RetmarkerAMD® (Retmarker SA, Coimbra, Portugal) is a semiautomatic grading software developed specifically for age-related macular degeneration (AMD). Pilot studies demonstrated higher sensitivity and specificity than manual grading and attested its capacity to decrease grading time and identify more AMD features, thus reducing human error . The aim of this study was to validate RetmarkerAMD® as an AMD grading tool, by comparing it with an already validated and widely used platform—Topcon IMAGEnet2000®.
Multicentre, cross-sectional study. A set of 202 colour fundus photographs (CFPs) randomly selected from a pool of eyes with and without AMD were used. All images had previously been graded by a senior retina specialist (gold standard) using Topcon IMAGEnet2000®. Two certified graders with different experience independently classified all CFPs using both platforms (Fig. 1; Supplemental Fig. 1) after brightness, contrast and colour balance standardization . Conversion of AMD staging from the Rotterdam classification to the AREDS  classification (Supplemental Tables 1 and 2) was achieved to allow a comparison between platforms.
Intra- and inter-grader agreement was evaluated by the percentage of agreement and the weighted Kappa coefficient considering linear weights .
The inter-grader analysis for all features analysed with RetmarkerAMD® is shown in Table 1. For AMD staging alone, an almost perfect agreement (93.0%; Kappa = 0.95, p < 0.001) was observed. The same was true for AMD staging using Topcon IMAGEnet2000® (90.1%; Kappa = 0.87, p < 0.001). Both graders showed a high agreement with the gold standard (90.1%; Kappa = 0.88, p < 0.001 and 87.1%; Kappa = 0.86, p < 0.001 for graders 1 and 2, respectively). Regarding the inter-modality analysis (Supplemental Table 3), a 76.8% agreement (Kappa = 0.73, p < 0.001) and a 70.8% agreement (Kappa = 0.67, p < 0.001) was observed for graders 1 and 2, respectively.
This study aimed to validate RetmarkerAMD® as a semiautomatic grading software for the fundoscopic changes associated with AMD. We used CFP because of its reproducibility and loyalty to clinical fundoscopy, making it easy to extrapolate results to clinical practice.
Regarding AMD staging, a considerably high agreement was found in both platforms. Subtle differences between graders may have been influenced by a higher level of experience of grader 1. In fact, grader experience is a factor used across studies to justify discrepancies on agreement analyses .
The comparison of intra-grader analyses using the two software systems revealed a substantial agreement. The clear overlap between early and intermediate stages where subtle and somewhat arbitrary differences are seen may have influenced the results. Classification bias may also have been introduced due to the conversion of the Rotterdam classification into the AREDS classification.
Despite several advantages, RetmarkerAMD® presents some limitations. First, it demands lesion identification by a human grader, a rate limiting and fatigable process. Second, this platform is not prepared to grade optical coherence tomography, a rapidly growing technology with promising outcomes in automatic and semiautomatic AMD grading.
By conducting a carefully planned study, we were able to demonstrate that RetmarkerAMD® is a reliable and consistent semiautomated grading tool for AMD. The validation of RetmarkerAMD® may prompt its use both in clinical studies and in clinical trials.
Marques JP, Costa M, Melo P, Oliveira CM, Pires I, Cachulo ML, et al. Ocular risk factors for exudative AMD: a novel semiautomated grading system. ISRN Ophthalmol. 2013;2013:464218.
Tsikata E, Lains I, Gil J, Marques M, Brown K, Mesquita T, et al. Automated brightness and contrast adjustment of color fundus photographs for the grading of age-related macular degeneration. Transl Vis Sci Technol. 2017;6:3.
Age-Related Eye Disease Study Research G. The Age-Related Eye Disease Study system for classifying age-related macular degeneration from stereoscopic color fundus photographs: the Age-Related Eye Disease Study Report Number 6. Am J Ophthalmol. 2001;132:668–81.
Landis JR, Koch GG. The measurement of observer agreement for categorical data. Biometrics. 1977;33:159–74.
Scholl HP, Peto T, Dandekar S, Bunce C, Xing W, Jenkins S, et al. Inter- and intra-observer variability in grading lesions of age-related maculopathy and macular degeneration. Graefes Arch Clin Exp Ophthalmol. 2003;241:39–47.
Conflict of interest
The authors declare that they have no conflict of interest.
Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
About this article
Cite this article
Marques, J.P., Pires, J., Simão, J. et al. Validation of RetmarkerAMD as a semiautomatic grading software for AMD. Eye 34, 600–602 (2020). https://doi.org/10.1038/s41433-019-0624-7