Drusen And Optic Nerve
Drusen And Optic Nerve.
Drusen are depositions of mucopolysaccharides and proteinaceous material that accumulate anterior to the lamina cribosa within the optic nerve head. Some believe that these depositions occur as a result of axonal degeneration of the optic nerve or axoplasmic transport stasis secondary to congenitally crowded optic nerve heads (Spencer 1978). They are more common among Caucasians and are believed to have an autosomal dominant pattern of inheritance with incomplete penetrance (Davis 2003).
However, this remains unproven. Both Lorentzen (1961) and Antcliff and Spalton (1999) were unable to verify this pattern of inheritance. An inherited optic nerve head dysplasia might be the primary risk factor for developing ONHD (Lee 2005). According to Lorentzen the condition is transmitted as an “irregularly dominant fashion” (Lorentzen 1961). The primary pathology arises from an inherited dysplasia of the optic disc and its blood supply which predispose to formation of optic disc drusen (Auw-Haedrich 2002).
Drusen can also occur in the optic nerve. These drusen are made up of protein and calcium salts and generally appear in both eyes. Unlike the drusen associated with AMD, optic nerve drusen (also known as optic disc drusen) are not related to aging and often appear in children. Optic nerve drusen usually do not affect vision, but some patients with these drusen may lose peripheral (side) vision. They may be associated with vision loss of varying degree occasionally resulting in blindness.
History Is Drusen Optic Nerve
A 19-year-old female initially presented to her local physician complaining of headaches, especially while reading. She was referred to her local optometrist who maximized her vision with an updated refraction. Shortly thereafter, however, the patient experienced continued blurred vision in the left eye only. Believing her lens correction to be too strong, she returned for another examination. A dilated fundus examination revealed that the optic discs had a “lumpy-bumpy” appearance, suspicious for optic disc drusen and she was referred to the University of Iowa Hospitals and Clinics for further evaluation. Other than mildly blurred vision, the patient denied any other ocular symptoms.
Examination of the patient’s optic nerves led to a high suspicion of multiple optic disc drusen. Futher testing including standardized echography which confirmed the presence of numerous highly reflective drusen within both optic nerve heads, OD > OS. Goldmann perimetry revealed enlargement of the blind spots and other small peripapillary scotomas. The patient’s vision was refracted to make sure her vision was correctly appropriately and she was instructed to return in 6 months.
Drusen are made up of lipids, a fatty protein. Drusen likely do not cause age-related macular degeneration (AMD). There are different kinds of drusen. “Hard” drusen are small, distinct and far away from one another. This type of drusen may not cause vision problems for a long time, if at all. “Soft” drusen are large and cluster closer together. Their edges are not as clearly defined as hard drusen. This soft type of drusen increases the risk for AMD.
What Causes Drusen
Drusen occur naturally with age. The exact relationship between degenerative macular disease and drusen is not clear. However, having soft drusen is a sign of AMD.
Health Symptoms of Drusen
Most Optic nerve drusen also often do not produce symptoms. However, some patients with optic nerve drusen experience vision problems, including loss of peripheral (side) vision and temporary flickering or graying out of their vision. Hard drusen are not a symptom of eye disease. Neither the presence of a large number of soft drusen is an early sign of dry age-related macular degeneration (AMD).
Who may have Drusen?
Drusen are typically a result of aging and are commonly found in people age 60 and older. Caucasians are more likely to develop drusen, as well as age-related macular degeneration (AMD). Soft drusen are associated with AMD. Risk factors for AMD include a family history of the disease, smoking and abnormal cholesterol levels. The risk of developing optic nerve drusen is also increased for people who are of Caucasian descent or who have a family history of the disease.
Patients with ONHD are often asymptomatic, thus the high rate of incidental discovery. The earliest symptoms of ONHD are abnormalities in peripheral vision or transient visual obscurations, such as flickering or “graying out” (Giovannini 2005, Davis 2003). Patients do not complain of central vision loss because central visual acuity is generally spared with optic disc drusen. Central acuity may be affected if subretinal choroidal neovascularization is present.
Also check:Optic Nerve Function
Drusen are detected during a dilated eye exam. To check your eyes, your ophthalmologist will dilate (widen) your pupils using dilating eyedrops and examine your eyes with an ophthalmoscope, a device that allows him or her to see the retina and other areas at the back of the eye. This examination will allow him or her to see if drusen are present.
If your ophthalmologist detects soft drusen, he or she may have you use an Amsler grid to check for macular degeneration symptoms such as wavy, blurry or dark areas in your vision. If your ophthalmologist thinks you have optic nerve drusen, he or she may order additional imaging tests to confirm the diagnosis.
Hard drusen do not need to be treated. If your ophthalmologist finds hard drusen during a routine eye exam, he or she may want to watch them regularly to make sure they do not develop into soft drusen.
Because soft drusen are a sign of age-related macular degeneration (AMD), your ophthalmologist will follow the AMD treatment appropriate for you. Trying to eliminate the drusen will not improve your AMD. If your condition is diagnosed early, you can take steps to help slow its progression, such as taking vitamin supplements, eating healthfully and not smoking.
Also, Age-related macular degeneration doesn’t affect your side (peripheral) vision and usually doesn’t cause total blindness. But it can reduce or eliminate your central vision — which is necessary for driving an automobile, reading and recognizing people’s faces. It may be beneficial for you to work with a low vision rehabilitation specialist, occupational therapist, your eye doctor and others trained in low vision rehabilitation. They can help you find ways to adapt to your changing vision.
For people with intermediate or advanced disease, taking a high-dose formulation of antioxidant vitamins and minerals may help reduce the risk of vision loss, the American Academy of Ophthalmology says. Research shows benefit in a formulation that includes:
500 milligrams (mg) of vitamin C.
400 international units (IU) of vitamin E.
10 mg of lutein.
2 mg of zeaxanthin.
25 or 80 mg of zinc (as zinc oxide)
2 mg of copper (as cupric oxide)