Abstract
Purpose :
Primary open angle glaucoma (POAG) has been associated with abnormal eye movements, including increased frequency of exploratory saccades, compared to controls, possibly as a compensatory strategy after visual field loss. However, little is known about the eye movements in POAG in the absence of visual field defects, which may interfere as a confounder. The aim of our study was to explore the characteristics of eye movements in patients at very early stages of glaucoma, with no visual field deficits, i.e. preperimetric POAG.
Methods :
Cross-sectional, observational study, exploring binocular eye movements in 16 patients with preperimetric POAG and 16 age-matched healthy controls. Patients with preperimetric glaucoma had anantomical evidence of glaucomatous optic neuropathy (cupped discs and characteristic thinning of the retinal nerve fiber layers on OCT), and initially raised intraocular pressure. Infrared oculography (EyeBrain, Paris), allowed measurements of visually–guided prosaccades (at 5, 10, 15 and 20° amplitude) and antisaccades (12° amplitude), using a gap (200ms) paradigm. Performance characteristics of eye movements were compared between the two groups in the prosaccade task (latency, gain, frequency of express-saccades) and in the antisaccade task (latency and rate of errors).
Results :
Preperimetric POAG patients did significantly more errors than controls during the antisaccade task (p<0.001), with significantly shorter saccadic latencies (p=0.02).During the prosaccade task, the mean saccadic latency was significantly shorter in the preperimetric POAG group than in controls (p<0.001); patients with preperimetric POAG also performed significantly more express-saccades than controls (p=0.012).
Conclusions :
Patients with preperimetric POAG display an inhability to suppress reflexive saccades in the antisaccades paradigm, with shortened latencies. Consistently, they perform more reflexive, expresss saccades towards peripheral visual stimuli, while prosaccades have shorter latencies, compared to healthy controls. Taken together, these findings suggest that even at a preperimetric stage, POAG is associated with disrupted inhibition of unwanted, reflexive saccades and inhibited ocular motor behaviour.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.