From the Guidelines
Optic nerve head drusen are generally asymptomatic and do not require specific treatment, but regular monitoring with visual field testing and fundus photography is essential to track any progression and potential visual field defects. Optic nerve head drusen are calcified deposits within the optic nerve head that can be congenital or acquired over time, appearing as yellowish, refractile bodies that can sometimes be mistaken for papilledema due to their elevation of the optic disc 1. The primary concern with optic nerve head drusen is the potential for visual field defects through compression of nerve fibers, which can be monitored through regular visual field testing and fundus photography 1.
Key Considerations
- Regular monitoring with visual field testing and fundus photography is crucial to track any progression and potential visual field defects
- Patients with drusen have a slightly increased risk of developing anterior ischemic optic neuropathy and retinal vascular occlusions, so management of cardiovascular risk factors is important
- Drusen form due to abnormal axonal metabolism and calcium deposition in mitochondria within the confined space of the optic nerve head, particularly in eyes with small scleral canals that predispose to axoplasmic stasis
Management
- No specific treatment is required for optic nerve head drusen as they are generally asymptomatic
- If visual field defects are detected, lowering intraocular pressure with medications like prostaglandin analogs (latanoprost 0.005% one drop daily) may be considered to reduce potential damage, though evidence for this approach is limited 1
- Management of cardiovascular risk factors is essential to reduce the risk of anterior ischemic optic neuropathy and retinal vascular occlusions 1
From the Research
Definition and Diagnosis of Optic Nerve Head Drusen
- Optic nerve head drusen (ONHD) is a condition characterized by calcific degeneration of axons within the optic nerve, leading to the formation of abnormal drusen bodies that can compress normal nerve structures and result in vision loss 2.
- ONHD can be diagnosed through clinical evaluation with a dilated funduscopic examination, and ancillary testing such as computed tomographic (CT) imaging, B-scan ultrasonography, autofluorescence imaging, nerve fiber layer imaging, and threshold visual field evaluation can help confirm the diagnosis 2.
- Optical coherence tomography (OCT) can be used to evaluate the nerve fiber layer and detect nerve fiber layer thinning in patients with ONHD, which can be indicative of glaucomatous damage 3.
Imaging and Detection of Optic Nerve Head Drusen
- Enhanced depth imaging optical coherence tomography (EDI-OCT) and swept source optical coherence tomography (SS-OCT) are new imaging modalities that can provide high-resolution images of ONHD and allow for the quantification of optic disc drusen dimensions and assessment of neighboring retinal structures 4.
- Optical coherence tomography angiography (OCTA) can be used to analyze peripapillary vessel density in patients with ONHD, which can help confirm the diagnosis and evaluate the progression of the condition 5.
Visual Field Defects in Patients with Optic Nerve Head Drusen
- Most patients with ONHD have visual field (VF) defects, which can include concentric VF constriction, arcuate scotoma, enlarged blind spot, unspecific VF defect, and nasal step 6.
- The type and severity of VF defects can vary depending on the location and visibility of the ONHD, with superficial ONHD tend to have more severe VF defects than buried ONHD 6.
- Patients with superficial ONHD tend to be older and have more severe functional and structural impairment than patients with buried ONHD, which may be due to the presence of calcification leading to greater axonal damage 6.