The Relationships Between Blink Rates Before, During Perimetry and Perimetry Reliability

Perimetry was performed using the Humphrey Visual Field Analyzer II (model 750) with the Swedish interactive threshold algorithm (SITA) standard strategy, the 30-2 program, and a size III white stimulus on a white background (equivalent to 31.5 apostilbs). The fixation loss, false positive, and false negative rates were used to assess the reliability of perimetry. (A) Data for patients with dry eye. (B) Data for normal control subjects. Group 1; eyes with decreased blink rates during perimetry in patients with dry eye; Group 2; eyes with increased or unchanged blink rates during perimetry in patients with dry eye; Group 3; eyes with decreased blink rates during perimetry in normal control subjects; Group 4; eyes with increased or unchanged blink rates during perimetry in normal control subjects. Pre-perimetry blink rates in the eyes with blink rates that decreased during perimetry varied from 3 to 44/min in patients with DE (Group 1) and from 4 to 48/min in normal control subjects (Group 3). Blink rates before perimetry in the eyes with blink rates that increased or remained unchanged during perimetry were < 17/min in patients with DE (Group 2) and 19/min in normal control subjects (Group 4), respectively (Fig 1). Blink rates during perimetry were significantly lower in Group 1 compared to Group 2, and in Group 3 compared to Group 4: Group 1, 4.6 (1.7-7.0 [0-21]) vs. Group 2, 13.4 (11.4-16.0 [2-39]) /min and Group 3, 2.6 (0.9-5.4 [0-12]) vs. Group 4, 20.1 (11.0-30.5 [4-36]) /min (P=0.007 and P<0.001, respectively, Fig 1). Fixation loss rate was significantly higher in eyes with decreased blink rates among patients with dry eye (P=0.002). Strip meniscometry value was directly correlated with fixation loss rate (r=0.341, P=0.025), and blink rate during perimetry was negatively was correlated with fixation loss rate (r=- 0.393, P=0.009). Dry Eye-related Quality of Life score was negatively correlated with false negative rate (r=- 0.323, P=0.035) in patients with dry eye. However, there were no apparent correlations among the perimetry reliability parameters and other parameters in normal control subjects.