Developing portable widefield fundus camera for teleophthalmology: Technical challenges and potential solutions

Abstract

A portable, low cost, widefield fundus camera is essential for developing affordable teleophthalmology. However, conventional trans-pupillary illumination used in traditional fundus cameras limits the field of view (FOV) in a snapshot image, and frequently requires pharmacologically pupillary dilation for reliable examination of eye conditions. This minireview summarizes recent developments in alternative illumination approaches for widefield fundus photography. Miniaturized indirect illumination has been used to enable compact design for developing low cost, portable, widefield fundus camera. Contact mode trans-pars-planar illumination has been validated for ultra-widefield fundus imaging of infant eyes. Contact-free trans-pars-planar illumination has been explored for widefield imaging of adult eyes. Trans-palpebral illumination has been also demonstrated in a smartphone-based widefield fundus imager to foster affordable teleophthalmology.

Multispectral Fundus Photography of Choroidal Nevi with Trans-Palpebral Illumination

“…However, it presents two significant limitations for the imaging and assessment of choroidal nevi: a limited field of view (FOV) and low choroidal lesion contrast. FOV of traditional fundus cameras typically ranges from 30° to 45° visual angle (45° to 68° eye angle) as it requires careful allocation of the available pupil for both illuminating and imaging pathes 13, 14 . Consequently, it becomes challenging to detect choroidal nevi, especially those located in the periphery of the fundus.…”

Spatial and spectral dependency of trans-palpebral illumination efficiency in widefield fundus photography

“…Multi-spectral widefield fundus photography is valuable for the clinical diagnosis and management of ocular conditions that may impact both central and peripheral regions of the retina and choroid [1,2]. However, obtaining a wide field of view (FOV) poses a challenge for traditional fundus cameras, as it requires careful allocation of the available pupil for both illuminating and imaging path [3].…”

Light color efficiency-balanced trans-palpebral illumination for widefield fundus photography of the retina and choroid

“…It is technically difficult to construct wide-field fundus cameras, due to its illumination mechanisms 13 . Conventional fundus cameras utilized trans-pupillary illumination; a donut-shape patterned illumination delivered to the interior of the eye 14 .…”