Abstract
Purpose :
Visual search plays a key role in everyday life, but most prior studies in the visually impaired have focused on finding objects in natural scenes. Here, we utilize a cross-sectional study to examine the effect of glaucoma and dry eye on a text-based visual search task. We hypothesize that glaucoma alone will prolong search time.
Methods :
Three groups of patients age 50 and above were enrolled: glaucoma patients with bilateral visual field (VF) loss; patients with signs and symptoms of dry eye; and glaucoma suspect controls with normal VFs and visual acuity (VA). Subjects searched yellow pages excerpts for a given phone number, and search time was recorded for three trials. Dry eye severity was assessed subjectively using total and symptom-related Ocular Surface Disease Index (OSDI) scores and objective measures (Schirmer’s wetting, corneal staining and tear-film break-up time). Search time was analyzed using multivariate generalized estimating equation models adjusting for age, education and cognitive ability. To determine if text-based search and reading represented the same underlying construct, correlations between search time and time required to complete a sustained reading task were also calculated.
Results :
Fifty glaucoma subjects, 48 dry eye subjects and 45 controls completed study procedures. Moderate correlations (r=0.57) were observed between search time and sustained reading time. Mean search time was 1.56s longer in glaucoma patients compared with controls (95% CI=1.25-1.96, p<0.001), and longer search times were noted amongst subjects with greater VF loss (β=+1.21s per 5 dB decrement VF mean deviation; 95% CI=1.12-1.30, p<0.001), worse contrast sensitivity (β=+1.11s per 0.1 decrement in logCS, 95% CI=1.05-1.18, p<0.001) and worse VA (β=+1.12s per 0.1 logMAR increment, 95% CI=1.11-1.25, p=0.03). Dry eye subjects demonstrated similar search times compared to controls. No association with search time was observed with OSDI symptom scores (p=0.21) or any objective measure of dry eye (p>0.05 for all).
Conclusions :
Text-based visual search is related, but distinct from reading speed and merits independent study. Search times are increased in glaucoma patients, but not those with dry eye. Glaucoma patients with more advanced disease may have greater difficulty finding relevant materials within text.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.