Which finding on fundoscopic exam is most consistent with loss of the retinal nerve fiber layer due to glaucoma?

• A. Papilledema
• B. Loss of retinal nerve fiber layer typically due to glaucoma or other optic neuropathies
• C. Increased intraocular pressure
• D. Macular edema

Answer: (B)

Loss of the retinal nerve fiber layer from glaucoma shows up on fundoscopic exam as thinning of the nerve fiber layer around the optic nerve, often with pallor of the neuroretinal rim and notching of the disc, and later with cupping as the optic cup enlarges. This thinning reflects loss of retinal ganglion cell axons and is the hallmark of glaucomatous optic neuropathy. The other findings describe different processes: papilledema is optic disc swelling from raised intracranial pressure; high intraocular pressure is a risk factor but not a direct fundoscopic sign of RNFL loss; macular edema involves fluid in the macula, not thinning of the RNFL. Therefore, the most consistent finding is the loss (thinning/pallor) of the retinal nerve fiber layer.