Dataset Information

Neuro-ophthalmological changes in healthy females exposed to a 5-day dry immersion: a pilot study.

ABSTRACT: After exposure to microgravity, astronauts undergo microgravity-induced thoraco-cephalic fluid shift, which may lead to ocular changes called "spaceflight associated neuro-ocular syndrome" (SANS). The onset of SANS may be multifactorial, including a potential elevation in intracranial pressure. Moreover, little is known about the impact of spaceflight on SANS in women due to the fact that fewer female astronauts have spent time in long-term missions. The objective is to determine whether similar ophthalmological changes occur in healthy women after short-term exposure to microgravity. The auto-refractometer was used to determine objective refraction. The best corrected distance visual acuity was assessed with a Monoyer chart. The ocular axial length was assessed using optical biometry. The applanation tonometry was used to determine intraocular pressure. Peripapillary retinal nerve fibre layer thickness (pRNFLT), macular total retinal thickness, and ganglion cell complex (GCC) were measured using optical coherence tomography. Ocular axial length is reduced after DI. pRNFL is thickest after DI specifically in the temporal, temporal-inferior, and nasal-inferior quadrants. Macular total retinal at the inferior quadrant of the 6-mm ring is thickest after DI. Global GCC is thinnest after DI. In this study, 5 days of DI induces slight but significant ophthalmological changes in women. However, these subtle changes do not correspond to criteria defined in SANS.

SUBMITTER: Kermorgant M

PROVIDER: S-EPMC10784282 | biostudies-literature | 2024 Jan

REPOSITORIES: biostudies-literature

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Neuro-ophthalmological changes in healthy females exposed to a 5-day dry immersion: a pilot study.

Kermorgant Marc M Chedmail Thibault T Varenne Fanny F Bareille Marie-Pierre MP Beck Arnaud A Billette de Villemeur Rebecca R Fournié Pierre P Grondin Lisa L Hélissen Ophélie O Membrives Charlotte C Nasr Nathalie N Pavy-Le Traon Anne A Soler Vincent V

NPJ microgravity 20240111 1

After exposure to microgravity, astronauts undergo microgravity-induced thoraco-cephalic fluid shift, which may lead to ocular changes called "spaceflight associated neuro-ocular syndrome" (SANS). The onset of SANS may be multifactorial, including a potential elevation in intracranial pressure. Moreover, little is known about the impact of spaceflight on SANS in women due to the fact that fewer female astronauts have spent time in long-term missions. The objective is to determine whether similar ...[more]

PMID: 38212301

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Project description:Dry immersion (DI) is a Russian-developed, ground-based model to study the physiological effects of microgravity. It accurately reproduces environmental conditions of weightlessness, such as enhanced physical inactivity, suppression of hydrostatic pressure and supportlessness. We aimed to study the integrative physiological responses to a 3-day strict DI protocol in 12 healthy men, and to assess the extent of multi-system deconditioning. We recorded general clinical data, biological data and evaluated body fluid changes. Cardiovascular deconditioning was evaluated using orthostatic tolerance tests (Lower Body Negative Pressure + tilt and progressive tilt). Metabolic state was tested with oral glucose tolerance test. Muscular deconditioning was assessed via muscle tone measurement. Results: Orthostatic tolerance time dropped from 27 ± 1 to 9 ± 2 min after DI. Significant impairment in glucose tolerance was observed. Net insulin response increased by 72 ± 23% on the third day of DI compared to baseline. Global leg muscle tone was approximately 10% reduced under immersion. Day-night changes in temperature, heart rate and blood pressure were preserved on the third day of DI. Day-night variations of urinary K+ diminished, beginning at the second day of immersion, while 24-h K+ excretion remained stable throughout. Urinary cortisol and melatonin metabolite increased with DI, although within normal limits. A positive correlation was observed between lumbar pain intensity, estimated on the second day of DI, and mean 24-h urinary cortisol under DI. In conclusion, DI represents an accurate and rapid model of gravitational deconditioning. The extent of glucose tolerance impairment may be linked to constant enhanced muscle inactivity. Muscle tone reduction may reflect the reaction of postural muscles to withdrawal of support. Relatively modest increases in cortisol suggest that DI induces a moderate stress effect. In prospect, this advanced ground-based model is extremely suited to test countermeasures for microgravity-induced deconditioning and physical inactivity-related pathologies.

Project description:Introduction: A decrease in sleep quality and duration during space missions has repeatedly been reported. However, the exact causes that underlie this effect remain unclear. In space, sleep might be impacted by weightlessness and its influence on cardiovascular function. In this study, we aimed at exploring the changes of night sleep architecture during prolonged, 21-day Dry Immersion (DI) as one of the ground-based models for microgravity studies and comparing them with adaptive changes in the cardiovascular system. Methods: Ten healthy young men were exposed to DI for 21 days. The day before (baseline, B-1), on the 3rd (DI3), 10th (DI10), and 19th (DI19) day of DI, as well as in the recovery period, 1 day after the end of DI (R + 1), they were subjected to overnight polysomnography (PSG) and ambulatory blood pressure monitoring. Results: On DI3, when the most severe back pain occurred due to the effects of DI on the spine and back muscles, the PSG data showed dramatically disorganized sleep architecture. Sleep latency, the number of awakenings, and the duration of wake after sleep onset (WASO) were significantly increased compared with the B-1. Furthermore, the sleep efficiency, duration of rapid eye movement sleep (REM), and duration of non-rapid eye movement stage 2 decreased. On DI10, subjective pain ratings declined to 0 and sleep architecture returned to the baseline values. On DI19, the REM duration increased and continued to rise on R + 1. An increase in REM was accompanied by rising in a nighttime heart rate (HR), which also shows the most significant changes after the end of DI. On DI19 and R + 1, the REM duration showed opposite correlations with the BP parameters: on DI19 it was negatively associated with the systolic BP (SBP), and on R + 1 it was positively correlated with the diastolic BP (DBP). Conclusion: An increase in REM at the end of DI and in recovery might be associated with regulatory changes in the cardiovascular system, in particular, with the reorganization of the peripheral and central blood flow in response to environmental changes.

Dataset Information

Neuro-ophthalmological changes in healthy females exposed to a 5-day dry immersion: a pilot study.

Publications

Neuro-ophthalmological changes in healthy females exposed to a 5-day dry immersion: a pilot study.

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