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Jena Tavormina, Ronald Hansen, Anne Moskowitz, Anne Fulton; Scotopic Spatial Summation in Retinopathy of Prematurity (ROP). Invest. Ophthalmol. Vis. Sci. 2013;54(15):5080.
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© ARVO (1962-2015); The Authors (2016-present)
To study scotopic spatial summation in children with a history of retinopathy of prematurity (ROP). Full-field electroretinograms give evidence of photoreceptor and post-receptor dysfunction in ROP subjects but provide no spatial information. Spatial summation is thought to depend on pooling of information by the post-receptor neural retina.
To determine the critical diameter for complete spatial summation, we are measuring rod-mediated thresholds for detection of brief-duration stimuli ranging from 0.4 to 10 degrees in diameter. Dark-adapted subjects with a history of ROP (N=5; median age 13 years) and age-similar controls (N=4; median age 14 years) have been tested. A two-alternative spatial forced choice method was used in conjunction with a staircase procedure. Stimuli were presented 20 degrees to the right or left of a central fixation target.
The median critical diameter for complete summation was 1.61 (range: 1.36 to 1.91) degrees in the ROP subjects and 1.30 (range 1.19 to 1.36) degrees in the controls. Critical diameter was significantly larger in ROP subjects (Fisher’s Exact Test, p=0.048). Interestingly, for the largest stimuli, thresholds in ROP subjects did not differ significantly from those in controls.
These results suggest a coarser spatial grain in the ROP retina. Pooling over a larger region may allow ROP subjects to achieve a normal threshold.
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