Evaluation of Autofluorescence Imaging with the Scanning Laser Ophthalmoscope and the Fundus Camera in Age-related Geographic Atrophy

Purpose

To compare fundus autofluorescence images (FAF) between a modified fundus camera (mFC) and a confocal scanning laser ophthalmoscope (cSLO).

Design

Evaluation of diagnostic technology.

Methods

Thirty-two eyes of 16 patients with age-related geographic atrophy (GA) treated in an institutional setting were included. FAF images were obtained with both the cSLO (excitation, 488 nm; emission, > 500 nm) and the mFC (excitation, approximately 500 to 610 nm; emission, approximately 675 to 715 nm). Using established algorithms, images were graded by two independent observers and agreements were evaluated. The main outcome measures were image quality, quantification of total atrophy, and classification of FAF patterns.

Results

In two eyes with advanced cataract (lens grade 7 according to the Age-Related Eye Disease Study classification), FAF image quality with both systems was not sufficient for any meaningful analysis. In the remaining 30 eyes, the mean differences of the interobserver agreements for atrophy quantification were 0.16 mm² (95% confidence interval [CI], 0.07 to 0.38) for mFC and 0.15 mm² (95% CI, −0.04 to 0.33) for cSLO images. Because of inferior signal-to-noise ratios, FAF pattern classification was possible in a lower number of mFC images (69%) compared with cSLO images (88%).

Conclusions

This study suggests that the agreements for atrophy quantification are similar with both devices. The lesser visualization of FAF patterns with the mFC and thus inferior determination of disease markers may be the result of the nonconfocality and the use of single instead of mean images compared with the cSLO. These findings may be important for the design of interventional trials as well as the routine use of FAF imaging in age-related geographic atrophy.