To begin, get the participant seated comfortably in front of the quantitative autofluorescence, or qAF device to ensure accurate image acquisition. Have the participant's chin and forehead pressed against the chin and headrest. Adjust the height of the chin rest until the lateral eyelid angle is at the same height as the red marking.
Then rotate the wheel on the recording device until the small vessels are in focus to ensure the image is focused in the near infrared modus. Zoom in on the eye by moving the camera forward until the image corners are evenly illuminated. As a rule of thumb, adjust the focus to the spherical equivalent.
Reduce the focus before qAF imaging by one or two diopters as blue QAF uses a shorter wavelength, and switch to the modus of the qAF device from the near infrared to the qAF mode. Readjust and upscale the illumination and fine-tune the focus of the image until the small vessels closest to the fovea are in focus and the image is brightly illuminated without red dots. To bleach the photoreceptor pigment in the field of view of the camera, wait for at least 30 seconds in the qAF mode before image acquisition.
To capture images, press Image Acquisition on the touchpad of the imaging device. Capture more than one qAF image in case of blinking or sudden eye movements during acquisition.
