May 2004
Volume 45, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2004
Night Vision Goggle Visual Performance after Refractive Surgery in Army Aviators
Author Affiliations & Notes
  • K.S. Bower
    Ophthalmology Service, Walter Reed Army Med Center, Washington, DC
  • C. Van de Pol
    US Army Aeromedical Research Lab, Ft. Rucker, AL
  • J.L. Greig
    US Army Aeromedical Research Lab, Ft. Rucker, AL
  • W.E. McLean
    US Army Aeromedical Research Lab, Ft. Rucker, AL
  • J.C. Rabin
    Pacific University College of Optometry, Forest Grove, OR
  • Footnotes
    Commercial Relationships  K.S. Bower, None; C. Van de Pol, None; J.L. Greig, None; W.E. McLean, None; J.C. Rabin, None.
  • Footnotes
    Support  none
Investigative Ophthalmology & Visual Science May 2004, Vol.45, 2824. doi:
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      K.S. Bower, C. Van de Pol, J.L. Greig, W.E. McLean, J.C. Rabin; Night Vision Goggle Visual Performance after Refractive Surgery in Army Aviators . Invest. Ophthalmol. Vis. Sci. 2004;45(13):2824.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Abstract: : Purpose: The Army is considering PRK and LASIK for their aviation population. However, there are concerns about the quality of vision and the visual recovery after refractive surgery, especially under night vision goggle (NVG) conditions. This study was designed to prospectively evaluate current pilots to determine the level of impact on NVG performance. Methods: Twenty current Black Hawk pilots were tested pre–operatively and 1 week, 1 month and 6 months after randomization to PRK or LASIK surgery. High contrast acuity and contrast sensitivity at 1, 2, 4, 8 and 16 c/deg under quartermoon (0.1 cd/m2) and overcast starlight (0.001 cd/m2) conditions was measured using computer–generated stimuli (PowerPoint® and Vision WorksTM for Windows) set for the wavelength sensitivity range of standard Aviator Night Vision System (ANVIS OMNI IV) goggles. The goggle output was 4 cd/m2 at quartermoon and 0.3 cd/ m2 at starlight. Results: PRK subjects experienced a greater decrease in NVG visual acuity at one week than LASIK subjects under quartermoon conditions (0.2 logMAR versus 0.05 logMAR; p<0.01). Loss of acuity under starlight conditions was not significant at one week. By one month post–op both groups trended towards improved visual acuity under both luminance conditions (0.05 logMAR). At one week post–op PRK subjects had a greater decrease in contrast sensitivity under both luminance conditions than LASIK subjects. Under quartermoon conditions the loss was in the low spatial frequency range and under the starlight conditions it was uniform across the CSF. By 6 months post–op both groups had improved sensitivity across the CSF for the quartermoon condition, however performance under starlight conditions remained depressed at mid–frequencies for the LASIK group. Conclusions: The transient decrease and subsequent recovery of visual performance with night vision goggles is in keeping with previous studies of low luminance visual performance after refractive surgery. PRK subjects experience a greater deficit in the early post–op period due to epithelial healing processes. Once healed, NVG visual performance was essentially equivalent between PRK and LASIK for all conditions except extreme low luminance (starlight). The residual decrease in mid–frequencies for LASIK warrants further investigation.

Keywords: refractive surgery: optical quality • contrast sensitivity • refractive surgery: comparative studies 
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