Abstract
Purpose :
Funduscopic examination clinical ophthalmology provides a sense of depth for ophthalmologists to better evaluate ocular health and disease progression. Optical coherence tomography can capture three-dimensional anatomy, but is not routinely available in the developing world. Therefore, we designed a cost-effective stereoscopic camera system able to produce optically registered photos of the fundus, which can be used for ophthalmic diagnosis and management in low resource settings.
Methods :
Fundoscopic images were taken using the Raspberry Pi (RPi) compute module 3+, RPi stereo camera module, and two 5-megapixel RPi camera modules. Each RPi camera module was encased in a 3D printed custom adapter allowing 6 degrees of freedom (forward/backward, left/right, up/down), attached to a Zeiss 6x18 T monocular, and then connected to a custom 3D printed binocular indirect ophthalmoscope case for the Heine Omega 180 (Fig 1B). The RPi camera modules’ central axes were manually aligned using text and a grid on a sample paper. The fundus was visualized through a Volk Digital Clear Field indirect ophthalmic lens that fit into a custom 3D printed focusing track. Light from the Heine Omega 180 was used for transpupillary illumination of the fundus for image acquisition. The entire image capture system was attached to an existing slit lamp for ease of test administration. All custom 3D printed parts were constructed using Polylactic Acid on the Fused Deposition Modeling 3D printer Prusa MK3. Both video capture and image acquisition were controlled by an in-house graphical user interface written in Python using the OpenCV library.
Results :
The tonal quality (brightness, contrast, color balance) of the color retinal photographs demonstrate adequate image quality for use in diagnostic evaluation. The optic nerve, macula, and retinal blood vasculature can be clearly visualized.
Conclusions :
We built an economic stereoscopic camera system that can capture clear images of the fundus, which can also be remotely accessed for teleophthalmology. Moreover, the high image quality-to-price ratio, stereoscopic function, and remote access make our camera system sustainable in developing countries.
This is a 2021 ARVO Annual Meeting abstract.