A novel space ocular syndrome is driving technology advances on and off the planet

摘要

Astronauts are experiencing ophthalmological changes including optic disc edema, globe flattening, choroidal folds, and significant hyperopic shifts. In a handful of cases in which it was measured, intracranial pressure as measured by lumbar punctures was elevated post-flight. The severity of symptoms is highly variable and the underlying etiology is unknown, but a spaceflight associated cephalad-fluid shift is thought to play a role. NASA requires portable, non-invasive, clinically-validated approaches to assessing the ocular and the cerebral physiological, anatomical, and functional changes. Multispectral Imaging (MSI) that enables instruments installed on satellites in space to observe Earth was applied in an ophthalmic medical device that is clinically being used on Earth and now being evaluated for use on humans in space. The Annidis RHA™ (Ottawa, Canada) uses narrow band light emitting diodes (LEDs) to create discrete slices of anatomical structures of the posterior pole of the eye. The LEDs cover a frequency range from 520 to 940 nm, which allow for specific visualization of the different features of the posterior segment of the eye including retina, choroid and optic nerve head. Interestingly, infrared illumination at 940 nm reflects from the posterior sclera, retro-illuminating the choroidal vasculature without the need for invasive contrast agents. Abnormalities in retinal, choroidal or cerebral venous drainage and/or arterial flow may contribute to the microgravity ocular syndrome (MOS) in astronauts; hence this space technology may prove to be invaluable for diagnosing not only the health of our planet but also of the humans living on it and above it.