May 2007
Volume 48, Issue 13
Free
ARVO Annual Meeting Abstract  |   May 2007
Visual Acuity, Contrast Sensitivity and Night Driving Visibility in Complaining LASIK Subjects
Author Affiliations & Notes
  • A. P. Ginsburg
    Vision Sciences Research Corp, San Ramon, California
  • S. V. Subramaniam
    Vision Sciences Research Corp, San Ramon, California
  • Footnotes
    Commercial Relationships A.P. Ginsburg, Vision Sciences Research Corp., C; S.V. Subramaniam, Vision Sciences Research Corp., E.
  • Footnotes
    Support None.
Investigative Ophthalmology & Visual Science May 2007, Vol.48, 1575. doi:https://doi.org/
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      A. P. Ginsburg, S. V. Subramaniam; Visual Acuity, Contrast Sensitivity and Night Driving Visibility in Complaining LASIK Subjects. Invest. Ophthalmol. Vis. Sci. 2007;48(13):1575. doi: https://doi.org/.

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

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Abstract

Purpose:: To determine the relationship between loss in visual acuity (VA), contrast sensitivity (CS) and night driving visibility distances in LASIK patients with unsatisfactory visual outcomes.

Methods:: This was a retrospective case control study of 21 patients who underwent bilateral conventional LASIK (Mean age = 39 ± 10.3 years). Binocular data with best correction was compared with 29 age-matched controls (Mean age = 44.9 ± 12.9 years). VA was measured using the ETDRS chart, CS by the Functional Acuity Contrast Test (FACT) chart and visibility distances of road signs/hazards by the Night Driving Simulator (NDS).

Results:: The mean logMAR VA of LASIK subjects was 0.056 ± 0.23 and that of the controls was -0.05 ± 0.06. CS was lower in LASIK subjects than the controls by 0.3 log units (50% loss) or more from 3 to 18 cpd under all visibility conditions (p=0.001). Decrease in night driving visibility for identification of road targets was greater than 25% compared to age-matched controls (p<0.001). Loss in NDS distances correlated better with loss in CS than with loss in VA. The best correlations were observed at the middle spatial frequencies of 3 and 6c/d (p<0.01), which is the peak of the human contrast sensitivity function (CSF). Regression predicted an increase in night driving identification distance loss by 37-40% in rural roads and 28-29% in city roads for an average increase in CS loss of 0.3 log units at 3 and 6c/d.

Conclusions:: Standard VA alone may be insufficient in assessing functional aspects of vision such as night driving visibility in complaining LASIK subjects. Sine-wave grating CS, in addition to VA testing, can be useful in evaluating the quality of functional vision in such patients.

Keywords: contrast sensitivity • visual acuity • refractive surgery: LASIK 
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