Optic Nerve Drusen
Drusen are small collections of protein material called hyalin. They most commonly form under the macula, where they are an indication of macular degeneration. Less commonly they form in the optic nerve. The right image is a normal nerve head, seen as a circle in the center of the photo, in the back of the eye. The left image shows small yellow deposits (the drusen) scattered within the optic nerve head. Drusen occur in about 1% of people, more commonly in caucasians. They are typically not present at birth. They become visible to eye doctors usually in the teens, and may become more prominent with age. Sometimes calcium forms inside them, in which case they are more obvious to examiners.
What are the symptoms of optic nerve drusen?
Fortunately optic nerve drusen rarely cause noticable vision symptoms. In fact, most people find out about the drusen when having a routine eye examination. Initially they can cause some diagnostic confusion, since the optic nerve swelling that is present can be mistaken for swelling caused by high pressure around the brain, which is more serious. Optic nerve drusen commonly cause mild side vision loss that can be detected by machines in the doctors office called "visual field" analyzers. The side vision loss is usually not appreciated by patients and not a functional concern.
Rarely the drusen can cause severe, noticable side vision loss. It would be extremely rare for drusen to cause central vision loss, usually as a result of a "choroidal neovascular membrane," which is a growth of new blood vessels near the optic nerve. These blood vessels can leak or bleed, causing loss of vision. Effective treatments are available for choroidal neovascular membranes if detected early enough.
What cause drusen in the optic nerve?
There is certainly a genetic component, since they often occur in multiple family members. Why some individuals are prone to this protein buildup is not known, however. The protein is thought to be a by-product of cell metabolism.
How are optic nerve drusen treated?
There are no proven preventative measures or treatments for optic nerve drusen. Fortunately symptoms are very rare, even if the drusen are severe. For the rare person who has symptomatic vision loss that is not due to a choroidal neovascular membrane, glaucoma drops to lower eye pressure may be tried. Choroidal neovascular membranes may be effectively treated if detected early with laser or injections of "VEGF inhibitors."
The North American Neuro-Ophthalmology Society publishes a web site with good patient information on this condition.