Spiral scanning improves subject fixation in widefield retinal imaging

Area of Science:

• Ophthalmology
• Medical Imaging
• Biomedical Engineering

Background:

• Point scanning retinal imaging, such as confocal scanning light ophthalmoscopy (cSLO), is prone to fixational motion artifacts.
• Existing fixation targets to reduce eye motion are often bulky and complex, limiting their use in certain devices like handheld scanners.

Purpose of the Study:

• To develop and evaluate a novel spiral scanning technique for cSLO that incorporates a virtual fixation target.
• To assess the efficacy of this spiral scanning method in reducing eye motion compared to conventional raster scanning.

Main Methods:

• A new cSLO device was designed to perform spiral retinal scans under pseudo-visible illumination, projecting a virtual bullseye fixation target.
• An imaging study involved 14 volunteers comparing spiral scanning to raster scanning (with and without a physical fixation target).
• Eye motion was quantified using image registration: strip-wise for raster scans and a novel ring-based method for spiral scans.

Main Results:

• The spiral scanning technique demonstrated a statistically significant reduction in subject eye motion.
• This reduction was observed when compared to raster scanning performed without a discrete fixation target.

Conclusions:

• Spiral scanning with a virtual fixation target is an effective method for reducing eye motion artifacts in cSLO.
• This technique offers a more feasible alternative to traditional fixation targets, especially for applications requiring compact imaging devices.