Optic nerve drusen (OND) represent retained hyaline bodies in the optic nerve. Typically, patients with ODD are asymptomatic and the findings disclosed only upon routine ocular evaluation. ODDs can be associated with retinitis pigmentosa, angioid streaks, Usher syndrome, Noonan syndrome and Alagille syndrome. They also might lead to a loss of visual field or, in rare cases, central acuity or anterior ischemic optic neuropathy.
The classic presentation of OND involves unilaterally or bilaterally elevated optic discs with irregular or “scalloped” margins, a small or nonexistent cup and unusual vascular branching patterns arising from a central vessel core. There may be refractile hyaline deposits visible on the surface of the disc or in the peripapillary area, making the diagnosis clear. In younger patients, the disc elevation tends to be more pronounced and the drusen less calcified and discrete, making them less visible ophthalmoscopically—complicating diagnosis.
If the diagnosis remains unclear on physical examination, further investigations are required to confirm the diagnosis and rule out disc edema. Imaging modalities include B-Scan ultrasonography, CT scan, fluorescein angiography, fundus autofluorescence, and optical coherence tomography. For both superficial and deep drusen, ultrasound may show a highly echogenic focus representing calcification in the disc. CT has utility in showing calcified drusen; however, it can not detect noncalcified drusen. Fluorescein angiography has classically been used to differentiate true disc edema. Fundus autofluorescence will demonstrate optic nerve drusen as bright hyperfluorescent foci in the disc, revealing all visible and most buried drusen. Optical coherence tomography will reveal nerve drusen as areas of irregular or spherical hyporeflective cores with a uniform internal structure and hyperreflective borders at the surface.
