Microgravity and Vision Impairments in Astronauts - download pdf or read online

By Erik Seedhouse

ISBN-10: 3319178695

ISBN-13: 9783319178691

ISBN-10: 3319178709

ISBN-13: 9783319178707

Recent missions on board the overseas area Station have published formerly unreported physiological outcomes of lengthy period house flight, quite in eyesight, and during this short Dr. Seedhouse studies the prevailing theories on what reasons this degeneration and the way lengthy it's going to final. particularly, 60% of long-duration crews have said subjective degradation in imaginative and prescient, a transparent indication that additional learn is critical sooner than astronauts embark on even longer-term area missions. reduced near-visual acuity was once pronounced in forty six% of ISS/Mir crewmembers, leading to a transformation of as much as 2 dioptres of their refractive correction. it truly is attainable that ophthalmic adjustments were current because the first days of spaceflight, yet have been attributed to different motives; this method of the difficulty in addition to different hypotheses are all offered in complete to provide a extensive beginning of the prevailing wisdom at the subject. The alterations have happened at numerous instances in the course of a project with various levels of visible degradation. a few circumstances resolved on go back to Earth, yet a number of crewmembers haven't regained pre-flight visible acuity, indicating the wear and tear should be everlasting. One rationalization of the syndrome has been attributed to hyperopic shift because of getting older, yet onboard research suggestions, together with visible acuity tests, retinal imagery, and ultrasound exam of the attention, has resulted in the recognition of a much wider syndrome. as well as imaginative and prescient alterations, stories have stated knocking down of the globe, swelling of the optic disc (papilledema), choroidal folds within the retina, swelling of the optic nerve sheath, and visible box defects. it truly is generally hypothesized that this spectrum of signs might be defined through an elevation of intracranial strain (ICP). developing the provenance of this clinical challenge, tracking its prevalence and resolving the indicators for destiny long-term house missions is a key problem for area medication. With this booklet, readers have an access aspect for realizing the entire scope of the matter and its attainable origins.

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Extra resources for Microgravity and Vision Impairments in Astronauts

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5 The effects of cerebrospinal fluid are implicated in intracranial pressure. (Illustration courtesy of NASA) ONSD, and since this is an indication of IIH, the hypothesis of ICP being a symptom of VIIP gained some more traction [18–20]. But only some. That was because the findings were inconclusive [21], since the post-flight images were taken a long time after landing—in some cases months or years! Another drawback to what had seemed promising evidence of the ICP link was the fact there was no control group to compare the ONSD measurements with.

For example, elasticity tends to decrease with age, so older individuals may be more susceptible to visual impairment. Elasticity may also be affected by the genetic luck of the draw—some individuals may not have vessels and tissues that are particularly compliant, which is another reason to perform phenotype testing, which is discussed later. 38 4 Papilledema and Microgravity-Induced Fluid Shift Imaging The problem even when using sensitive imaging techniques is that the structures being imaged are very small.

Jacobson DM. Intracranial hypertension and the syndrome of acquired hyperopia with choroidal folds. J Neuroophthalmol 1995;15:178–85 16. Brodsky MC, Vaphiades M. Magnetic resonance imaging in pseudotumor cerebri. Ophthalmology 1998;105:1686–93 17. Cheng H, Nair G, Walker TA, et al. Structural and functional MRI reveals multiple retinal layers. Proc Natl Acad Sci USA 2006;103:17525–30. Epub 2006. Nov 6. 18. Georgouli T, James T, Tanner S, et al. High-resolution microscopy coil MREye. Eye (Lond) 2008;22:994–96.

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Microgravity and Vision Impairments in Astronauts by Erik Seedhouse

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