Purpose: To analyze the spontaneous eye-blink rate (SEBR) and blinking pattern in patients with moderately dry eyes during video display terminal (VDT) use.
Methods: The SEBR of 30 patients with dry eye syndrome (median age 44.8 years, range 18 - 67 years) was measured using a computer-based video analysis system. Only complete eye blinks were recorded during 10 min of conversation, during initial VDT use and again after a preceding work period of 30 min.
Results: In comparison with SEBR during conversation (mean value 16.8 blinks/min, standard deviation 16.8 blinks/min) the SEBR significantly decreased during initial VDT use (6.6+/-4.8; P<0.001) and remained significantly decreased during re-measurement after 30 min (5.9+/-4.6; P<0.001). SEBR was not significantly different between initial VDT use and re-measurement after 30 min ( P=0.65). The SEBR was characterized by marked interindividual variability during conversation and VDT use. No significant correlation was found between SEBR (either during conversation or during VDT use), and the quality (tear break-up time) or quantity (Schirmer I test, Jones test) of the tear film. Typical blinking patterns were found to be (1). a relatively time-independent, irregular pattern, (2). an initial phase of 2-4 min with shorter inter-eye-blink intervals, and (3). alternating periods of higher and lower inter-eye-blink intervals.
Conclusions: Reduction of the SEBR during VDT use is primarily determined by marked visual attention, resulting in an exacerbation of dry eye symptoms in predisposed humans. High interindividual variability and distinct patterns of eye blinking may be key factors in further clarification of VDT-eye interactions and develop individually designed solutions to prevent desiccation during VDT use.