Purpose: To investigate the effect of different blink methods on fluorescein break-up time (FBUT) and fluorescein break-up pattern (FBUP).
Subjects and methods: In this study, we examined 81 eyes of 81 subjects with dry eye [11 eyes of 11 male, 70 eyes of 70 female, mean age: 62.5±12.8 (standard deviation) years] who met the diagnostic criteria of dry eye proposed by the Japan Dry Eye Society (updated in 2016). The patients were instructed to blink with three different blink methods in the following order: 1) naturally open the eye after naturally closing it (natural load); 2) rapidly open the eye after gently closing it (gentle load); and 3) rapidly open the eye after strongly closing it (strong load). After each blink, the patients were instructed to keep the eye open. During this procedure, FBUT was measured three times, in the order of 1～3, and different types of FBUP were evaluated, including area break (AB), line break (LB), spot break (SB), dimple break (DB), and random break (RB).
Results: FBUT for the natural, gentle, and strong loads was 2.7±1.9,1.9±2.3, and 2.1±2.2 seconds, respectively. FBUT for the natural load was significantly longer than for the gentle or strong loads (p<0.01, respectively), but no significant difference was noted between the gentle and strong loads (p=0.15). For the natural, gentle, and strong loads, the number of occurrences of FBUP were as follows: AB (4,4, and 4); LB (4,7, and 2); SB (1,7, and 5); DB (22,29, and 28); RB (49,23, and 33); SB+DB (0,7, and 6); LB+DB (1,1, and 1), and SB+LB (0,3, and 2), respectively. Thus, SB and SB+DB appeared significantly more in the gentle and strong loads and less in the natural load (p<0.01). RB appeared the most in the natural load (p<0.01).
Conclusion: Considering the possibility that FBUT and FBUP may be altered due to extravasation of meibomian lipids and decrease in lacrimal fluid retention when the eye is strongly closed, it may be most effective to ask the patients to gently close their eyes and then rapidly open them when evaluating FBUP during treatment for dry eye.
Nippon Ganka Gakkai Zasshi (J Jpn Ophthalmol Soc) 125: 947-953,2021.