Ophthalmic changes associated with long-term exposure to microgravity

Spaceflight associated neuro-ocular syndrome (SANS) and the neuro-ophthalmologic effects of microgravity: a review and an update

“…60 The ongoing debate has prompted revisiting some of the other risk factors including carbon dioxide and in particular the role of hypercapnia in increased ICP and in terrestrial analogs (e.g., head down tilt studies) that may mimic the cephalad fluid shift. Renewed interest in the role of ICP [60][61][62][63][64][65][66][67][68][69] in SANS has led to discussion about the feasibility of performing a lumbar puncture in space despite the obvious logistical and operational challenges to an in-flight invasive procedure. [70][71][72] Non-invasive assessment of ICP have not been reliably validated on earth but ultrasound is available on the ISS and the possibility of ultrasonographic metrics (e.g., optic nerve sheath diameter, CSF in the sheath) remain an area of continued research.…”

“…Likewise terrestrial head down studies with and without hypercapnia have demonstrated increased retinal nerve fiber layer on OCT and might still prove to be a suitable terrestrial analog to test hypotheses and potential countermeasures to SANS. [73][74][75][76][77][78][79][80][81][82] These countermeasures include metabolic and pharmacologic treatments 69,[83][84][85][86][87] in the one carbon pathways; 63,69 lower body negative pressure; [74][75][76] and swim goggles to affect the translaminar pressure gradient. While current data does not seem to support prolonged, significant elevations of ICP to the levels seen in IIH, throughout LDSF, Lawley et al proposed that even mild elevations of ICP for a prolonged duration may contribute to the structural changes seen in SANS.…”

Papilloedema in a Patient with Cervical Dystony - A Case Report

“…These changes are described in literature as space-flight associated neuro-ocular syndrome [12]. One of the reasons of the syndrome also consists in the venous blood outflow disturbance on the jugular veins from the brain in the microgravity space flight [13,14]. Long observation over patients with similar pathogenesis of papilledema can bring more data for studying the influence of microgravity on the optic nerve.…”

Spaceflight-Associated Neuro-Ocular Syndrome: Clinical Features and Classification

“…Modern ophthalmological equipment has accumulated in the US section, including a tonometer to measure the intraocular pressure, an eye ultrasound system, a fundus camera to take images of the fundus, and an optical coherence tomography (OCT) system to examine the retina and optic nerve (ON). In-flight examinations are carried out by astronauts during telemedical communication with the Mission Control Center [1,2].…”

“…Tron [6] and Frisen [7] have developed papilledema staging systems based on examination of the fundus with an ophthalmo-scope and a fundus camera. However, optical coherence tomography (OCT) is the most informative method to assess the condition of the chorioidea, retina, and ON in astronauts [1].…”