Abstract
Purpose: :
Purpose of this study was to explore the influence of tear film on visual acuity by measuring post-blink blur time (PBBT) using standard Snellen charts, in subjects with and without tear film dysfunction symptoms, to ascertain whether this parameter could be quantified by using subject's time interval estimation, to explore method's repeatability and ease of implementation in everyday clinical practice, and, finally, to find whether results of this test correlate with any other observed parameter.
Methods: :
Standard ophthalmology practice equipment was used: Snellen charts and slit lamp. Chronometer was used by the examiner for checking subject's measurement. Slit lamp examination included the estimation of conjunctival hyperemia, LIPCOF test, TBUT test, corneal fluorescein staining and the Meibomian gland expression.
Results: :
200 subjects were enrolled in study (age 18-75), 100 in group with tear film dysfunction symptoms and 100 in group without such symptoms.Statistically significant difference between PBBT values measured by both the subject and examiner was found between groups, with lower values in group with tear film dysfunction symptoms. Moderate corelation was found between TBUT and PBBT measurements.
Conclusions: :
PBBT, measured by the subject, was found to be reliable tool in detecting dry eye. Furthermore, it is simple, quick and noninvasive diagnostic tool, requiring only Snellen charts. High repeatability and negligible difference between values measured on both eyes enable clinician to obtain relevant measurement by measuring only one eye once, although pre-test measurement is recommended to test patient's cooperation. 7 seconds are proposed as cutoff between normal and pathologic values.
Keywords: cornea: tears/tear film/dry eye • visual acuity