Abstract
Purpose :
A few studies have reported pupillary reactions (PR) to two wavelengths (blue & red) and polychromatic light in emmetropes (individuals with normal vision) and myopia (individuals with nearsightedness). These studies have shown that the pupillary response of emmetropes is generally more sensitive to short wavelengths of light (e.g., blue light) compared to long wavelengths (e.g. red light), while there is no consensus on myopia, with some showing the opposite response to emmetrope or others not showing a difference. The studies observing a difference have attributed it to the refractive errors and corresponding effect on the depth of focus. The understanding from chromatic PR analysis in emmetropes and myopes can provide insight into the underlying physiological differences between these two groups and has potential applications in fields such as vision rehabilitation.
Methods :
50
students (30 were myopes and 20 emmetropes) were recruited. The design for stimulus presentation was single-colours (generated by HSL values) LCD screen of a laptop fitted with a Tobii X30 eye tracker. The paradigm had 6 colour screens of purple, indigo, blue, Green, yellow, red, plus white light and no illumination , each displayed for 3 seconds interspersed with a grey light screen presented for 6 seconds. The screen and eye tracker were at 56 cm from the participant, and continuous binocular pupil size changes were captured at 30Hz. Data analysis included calculating the latency, maximum constriction/dilation (in the case of no illumination) amplitude, and maximum velocity. As a pilot study, the median values were analysed to inspect trends.
Results :
The maximum difference in latency was observed for red and no-illumination (dark) conditions, with myopes showing a significantly lower value for red and higher for dark conditions. The pupillary construction amplitude ( MCA )and the constriction velocity (MCV) values show minimal between group differences, with white light MCA being marginally lower for myopes.
Conclusions :
With the minimal dataset, a trend was observed that shows probable differential responses in measurable metrics as a function of wavelength. Further analysis would include post-illumination pupillary reflex, an indicator of intrinsically photosensitive retinal ganglion cells, to reach a consensus on the effect, if any, of refractive errors as a function of age, race, and environment on PR.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.