[The Video Tearscope: a new method for evaluating lacrimal film in vivo]

The lacrimal film has trophic, immunological, antimicrobial, and anti-inflammatory roles. The lipidic phase of the tear film reduces surface stresses and limits tear evaporation. We present a reproducible and noninvasive investigation of the lacrimal film, the Video Tearscope (Vi-Te), which analyzes the after-blinking tear stabilization time and the different types of blinking. Vi-Te consists of a numerical video recording of the specular reflexion produced by the Tearscope Plus adapted to a biomicroscope.

Twenty-four normal subjects and ten patients with dry eye syndrome were included. We studied the blinking types and LFST using the Vi-Te technique. The analysis was carried out at 25 images/s, corresponding to an in-between image interval of 40 ms.

Four types of spontaneous blinking were observed: complete, subtotal (99%-70% occlusion), partial (69%-20%), and abortive (less than 20%). We obtained a LFST value of 0.65+/-0.12s for the control group versus 2.34+/-1.28 s for the dry eye syndrome group. The difference was significant between the two groups for the LFST (p<0.001) for complete blinking.

The Video Tearscope is a promising technique that provides new insights into tear film stability and physiology. The main weakness of this technique, however, is the time required for video analysis (20-45 min per case). Despite this drawback, additional studies should be undertaken in order to establish standards for evaluating ocular surface disorders in a completely noninvasive way.