Purchase this article with an account.
devrim toslak, changgeng liu, Minhaj Nur Alam, Xincheng Yao; Miniaturized indirect ophthalmoscopy for nonmydriatic wide-field fundus photography. Invest. Ophthalmol. Vis. Sci. 2018;59(9):4684.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
A low-cost portable fundus imager is essential for emerging telemedicine screening of diabetic retinopathy, retinopathy of prematurity, etc. However, existing portable fundus cameras have limited field of view and frequently require pupil dilation. This study is to test the potential of using miniaturized indirect ophthalmoscopy (MIO) for constructing a low-cost, portable, nonmydriatic, wide-field fundus camera.
We have recently demonstrated MIO for mydriatic smartphone fundus photography with 92° field of view in single-shot image. Here, we refine and extend the MIO for constructing a benchtop prototype fundus camera for nonmydriatic photography. The prototype device consists a near-infrared light source for retinal guidance and a white light source for retinal illumination. A 40 diopter ophthalmic lens is used to form the aerial image of the retina. An 8mm, F2.5 micro video lens is used for relaying the image of the retina to the sensor of the camera. Once the retina is focused under near-infrared light guidance, the white light source is triggered to acquire two different images of the retina. First, infrared light is switched to visible light and one retinal image is captured. Then the optical axis of illumination light is tilted ~8° relative to the optical axis of ophthalmic lens to capture the second retinal image. The whole process takes ~300 milliseconds that is less than pupillary reaction time for visible light illumination. Incorporating the two captured images, image registration and glare elimination methods are used to remove cornea reflectance artifacts.
Figure 1 shows fundus images collected from a healthy subject. Fig.1A is the first image and Fig.1B is the second image captured by tilting the objective lens. Fig.1C is the reconstructed cornea reflectance artifact-free image with field of view at ~90° internal angle.
In coordination with near-infrared light guidance, MIO is used to achieve nonmydriatic fundus photography with 90° field of view in single-shot images. A dual-image approach, based on optical axis tilting and digital data processing, has been demonstrated to achieve cornea reflectance artifact-free imaging. This work lays out the technical foundation to develop the next-generation portable fundus camera for affordable telemedicine screening of eye diseases.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Figure 1. Single-shot (A, B) and reconstructed reflectance artifact-free (C) images.
This PDF is available to Subscribers Only