Abstract
Abstract: :
Purpose: Patients with AMD have several imaging modalities carried out regularly. Combined grading of these and correlation with visual outcome has yet to be introduced into clinical practice. In this study we introduce a new grading model of autofluorescence images (AF), compare it with fluorescein angiography (FFA) and digital colour fundus photos (CL) and test for inter–intraobserver reliability.Methods: A total of 448 eyes of 224 patients with bilateral CNV due to AMD and 85 with unilateral CNV were enrolled. Of these,71 eyes of 54 patients with bilateral or unilateral CNV had CL,FFA and AF fulfilling the inclusion criterion of having all 3 types of imaging carried out on the same day or within 14 days. CL and FFA images of macula were taken by TOPCON TRC 501X fundus camera. AF was recorded with a confocal scanning laser ophthalmoscope (Heidelberg Retinal Angiograph). The grading of CL was performed with a standard grid template by a trained grader based on the International ARM classification;FFA and AF images were independently graded by 2 trained retinal specialists, using the proposed grading scale to assess inter–observer reliability. Overall,30% of all 3 types of images were re–graded after at least 14 days interval to assess intra–observer variability.Results:The Intergrader agreement was exact for classification of CNV,k =1,00; almost perfect for FFA features,k=0.83 and correspondence of decreased AF to CL,k = 0.94;substantial for patterns of decreased and increased AF,k= 0.80;k = 0.78,correspondence of patterns of increased AF to FFA and to CL,k = 0.78;k = 0.74 and background AF,k = 0.72;moderate for CNV diameter in FFA,k = 0.45,FFA pattern,k = 0.43,dimension of increased and decreased AF,k = 0.5;k = 0.56;fair for quality of FFA and AF images,k = 0.21;k = 0.26.The intragrader agreement varied from exact to substantial for all categories studied. Diffuse and reticular patterns of decreased AF and reticular pattern of increased AF were correlated to visual acuity worse than 6/24.Conclusions:This combined grading system seems reliable enough for evaluating the 3 imaging modalities at the same time and is suitable for use in epidemiological studies and therapeutic trials where such grading is warranted. Certain AF patterns can predict VA outcome better than one might have predicted based on FFA. Further studies are needed on extended patient groups to evaluate its usefulness in clinical settings for predicting VA for patients undergoing PDT.
Keywords: age-related macular degeneration • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retinal pigment epithelium