Purchase this article with an account.
L. N. McLin, Jr., B. K. Foutch, J. M. Stringham, P. A. Smith, B. J. Novar, P. V. Garcia; Disability Glare From Red and Green Laser Sources. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2002.
Download citation file:
© ARVO (1962-2015); The Authors (2016-present)
Disability glare spread functions have been developed using broadband white lights as sources. However, there is little information concerning the effect of wavelength with eccentricity, and multiple sources on disability glare. This study investigated disability glare effects for red and green laser sources with different visual angle separations and intensities. Additionally, disability glare effects were investigated with respect to right vs. left visual field placement of laser glare.
A QUEST adaptive staircase algorithm was used in conjunction with a 2AFC task to determine contrast thresholds during glare exposure in nine healthy adult subjects. The stimulus was a stationary 4 cpd Gabor patch, subtending 1 degree of arc. Red (635nm) and green (532 nm) laser glare sources were placed 2.5, 5.0 and 10 degrees eccentric to the Gabor patch. Contrast thresholds were analyzed using univariate ANOVA [with an 8 (laser conditions) x 3 (eccentricities) x 2 (intensities) design.]
Contrast thresholds decreased significantly with increased laser eccentricity (F = 311, p < 0.001), and decreased laser intensity (F = 81, p < 0.001). For the single laser conditions, laser glare in the right visual field was found to be more effective than the left, regardless of wavelength (F = 3.94, p = 0.04). Despite a compensatory upward adjustment of the red irradiance relative to the green to allow for spectral sensitivity differences, there was a main effect of wavelength (F = 20.6, p < 0.001), with green laser glare shown to be more effective than red. Interestingly, however, the red:green disability glare ratio increased significantly with increased eccentricity (F = 14.63, p < 0.001). Two laser sources were more effective than a single source (F = 27.381, p < 0.001), and could be predicted by combining the effects of single nasal and temporal sources.
These results provide important new disability glare data concerning differential wavelength and multiple source effects. The differences in red and green disability glare at different eccentricities suggest a difference in the slope of red vs. green disability glare functions. The unexpected increase in disability glare from laser placement in the temporal visual field warrants further study.
This PDF is available to Subscribers Only