Prolonged exposure to microgravity results in multiple alterations to the visual system. This issue may result in changes in vision for the astronauts and potentially makes it difficult for them to complete tasks in-flight due to these visual changes. To develop countermeasures to overcome these changes to the eye, NASA needs to monitor the retina inflight. The current equipment on the ISS to view/monitor the retina is too large, requires two astronauts to operate, requires dilation, and is prone to breaking down. As a result, images of the retina are taken very infrequently at a rate of about once per month. We are developing a small (about the size of a diver’s mask) proof-of-concept self-operated, high-resolution, wide-angle retinal imaging device designed specifically to minimize crew training, save crew time, and eliminate the need to dilate the astronaut. This proof-of-concept device which will be demonstrated to NASA and we will provide recommendations for further development leading to a device that can be used on the ISS.
Development of a Proof-of-Concept in-Flight Unobtrusive Retinal Imaging System
Ned Nestorovic, M.S.
Seattle Photonics Associates
A very high resolution imaging system and retinal illumination system will be delivered to NASA. This system will be comprised of a high-resolution optical imaging/illumination system that will be very compact (for example, could be eventually be deployed in a diver’s mask) and still meet NASA requirements. Some benefits of this technology, compared to existing retinal imaging systems on the ISS are:
- single astronaut user;
- under three-minute reading of both eyes;
- up to 40 degrees of high resolution retinal image;
- reasonably small form factor and no requirement for cabin dimming or other environmental changes.
We will use custom made lenses in the optical system. The imaging system will provide a reasonably sized eyebox to allow for variable head/eye placement. An infrared eye-safe retinal illumination system that is co-aligned with the imaging system will be delivered as well.
The system will demonstrate real-time video acquisition, using a laptop or tablet. It will also demonstrate cropping, resizing and basic stitching of two overlapping images if available. This cropping, resizing and basic stitching will be done manually and will be referenced to an existing image of the retina in the eye model. Recommendations for possible approaches to automate this process in follow-on projects will be provided.
This technology has many potential benefits and applications in the commercial market on earth. The retinal imaging device could be developed to be a:
- Low cost “at-home monitoring device” that will provide eye doctors with vital and timely images of patient’s retinas without the need to come into the office;
- Part of a kiosk health monitoring system that can provide not only a comprehensive telemedicine eye exam but an overall health assessment;
- Low-cost retina screening device in remote areas where minimally skilled health workers can provide a retinal image for doctors via a telemedicine format.