Persistent Fetal Vasculature Syndrome
(Persistent Hyperplastic Primary Vitreous)
Parag K. Shah, DNB; V. Narendran, DNB; N. Kalpana, DNB.
Department of Pediatric Retina & Ocular Oncology, Aravind Eye Hospital & Postgraduate Institute of Ophthalmology, Avinashi Road, Coimbatore – 641014.
Email: drshahpk2002@yahoo.com
Definition
It is a congenital ocular disorder where fetal vasculature persists. It can be either subtle (no disturbance in vision) or severe (profound visual loss)
Anatomy
The fetal vasculature is composed of two parts:
- Tunica vasculosa lentis: It is situated anteriorly encircling the lens. It has anterior and posterior divisions. Anterior division has additional attachments to the pupillary frill of the iris. Posterior division has additional attachments to the ciliary process and continues with the hyaloid artery posteriorly.
- Hyaloid artery: It is situated porteriorly behind the lens. It is also called primary vitreous. The hyaloid vessel extends from posterior surface of lens to the disc. The vasculature fills the vitreous cavity & has many attachments to the retinal surface
Normal regression of embryonic vascular system1
During development blood flow to the eye is through hyaloid artery. At the 240-mm stage (seventh month), blood flow in the hyaloid artery ceases. Hyaloid vascular regression occurs in following manner:
The developing lens separates the fetal vasculature from vascular endothelial growth factor (VEGF) producing cells, inducing apoptosis.
Pathologies of the Primary Vitreous1
Persistence of the hyaloid vascular system occurs in 3% of full-term infants and in 95% of premature infants. There is a spectrum of disorders resulting from persistence of the fetal vasculature.
- Mittendorf s dot is a remnant of the former site of anastomosis of the anterior tunica vasculosa lentis and posterior hyaloid artery. It is usually inferonasal to the posterior pole of the lens and is not associated with any known visual dysfunction (Figure 1).
Figure 1: Mittendorf’s dot (white arrow).
- Bergmeister's papilla is the occluded remnant of posterior portion of the hyaloid artery, associated with glial tissue. It appears as a gray, linear structure anterior to the optic disc (Figure 2). It also has no visual dysfunction.
Figure 2: Bergmeister's papilla (white arrow).
- Vitreous cysts are generally benign lesions that are found in eyes with abnormal regression of the anterior or posterior hyaloid vascular system. It can occur in otherwise normal eyes or eyes with coexisting ocular disease, such as retinitis pigmentosa, retinochoroidal colobomas and uveitis. Vitreous cysts are generally not symptomatic and thus do not require surgical intervention (Figure 3).
Figure 3: Vitreous cyst (white arrow) seen just behind the lens.
- Persistent Fetal Vasculature Syndrome (PFVS)3,4
Persistent hyperplastic primary vitreous (PHPV)
As mentioned earlier, it is a congenital ocular disorder in which fetal vasculature does not regress. It is unilateral approximately 90% of the time. No single gene has been identified. The new terminology for Persistent Hyperplastic Primary Vitreous (PHPV) is Persistent Fetal Vasculature Syndrome (PFVS).5 PFVS emphasizes not only the importance of both anterior tunica vasculosa lentis and posterior persistent hyaloid system but also represents the spectrum of structural changes which can present within the eye.
PFVS does not progress during the course of the child's life, but tractional intraocular changes can occur later, most likely due to eye growth. The stalk also can cause traction on the posterior lens capsule leading to posterior lenticonus. Traction on the ciliary body can lead to hypotony. Traction on the retina, leads to tractional retinal detachment.
There are three types of PFVS:
- Anterior PFVS: It has predominant features of persistent anterior tunica vasculosa lentis without much or any posterior hyaloid component.
Clinical features (Figure 4):
Figure 4: Anterior PFVS showing microphthalmos with cataract.
