Nasa – prospective observational study of ocular health in iss crews electricity bill nye


The purpose of this study is to collect evidence to characterize the risk and define the visual changes, vascular changes, and central nervous system (CNS) changes, including intracranial pressure, observed during long-duration exposure to microgravity, including postflight time course for recovery to baseline. This study gathers information that can be used to assess the risk of Microgravity-Induced Visual Impairment/Intracranial Pressure (VIIP) and guide future research needs.

1. It is expected that some crew members may experience meaningful and detectable in-flight changes in at least one or more of the following: clarity of vision (visual acuity), pressure inside the eyeball (intraocular pressure), swelling of the optic disc (optic disc edema or papilledema), folds in the vascular layer of the eye (choroidal folds), optic nerve sheath distention, elongation of the optic nerve resulting from an increase in cerebrospinal fluid or CSF (optic nerve tortuosity), optic nerve-to-sheath ratio, flattening of the back part of the eye (globe flattening), and retinal "cotton-wool spots" (retinal nerve cells damaged by lack of blood flow), cardiovascular and cerebrovascular compliance and intracranial pressure.

2. It is expected that some crew members may experience meaningful pre- to postflight changes in one or more of the following: visual acuity, intraocular pressure, optic disc edema (papilledema), retinal nerve fiber layer, choroidal folds, optic nerve sheath distention, optic nerve tortuosity, globe flattening, retinal "cotton-wool spots", smaller changes in blood volume relative to increases in blood pressure (vascular compliance), intracranial pressure, increased CSF production, signs of elevated CSF pressure (pituitary concavity), and areas of constriction within veins of the brain.

Intraocular Pressure and Blood Pressure: Intraocular pressure (IOP) is the fluid pressure of the aqueous humor inside the anterior chamber of the eye. Tonometry is performed on the right and left eye using a commercial tonometer. In preparation for the measurement, 2 drops of Proparacaine, an anesthetic, are administered in each eye. The operator stabilizes the subject’s head and gently taps the tonometer tip to the clear surface of the open eye, directly over the pupil, to obtain the measurement. At least one operator per increment must be trained to collect data. Prior to data collection, the operator practices on the "eye simulator" to establish operator precision and accuracy. Tonometry cannot be effectively performed on oneself using the Tono-pen® tonometer; therefore, if the operator also participates as a subject, a second operator must be trained. Immediately prior to tonometry, a blood pressure measurement is obtained after 5 minutes of rest. After completing tonometry, an 8-hour rest is required prior to performing any other ocular test (overnight preferred).

Results from Ocular Health address several gaps in current knowledge, including physical and functional changes in the eyes during and after spaceflight. Systematic measurements of the visual, vascular, and central nervous system can inform future research, and develop countermeasures to safeguard crew members’ vision. In addition, results can demonstrate the potential risk for crews on long-duration space missions. If microgravity is entirely or partially responsible for changes to the visual system, crews operating on missions five times longer than current space station expeditions may be negatively impacted.

Ocular Health provides insight into structural changes that can occur in the eyes and nervous system, which could be relevant for patients suffering from a wide range of ocular diseases, such as glaucoma. It also provides data that could be used to help patients suffering from brain diseases, such as hydrocephalus and high blood pressure in the brain.

A total of 12 subjects are required for this investigation. In-flight sessions are planned at FD10, FD30, FD60, FD90, FD120, and R-30 for a mission duration of six months and FD10, 30, 90, 150, 210, 270, and R-30 for a mission duration of one year. Tolerance for each test session is +7 days, with at least 14 days between the last test of one FD session and the first test of the next FD session. All activities associated with the session required on a given FD may occur within a 5 day window. Both an operator and a subject are required for the ultrasound scans, fundoscopy, tonometry, OCT, and blood pressure, along with real-time video downlink to enable remote guidance by ground experts.