Abstract
Purpose: :
Since 2003 the parapapillary autofluorescence (PAF) at zone alpha has been proven as an indicator for manifest or early glaucomatous optic neuropathy. In all former studies the scanning laser ophthalmoscopy has been used to investigate PAF. In our study, we evaluate the PAF-analysis with a modified fundus camera as a clinical alternative to the scanning laser ophthalmoscopy technique (laser scanning vs. light photography).
Methods: :
Controlled, prospective cross sectional study on 128 consecutive eyes (age: 63,9 ± 14,3 years; sex: 71 woman, 54 men). All patients were examined using the following methods: slit lamp biomicroscopy, ophthalmoscopy, applanation tonometry and medical history. The minimal visual acuity was 20/80. PAF was examined with HRA II (Heidelberg Retina Angiograph II, 3 series, 9 images each, 1 mean image) and a fundus camera (Zeiss FF450plus). A 30° large parapapillary area was investigated using both diagnostic devices. The PAF was measured with the software Heidelberg Eye Explorer® (HRA II) and the planimetric software AnalySIS® (fundus photographs). Two experienced ophthalmologists analysed the PAF.
Results: :
PAF was detected in 106 of 128 eyes. in 88 eyes with HRA II and in 84 eyes with FF450plus technique. With both methods 66 eyes showed a PAF. PAF-size and -location as well as PAF-distance in those identic eyes differed significantly. The PAF-size was measured with HRA II (0.16 ± 0.13 mm²) and FF450plus (0.11 ± 0.07 mm²; p<0.001). Mean PAF distance from the optic nerve head was 0.21± 0.18 mm² with HRA II and 0.25 ± 0.16 mm² with FF450 plus (p = 0,003). The planimetric optic nerve head excavation was measured unequal in both techniques, however the area of optic nerve head and atrophic zone alpha did not differ significantly.
Conclusions: :
For clinical use of PAF, the HRA seems to be the gold standard. A detection of PAF was possible with HRA and FF, however both methods measure a different PAF-size and -distance. Different fluorophores in zone alpha, different scan depth and overlay effects of autofluorescence in FF may be the cause of the discrepancy of PAF-measurements with both methods.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • optic nerve • ipofuscin