Abstract
Purpose :
Studying accommodation behavior consistently in non-human primates (NHPs) is challenging. While most studies either perform refractive screening of awake NHPs or induce accommodation pharmacologically or electrically in anesthetized animals pharmacologically or, accommodation research in awake-behaving NHPs is scarce. To evaluate a wireless intraocular ciliary muscle (CM) biopotential sensor, an experimental setup for NHPs was developed for controlled presentation of accommodative stimuli and photorefraction of the crystalline lens. Here we present the experimental setup and preliminary data obtained in humans.
Methods :
The setup (Fig. 1A) is a funnel-shaped perspex viewing tube (to avoid distraction) with attached handles and a juice delivery pipe for motivational rewards, placed in front of a monkey chair. It contains 4 near displays (ILI9341 2.2”, ILI Technology Corp.,Taiwan; 25, 33, 40, 50cm) and one far monitor (200cm). Wildlife movies are shown alternately (10-15s) on the far or a random near display connected to a wirelessly controlled Raspberry Pi 4b. Refractive state, pupil diameter, and gaze were recorded with a PowerRefractor (Schaeffel 1987). Fixation and refractive changes of the left eye of two male humans (S1: 30y, sph -0.25D; S2: 29y, sph -3.75D) were recorded. Acceptability was assessed in a test-naïve monkey (Macaca fascicularis). The experiment was approved by the local authorities.
Results :
The subjects maintained stable fixation for 30s, with mean 95% deviations of 0.05° (horizontal) and 0.07° (vertical), respectively. (Fig. 1B, top). Refractive states were correlated with the accommodative demands (Fig. 1B, bottom). Pupil diameters showed little variation, even for near targets. (S1: 4.45±0.44mm; S2: 5.43±0.34mm). Detailed results are presented in Table 1. The NHP voluntarily tolerated the setup and fixated on the active displays.
Conclusions :
The results from the human subjects indicate that the simple and low-cost setup provides reliable recording of gaze, pupil diameter, and refractive state at high sampling frequency. A test-naïve NHP tolerated the setup well, but refraction measurements were not yet possible without further training. The setup is used for assessing a novel intraocular sensor’s ability to record ciliary muscle biopotentials and may prove useful in related NHP research.
This abstract was presented at the 2024 ARVO Annual Meeting, held in Seattle, WA, May 5-9, 2024.