| Summary: | <p>Abstract</p> <p>Background</p> <p>Fundus autofluorescence (AF) imaging using confocal scanning laser ophthalmoscopy (cSLO) provides an accurate delineation of areas of geographic atrophy (GA).</p> <p>Automated computer-assisted methods for detecting and removing interfering vessels are needed to support the GA quantification process in longitudinal studies and in reading centres.</p> <p>Methods</p> <p>A test tool was implemented that uses region-growing techniques to segment GA areas. An algorithm for illuminating shadows can be used to process low-quality images. Agreement between observers and between three different methods was evaluated by two independent readers in a pilot study. Agreement and objectivity were assessed using the Bland-Altman approach.</p> <p>Results</p> <p>The new method (C) identifies vascular structures that interfere with the delineation of GA. Results are comparable to those of two commonly used procedures (A, B), with a mean difference between C and A of -0.67 mm<sup>2 </sup>(95% CI [-0.99, -0.36]), between B and A of -0.81 mm<sup>2</sup>, (95% CI [-1.08, -0.53]), and between C and B of 0.15 mm<sup>2 </sup>(95% CI [-0.12, 0.41]). Objectivity of a method is quantified by the mean difference between observers: A 0.30 mm<sup>2 </sup>(95% CI [0.02, 0.57]), B -0.11 mm<sup>2 </sup>(95% CI [-0.28, 0.10]), and C 0.12 mm<sup>2 </sup>(95% CI [0.02, 0.22]).</p> <p>Conclusion</p> <p>The novel procedure is comparable with regard to objectivity and inter-reader agreement to established methods of quantifying GA. It considerably speeds up the lengthy measurement process in AF with well defined GA zones.</p>
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