Vection Responses in Patients With Early Glaucoma.

PURPOSE

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.

METHODS

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.

RESULTS

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.

CONCLUSIONS

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.