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A. Rosa, P. Baptista, A. Santos, M. Soares, R. Bernardes, A. Schwartz, W. Carter, J. Cunha-Vaz; Quantitative Fluorescein Angiograms. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2587.
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© ARVO (1962-2015); The Authors (2016-present)
Clinical assessment of quantitative fluorescein angiograms based on novel instrumentation adaptation.
Fluorescein angiograms were simultaneously performed on patient’s retinas and on standard cells composed of two sets of five standard fluorescein solutions mimicking the environmental conditions of the plasma and vitreous, respectively. From automatically established calibration plots (on a scan basis), regular gray-scale fluorescein angiograms were converted into absolute concentration image maps independent from instrumentation setup and operator. Diabetic retinopathy eyes, eyes before and 3 days after laser photocoagulation, and fellow-eyes from patients with choroidal neovascularization were imaged using this new technique.
Repetitive measurements over patients clearly show the advantage of correcting for instrumentation setup. Comparison of scans taken before and after laser photocoagulation demonstrates background values within the same range (serum[ng/ml]/vitreous [ng/ml]), 329/197 to 366/191 and the expected increase over laser spots of 869/352 to 2479/761, 1611/510 to 2504/766 and 435/232 to 2395/742. Background values were found to range from 170/108 to 340/160 for non-photocoagulated eyes.
Quantitative fluorescein angiograms compare favorably with conventional fluorescein angiograms by removing instrumentation setup bias and by allowing absolute concentration image maps to be built and comparable. Furthermore, the use of a non-linear color-coded map allows the detection of subtle differences not visible on regular fluorescein angiograms. It is realized that this first step needs to be complemented by other standardization procedures, e.g., by fundus reflectance.
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