It’s been an exciting past year for space discovery. It seemed you couldn’t escape an aeronautical news story—from the February 2018 launch of the Tesla Roadster hitching a ride on SpaceX’s Falcon Heavy rocket to China’s robotic Chang’e 4 mission landing on the far side of the moon in January 2019, and sadly, to NASA declaring Opportunity rover dead after a remarkable 15 years exploring Mars.

Besides exploring unknown worlds beyond Earth, space exploration also helps us understand our own. Take for example, the current mission involving optical coherence tomography (OCT) technology.

In May 2018, NASA launched Heidelberg Engineering’s SPECTRALIS with the OCT2 Module to the International Space Station (ISS). Its flight aboard the Antares 230 Cygnus CRS OA-9 departed from Wallops Island, VA, and the imaging platform was placed into service in December. The instrument replaced the SPECTRALIS OCT that has been in operation at the ISS since 2013.

The purpose of the OCT’s mission is to better understand Space Flight Associated Neuro-Ocular Syndrome (SANS). By imaging the choroid and optic nerve of astronauts during flight and upon return to Earth’s gravity, it will help researchers counter the effects of SANS in future, farther, space travel.

According to NASA, the use of the OCT device will monitor the changes to crew members’ eyes during the mission and provide real-time medical evaluations to physicians on the ground. The use of OCT technology will also improve data gathering for investigations studying visual impairment and intracranial pressure in space.
Ongoing research through NASA’s Vision Impairment and Intracranial Pressure (VIIP) project has been studying the effects of long-term exposure to microgravity on the structure of the eye. Dilated fundus examinations with binocular ophthalmoscopy, cycloplegic refraction, OCT, magnetic resonance imaging (MRI) of orbits, and fundus photography for before and after space missions are just several ophthalmic procedures performed on astronauts.

In one VIIP study, 27 astronauts underwent thin-section, 3D, eye orbital, and conventional MRI brain scans. Eight astronauts underwent repeat imaging after an additional mission in space. All astronauts had previous exposure to microgravity. Image analysis of the optic nerve sheath, optic disc, posterior globe, and pituitary gland was performed and compared for association with intracranial evidence of excessive fluid buildup inside the skull, cells, tissues, or body cavities, venous blood clotting in the brain and/or mass lesion.

MRI findings suggest that intracranial hypertension is an important component to visual acuity degradation, but since not all astronauts show visual acuity degradation, existing risk factors could be to blame. By using OCT imaging they hope to better understand the cause-and-effect relationship of intracranial pressure after exposure to microgravity and who may be at risk.

Back on earth, OCT is used to diagnosis and monitor the progression of diseases such as diabetic retinopathy, retinal vascular disease, vein occlusion, artery occlusion, macular degeneration and glaucoma. In this issue, we explore how glaucoma can be monitored with OCT angiography—a feature that is on the OCT2 Module—to get a better understanding of disease progression. The latest frontier of this technology is sure to push the boundaries of treatment. ***


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