To develop a novel method for measuring tear break-up time (BUT) by continuously measuring higher order wavefront aberrations using a Hartmann-Shack (H-S) aberrometer.
Wavefront aberrations up to the sixth order for a 4-mm pupil were measured in six eyes of six normal subjects using an H-S aberrometer. The aberrometry was performed once every second for up to 50 s under topical anesthesia. The sequence of the points was divided into two stages, and the BUT was defined as the wavefront border of the stages (WFBUT). The WFBUT was compared with the BUT by the conventional fluorescein method (FLBUT) or by the disruption of placid-ring images (PLBUT).
In three eyes, the WFBUT (average, 10.9 ± 1.1 s) was shorter than the PLBUT (average, 17.5 ± 2.5 s), while in the other three eyes the WFBUT (average, 21.5 ± 2.2 s) was longer than PLBUT (average, 8.1 ± 2.2 s). The FLBUT was shorter than WFBUT or PLBUT in most cases.