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MB Baldwin, KM Mohan, V Dobson, SM Delaney, VL Ellis; The Influence of Stimulus Size on Monocular Measured Visual Field Extent in 3- and 7-Month-Old Infants . Invest. Ophthalmol. Vis. Sci. 2002;43(13):4706.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the influence of 3-dimensional peripheral stimulus size on measured visual field extent in young infants. Methods: Monocular visual fields were measured in 120 infants (for 3 and 7 months n=60 each) and 24 adults, using a double-arc perimeter (arms at 45º, 135º, 225º, 315º). The central stimulus was a ring of 8 yellow 1º-diameter LEDs illuminated sequentially during testing. The peripheral stimulus was a white sphere mounted on a black wand. Half of the subjects were tested with a 1.5º sphere and half were tested with a 6º sphere. A kinetic perimetry procedure was used, in which the subject fixated the central stimulus while an experimenter smoothly moved the white sphere along a perimeter arm toward fixation at 3.4º/sec. A trial ended when the subject looked toward the correct perimeter arm. The location of the leading edge of the sphere at the time of the eye movement was recorded. Each subject completed 8-12 trials (2-3 trials/arm). Visual field extent for each arm was the median of all trials completed on that arm. Repeated measures ANOVA was conducted, with stimulus size and age as between-subjects factors, and nasal vs temporal visual field (VF) as a within-subject factor. Results: There were main effects of nasal vs temporal VF (p<0.001, nasal visual field was larger than temporal visual field), age (p<0.001, MVFE increased with age) and stimulus size (p<0.05). Planned comparisons showed that the 6º stimulus produced larger MVFE than the 1.5º stimulus for 3-month-olds (p<0.01) and for 7-month-olds (p<0.05) but not for adults (p≷0.05). The main effects of nasal vs temporal VF and age were qualified by a significant interaction (p<0.001). Post-hoc t-tests with Bonferroni correction showed that the difference between the nasal and temporal VF increased with age (3- vs 7-mos, p=0.051; 3-mos vs adults, p=0.003; 7-mos vs adults, p=0.024). Conclusions: With 3-dimensional stimuli, increasing stimulus diameter from 1.5º to 6º enhances measured visual field extent in young infants. Research with adults has shown that this effect may be partially due to attentional factors (Mohan et al. ARVO, 2001). Further research is needed to determine whether attentional factors are influencing these results with infants.
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