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André Ruppert, Sarah Godoi, Nivaldo Sena, Katharina Messias, Rafael Arcieri, Andre Messias; Effect of Pupil Dilatation on Normative Data for Full-Field Stimulus Threshold (FST) for White, Blue and Red Stimulus Colors. Invest. Ophthalmol. Vis. Sci. 2013;54(15):685.
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© ARVO (1962-2015); The Authors (2016-present)
To describe normative data for full-field stimulus threshold (FST), measured with white, blue, red stimulus, and investigate the effects of pupil dilatation on sensitivity thresholds. In addition, data is compared to Retinitis Pigmentosa patients that show typical concentric visual field constriction, but good fixation.
Data from 20 normally sighted subjects (40 eyes) aging from 18 to 54 years (mean ± SD: 28 ± 9 years) was analyzed. FST was psychophysically determined after 25 minutes dark adaptation using Espion E2 system with the ColorDomeTM LED full-field stimulator (Diagnosys LLC, Lowell, MA), using white (6500 K), blue (465 to 470 nm), and red (635 to 638 nm) stimulus. Only left eyes pupils were dilated for comparison. Data was compared to results from 15 Retinitis Pigmentosa (RP) patients (n=30 eyes).
There was statistically significant difference between FST measured on dilated (DP) vs. non-dilated (nDP) pupils for white stimulus: 43.5 ± 1.0 dB and 41.0 ± 1.0 dB (P=0.0011) and blue: 49.6 ± 1.0 dB and 48.2 ± 0.9 dB(P=0.0084; paired t-Test), for DP and n-DP respectively, but this difference was not observed for the red stimulus: 25.6 ± 0.9 dB and 25.3 ± 0.7 dB (P=0.3303). Mean FST was significantly lower (P<0.05) in RP patients, and the difference between normal and RP was higher for white: 26.3 ± 1.7 dB and blue: 28.4 ± 2.0 dB; than for red stimulus: 12.0 ± 1.2 dB (P<0.05).
The data suggests that pupil dilatation has significant influence on FST for white and blue, but not for red stimulus, and this might be explained by the higher concentration of the red-sensitive photoreceptors on the central retina. As expected, the differences between FST in normal and RP patients are higher for blue and white than for red stimulus.
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