Persistent Fetal Vasculature Syndrome (PFVS)
Usually, PFVS is found in one eye that is somewhat smaller than the better eye and has a white pupil reflex and elongated ciliary processes. This set of findings does not tell the examiner whether retinal dysplasia is present or not. In some eyes the stalk of persistent fetal vessels may not opacify the visual axis of the lens (the part light rays pass through the lens giving best vision). This stalk can pull on the retina and disturb it as well as pull on the lens causing it to be poorly shaped (posterior lenticonus). This child usually does not have the white pupil and is often diagnosed at a later age.
In our experience, ultrasound, visual evoked potential response or electroretinography testing are not reliable in answering that question. At this time there are no other known systemic problems associated with PFVS. At this time no genetic mutations have been associated with the typical unilateral PFVS. About 10% of infants affected by PFVS have both eyes involved. These children more frequently have retinal dysplasia. Bilateral PFVS is also not associated with systemic changes. There is however a disease that can be indistinguishable from bilateral PFVS with extensive retinal dysplasia called Norrie’s disease. In this process the child may be affected with hearing loss or other central nervous system problems. Genetic testing is available for Norrie’s disease. As with many diseases known to be under genetic control, there may be several mutations. Norrie’s disease testing will confirm the diagnosis in 80% of the cases, leaving 20% of children where a mutation cannot be found, but clinical examination confirms Norrie’s disease. See Norrie's website at: http://www.norriedisease.org/
Therapy for PFVS is surgical, usually with removal of the lens and persistent vascular stalk tissue. It can accomplish several things. It may reduce the risk of glaucoma (high pressure in the eye) and usually clears the opaque tissue out of the eye allowing light to reach the retina. It also can relieve pulling or distortion of the retina.The retina now being seen allows the physician to form an opinion as to the amount or absence of retinal dysplasia.
In the past, we felt that the clinical exam could tell all we needed about retinal dysplasia, but now with the availability of flourescein angiography and OCT testing in infants under anesthesia, we can be much more accurate about microscopic retinal dysplasia.
If the eye has no retinal dysplasia, there still is a great challenge to overcome occlusive amblyopia (the eye doesn’t want to function because messages were not sent to the brain during the early formative months). This can often be helped by contact lenses and patching the stronger eye. This should only be done with the advice of an ophthalmologist.
See one mom's blog about her son with PFVS: http://thomasmarshalldoesitall.blogspot.com
ablation – The removal or destruction of tissue
acuity , visual acuity – Measure of the eye’s ability to distinguish object details and shape. This measurement is usually defined by the smallest detail the person can see at a specified distance (usually 20 feet or 6 meters).
20/20 or 6/6 – Normal visual acuity is identified when a person is able to read on an eye chart at a distance of 20 feet (or 6 meters) what is average to be seen at that distance.
20/200 – A reading of 20/200 on an eye chart means that the person can see at 20 feet what someone with average acuity can see at 200 feet. In the United States “legal blindness” is defined as 20/200 vision.
bilateral – Affecting both eyes.
ciliary processes – The innermost part of the tissue inside the eye. The 70 ciliary processes secrete aqueous fluid and acts as the attachment site for the ligaments that hold up the lens.
dysplasia – Abnormal development or growth of cells, tissues or organs.
electroretinography – Test which provides a measure of retinal functioning caused by light stimulation to the retina.
flourescein angiography (FA) –A test where vegetable based dye is injected into an arm vein, then rapid, sequential photographs are taken of the eye as the dye circulates.
lenticonus- An abnormal cone shaped protrusion of the lens, usually on the front surface.
opaque – A cloudiness which causes the inability of light to go through a normally transparent part in the eye.
mutations – A change in the genetic material passed down from an individiual’s parents.
O.C.T. – generates a cross-sectional image through the retina and gives information not found by F.A.
peripheral vision – side vision.
systemic – Affecting the body generally, rather than a specific area.
ultrasound – A test where the transmission of high frequency sound waves go into the eye and are reflected by the tissue in the eye and displayed on a screen so that the inside parts of the eye can be seen.
unilateral –Affecting only one eye.
vascular – Referring to a blood or lymph vessel.
vasculature – The arrangement of blood vessels in an organ or part.
visually evoked potential or response (VEP or VER) – A computerized test which records the electrical activity in the brain caused by stimulating the retina with light flashes. This test is used to determine whether the eye and brain and working together.