Persistent fetal vasculature (PFV) refers to a developmental disorder of the eye and present at birth. The disorder was previously called persistent hyperplastic primary vitreous, but the term was considered inaccurate due to anatomic reasons. PFV occurs when the embryonic blood vessels fail to completely wither or disappear once the eye has finished developing in a fetus. Failure by the blood vessels to regress results in structural abnormalities that can lead to vision impairment. PFV commonly causes cataracts in infants. Other vision problems caused by PFV include strabismus (misalignment or crossing of the eye), amblyopia (lazy eye), glaucoma (increased eye pressure), or a detached retina. Often, PFV will affect one eye, but when both eyes are affected, the infant should be examined for other underlying genetic or systemic conditions like Norrie disease.
- Anterior PFV can cause cataracts
- Posterior PFV damages the retina to result in tractional retinal detachment, optic nerve hypoplasia, vitreous hemorrhage, retinal folds, etc.
- Combination of anterior and posterior PFV can lead to microphthalmia (one or both eyes are abnormally small), leukocoria (white rather than usual black pupil), and cataracts (cloudy lens)
Causes & Risk Factors
PFV causes remain unknown, although some families have recorded more than one family member having the condition.
Signs & Symptoms
The signs and symptoms of PFV usually become apparent at birth or a few weeks later. These signs and symptoms manifest differently in each child. They include:
- Strabismus or eye misalignment
- One eye is smaller than the other
- Nystagmus (an abnormal movement of the eyes)
- Leukocoria, which is caused by abnormal tissue behind the lens
- The tunica vasculosa lentis and hyaloid fetal vasculature. These should have regressed around the fortieth week of pregnancy but can be visualized on examination
Diagnosis of PFV is made through:
- Past medical and ocular history
- Pupillary examination
- A slit-lamp examination
- Measuring intraocular pressure
- Ocular examination where visual acuity is checked
- Assessment for ocular alignment or strabismus tests
- Dilated fundus exam where the vitreous, optic disc, macula, and other structures are examined
- Imaging modalities to visualize PFV. Computed tomography (CT) helps detect microphthalmia and other signs. Magnetic resonance imaging (MRI) can show a shallow anterior chamber, a flattened lens, etc. A persistent anterior tunica vasculosa lentis may show on a fluorescein angiography test. Fundus photography helps to visualize the remaining tortuous fibrotic vascular structures if leukocoria is not severe. Ultrasonography is used to visualize the fibrovascular hyaloid remnant and retinal detachment. Imaging tests also help rule out associated diseases such as retinoblastoma, Norrie disease, familial exudative vitreoretinopathy, incontinentia pigmenti, and Coats disease.
Treatment aims to improve vision by restoring the normal anatomy and function of the eye. With appropriate treatment, the eye will grow normally. The type of treatment will depend on the severity of PFV. Some cases are not severe and can be managed by observation.
One eye may be patched to minimize amblyopia, and glasses used to ensure that the child’s vision develops appropriately.
Surgery can be used to manage PFV if the disease progresses to affect vision. The surgeon removes the cloudy lens and replaces it with an intraocular lens. Strabismus is corrected through eye muscle surgery. If the retina pulls away from the back of the eye, it can be reattached through retinal surgery or vitrectomy. Surgery is considered for leukocoria too. Surgery is also performed to remove the fibrovascular remnants and prevent glaucoma, phthisis (pulmonary tuberculosis), and retinal detachment from developing. The surgeon can also remove a plaque on the posterior lens to improve visual acuity. A stalk that forms in the eye from the fetal vasculature can be removed to enable the eye to continue growing normally.
Prognosis & Long-Term Outlook
PFV prognosis depends on the treatment used. Visual outcomes are useful when the disease is less severe. However, vision may be quite poor in severe cases even following surgery where the visual system still does not develop.
Prevention & Follow Up
Due to the sensitive nature of an infant's visual system, continued follow-up is recommended. The doctor regularly checks intraocular pressure in the event glaucoma should develop. The child may be required to wear contact lenses and glasses to ensure the visual system develops well and be patched on the eye to manage amblyopia. Sometimes, the infant may require a repeat, or other surgeries if there is need.