Persistent fetal vasculature (PFV) is a congenital eye condition where blood vessels that support eye development in the womb fail to disappear before birth. Previously known as persistent hyperplastic primary vitreous (PHPV), it is a common eye malformation present at birth. The remnants of these vessels can cause a spectrum of structural issues, potentially leading to vision impairment. PFV affects only one eye in most cases, though it can occur in both.
Normal Fetal Eye Vasculature Development
During fetal development, a temporary network of blood vessels called the hyaloid vascular system nourishes the growing structures inside the eye, particularly the lens. This system includes the hyaloid artery, extending from the optic nerve to the lens, and a mesh of vessels surrounding the lens called the tunica vasculosa lentis.
As the eye matures and develops its permanent retinal blood supply, the hyaloid system is no longer needed. A programmed regression begins around the 14th week of gestation and is usually complete by 35 to 36 weeks. This process ensures the vitreous cavity becomes clear, allowing light to pass unobstructed to the retina.
What is Persistent Fetal Vasculature?
The exact cause for the failure of these vessels to regress is not fully understood, but genetic factors are sometimes implicated, especially when both eyes are affected. The remaining blood vessels and associated fibrous tissue can interfere with the eye’s normal anatomy and function.
The condition is classified into three types based on the location of the persistent vessels. Anterior PFV involves remnants in the front of the eye, while posterior PFV involves remnants in the back, such as a stalk from the optic nerve. A mixed type, combining features of both, is the most common presentation.
Clinical Manifestations and Associated Complications
The signs of PFV are often noticed at birth or within the first few weeks of life. A primary sign is leukocoria, a white reflection in the pupil, which requires prompt medical evaluation as it can also indicate retinoblastoma, a rare eye cancer. Other signs include a smaller-than-normal eye (microphthalmia), misaligned eyes (strabismus), and involuntary eye movements (nystagmus).
The presence of these persistent vascular structures can lead to several complications that affect vision. Cataracts (clouding of the lens) are very common. The traction from fibrous remnants can pull on the retina, leading to a retinal detachment, or distort other structures, which may cause high pressure inside the eye (glaucoma).
Diagnostic Evaluation
An ophthalmologist diagnoses PFV through a comprehensive eye examination. For infants, this may be performed under anesthesia to allow for a thorough evaluation of the eye’s internal structures.
To confirm the diagnosis and determine its extent, specialized imaging tests are used. B-scan ultrasonography is a common tool, using sound waves to create an image of the eye’s interior when a cataract obstructs the view.
Other imaging like Optical Coherence Tomography (OCT) provides detailed, cross-sectional images of the retina. MRI or CT scans may be used in complex cases to fully assess the eye’s structure and rule out other conditions.
Management Strategies for PFV
Management of PFV is individualized based on severity and complications. For mild cases that do not affect the visual axis, careful observation and regular monitoring may be sufficient.
In many cases, surgery is necessary to clear the visual axis and manage complications like glaucoma or retinal detachment. Common procedures include lensectomy (lens removal) and vitrectomy (removal of the vitreous gel and vascular stalk). Surgery is often performed within the first few months of life to support visual development.
Following surgery, visual rehabilitation is a component of care. This includes treatments for amblyopia (lazy eye), such as patching the stronger eye. Corrective lenses are often required after a lensectomy, and lifelong follow-up is necessary to manage long-term complications.