Eye Movements Alterations During Reading Process in Patients with Glaucoma: a Microperimeter Study

Abstract

Purpose: To assess reading process and eye movements alterations in patients with primary open angle glaucoma (PAOG) at different stages of visual field defects using Microperimeter.

Methods: The study included 32 patients with PAOG at early and moderate stages (Glaucoma Staging System-2, Brusini P, 2006) without defects in the central 10° and 34 age- and sex-matched controls. The protocol was approved by the Ethics Committee of our University and followed the tenets of the Declaration of Helsinki. Written informed consent was obtained. The glaucoma group included 16 men and 16 women ranging in age from 48 to 72 years old with middle school educational level. All glaucoma patients had visual field defects, glaucomatous changes in the optic disc and open iridocorneal angle. The control group had a complete ophthalmological examination and a computerized visual field test. Reading speed, accuracy and comprehension skills were evaluated with specific tests. In all participants, reading process was tested with Microperimeter Nidek MP-1 (MP-1). For our study a printed text was implemented in the MP-1 software as fixation target and eye movements during reading were recorded by the eye-tracker of the instrument. The following parameters were provided by the MP-1: mean ocular movements speed and the minimum and maximum extension of the eye movements along the horizontal and vertical axis.

Results: No significant differences in reading speed, accuracy and comprehension were observed in patients with PAOG compared to the controls. The values of the maximum horizontal and vertical eye movements extension were significantly increased in patients with PAOG compared to controls (4.75 ± 2.57 versus 3.38 ± 0.67, p = 0.003; and 4.39 ± 1.43 versus 3.34 ± 0.52, p<0.001, respectively). These differences were statistically significant even comparing only stage 1 patients to controls.

Conclusions: We observed that in patients with early and moderate PAOG the eye movements pattern during reading was significantly altered compared to controls. These changes may be the result of a neurodegenerative process involving the magnocellular pathway of the central visual system that has been implicated in the eye movements control during reading.

Keywords: 524 eye movements: recording techniques • 672 reading • 758 visual fields