A simple, non-invasive technique of assessing the stability of the human precorneal tear film is tested for usefulness in diagnosing subjects with dry eye. Changes are observed in the reflection of the keratometer mire, which is in the form of a grid pattern (HIR-CAL Grid). Thinning and breaks in the tear film appear as random discontinuities in the grid image. The stability of the pre-corneal tear film was assessed (based on tear pre-rupture phase time (TP-RPT)) in nine normal subjects and nine subjects with dry eye. There was a significant difference between the groups, the dry eye TP-RPT averaging 27% less than the TP-RPT of normal eyes. This supports the findings of other non-invasive approaches in measuring tear film stability. Applications of this technique include diagnosing dry eye and selecting successful contact lens wearers.
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