Parapapillary autofluorescence as indicator for glaucoma

BACKGROUND: A pronounced fundus autofluorescence (lipofuscin) occurs in eyes with AMD. Parapapillary lipofuscin accumulation in the retinal pigment epithelial cells was observed in eyes with advanced glaucoma histologically. The aim of this study was to evaluate the parapapillary autofluorescence (PAF) in vivo in healthy eyes (controls), and in eyes with primary open angle glaucoma (POAG), pseudoexfoliation glaucoma (PSXG) or normal tension glaucoma (NTG). PATIENTS AND METHODS: Controlled cross-sectional analysis was performed on 281 consecutive eyes (98 controls, 95 POAG, 32 PSXG, 56 NTG). Eyes with fundus pathologies were excluded. The confocal scanning laser ophthalmoscope HRA II (Heidelberg Retina Angiograph II) was used after lipofuscin-excitation with an argon blue laser (488 nm) to detect PAF in the spectrum above 500 nm. PAF area and PAF distance to the optic nerve head were analyzed using the HRA standard software. Two experienced ophthalmologists classified independently the stage of glaucomatous optic nerve head atrophy (GONHA) using 15 degrees fundus photographs. RESULTS: Vital optic nerve heads had smaller PAF areas (stage 0: 0.07 +/- 0.09 mm (2)) in contrast to advanced stages of GONHA (stages 1 to 4: 0.27 +/- 0.46 mm (2); p < 0.001; logistic regression Cox and Snell: r = 0.7; p = 0.015). The PAF distance to the optic nerve head was lower in controls (0.12 +/- 0.08 mm) than in eyes with POAG, PSXG, or NTG (0.25 +/- 0.21 mm, Bonferroni: p < 0,004). The PAF area correlated significantly with the stage of GONHA (stage 1: 0.23 +/- 0.23 mm (2), stage 2: 0.24 +/- 0.19 mm (2), stages 3 and 4: 0.34 +/- 0.73 mm (2), p < 0.01). No significant difference of PAF area was found between the glaucoma types. However, the distance between PAF and optic nerve head was higher in POAG (0.28 +/- 0.26 mm) than in NTG (0.24 +/- 0.07 mm) or in PSXG (0.18 +/- 0.07 mm, Bonferroni: p < 0.03). CONCLUSIONS: A pronounced fundus autofluorescence was detected as a sign of increased lipofuscin accumulation in the parapapillary atrophic zone of eyes with POAG, PSXG, and NTG in contrast to controls. The PAF analysis may provide an indicator for glaucomas in the future.