Persistent Fetal Vasculature Syndrome (PFVS)
Persistent fetal vasculature syndrome (PFVS) has replaced the older
name of persistent hyperplastic primary vitreous. The new name is better
because it acknowledges that two parts of the fetal vasculature can
persist leaving the eye with an opaque lens and vascular stalk of
tissue. One of the changes that the name does not imply is that the
retina (the part of the eye that processes light and sends it to the
brain) may also be altered either in larger or microscopic amounts
called retinal dysplasia.
 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.
Therapy
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.
GLOSSARY OF TERMS:
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.
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