PMID- 15252351
OWN - NLM
STAT- MEDLINE
DCOM- 20040809
LR  - 20190911
IS  - 1040-5488 (Print)
IS  - 1040-5488 (Linking)
VI  - 81
IP  - 7
DP  - 2004 Jul
TI  - Using the Freiburg Acuity and Contrast Test to measure visual performance in USAF 
      personnel after PRK.
PG  - 516-24
AB  - PURPOSE: Photorefractive keratectomy (PRK) may be an alternative to spectacle and 
      contact lens wear for United States Air Force (USAF) aircrew and may offer some 
      distinct advantages in operational situations. However, any residual corneal haze 
      or scar formation from PRK could exacerbate the disabling effects of a bright 
      glare source on a complex visual task. The USAF recently completed a longitudinal 
      clinical evaluation of the long-term effects of PRK on visual performance, 
      including the experiment described herein. METHODS: After baseline data were 
      collected, 20 nonflying active duty USAF personnel underwent PRK. Visual 
      performance was then measured at 6, 12, and 24 months after PRK. Visual acuity 
      (VA) and contrast sensitivity (CS) data were collected by using the Freiburg 
      Acuity and Contrast Test (FrACT), with the subject viewing half of the runs 
      through a polycarbonate windscreen. Experimental runs were completed under 3 
      glare conditions: no glare source and with either a broadband or a green laser 
      (532-nm) glare annulus (luminance approximately 6090 cd/m) surrounding the 
      Landolt C stimulus. RESULTS: Systematic effects of PRK on VA relative to baseline 
      were not identified. However, VA was almost 2 full Snellen lines worse with the 
      laser glare source in place versus the broadband glare source. A significant 
      drop-off was observed in CS performance after PRK under conditions of no glare 
      and broadband glare; this was the case both with and without the windscreen. As 
      with VA, laser glare disrupted CS performance significantly and more than 
      broadband glare did. CONCLUSIONS: PRK does not appear to have affected VA, but 
      the changes in CS might represent a true decline in visual performance. The 
      greater disruptive effects from laser versus broadband glare may be a result of 
      increased masking from coherent spatial noise (speckle) surrounding the laser 
      stimulus.
FAU - Dennis, Richard J
AU  - Dennis RJ
AD  - Karta Technologies, Inc., San Antonio, TX 78232, USA. 
      richard.dennis@brooks.af.mil
FAU - Beer, Jeremy M A
AU  - Beer JM
FAU - Baldwin, J Bruce
AU  - Baldwin JB
FAU - Ivan, Douglas J
AU  - Ivan DJ
FAU - Lorusso, Frank J
AU  - Lorusso FJ
FAU - Thompson, William T
AU  - Thompson WT
LA  - eng
PT  - Journal Article
PL  - United States
TA  - Optom Vis Sci
JT  - Optometry and vision science : official publication of the American Academy of 
      Optometry
JID - 8904931
SB  - IM
MH  - Adult
MH  - Contrast Sensitivity/*physiology
MH  - Cornea/surgery
MH  - Female
MH  - Glare
MH  - Humans
MH  - Lasers, Excimer
MH  - Male
MH  - Middle Aged
MH  - Military Personnel
MH  - Myopia/*surgery
MH  - *Photorefractive Keratectomy
MH  - United States
MH  - Vision Tests/*methods
MH  - Visual Acuity/*physiology
EDAT- 2004/07/15 05:00
MHDA- 2004/08/10 05:00
CRDT- 2004/07/15 05:00
PHST- 2004/07/15 05:00 [pubmed]
PHST- 2004/08/10 05:00 [medline]
PHST- 2004/07/15 05:00 [entrez]
AID - 00006324-200407000-00013 [pii]
AID - 10.1097/00006324-200407000-00013 [doi]
PST - ppublish
SO  - Optom Vis Sci. 2004 Jul;81(7):516-24. doi: 10.1097/00006324-200407000-00013.