Persistent fetal vasculature (PFV) is a congenital eye condition in which blood vessels that normally nourish the developing eye before birth fail to disappear on schedule. Every human eye relies on a temporary network of blood vessels during fetal life, but these vessels are supposed to dissolve before or shortly after birth. When they do not, the leftover tissue can cloud the lens, pull on the retina, and threaten vision in the affected eye. PFV is the leading non-cancerous cause of a white pupil reflex in infants, and distinguishing it from retinoblastoma is one of the first diagnostic challenges it presents.
The Blood Vessels Every Eye Is Supposed to Lose
During fetal development, the eye has its own dedicated blood supply called the hyaloid vascular system. This temporary capillary network feeds the developing lens and retina at a stage when the retina’s own permanent blood vessels have not yet formed.1PubMed Central. Functional OCT angiography reveals early physiological dysfunction of hyaloid vasculature in developing mouse eye The system includes a hyaloid artery running from the optic nerve through the vitreous gel to the back of the lens, along with a web of smaller vessels around and behind the lens.
Once the retina’s permanent vasculature starts growing, the hyaloid system becomes redundant. The body dismantles it through a coordinated process involving programmed cell death and a related cleanup pathway called autophagy, where cells essentially digest themselves. Research in developing eyes has shown that these two processes work in tandem: as the retinal vessels expand, endothelial cells lining the hyaloid vessels undergo both classic programmed death and autophagy-driven destruction.2PubMed. Autophagy-induced regression of hyaloid vessels in early ocular development In humans, this regression is largely complete by the third trimester, though small remnants sometimes linger for weeks after birth with no consequences.
Retinal neurons appear to orchestrate the timing. They act as sponges for vascular endothelial growth factor (VEGF), a potent signal that keeps blood vessels alive and growing. By soaking up excess VEGF, neurons starve the hyaloid vessels of their survival signal. Animal studies have shown that when neurons lose their ability to capture VEGF, the hyaloid vessels overgrow dramatically and persist well past the point when they should have vanished.3PubMed Central. Developmental regression of hyaloid vasculature is triggered by neurons PFV, in essence, is what happens when this carefully timed demolition stalls.
What Causes the Regression to Fail
Most cases of PFV appear sporadically, meaning there is no family history and no identifiable inherited mutation. Still, genetic research has uncovered a growing list of genes whose disruption can produce PFV, either in isolation or as part of a broader syndrome. A bioinformatics analysis identified 14 hub genes linked to the condition, many of them involved in eye development, VEGF signaling, and the pathways that govern programmed cell death.4PubMed Central. Identification of Key Genes and Pathways in Persistent Hyperplastic Primary Vitreous of the Eye Using Bioinformatic Analysis
Some of the genetic associations are striking. Mutations in the Norrie disease protein gene (NDP) have been found in cases of bilateral PFV, where both eyes are affected.5PubMed Central. Bilateral persistent fetal vasculature due to a mutation in the Norrie disease protein gene NDP is also involved in familial exudative vitreoretinopathy (FEVR), a separate retinal vascular disorder, and researchers have noted that several FEVR-related genes overlap with those implicated in PFV and other pediatric retinal vascular conditions. A variant in the MIP gene, which encodes a lens water channel protein, has been linked to bilateral PFV with cataracts and abnormally small eyes.6PubMed. First implication of MIP in bilateral microphthalmia with persistent fetal vasculature And PFV can show up as part of Walker-Warburg syndrome, a severe genetic condition affecting the brain, muscles, and eyes, where mutations in genes like RXYLT1 have been identified.7PubMed Central. Retinal Manifestations of Walker–Warburg Syndrome in Two Siblings with RXYLT1 Mutations
The emerging picture is that many different genetic disruptions can lead to the same endpoint: blood vessels that fail to regress. What they tend to share is interference with one or more of the signals that tell those vessels to die off, whether that involves VEGF regulation, cell-death machinery, or the structural scaffolding of the developing eye.
How PFV Presents in Infants
PFV typically shows up in the first weeks to months of life. The classic presentation is a white pupil (leukocoria), a small eye (microphthalmia), and sometimes visible abnormal tissue behind the lens.8PubMed Central. Non-typical persistent hyperplastic primary vitreous: a rare case report and review of the literature Parents often notice the white pupil in photographs or when the child’s eyes catch light. In most cases only one eye is involved, which helps distinguish PFV from many inherited retinal conditions that tend to affect both eyes. When PFV is bilateral, the chances of an underlying genetic syndrome are higher.
