Optic disc drusen are abnormal, calcified deposits that accumulate within the optic nerve head, the front portion of the optic nerve where it connects to the retina. These deposits are commonly found in both eyes, affecting about 75% of individuals.
Optic disc drusen differ from macular drusen, which are deposits found under the retina associated with age-related macular degeneration (AMD). Unlike macular drusen, optic disc drusen are not linked to aging and can appear in children. Their distinct location and composition set them apart.
Causes and Development
Optic disc drusen formation is not fully understood, but a strong genetic component is believed to be involved, with many cases being inherited. The drusen are made of proteinaceous material that calcifies over time.
These deposits typically begin as “buried” drusen during childhood, located deeper within the optic nerve head and not visible during routine eye exams. Over decades, these buried drusen enlarge and calcify, gradually emerging closer to the disc surface and becoming apparent in adulthood.
Diagnosis and Detection Methods
An ophthalmologist may suspect optic disc drusen during a dilated eye examination if the optic nerve head appears elevated with indistinct margins. Superficial drusen can sometimes be seen as yellowish-white bodies on the disc surface. However, specialized imaging tests are often needed for definitive confirmation, especially for buried drusen.
B-scan ultrasonography is a reliable method for detecting optic disc drusen. This test uses sound waves to image the eye’s internal structures. Drusen appear as highly reflective areas within the optic nerve head.
Optical Coherence Tomography (OCT) provides high-resolution, cross-sectional images of the optic nerve. OCT can reveal the internal structure of drusen and help differentiate them from true optic disc swelling. Fundus Autofluorescence (FAF) is also used. Superficial optic disc drusen contain naturally fluorescent compounds that cause them to autofluoresce under special light, making them visible.
Potential Vision Complications
Many individuals with optic disc drusen experience no symptoms and maintain good central vision, with the condition often discovered incidentally during an eye examination. However, optic disc drusen can lead to vision problems.
The most common vision issue is a slow, progressive loss of peripheral vision. This visual field loss develops gradually and may not be noticed until it becomes more advanced.
Less common, but more serious, complications can arise, particularly those affecting the blood supply to the optic nerve. These vascular complications include Non-Arteritic Anterior Ischemic Optic Neuropathy (NAION), which causes sudden vision loss due to insufficient blood flow, and Choroidal Neovascularization (CNV), involving the growth of abnormal blood vessels under the retina that can leak fluid or blood and cause central vision loss. These complications warrant prompt medical attention.
Monitoring and Management
There is no treatment to remove or reverse optic disc drusen. Management focuses on regular monitoring to detect potential vision complications early.
Individuals with optic disc drusen require routine follow-up appointments with an ophthalmologist. These visits include visual field testing to map peripheral vision and OCT scans to monitor the optic nerve head for swelling, nerve fiber layer thinning, or new blood vessels.
If complications like choroidal neovascularization (CNV) occur, specific treatments are available to manage them, such as injections of medications into the eye. Regular monitoring allows for timely intervention.