Vection Responses in Patients With Early Glaucoma

Our lab has previously shown that patients with early glaucoma have longer vection latencies than controls. We attempted to explain this finding using a combined index of structure and function (CSFI), as proposed by Medeiros and colleagues. The CSFI estimates the proportion of retinal ganglion cell loss.

Roll and circular vection were evoked using a back-projected screen (experiment 1) and the Oculus Rift system (experiment 2). Vection latency and duration were measured using a button response box. In experiment 1, tilt angles were measured with a tilt sensor, whereas subjective tilt was determined using a joystick attached to a protractor. In experiment 2, subjective vection strength was rated on a 1 to 10 scale. These measurements were compared with the CSFI, which utilizes visual field and optical coherence tomography data.

For experiment 1 we tested 22 patients (mean age, 70.3±6 y) with glaucoma and 18 controls (mean age, 54.6±9 y); and for experiment 2 we tested 24 patients (mean age, 71.1 ±5 y) and 23 controls (mean age 61.4±10 y), but not all patients experienced vection. In both experiments, vection latency was significantly longer for patients than for controls (smallest P=0.02). The CSFI was not related to vection latency, duration, or objective and subjective measures of vection strength (smallest P=0.06) in either experiment.

Two experiments have replicated the finding that vection responses are longer in patients with glaucoma than in controls; however, the CSFI is not related to vection responses.