Clinicians classify PFV based on where in the eye the leftover tissue sits. Anterior PFV involves structures near the front of the eye, particularly a fibrovascular membrane behind the lens, sometimes with elongated ciliary processes that are pulled inward. Posterior PFV involves a stalk of tissue running from the optic disc through the vitreous, often still connected to the back of the lens. Combined PFV, the most common and often most severe form, involves both zones. One imaging study of combined PFV classified the stalks into four shapes based on ultrasound appearance, with roughly equal distribution among “I,” “Y,” inverted “Y,” and “X” configurations.9Ophthalmology. Combined Persistent Fetal Vasculature: A Classification Based on High-Resolution B-Mode Ultrasound and Color Doppler Imaging
Pathological examination of the tissue removed during surgery reveals a mix of fibrovascular tissue, smooth-muscle-like cells, and sometimes signs of old bleeding.10PubMed Central. Clinical and pathological characterization of persistent fetal vasculature associated with vitreous hemorrhage In some specimens, researchers have found evidence of extramedullary hematopoiesis, where the leftover tissue retains fetal-like blood cell production, a sign of just how developmentally primitive the remnants are.11PubMed Central. A clinicopathological study of persistent fetal vasculature
The Critical Distinction from Retinoblastoma
Any infant who presents with a white pupil needs urgent evaluation, because leukocoria is also the hallmark of retinoblastoma, a malignant eye tumor. Getting this distinction right is literally life-or-death: retinoblastoma requires chemotherapy or enucleation (removal of the eye), while PFV is treated with surgery to remove the remnant tissue and preserve whatever vision is possible.
MRI has become a key tool in sorting this out. A study comparing imaging features across retinoblastoma and its look-alikes (PFV and Coats’ disease, collectively called pseudoretinoblastoma) found several features that reliably distinguish them. A larger-than-normal eye, vitreous seeding, and a sharp V-shaped retinal detachment were almost exclusively seen in retinoblastoma. In contrast, a smaller eye, lens or ciliary body deformations, a central stalk running between the optic disc and lens, and the absence of calcifications pointed strongly toward pseudoretinoblastoma, with specificity ranging from about 91% to 100%.12PubMed Central. MR Imaging Features to Differentiate Retinoblastoma from Coats’ Disease and Persistent Fetal Vasculature The central stalk is particularly telling: it is a direct remnant of the hyaloid artery and essentially does not occur in tumors.
Still, borderline cases exist, and some children undergo unnecessary enucleation because PFV is mistaken for retinoblastoma. The stakes of the differential diagnosis are high enough that many centers now obtain MRI before any irreversible surgical decision.
Surgical Treatment and Timing
Not every case of PFV requires surgery. Mild anterior forms, where the remnant tissue is small and not pulling on surrounding structures, can sometimes be monitored. When intervention is needed, the severity and location of the disease dictate the approach. Mild-to-moderate anterior PFV may be treated with lens removal alone or with a lens-sparing vitrectomy, which removes the vitreous gel and the abnormal tissue while trying to keep the natural lens. Severe anterior or combined cases typically need a full vitrectomy combined with lens extraction.13PubMed Central. Outcomes and surgical management of persistent fetal vasculature
The technical challenges are real. The hyaloid artery can bleed when cut, so surgeons use endodiathermy, a form of internal cautery, to seal vessels during the procedure.14PubMed. Management of severe persistent fetal vasculature: case series and review of the literature Protecting the corneal endothelium and completely removing remnants of the lens capsule are critical technical priorities, since residual tissue can contract and cause problems later.15Acta Ophthalmologica. Surgical treatment of Persistent Fetal Vasculature (PFV) Choosing the right surgical entry point matters too. One retrospective study found that a corneal approach to the surgery was associated with a substantially lower risk of retinal detachment compared to entering through the pars plicata, which is a structure just behind the iris.16PubMed Central. Surgical Parameters and Prognostic Factors in Persistent Fetal Vasculature: Insights from a Retrospective Cohort Study
Timing is one of the strongest prognostic factors. In that same study, surgery before three months of age improved visual outcomes regardless of whether retinal detachment occurred.16PubMed Central. Surgical Parameters and Prognostic Factors in Persistent Fetal Vasculature: Insights from a Retrospective Cohort Study An older cohort found that children who had surgery before a median age of 77 days were roughly 13 times more likely to achieve at least counting-fingers vision than those operated on later. The window for useful intervention is narrow because the infant visual system is developing rapidly during the first months of life, and any obstruction of the visual axis during this period can cause dense amblyopia that even perfect surgery cannot fully reverse.
Complications After Surgery
Postoperative complications are common enough that families should be prepared for a long follow-up period. A review of published complication rates found that glaucoma occurs in roughly 10% to 25% of cases, retinal detachment in about 5% to 21%, and posterior capsular opacification, where a film regrows behind the implanted lens, in about 12% to 21%. Pupillary membrane formation, phthisis bulbi (a shrunken, nonfunctional eye), and vitreous hemorrhage round out the list of risks.17The Open Ophthalmology Journal. Pediatric Surgical Outcomes of Persistent Fetal Vasculature: A Five-Year Retrospective Study at a Tertiary Eye Center in Kazakhstan Phthisis is particularly feared; in cases with severe anterior PFV and retinal stretching, half of affected eyes went on to develop it.18PubMed. Severe anterior persistent fetal vasculature: the role of anterior retinal elongation on prognosis
Glaucoma deserves special attention because it can develop months or even years after surgery. The mechanism is not always clear-cut; it may relate to structural changes in the drainage angle of the eye, scarring from surgery, or lens-related factors. Families are usually counseled to monitor eye pressure indefinitely, even when the initial surgery goes well.
