Abstract
In conventional fundus photography, trans-pupillary illumination delivers illuminating light to the interior of the eye through the peripheral area of the pupil, and only the central part of the pupil can be used for collecting imaging light. Therefore, the field of view of conventional fundus cameras is limited, and pupil dilation is required for evaluating the retinal periphery which is frequently affected by diabetic retinopathy (DR), retinopathy of prematurity (ROP), and other chorioretinal conditions. We report here a nonmydriatic wide field fundus camera employing trans-pars-planar illumination which delivers illuminating light through the pars plana, an area outside of the pupil. Trans-pars-planar illumination frees the entire pupil for imaging purpose only, and thus wide field fundus photography can be readily achieved with less pupil dilation. For proof-of-concept testing, using all off-the-shelf components a prototype instrument that can achieve 90° fundus view coverage in single-shot fundus images, without the need of pharmacologic pupil dilation was demonstrated.
Highlights
Wide field fundus photography is desirable for screening, diagnosis, and treatment evaluation of diabetic retinopathy (DR)[1,2], retinopathy of prematurity (ROP)[3,4] and other eye diseases that can produce morphological abnormalities at peripheral areas of the retina
Without the need for pharmacologic pupil dilation, we have demonstrated nonmydriatic wide field fundus photography using a smartphone-based prototype[13]
In order to verify the potential feasibility of using the trans-pars-planar illumination based fundus camera for quantitative imaging, we explored automated classification of arteries and veins, quantitative analysis of blood vessel diameter and tortuosity, and arteriolar-to-venular diameter ratio (AVR)
Summary
Wide field fundus photography is desirable for screening, diagnosis, and treatment evaluation of diabetic retinopathy (DR)[1,2], retinopathy of prematurity (ROP)[3,4] and other eye diseases that can produce morphological abnormalities at peripheral areas of the retina. Traditional fundus cameras employ trans-pupillary illumination, i.e., a donut-shaped illumination pattern projected to the peripheral area of the pupil. Additional challenges with trans-pupillary illumination include glare caused by light reflection from the cornea and crystalline lens[5,7], and the requirement of adequate pupil dilation for wide field examination. Trans-scleral illumination has been proposed as one alternative illumination method to achieve wide field fundus examination not requiring pharmacologic pupil dilation[10,11]. Trans-scleral illumination delivers the illumination light from the region outside of the pupil, and can increase the available FOV for fundus pho-. Without the need for pharmacologic pupil dilation, we have demonstrated nonmydriatic wide field fundus photography using a smartphone-based prototype[13]. Contact-free imaging is desirable for easy-to-use clinical deployments
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