Fluorescein filling defects and quantitative morphologic analysis of the optic nerve head in glaucoma

To evaluate absolute filling defects of the optic nerve head in normal tension glaucoma (NTG) and primary open-angle glaucoma (POAG) and to compare the filling defects with topographic analysis of the optic disc.

Twenty-five patients with NTG, 25 patients with POAG, and 25 age-matched controls were included. Fluorescein angiograms were performed by means of a scanning laser ophthalmoscope. The extent of absolute filling defects of the optic nerve head was assessed using digital image analysis of early-phase angiograms. Topographic measurements of the optic disc were acquired using the Heidelberg Retina Tomograph II.

Absolute filling defects were significantly larger (P =.001) and were seen more often (P<.001) in patients with NTG (n = 18) and POAG (n = 19) compared with controls (n = 3). Rim area (P =.006), rim volume (P =.007), cup-disc area ratio (P =.008), linear cup-disc ratio (P =.005), maximum cup depth (P =.002), cup shape measure (P =.03), and nerve fiber layer thickness (P =.008) and cross-sectional area (P =.006) were significantly different between patients with glaucoma and controls. Absolute filling defects were significantly correlated with cup area (r = 0.31; P =.007), rim area (r = -0.38; P<.001), rim volume (r = -0.35; P =.002), cup-disc area ratio (r = 0.49; P<.001), linear cup-disc ratio (r = 0.48; P<.001), cup shape measure (r = 0.27; P =.02), and nerve fiber layer thickness (r = -0.33; P =.004) and cross-sectional area (r = -0.30; P =.009).

Fluorescein filling defects of the optic disc are present in NTG and POAG. The extent of these filling defects is correlated with the morphologic disc damage.