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C. E. Teixeira, L. C. L. Silveira, J. Kremers; Center-Surround Interactions in Flicker Perception of Glaucoma Patients. Invest. Ophthalmol. Vis. Sci. 2010;51(13):5515.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate lateral interactions in flicker perception of glaucoma patients using psychophysical methods.
Subjects matched the perceived flicker strength in a center of a reference stimulus surrounded by a simultaneously flickering annulus (50% Michelson contrast in both stimuli) by adjusting the modulation depth in a test stimulus physically identical to this center stimulus but without the annulus. Using LCD goggles synchronized to the frame rate of a CRT screen, the center and annulus could be presented monoptically or dichoptically. In the monoptic condition, center-surround interactions can have a subcortical and cortical origin. In the dichoptic condition, center-surround interactions cannot occur in the retina and the LGN and therefore isolates the cortical component. Participants were age-matched control subjects (n=7) and pre-perimetric (n=12) and perimetric (n=4) patients. Paired t test was used in statistical analysis.
The perceived flicker strength was larger when the center and annulus stimuli modulated in counterphase than when modulated in-phase. In addition, this center-surround interaction was larger in the monoptic condition. A significant difference between control subjects and perimetric patients data was found in counter-phase dichoptic condition (P=0,0402). Although no statistical difference was found between control subjects and pre-perimetric patients data (P>0.05), some pre-perimetric patients showed clearly altered perceived flicker strengths.
The evaluation of center-surround interactions in flicker perception can potentially reveal glaucomatous changes in subcortical and cortical mechanisms.
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