excerpts from VHL Handbook
When capillaries form hemangioblastomas (also called retinal capillary hemangioblastomas or retinal angiomas) in the back of the eye, they start out extremely small and difficult to see. The capillaries themselves are less than the diameter of a red blood corpuscle, one of the cells that make up the blood.
When hemangioblastomas begin, they often grow around the equator or periphery of the retina, far away from the area of central vision. Unlike the equator drawn around the globe of the world, the equator of the eye is vertical. As you stand, draw a circle around your eye from eyebrow to nose and around—this is the equator.
To see this area, your ophthalmologist or optometrist must dilate your eye, use high-powered magnifying lenses, and look from side angles. It is more than the usual eye examination. Tell your doctor if there is VHL in your family so that he or
she will be sure to do this thorough examination and find any small hemangioblastomas. Treating them in the early stages is important. A referral to a retinal specialist will be required for treatment of these tumors.
Not all ophthalmologists and optometrists are familiar with VHL; it is better to use a specialist familiar with VHL who is qualified to perform a thorough dilated examination of the fundus and periphery with an indirect ophthalmoscope.
The objective of treatment is to stop growth of the hemangioblastoma while it is still so small that it does not affect your vision. Treatments generally include laser treatment (light surgery) or cryotherapy (freezing). If the retina is detached from the back of the eye as a result of leakage from the hemangioblastoma or as a result of fibrous tissue that has grown in the eye and pulling on the retina, then vitreoretinal surgery may be necessary. Leaflets on these treatments are produced by the American Academy of Ophthalmology and other professional associations, which are usually available from your ophthalmologist or retinal specialist.
Sixty percent of people with VHL have retinal lesions. People as young as 3 and sometimes even younger can be affected, making screening children very important. Children who have a positive DNA diagnosis of VHL should be screened for eye lesions beginning at age 1.
New hemangioblastomas can occur throughout life, so regular eye exams in affected individuals are important. Generally, smaller lesions can be treated more successfully and with fewer complications than larger ones. Leakage or bleeding from larger hemangioblastomas can lead to serious vision damage or retinal detachment, so early treatment and careful management is very important to preserve vision. Untreated or partially-treated hemangioblastomas that are not actively bleeding or leaking can stimulate the growth of fibrous tissue in the eye that can endanger vision and need to be regularly assessed.
Lesions on or near the optic nerve are very difficult to treat successfully and there is no consensus among doctors on the best treatment approach. Fortunately, they tend to grow slowly. Contact the VHL Alliance for the latest recommendations.
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