TY - JOUR
T1 - Ocular outcomes evaluation in a 14-day head-down bed rest study
AU - Taibbi, Giovanni
AU - Cromwell, Ronita L.
AU - Zanello, Susana B.
AU - Yarbough, Patrice O.
AU - Ploutz-Snyder, Robert J.
AU - Godley, Bernard F.
AU - Vizzeri, Gianmarco
N1 - Publisher Copyright:
© by the Aerospace Medical Association, Alexandria, VA.
PY - 2014
Y1 - 2014
N2 - Introduction: We evaluated ocular outcomes in a 14-d head-down tilt (HDT) bed rest (BR) study designed to simulate the effects of microgravity on the human body. Methods: Healthy subjects were selected using NASA standard screening procedures. Standardized NASA BR conditions were implemented (e.g., strict sleep-wake cycle, standardized diet, 24-hour-a-day BR, continuous video monitoring). Subjects maintained a 6° HDT position for 14 consecutive days. Weekly ophthalmological examinations were performed in the sitting (pre/post-BR) and HDT (in-bed phase) positions. Equivalency tests with optimal-alpha techniques evaluated pre/post-BR differences in best-corrected visual acuity (BCVA), spherical equivalent, intraocular pressure (IOP), Spectral-domain OCT retinal nerve fiber layer thickness (RNFLT), optic disc and macular parameters. Results: 16 subjects (12 men and 4 women) were enrolled. Nearly all ocular outcomes were within our predefined clinically relevant thresholds following HDTBR, except near BCVA (pre/post-BR mean difference: -0.06 logMAR), spherical equivalent (-0.30 D), Tonopen XL IOP (+3.03 mmHg) and Spectralis OCT average (+1.14 m m), temporalinferior (+1.58 m m) and nasal-inferior RNFLT (+3.48 m m). Modified Amsler grid, red dot test, confrontational visual field, and color vision were within normal limits throughout. No changes were detected on stereoscopic color fundus photography. Discussion: A few functional and structural changes were detected after 14-d HDTBR, notably an improved BCVA possibly due to learning effect and RNFL thickening without signs of optic disc edema. In general, 6° HDTBR determined a small nonprogressive IOP elevation, which returned to baseline levels post- BR. Further studies with different BR duration and/or tilt angle are warranted to investigate microgravity-induced ophthalmological changes. Keywords: microgravity, intraocular pressure, retinal nerve fiber layer, optimal alpha.
AB - Introduction: We evaluated ocular outcomes in a 14-d head-down tilt (HDT) bed rest (BR) study designed to simulate the effects of microgravity on the human body. Methods: Healthy subjects were selected using NASA standard screening procedures. Standardized NASA BR conditions were implemented (e.g., strict sleep-wake cycle, standardized diet, 24-hour-a-day BR, continuous video monitoring). Subjects maintained a 6° HDT position for 14 consecutive days. Weekly ophthalmological examinations were performed in the sitting (pre/post-BR) and HDT (in-bed phase) positions. Equivalency tests with optimal-alpha techniques evaluated pre/post-BR differences in best-corrected visual acuity (BCVA), spherical equivalent, intraocular pressure (IOP), Spectral-domain OCT retinal nerve fiber layer thickness (RNFLT), optic disc and macular parameters. Results: 16 subjects (12 men and 4 women) were enrolled. Nearly all ocular outcomes were within our predefined clinically relevant thresholds following HDTBR, except near BCVA (pre/post-BR mean difference: -0.06 logMAR), spherical equivalent (-0.30 D), Tonopen XL IOP (+3.03 mmHg) and Spectralis OCT average (+1.14 m m), temporalinferior (+1.58 m m) and nasal-inferior RNFLT (+3.48 m m). Modified Amsler grid, red dot test, confrontational visual field, and color vision were within normal limits throughout. No changes were detected on stereoscopic color fundus photography. Discussion: A few functional and structural changes were detected after 14-d HDTBR, notably an improved BCVA possibly due to learning effect and RNFL thickening without signs of optic disc edema. In general, 6° HDTBR determined a small nonprogressive IOP elevation, which returned to baseline levels post- BR. Further studies with different BR duration and/or tilt angle are warranted to investigate microgravity-induced ophthalmological changes. Keywords: microgravity, intraocular pressure, retinal nerve fiber layer, optimal alpha.
KW - Intraocular pressure
KW - Microgravity
KW - Optimal alpha
KW - Retinal nerve fiber layer
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U2 - 10.3357/ASEM.4055.2014
DO - 10.3357/ASEM.4055.2014
M3 - Article
C2 - 25245897
AN - SCOPUS:84907220129
SN - 0095-6562
VL - 85
SP - 983
EP - 992
JO - Aviation Space and Environmental Medicine
JF - Aviation Space and Environmental Medicine
IS - 10
ER -