Repeatability and reliability of quantitative fundus autofluorescence imaging in patients with early and intermediate age‐related macular degeneration

Abstract

Purpose Quantification of fundus autofluorescence has only recently become available. We report our findings on the evaluation of the repeatability and reliability of quantitative fundus autofluorescence (qAF) measurements in patients with early and intermediate age‐related macular degeneration (AMD), using the first approved and commercially available instrument. Methods A total of 43 eyes of 22 patients (aged between 52 and 84 years) diagnosed with early and intermediate AMD were included. All eyes were imaged at day 1, 3 months and 6 months using a modified scanning laser ophthalmoscope, equipped with an internal fluorescent reference. Mean qAF values were calculated for the fovea and for each concentric ring of the Delori pattern. Repeatability and reliability were calculated using Bland–Altman analysis and intraclass correlation (ICC). Results The mean patient age was 73.5 ± 7.9 years. Sixteen patients (73%) were female. qAF repeatability of the eight segments in the middle ring of the Delori pattern (qAFM8) for between sessions was ±8.2%. Agreement at 3‐ and 6‐month follow‐up in eyes without retinal changes was ±8.3% and ±9.8%, respectively. Reliability of qAFM8 was high for all images acquired [ICC = 0.98 (CI: 0.96–0.99), 0.97 (0.93–0.99) and 0.98 (0.92–0.99)]. Agreement at 3‐ and 6‐month follow‐up in eyes with retinal changes was ±18.1% and ±20.2%, respectively. Intraclass correlation (ICC) was slightly lower in eyes with retinal changes at 0.93 (0.84–0.97) and 0.96 (0.91–0.98), respectively. Conclusions Quantitative autofluorescence shows excellent repeatability and reliability as well as follow‐up agreement in patients with early and intermediate AMD without retinal changes. This is relevant when conducting longitudinal studies using qAF.

Impact of Drusen Volume on Quantitative Fundus Autofluorescence in Early and Intermediate Age-Related Macular Degeneration

“…However, we did exclude patients with considerable cataract and believe by proper evaluation, age correction, as well as statistical model we were able to avoid the effect of lens status on qAF. Another limitation from using qAF is that it shows same session repeatability of approximately 68.0% in patients with AMD, 34 which may potentially affect the short-term association due to minor changes in drusen volume. Although drusen volume has been described as a monitoring marker in early and interme- diate AMD with adequate repeatability and reproducibility, qAF changes might be better detectable in long-term studies.…”

“…32 Quantitative autofluorescence (qAF), a method recently presented by Delori et al, 33 quantifies FAF signals by using a cSLO modified by an internal reference and shows good reliability and repeatability in patients with AMD. 34 The FAF signal distribution shows the signal is at its minimum at the fovea due to absorption by macular pigment and maximum between 78 and 158 from the fovea, with a peak in the superotemporal region. 20,35 Patients with AMD have been found to have overall lower levels of qAF than healthy agematched individuals.…”

Quantitative Fundus Autofluorescence in Systemic Chloroquine/Hydroxychloroquine Therapy

“…This enables comparison of AF intensities intra-and interindividually, as well as in long-term follow-up. 24 As for conventional short wavelength FAF, QAF has shown good repeatability 25 and can serve as a diagnostic tool for the healthy and diseased retina, especially in diseases with high potential of FAF alterations in the course of the disease or during treatment. [26][27][28] The purpose of this study was to use the experimental QAF technique in addition to the recommended screening tests in patients routinely examined at our department due to systemic CQ/HCQ intake.…”

Quantitative Fundus Autofluorescence: Advanced Analysis Tools

“…This standard reference is simultaneously excited during each FAF image acquisition and the FAF images can then be normalized to the standard reference signal, independent of camera and image acquisition settings. 13 Since then, QAF has been performed in studies with healthy 14,15 and diseased eyes, such as in AMD, hereditary retino-/maculopathies, [16][17][18][19][20][21] and inflammatory diseases. 22 The analysis of QAF fundus images, however, still remains fragmentary because only a small area of the posterior pole is used for analysis.…”