Visual Outcomes and Realistic Expectations
One of the harder conversations in pediatric ophthalmology involves setting expectations for PFV. Even with timely, technically successful surgery, many children end up with limited vision in the affected eye. Posterior disease, microphthalmia, glaucoma, and amblyopia all independently limit visual acuity outcomes.19PubMed. Visual and anatomic outcomes with or without surgery in persistent fetal vasculature A child with isolated, mild anterior PFV has the best chance of gaining useful vision, while one with combined disease, a very small eye, or retinal detachment faces much longer odds.
Early surgery clearly helps, but “helps” here is relative. In the study where surgery before 77 days dramatically improved the odds of counting-fingers vision or better, the bar for success was still quite low by adult standards. Only about 18% of surgical patients achieved 6/60 vision or better at final follow-up. That said, even modest visual input from the affected eye can contribute to depth perception and peripheral awareness, and it may protect against the long-term complications of having one completely non-seeing eye, including phthisis and the cosmetic concerns that come with it.
Amblyopia therapy, which involves patching the stronger eye to force the brain to use the weaker one, is a routine part of post-surgical management. Contact lenses or glasses correct the refractive error created by lens removal, and the patching regimen can last years. Compliance is a challenge, especially in young children, but it remains one of the most important determinants of final visual function.
What Animal Models Have Revealed
Much of what we understand about the molecular machinery behind PFV comes from genetically engineered mice. Mice whose genes for Bax and Bak, two proteins that execute programmed cell death, were both knocked out retained their fetal vasculature into adulthood. Their eyes still contained a hyaloid artery and surrounding vessels, though interestingly, the pupillary membrane portion regressed normally, suggesting different parts of the hyaloid system depend on different death signals.20JAMA Ophthalmology. Persistent Fetal Ocular Vasculature in Mice Deficient in Bax and Bak
Mutations in the Lama1 gene, which encodes a component of the basement membrane scaffolding called laminin, also produce PFV-like features in mice, along with abnormal blood vessel growth on the retinal surface.21PubMed Central. Lama1 mutations lead to vitreoretinal blood vessel formation, persistence of fetal vasculature, and epiretinal membrane formation in mice A broad review of knockout models found that many different genetic disruptions share common cellular defects: altered cell migration, increased cell proliferation, and decreased programmed cell death. The authors proposed that integrins, a family of cell-surface receptors that connect cells to their surrounding matrix, may be a unifying player in the disease, since integrins regulate all three of those behaviors.22PubMed. Different gene knockout/transgenic mouse models manifesting persistent fetal vasculature: Are integrins to blame for this pathological condition?
These animal models are more than academic exercises. They offer the most realistic path toward future therapies that might prevent PFV altogether, or at least reduce its severity. If the integrin hypothesis holds, for example, it could open the door to targeted treatments that encourage the hyaloid system to regress even when the normal signals have failed. That remains speculative, but the genetics are moving faster than the clinical tools, and the gap between bench and bedside is narrower than it was even a decade ago.
Why the Old Name Still Floats Around
You will still encounter the term “persistent hyperplastic primary vitreous” (PHPV) in older textbooks and even some recent case reports.8PubMed Central. Non-typical persistent hyperplastic primary vitreous: a rare case report and review of the literature The renaming to “persistent fetal vasculature” happened in the late 1990s and was meant to be more anatomically accurate. PHPV implied the vitreous itself was the problem, when in reality the issue is the blood vessels within and around the vitreous that failed to regress. PFV also better captures the spectrum of disease, since not all cases involve hyperplasia (overgrowth) and not all are confined to the primary vitreous. The old name is not wrong per se, but it paints a narrower picture than the condition warrants. If you are reading a paper that uses PHPV, it is describing the same thing.
Overlapping Pediatric Retinal Vascular Conditions
PFV does not exist in a vacuum. It shares genetic and clinical features with several other pediatric retinal vascular disorders, including familial exudative vitreoretinopathy (FEVR), retinopathy of prematurity (ROP), and Coats’ disease. Research has shown that pathogenic variants in some of the same genes implicated in FEVR are also found in PFV and Coats’ disease, suggesting these conditions may sit on a spectrum rather than being entirely separate entities. The emerging view is that genetic variants create a vulnerable background, and additional factors like prematurity or oxygen exposure determine which specific phenotype develops.23PubMed Central. Pediatric retinal vascular disorders: From translational sciences to clinical practice
This overlap has practical implications. A child diagnosed with PFV who also carries a mutation in a FEVR-related gene may be at risk for vascular abnormalities in the fellow eye, even if that eye looks normal at first. Genetic testing in bilateral or familial cases can inform surveillance strategies and, in some situations, guide family counseling about recurrence risk in future pregnancies. The field is still working out how broadly to apply genetic screening in isolated, unilateral PFV, where the yield of finding a causative mutation is lower, but the direction of travel is toward more testing rather than less.