Comparison Among Different Diagnostic Methods In The Study Of Type And Activity Of Choroidal Neovascular Membranes In Age-Related Macular Degeneration

Abstract

Purpose: : To determine inter-observer agreement in classifying the subtypes of choroidal neovascularization (CNV), as well as in the decision of retreatment, in patients affected by exudative age-related macular degeneration (ARMD). Different imaging techniques were evaluated individually and compared to the gold standard, defined as a decision based upon all the imaging techniques.

Methods: : 35 patients with newly diagnosed CNV in ARMD were evaluated after a loading phase with 3 monthly intravitreal injections of ranibizumab. CNV subtype and activity were evaluated using optical coherence tomography (OCT), infrared (IR), fundus autofluorescence (FAF), fluorescein angiography (FA) and indocyanine green angiography (ICGA) images. The evaluation was performed independently by ten different retina specialists, two for each test. Other two operators analyzed all the information available together (gold standard). Agreement was evaluated with Cohen's k statistics. Association between single test vs gold standard was evaluated with Fisher Exact Test.

Results: : The k coefficient regarding the types of CNV was 0.63 (CI 0.40,0.86) for the gold standard, 0.62 (CI 0.42,0.83) for OCT, 0.37 (CI 0.16,0.58) for FA and 0.21 (CI -0.14,0.56) for ICGA. The k coefficient regarding the retreatment decision was 0.76 (CI 0.54,0.98) for the gold standard, 0.77 (CI 0.55,0.98) for OCT, 0.68 (CI 0.42,0.94) for IR, 0.60 (CI 0.34,0.86) for FAF, 0.26 (CI -0.07,0.58) for FA and 0.23 (CI -0.08,0.54) for ICGA. Regarding the association of the single imaging techniques compared to the gold standard in defining CNV activity, FA, OCT and IR showed good results (p=0.006, p<0.001, p=0.011, respectively). On the contrary, FAF and ICGA did not show association with the gold standard (p=0.74 and p=0.17, respectively).

Conclusions: : The results show that OCT and IR evaluations of CNV activity are reproducible and strongly associated with the gold standard. By contrast, FA evaluation is associated with the gold standard, but it shows poor reproducibility.

Keywords: age-related macular degeneration • retinal neovascularization • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)