Impact of tear metrics on the reliability of perimetry in patients with dry eye

Background The application of artificial tears before performing perimetry can improve the reliability and results of perimetry in patients with glaucoma and dry eye (DE). However, the effects of ocular surface and tear film conditions on perimetry measurements and reliability have not been fully characterized. Methods This prospective, cross-sectional, multicenter study investigated tear metrics in perimetry and assessed the relationships that existed among ocular surface condition, tear condition, and perimetry reliability. Forty-three eyes (43 patients) with DE disease according to the 2016 Japanese diagnostic criteria of DE and 43 eyes (43 subjects) of age- and visual field mean deviation-matched normal control subjects were studied. Perimetry was performed using the Humphrey Field Analyzer (30–2 SITA-Standard). Schirmer’s test, strip meniscometry value, blink rate, tear film break-up time (TFBUT), fluorescein staining of ocular surface, and Dry Eye-related Quality of Life Score (DEQS) were measured. Blink rate was re-measured during perimetry. TFBUT and fluorescein staining were re-evaluated after perimetry. Perimetry reliability was evaluated with fixation loss, false-positive, and false-negative rates. Results Blink rate during perimetry was significantly lower for both patients with DE and normal controls (both P<0.001). TFBUT after perimetry was significantly higher than before perimetry in patients with DE (P<0.001). Fluorescein staining of ocular surface was significantly increased in patients with DE and normal control subjects (P = 0.002 and P<0.001, respectively). Spearman correlation analysis revealed that blink rate during perimetry was negatively correlated with fixation-loss rate (r = -0.393, P = 0.009) in patients with DE. Conclusions Performing perimetry was associated with a significant change in tear condition and ocular surface condition in both patients with DE and normal control subjects. The changes in tear condition and ocular surface condition may impact the reliability of perimetry in patients with DE.