has demonstrated at this age that the hyaloid artery is completely regressed in 20% of fetuses, incompletely in 20%, and continues to have blood in 60% [14, 15].

During the seventh month, blood flow in the hyaloid artery has ceased and the artery has become very narrow [6, 12]. By 29 weeks, no hyaloid artery system can be seen on ultrasound [14]. The posterior portion of the hyaloid artery begins to regress [2] and by the eighth month, the hyaloid artery has lost its connection to the optic nerve [6, 12]. The vessels curl and form corkscrews behind the lens after losing the proximal connection [6]. The anterior portion of the hyaloid artery drops inferiorly within Cloquet’s canal. By the middle of the eighth month, the central loops of the pupillary membrane have atrophied and the lesser circle of the iris is the sole channel of the return of blood reaching the central portion of the iris [6].

8.3 Clinical Findings

The clinical findings of PFV can affect virtually any structure in the eye and can range in severity from an isolated Bergmeister papilla to a microphthalmic eye with multiple anomalies. The persistent fetal vessels can lead to either primary or secondary malformations which present at birth or years later.

8.3.1 Primary anomalies

These findings are directly caused by the persistent fetal vessels interfering with normal ocular development.

Persistent pupillary membrane: This is a common clinical finding related to persistence of the anterior TVL. These membranes have been noted in up to 95% of normal newborns and disappear shortly after birth [4, 6, 16]. Normally, these vessels begin to regress during the fifth month of gestation [6], however, their persistence can give rise to numerous clinical findings including irregular looping vessels, correctopia, and congenital ectropion uveae [4].

Iridohyaloid blood vessels: (Fig. 8.3) Persistence of the iridohyaloid vessels or lateral TVL may create numerous signs including prominent radial vessels in the iris stroma [4, 12], a notch in the pupil (which can be subtle), or

Fig. 8.3 Posterior PFV. Note the prominent radial vessels in the iris stroma

anastamoses with a vascular retrolental membrane (RLM) [4, 8]. Additionally, persistence of the iridohyaloid vessels may impede proper lens-zonule development. Goldberg noted an association of persistent iridohyaloid blood vessels with congenital absence of the fovea and stressed that eyes with PFV may have seemingly unrelated anterior and posterior findings [12].

Mittendorf dot: The termination of the hyaloid artery. It is seen in 0.7–2% of normal population and is of no visual significance [4].

RLM: (Fig. 8.4 and 8.5) This finding is caused by persistence of the posterior TVL and hyaloid system with hyperplasia of surrounding mesoderm [13]. It may occur with a completely regressed hyaloid artery.

Fig. 8.4 Shows a 3 mm white retrolental plaque in the typical off-axis position

Fig. 8.5  A narrow slit beam clearly locates the white tissue to the retrolental space with extensions to the posterior capsule. This is the same plaque seen in Fig. 8.4

The tissue is typically thickest centrally [1] and has vessels in a radial pattern, which can help distinguish from the more random pattern seen with stage V ROP (retinopathy of prematurity). Goldberg has proposed the term brittle star sign after the marine echinoderm this vascular pattern resembles [4]. The RLM may range from 1 to 6 mm and incorporate ciliary processes and peripheral retina.

Hyaloid artery: The hyaloid artery begins to atrophy during the seventh month of gestation and initially loses its connection to the optic nerve. The vessel then involutes and falls inferiorly into the vitreous from its attachment to the lens. The hyaloid artery can persist in many forms (Fig. 8.6). It can insert into the posterior pole of the lens, or be incorporated into a posterior fibrovascular sheath [17].

Fig. 8.6  Persistant hyaloid artery

Nonattachment of the retina: Also termed congenital retinal fold, this finding is felt to be secondary to persistent attachment of the primary vitreous and blood vesselstoonesideofthedevelopingopticcup.Consequently, the developing secondary vitreous is unable to form a plane to separate the retina and primary vitreous [4]. The retina may be adherent to the ciliary body or dragged centrally into the posterior fibrovascular sheath (Fig. 8.4) [18]. Retinal detachment (RD) has been noted in 56% of patients with PFV [3, 18].

Macular hypoplasia and optic nerve hypoplasia: It is unclear why the disruption of fetal vasculature regression causes these findings. The presence of macular or optic nerve hypoplasia has been noted to portend a poor visual prognosis [19].

Bergmeister papilla: This can occur in isolation in many normal subjects or associated with other remnants of the fetal vasculature.

Microphthalmia: Seen in 66–84% of eyes [3, 18], it can range from a normal appearing globe with a small cornea, to a very small eye. The globe however may be normal size or even buphthalmic, if congenital glaucoma develops [12, 18].

8.3.2  Secondary findings

The structural changes caused by PFV can lead to numerous secondary complications. The sequelae of these primary anomalies can manifest from months to years after birth.

Cornea: The cornea may become opaque in PFV usually due to glaucoma or phthisis bulbi. Additionally, a central defect in Descemet’s membrane leading to a Peter’s like leukoma has been reported in PFV [18].

Anterior chamber: May be shallow and lead to angle closure glaucoma due to intumescent lens formation [20].

Cataract: Many authors have noted the lens in eyes with PFV is initially clear, and becomes cataractous in the first few postnatal months [20]. Pollard commented that the posterior lens capsule is absent in 50% of patients with PFV. This absence leads to migration of lens epithelial cells, absorption of lens material and replacement of the lens with mesenchymal [18] or adipose­ tissue [20].