Comments and Conclusions
- Black lines, or slits, that separate white nerve fiber layer bundles may seem like a loss of nerve fibers. If a slit is narrower than the width of a major blood vessel, and if it does not widen towards the periphery or taper towards the disc, the slit is likely physiological and not progressive.5
- Slits that are narrower than major blood vessels are seen in 10% of the population.5
- Wedge defects are wider in the peripheral retina and narrower closer to the disc due to the fact that the nerve fibers converge onto (and radiate from) the disc.3,5
- Nerve fibers in the periphery of the fundus lie deep within the retinal nerve fiber layer. Nerve fibers neurologically wired to photoreceptors in the posterior pole lie superficially within the nerve fiber layer ( i.e. closer to the vitreous), overlapping or intermingling with the fibers arising from the periphery.3,4
- Many wedge defects that are obvious 4-5 disc diameters away from the optic nerve converge towards the disc and often seem to disappear. Such RNFL defects typically do not result in optic disc cupping.
- Although contrary to traditional teaching. early detection of RNFL defects is often far simpler in a panoramic image than in a high magnification disc image.
- The correlation of panoramic RNFL images with GDx and OCT RNFL measurements appears higher than with disc topography analysis.
- RNFL defects can be documented with Panoramic imaging in typical glaucoma with glaucomatous cupping, in glaucoma without obvious cupping and in non-glaucomatous optic neuropathy.