Optic disc drusen (ONHD) are granular structures formed by deposition of hyaline material and calcification in the lamina cribrosa of the anterior optic nerve. They are congenital but often inconspicuous in childhood, and are frequently discovered incidentally during fundus examinations for health checkups or other diseases.
Ophthalmoscopically, they are classified into superficial and buried types.
The prevalence is 0.34% (clinical studies) to 2% (autopsy studies). In Japan, the incidence is 0.04%, slightly lower than in Western countries. Three-quarters of cases are bilateral, and autosomal dominant inheritance with incomplete penetrance is suggested.
In the differential diagnosis of glaucoma, optic disc drusen should be considered as one of the non-glaucomatous optic disc abnormalities1)2).
They are different diseases. Drusen in age-related macular degeneration are deposits that accumulate beneath the retinal pigment epithelium and occur in the macula. Optic disc drusen are calcified deposits associated with axonal degeneration within the optic nerve head, and they differ in location, pathogenesis, and clinical significance.
Usually asymptomatic. Because visual field defects progress slowly, they are often unnoticed. Rarely, patients may complain of the following.
Superficial Drusen
Appearance: Yellow-white to pink nodules visible on the disc surface
Visual field defects: Visual field loss in 71% of eyes with visible drusen
NFL changes: Focal thinning corresponding to the quadrant with dense drusen. May also be diffuse
Diagnosis: Relatively easy to identify on fundus examination
Buried Drusen
Appearance: Edematous-appearing disc with blurred margins. Presents as pseudopapilledema
Visual field defects: Visual field loss in 25–30% of eyes presenting only with pseudopapilledema
NFL changes: Red-free photography may not show NFL changes clearly
Diagnosis: Detection of calcification by ultrasound B-mode, CT, or OCT is necessary
The exact etiology is unknown, but it is thought to be a byproduct of axonal degeneration.
Drusen increase with age, and both NFL thinning and visual field defects progress slowly over time. Worsening of visual field constriction at a rate of about 1.6% per year has been reported.
Optic disc drusen induce crowding of the optic disc and have been reported to be associated with the onset of NA-AION in patients under 50 years of age, albeit rarely3).
Elevation, cupping, and blurred margins of the optic disc are confirmed. The absence of hyperemia and microvascular abnormalities on the disc surface distinguishes it from papilledema. A comprehensive evaluation including fundus examination under mydriasis is necessary 2).
| Finding | Optic Disc Drusen | Papilledema |
|---|---|---|
| Color | Yellow-white | Red |
| Physiological cupping | Absent | Preserved (early) |
| Hemorrhage | Rare | Present |
Optic disc drusen show no hyperemia, no capillary dilation or hemorrhage on the disc surface, and the vessels on the disc can be clearly traced. For definitive diagnosis, detection of calcification by B-mode ultrasound or OCT is useful4). Fluorescein angiography shows no dye leakage from the disc, which helps differentiate from papilledema. The absence of change in disc findings during follow-up is also important for confirming pseudopapilledema.
There is no treatment for drusen themselves. Management and treatment of complications are the mainstay.
Currently, there is no treatment to eliminate optic disc drusen. Drusen tend to increase with age. However, visual impairment is usually mild, and sudden vision loss is rare. The best approach is regular examinations for early detection and management of complications.
Ultrastructural studies of optic disc drusen show the following process:
Drusen vary from 2–3 small nodules to aggregates of up to 40–50.
The causes of visual field defects are thought to include direct compression of optic nerve fibers by drusen, ischemia of the optic disc, and impaired axonal transport 3). The size and location of optic disc drusen do not always correspond to the visual field defects.
Drusen are aggregates of calcified material that accumulate due to changes in axonal transport and worsen crowding of the optic disc. This is rarely associated with the development of NA-AION, especially in patients under 50 years of age 3). In a multicenter retrospective study, optic disc drusen were identified by OCT in more than 50% of NA-AION patients under 50 years of age 3).
OCT is currently considered the gold standard imaging method for noninvasively detecting both buried and superficial drusen 4). It can identify buried drusen and detect PHOMS on cross-sectional images, and is also useful for detecting non-calcified buried drusen that were missed by conventional B-mode ultrasound.
Optic disc drusen is a chronic progressive optic nerve disease, with a reported worsening of visual field constriction of about 1.6% per year. Thinning of the NFL correlates with the degree of clinically visible drusen and often precedes visual field defects.
Optic disc drusen are rarely associated with the development of NA-AION. Particularly in patients under 50 years of age, drusen may induce excessive crowding of the optic disc and increase the risk of ischemia 3).
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Salvetat ML, Pellegrini F, Spadea L, et al. Non-Arteritic Anterior Ischemic Optic Neuropathy (NA-AION)—A Comprehensive Review. Vision. 2023;7:72.
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