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- 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?
Research Proposal Submitted to Spaceport
Cyclops: A Biomechanical Characterization of Hypergravity-Induced Globe Flattening of B. taurus for Evaluation of Spaceflight Launch and Landing Contributions to Spaceflight Associated Neuro-Ocular Syndrome(SANS)
Spaceflight Associated Neuro-Ocular Syndrome (SANS) is acollection ofimpairmentsto astronaut visual acuity associated with spaceflight and characterized by long-term altered neuro-ocular structure and function(Lee et al., 2020). SANS has beenidentified by the NASA Human System and Risk Board as a mitigationpriorityfor future manned deep-space journeys, as presently up to 75% of all astronautsexperience reduced visual acuity including persistentocular structural changes several years following long-duration spaceflight(Stenger et al., 2017; Yang et al., 2022; Lee et al., 2020).
The precise etiology of SANS is currently unclear, although extended measurementof visual acuity ispresentlyincorporated inroutine International Space Station (ISS) biometric monitoring and has been studied since the Mercury program (Lee et al., 2020; Duntley et al., 1966). ISS biometric monitoring has identifieda number of conditions characterizingSANS including bilateral optic discedema, globe flattening, choroidal and retinal folds, and hyperopic refractive error shifts (Lee et al., 2020).Theseobserved visual acuities presenttwoleading proposed etiologiesof SANS—elevated intracranial pressure (ICP) from cephalad fluid shifts and compartmentalization of cerebrospinal fluid (CSF) within the orbital optic nervesheath (Lee et al., 2020).
While ICP is generally the preferred mechanistic hypothesis for SANS, several factors challenge the ICP hypothesis. Most notably, terrestrial ICP is usually caused by idiopathic intracranial hypertension(IIH) resulting in similar physiological manifestations as SANS including optic disc edema, globe flattening, choroidal folds, or hyperopic shifts. However, despite 90% of IIH patients presenting chronic severe headaches, 68% of IIH patients presenting transient visual obscurations, and 30% of IIH patients presenting diplopia, no astronaut with identified SANS symptoms of optic disc edema, globe flattening, choroidal folds or hyperopic shifts presented with chronic severe headaches, transient visual obscurations or diplopia (Lee et al., 2020). Other discrepancies between SANS and IIH including asymmetric disc edema challenge the ICP hypothesis, introducing the possibility of additional etiological contributions from other sources of ICP outside of cephalad fluid shifts (Lee et al., 2020).
One major understudied element of spaceflight effects on visual acuity is the hypergravity environment of launch. ISS biometric monitoring including high-resolution 3-Tesla magnetic strength MR imaging of head and orbits are only collected “prior to and assoon as possible after spaceflight” (Lee et al., 2020). Several functional barriers prevent in-vivo investigation of ocular performance during launch including lack of instruments aboard launch vehicles to perform necessary biomedical monitoring such as Amsler grid, ophthalmoscopy, tonometry, fundus photography, orbital ultrasound and OCT—all available on the ISS (Lee et al., 2020). Additionally, the necessity for astronautsto remain restrained to their seats for launch safety and perform vehicle-related activity during launch limit the scope of visual acuity monitoring that may be performed during launch.
To address this gap in spaceflight hypergravity effects on visual acuity, Cyclops is a proposed sounding rocket payload experiment investigating of the biomechanical effects of hypergravity on the SANS symptom of hyperopic globe flattening of an in-vitro B. taurusocular specimen. Cyclops will specifically test the hypothesis that launch and landing conditions contribute significant gravity-induced ocular pressure in addition toICP by observing whether the amount of globe flattening observed during a sounding rocket flight is on the order of overall globe flattening levels measured in SANS-affected astronauts.
Globe flattening shall specifically be characterized through repeated in-flight axial imaging of the specimen to produce a relationship between axial length change and hypergravity pressure(Sibony et al., 2023). An example of an ultrasound globe flattening observation is provided in Figure 1., though an in-vitro sample will allow for traditional optical imaging to measurement of globe flattening without need for ultrasound.
Figure 1. Schematic of hyperopic globe flattening to be measured with Cyclops. Adapted from
Velezet al., 2017.
The payload is designed to be approximately 10 lbs. and stored within in a standard 3U Cubesat dispenser (contained completely within dims ions of 10x10x30 cm). The payload is additionally designed to be able to integrate modularly with the rest of the vehicle, with minimal interference with launch operations.