Virtually structured detection enables super-resolution imaging of rod and cone photoreceptors in awake human

Abstract

Purpose : To demonstrate the feasibility of using virtually structured detection (VSD) for super-resolution imaging of retinal photoreceptors in awake human.

Methods : A line-scanning laser ophthalmoscopy was developed in conjunction with a high-speed CMOS camera to record the two-dimension (2D) line pattern profiles at a rate of 25,000 Hz to minimize the effect of eye movements from intra-frame blur. Digital registration was implemented to further compensate for inter-frame movements, before VSD processing. An objective method was developed to derive modulation transfer function (MTF) from the line pattern profiles, and thus allowed quantitative estimation of the cut-off frequency required for VSD processing. Dynamic motility processing of photoreceptor reflectance was applied to further improve the visibility of rod and cone photoreceptors.

Results : Figure 1A illustrates a representative line-scan confocal image before VSD processing. VSD processing improved image quality (Fig. 1A2). Applying motility processing further improved the image resolution and contrast to differentiate individual rod (green arrows in Fig. 1B3) and cone (red arrows in Fig. 1B3) photoreceptors.

Conclusions : An objective method has been developed to derive MTF for quantitative estimation of the cut-off frequency required for VSD processing. In conjunction with rapid line-scan imaging, VSD enabled resolution improvement for unequivocal observation of individual retinal photoreceptors without the involvement of adaptive optics. Dynamic motility processing further enhanced the image contrast to differentiate rod and cone photoreceptors.

This is a 2020 Imaging in the Eye Conference abstract.