Abstract
Purpose: :
Little is known about eye movements in patients with glaucoma. The aim of this pilot study is to test the hypothesis that patients with bilateral glaucoma exhibit different eye movements compared to normally-sighted subjects when passively viewing computer displayed photographs, or searching for features or items within them.
Methods: :
Eight patients with bilateral glaucoma, of 20 planned, (age range: 57 to 80 years, with Humphrey visual field MDs ranging from -3.6 to -28.1dB) and 6 age-matched subjects with normal vision, of 10 planned, (age range: 57 to 82 years) viewed 28 randomised digital photographs of natural scenes displayed on a computer screen for 3 seconds each. Subjects were instructed to view the images as they would when looking at a slideshow. They were then asked to view another set of images but were asked to find a feature or item in the scene. Eye movements were recorded using an EyeLink II (SR Research Ltd, Canada) sampling at 500Hz. Number of saccades, fixation duration and saccade amplitude in each task were analysed.
Results: :
For the passive viewing condition, there was a 10.3% reduction in the average number of saccades for glaucoma patients (p<0.001; ANOVA). Saccadic amplitude is decreased by an average of 1.1 degrees (p<0.001; ANOVA) and fixation duration increased by an average of 35ms (p<0.001; ANOVA). However, for the search task there were no statistically significant differences in average saccade numbers, saccade amplitude and fixation duration (all p>0.05 ANOVA).
Conclusions: :
These preliminary results provide evidence that eye movement patterns in patients with glaucoma differ from normal-sighted subjects when viewing photographs and images. Patients with glaucoma make fewer, smaller saccades compared to controls when passively viewing but the effect dissipates when the subject is asked to search the image. Eye movements in glaucoma might inform us about functional deficits of the disease.
Keywords: eye movements • visual fields