Lamina Cribrosa Pore Diameter and Spacef light-Associated Neuro-ocular Syndrome

摘要

To the Editor Recently, Scott et al proposed a potentially simple treatment for spaceflight-associated neuro-ocular syndrome (SANS) with commercially available swimming goggles. The work and hypothesis of Scott et al regarding the countermea-sures for SANS was interesting. In this letter, we point out potentially anticipated consequences for the lamina cribrosa (LC) of increasing the intraocular pressure (IOP) and intra-cranial pressure (ICP). The LC has a complex, 3-dimensional collagenous structure through which the retinal ganglion cell axons pass to reach the brain. Changes in the laminar structure may cause a biological cascade leading to impaired vision, which is often observed in individuals with glaucoma and idiopathic intra-cranial hypertension. Therefore, distortion in the LC caused by changes in IOP and ICP might lead to SANS. Hydrostatic calculations of IOP and ICP at the level of the LC have indicated that they increase to 19.1 mm Hg and 12.4 mm Hg, respectively, in the -9?head-down tilt test, which simulates a microgravity environment.3 Moreover, the pore diameters in the LC of rhesus monkeys decrease with artificially increasing IOP at a fixed ICP of 10 mm Hg but increase with increasing IOP at a fixed ICP of 35 mm Hg.