Abstract
Purpose :
To investigate whether patients with pre-perimetric glaucoma have different eye-hand latency in grasping tasks under crowding. Hypotheses: 1) These patients have longer latencies than controls and 2) crowding affects latency.
Methods :
4 patients from the Glaucoma Clinic (age: 53–75 years) and 3 healthy controls (age: 41–55 years) participated. For patients, their visual fields’ mean deviation, average retinal nerve fiber thickness, and vertical cup-to-disc ratio ranged from −0.89 to +3.3 dB, 64 to 94 μm and 0.52 to 0.80 (mean: +0.86 dB; 81 μm; 0.67), respectively. Participants performed an object gasping task with eye and hand movement tracking (EyeLink and Leap). The better eye with at least 20/50 near-distance visual acuity was tracked. A vertical whiteboard was placed with only one white target object (control condition), or the white target surrounded by four colored objects along the azimuth. The crowding objects were set up either 5° (narrow crowding) or 10° apart (wide crowding). The target object was placed at the center or at the ±5° (or ±10°) position. At start of each trial, a board with a fixation target hid the whiteboard. After 3 seconds, this board was removed rapidly by the experimenter. The participant grasped the white target object and moved it to a marked target location as quickly and accurately as possible. Each crowding condition was repeated 12 times to obtain mean eye latency (first reported saccade by EyeLink after revealing the whiteboard) and reach latency (when hand velocity exceeded 10 mm/s). The difference between the two was defined as the eye-hand latency.
Results :
Glaucoma subjects had on average (±standard error) +105±89 ms longer eye-hand latency than controls across all conditions. This difference was +116±92, +111±93, and +88±84 ms in control, wide, and narrow conditions, respectively. However, crowding had no effect on latency: the averages were 237±70, 256±41, and 272±35 ms in controls, and 354±65, 366±73, 360±66 ms in glaucoma subjects. Latency did not correlate with age (r=0.09, p=0.85).
Conclusions :
Patients with early glaucoma have longer eye-hand latency (i.e., they initiate hand movement slower) than controls in grasping tasks. Crowding appears to have no effect on latency. Further limb kinematic parameters will be investigated.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.