, P = 0.0006). A TBUT of less than 15 secs was more significantly associated with eyes with pterygia compared to control eyes. Unstable tear film (TBUT less than 10 secs) was found in 12(16.4%) eyes with pterygia, compared to 4(5.4%) eyes with pingueculae and 4(5.4%) control eyes. Unstable tear film was significantly associated with eyes with pterygia (P = 0.027).


CONCLUSION
Tear film abnormalities are associated with pterygium but not with pinguecula in the subjects studied. TBHT may vary in different populations.