Purpose:
To investigate the effect of spaceflight on human eyeballs (particularly during ascent, not microgravity). This seeks to provide more insight into what could be the cause of Spaceflight Associated Neuro-Ocular Syndrome (SANS)- a visual-impairment condition experienced by approximately 70% of astronauts which still has an unknown cause.
Existing Research:
- Very little research on ascent – hence why this is interesting!
- Expected that this is determined by elastic properties of the optic nerve (and maybe eye) which would be affected if the eyeballs are squished launch and landing – https://pure.rug.nl/ws/portalfiles/portal/133399769/1_s2.0_S0142961219308397_main.pdf
- Closest we get is this: (Tl; dr: they started measuring 21 minutes after weightlessness still on flight but not during the initial time period of launch itself)
In 1994 a Russian publication provided evidence of ICP measurements during shortduration spaceflight in a Macaque monkey named Krosh on the biosatellite Cosmos-2229 (Krotov et al. 1994). A surgically implanted pressure sensor was placed in contact with the dura mater 25-30 days before launch. ICP was measured during seven 5-minute sessions throughout the 20 hours before launch, continuously for 2 hours starting 21 minutes after entering weightlessness, and then for 5 minutes every 2 hours throughout the duration of the flight. Before launch, while in the rocket on the launch pad, ICP in the “physical mid-position” (head and legs at the same level) averaged 10.23 ± 0.12 mmHg (range: 8.5 – 12.1 mmHg). During the final 2 hours before flight the average ICP was 11.66 ± 0.09 mmHg. Twenty-two minutes after entering weightlessness ICP was 13.78 mmHg and continued to increase to ~15 mmHg over the first few hours. By flight days 3 to 5 ICP reached an average of 14 mmHg, driven in large part by increased ICP during the night. Conversely, from flight days 6 to 9 ICP was higher during the day than at night and the average ICP returned to values that were similar to preflight baseline. Disruption in the sleep-wake cycle throughout the mission led to the changes in the circadian pressure rhythm such that ICP was higher at night than during the day on flight day 8 and 9. The ICP pulse also demonstrated changes during weightlessness, with a decrease in amplitude of the arterial component and an increase in amplitude of the venous component. This also tended to return toward preflight morphology during flight days 5 to 9. In comparison to the 4 mmHg change in ICP observed from preflight to weightlessness, posture changes on Earth (moving the monkey from upright to supine) increased ICP by 10 mmHg.
Source: https://humanresearchroadmap.nasa.gov/Evidence/reports/SANS.pdf
Potentially Related Phenomenon:
- hyperopia: eye condition in which deformations in anatomical geometry of the eye result in farsightedness
Velez, G., Tsang, S. H., Tsai, Y.-T., Hsu, C.-W., Gore, A., Abdelhakim, A. H., Mahajan, M., Silverman, R. H., Sparrow, J. R., Bassuk, A. G., & Mahajan, V. B. (2017). Gene therapy restores Mfrp and corrects axial eye length. Scientific Reports, 7(1). https://doi-org.ezproxyberklee.flo.org/10.1038/s41598-017-16275-8
Our Research Objective:
To measure eye deformation experienced during ascent to inform whether or not changes in eye elasticity could be a cause of SANS.
An overview of how we intended to conduct this research:
- place eyeballs within the payload of our rocket and collect images of them during ascent
- analyze these images for any deformations in the eye
Experimental specifics:
- Raspberry Pi cameras would be used to collect images of the eyes
- LEDs would be placed inside the pressure vessel so that there would be enough light to capture images of the eyes
- cow eyeballs would be used (since applying this experiment to human eyeballs would be invasive) and would be oriented facing upward (similar to how astronauts face upward during rocket launches)
- three eyeballs would be used to provide more data (preferably more eyeballs, but limited to three due to other design constraints)
- the eyes would be secured within a pressure vessel (to prevent other factors from deforming the eyeballs)
- vibration damping materials would surround the pressure vessel, to ensure the eyes remain secured
Unanswered research problems:
- How do we ensure the eyeballs remained preserved while they are in the rocket? (especially since launch is in New Mexico during the summer)
- proposed potentially using ice packs to surround the eyeballs (likely outside of the pressure vessel)
- Will our current measures be enough to ensure the eyeballs do not move around during launch?
- How can we recover the images after launch?
- How can we measure and how do we quantify our results? Will the image quality of the recovered data be sufficient to depict any notable changes in eye shape?