Ocular outcomes comparison between 14- and 70-day head-down-tilt bed rest

Giovanni Taibbi, Ronita L. Cromwell, Susana B. Zanello, Patrice O. Yarbough, Robert J. Ploutz-Snyder, Bernard F. Godley, Gianmarco Vizzeri

Research output: Contribution to journalArticle

14 Citations (Scopus)

Abstract

PURPOSE. To compare ocular outcomes in healthy subjects undergoing 14- and/or 70-day headdown- tilt (HDT) bed rest (BR). METHODS. Participants were selected by using NASA standard screening procedures. Standardized NASA BR conditions were implemented. Subjects maintained a 68 HDT position for 14 and/or 70 consecutive days. Weekly ophthalmologic examinations were performed in the sitting (pre/post-BR only) and HDT positions. Mixed-effects linear models compared preand post-HDT BR observations between 14- and 70-day HDT BR in best-corrected visual acuity, spherical equivalent, intraocular pressure (IOP), Spectralis OCT retinal nerve fiber layer thickness, peripapillary and macular retinal thicknesses. RESULTS. Sixteen and six subjects completed the 14- and 70-day HDT BR studies, respectively. The magnitude of HDT BR–induced changes was not significantly different between the two studies for all outcomes, except the superior (mean pre/post difference of 14- vs. 70-day HDT BR: +4.69 μm versus +11.50 μm), nasal (+4.63 μm versus +11.46 μm), and inferior (+4.34 μm versus +10.08 μm) peripapillary retinal thickness. A +1.42 mm Hg and a +1.79 mm Hg iCare IOP increase from baseline occurred during 14- and 70-day HDT BR, respectively. Modified Amsler grid, red dot test, confrontational visual field, color vision, and stereoscopic fundus photography were unremarkable. CONCLUSIONS. Seventy-day HDT BR induced greater peripapillary retinal thickening than 14-day HDT BR, suggesting that time may affect the amount of optic disc swelling. Spectralis OCT detected retinal nerve fiber layer thickening post BR, without clinical signs of optic disc edema. A small IOP increase during BR subsided post HDT BR. Such changes may have resulted from BR-induced cephalad fluids shift. The HDT BR duration may be critical for replicating microgravity-related ophthalmologic changes observed in astronauts on ≥6-month spaceflights.

Original languageEnglish (US)
Pages (from-to)495-501
Number of pages7
JournalInvestigative Ophthalmology and Visual Science
Volume57
Issue number2
DOIs
StatePublished - Feb 1 2016

Fingerprint

Head-Down Tilt
Bed Rest
Intraocular Pressure
United States National Aeronautics and Space Administration
Nerve Fibers
Fluid Shifts
Astronauts
Weightlessness
Space Flight
Color Vision
Papilledema
Visual Field Tests
Photography
Optic Disk

Keywords

  • Bed rest
  • Intraocular pressure
  • Microgravity
  • Optic disc
  • Spectralis OCT

ASJC Scopus subject areas

  • Ophthalmology
  • Sensory Systems
  • Cellular and Molecular Neuroscience

Cite this

Taibbi, G., Cromwell, R. L., Zanello, S. B., Yarbough, P. O., Ploutz-Snyder, R. J., Godley, B. F., & Vizzeri, G. (2016). Ocular outcomes comparison between 14- and 70-day head-down-tilt bed rest. Investigative Ophthalmology and Visual Science, 57(2), 495-501. https://doi.org/10.1167/iovs.15-18530

Ocular outcomes comparison between 14- and 70-day head-down-tilt bed rest. / Taibbi, Giovanni; Cromwell, Ronita L.; Zanello, Susana B.; Yarbough, Patrice O.; Ploutz-Snyder, Robert J.; Godley, Bernard F.; Vizzeri, Gianmarco.

In: Investigative Ophthalmology and Visual Science, Vol. 57, No. 2, 01.02.2016, p. 495-501.

Research output: Contribution to journalArticle

Taibbi, G, Cromwell, RL, Zanello, SB, Yarbough, PO, Ploutz-Snyder, RJ, Godley, BF & Vizzeri, G 2016, 'Ocular outcomes comparison between 14- and 70-day head-down-tilt bed rest', Investigative Ophthalmology and Visual Science, vol. 57, no. 2, pp. 495-501. https://doi.org/10.1167/iovs.15-18530
Taibbi G, Cromwell RL, Zanello SB, Yarbough PO, Ploutz-Snyder RJ, Godley BF et al. Ocular outcomes comparison between 14- and 70-day head-down-tilt bed rest. Investigative Ophthalmology and Visual Science. 2016 Feb 1;57(2):495-501. https://doi.org/10.1167/iovs.15-18530
Taibbi, Giovanni ; Cromwell, Ronita L. ; Zanello, Susana B. ; Yarbough, Patrice O. ; Ploutz-Snyder, Robert J. ; Godley, Bernard F. ; Vizzeri, Gianmarco. / Ocular outcomes comparison between 14- and 70-day head-down-tilt bed rest. In: Investigative Ophthalmology and Visual Science. 2016 ; Vol. 57, No. 2. pp. 495-501.
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N2 - PURPOSE. To compare ocular outcomes in healthy subjects undergoing 14- and/or 70-day headdown- tilt (HDT) bed rest (BR). METHODS. Participants were selected by using NASA standard screening procedures. Standardized NASA BR conditions were implemented. Subjects maintained a 68 HDT position for 14 and/or 70 consecutive days. Weekly ophthalmologic examinations were performed in the sitting (pre/post-BR only) and HDT positions. Mixed-effects linear models compared preand post-HDT BR observations between 14- and 70-day HDT BR in best-corrected visual acuity, spherical equivalent, intraocular pressure (IOP), Spectralis OCT retinal nerve fiber layer thickness, peripapillary and macular retinal thicknesses. RESULTS. Sixteen and six subjects completed the 14- and 70-day HDT BR studies, respectively. The magnitude of HDT BR–induced changes was not significantly different between the two studies for all outcomes, except the superior (mean pre/post difference of 14- vs. 70-day HDT BR: +4.69 μm versus +11.50 μm), nasal (+4.63 μm versus +11.46 μm), and inferior (+4.34 μm versus +10.08 μm) peripapillary retinal thickness. A +1.42 mm Hg and a +1.79 mm Hg iCare IOP increase from baseline occurred during 14- and 70-day HDT BR, respectively. Modified Amsler grid, red dot test, confrontational visual field, color vision, and stereoscopic fundus photography were unremarkable. CONCLUSIONS. Seventy-day HDT BR induced greater peripapillary retinal thickening than 14-day HDT BR, suggesting that time may affect the amount of optic disc swelling. Spectralis OCT detected retinal nerve fiber layer thickening post BR, without clinical signs of optic disc edema. A small IOP increase during BR subsided post HDT BR. Such changes may have resulted from BR-induced cephalad fluids shift. The HDT BR duration may be critical for replicating microgravity-related ophthalmologic changes observed in astronauts on ≥6-month spaceflights.

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