Delayed saccadic eye movements in glaucoma

Raageen Kanjee,¹ Yeni H Yücel,^1,2 Martin J Steinbach,^3,4 Esther G González,^3,4 Neeru Gupta<sup>1,2,5

1</sup>Ophthalmology and Vision Sciences, Laboratory Medicine and Pathobiology, St Michael's Hospital, University of Toronto, ²Keenan Research Centre at the Li Ka Shing Knowledge Institute of St Michael's Hospital, ³Toronto Western Hospital, University Health Network, ⁴Centre for Vision Research, York University, ⁵Glaucoma and Nerve Protection Unit, St Michael's Hospital, Toronto, ON, Canada

Purpose: To determine whether saccadic eye movements are altered in glaucoma patients.
Patients and methods: Sixteen patients with glaucoma and 21 control subjects were prospectively studied. Patients participated in a pro-saccade step task. Saccades were recorded using a noninvasive infrared oculometric device with head-mounted target projection. Medians of saccade reaction time, duration, amplitude, and peak velocity; frequency of express saccades; and percentage of trials with direction error were recorded. t-tests were used to compare the glaucoma and age-matched control groups. A correlation analysis of saccade parameters with visual field loss was also performed.
Results: Median saccade reaction times were significantly prolonged in glaucoma patients compared with controls (220.9 ± 49.02 ms vs 192.1 ± 31.24 ms; t-test: P = 0.036). Median duration, median amplitude, and median peak velocity of saccades did not show significant differences between glaucoma and control groups (P > 0.05). Frequency of express saccades was significantly decreased in glaucoma patients compared with controls (1.75 ± 2.32 vs 7.0 ± 6.99; t-test: P = 0.007). Saccade parameters in glaucoma patients showed no significant correlation with visual field loss.
Conclusion: Saccadic eye movements are significantly delayed in patients with early, moderate, or advanced glaucoma. Determination of median saccade reaction time may offer a novel functional test to quantify visual function in glaucoma patients. Further studies are needed to determine pathological processes implicated in delayed initiation of saccades, and to assess whether alteration of saccades affects daily activities in glaucoma patients.

Keywords: visual field, latency, visual dysfunction, brain, superior colliculus, quality of life