Reproducibility of fundus autofluorescence measurements obtained using a confocal scanning laser ophthalmoscope

Aim-To evaluate the reproducibility of the background fundus autofluorescen ce measurements obtained using a confocal scanning laser ophthalmoscope. Methods-10 normal volunteers and 10 patients with retinal disease were incl uded in the study. One eye per subject was chosen randomly. Five images of the same eye of each individual were obtained, after pupillary dilatation, by two investigators using a confocal scanning laser ophthalmoscope. Backgr ound fundus autofluorescence was measured at 7 degrees temporal to the fove a in normal volunteers and between 7 and 15 degrees temporal to the fovea i n patients. Within session reproducibility of the measurements obtained by each investigator and interobserver reproducibility were evaluated. Results-For investigator 1 the median values of fundus autofluorescence obt ained were 31.9 units for normal volunteers and 27.3 units for patients. Th e median largest difference in readings in normal volunteers was 5.7 units (range 1.4-13.5 units) and in patients 4.2 units (1.5-15.1 units). For inve stigator 2 the median values of fundus autofluorescence obtained were 28.9 units for normal volunteers and 27.4 units for patients. The median largest difference in readings in normal volunteers was 3.6 units (2.7-11.7 units) , and in patients 4.1 units (1.5-9.3 units). The median interobserver diffe rence in readings in normal volunteers was 3.3 units and for patients 6.6 u nits. The median greatest interobserver difference in measurements obtained for normal volunteers was 8.8 units (8.4-23.0 units) and for patients 11.1 units (7.1-40.8 units). Conclusion-Within session reproducibility of the measurements of background fundus autofluorescence was satisfactory. Although interobserver reproduci bility was moderate, the variability of the measurements of fundus autofluo rescence between observers appears to be small when compared with variation in fundus autofluorescence with age and disease.