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Teenager has blurry vision in one eye since birth
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A 13-year-old white female presented for a comprehensive eye exam. She said she had blurry vision in the left eye since birth, with no change in the quality of vision. Her guardian noted that a previous optometrist told her she had a congenital malformation in the left eye. She was a full-term baby with an unremarkable delivery, her systemic health was normal, she was taking no medication and had no known allergies.
Entering uncorrected visual acuity was 20/20 OD, 20/60 OS. Extraocular muscle excursions were full and smooth in each eye, and confrontation visual field was full in each eye. She was slightly exophoric at near without correction. IOP was 23 mm Hg OD and 25 mm Hg OS via Goldmann applanation. The patient’s anterior segment exam was unremarkable in the right eye, but she had trace posterior subcapsular cataract in the left eye. Corneal diameter was 12 mm in each eye. Her best-corrected visual acuity was 20/15 OD with -0.25 D -0.25 D x 110, and 20/40- OS with -0.50 D sph.
The patient’s dilated retinal exam was unremarkable in the right eye, but the left eye revealed a funnel-shaped opaque canal emanating from the optic disc to the posterior lens. The inferior vitreous base was opaque with pigmentary changes at the posterior border. It was difficult to discern whether that opacified vitreous was associated with any contraction or underlying retinal anomaly. Some parapapillary nerve fiber layer contraction was noted, causing moderate macular puckering.
The dilated retinal exam was unremarkable in the right eye.
Images: Weidmayer SL
Differential diagnoses, mostly for the often-associated leukocoria, include congenital cataract, retinoblastoma, retinopathy of prematurity (ROP), familial exudative vitreoretinopathy, Coats’ disease, ocular toxocariasis and persistent hyperplastic primary vitreous (PHPV). PHPV is now referred to as persistent fetal vasculature.
Differentiating these clinical problems is fairly straightforward, but imaging may be helpful, particularly to rule out retinoblastoma. The globe and axial length tends to be small with PHPV, evident with A-scan ultrasonography. Associated retinal detachments are hyperechoic with B-scan ultrasonography, hyperdense by computed tomography (CT) and hyperintense with magnetic resonance imaging (MRI). Cloquet’s canal within the vitreous cavity would be visualized in similar fashion with such imaging; color Doppler may show vascularization and arterial blood flow within Cloquet’s canal.
The dilated retinal exam in the left eye revealed a funnel-shaped opaque canal emanating from the optic disc to the posterior lens.
On MRI, PHPV appears as a triangular retrolental soft tissue mass with the long central stalk extending to the optic nerve. Imaging is not typically necessary because of obvious clinical signs of PHPV, but may be necessary if the posterior segment is obscured. Retinoblastoma is differentiated by the presence of a calcified mass on CT and hyperintense T1-weighted but hypointense T2-weighted MRI. ROP can be ruled out based on lack of associated history of prematurity and exposure to high levels of oxygen.
This patient’s diagnosis
The patient was diagnosed with PHPV manifesting as a persistent hyaloid artery remnant with a prominent Cloquet’s canal and macular puckering secondary to this structural abnormality causing nerve fiber layer traction.
Due to my uncertainty regarding the peripheral vitreous/retinal status, I consulted a retinal specialist for an evaluation. She was seen shortly thereafter; the retinal specialist noted that the peripheral findings were just opacified vitreous base without contraction, a result of PHPV. He recommended no additional treatment unless macular traction worsens and a 6-month follow-up to re-evaluate.
Development of hyaloid vasculature
The hyaloid vasculature is a dense, but temporary intraocular vascular bed during embryonic development. The ocular vascular system arises from mesoderm, and the hyaloid artery emerges from the dorsal ophthalmic artery beginning around the seventh week of development. This hyaloidal artery traverses the primitive vitreous and reaches the developing lens, where it branches to form a capillary network over the lens’ posterior surface called the tunica vasculosa lentis. It connects to the choroid via anastomoses with the annular vessel and expands to the anterior lens to form the pupillary membrane. The hyaloidal vasculature lacks veins entirely; its drainage is completed by choroidal veins.
The hyaloid system then begins to regress concurrently with the formation of the retinal vasculature beginning around the 20th week of gestation and is normally completely regressed by birth. The primary vitreous condenses into Cloquet’s canal, and secondary vitreous fills the vitreal cavity. While the formation and regression of the hyaloidal system is not completely understood, it is believed that the various isoforms of vascular endothelial growth factor (VEGF) play a role both in the development and regression of this system.
Several ocular anomalies, known as PHPV or persistent fetal vasculature, are related to the failure of the hyaloid vasculature to completely regress. There certainly are many variants of PHPV, which can affect the anterior and/or posterior chamber structures; however, most patients affected with PHPV have a combination of anterior and posterior manifestations.
Sara L. Weidmayer
These can bridge a wide spectrum of severity; mild findings include a Mittendorf dot on the posterior lens capsule, a noticeable stalk representing Cloquet’s canal or Burgmeister’s papilla at the optic nerve head. However, the result of PHPV can be severe, including cataract, lens capsule rupture, persistent pupillary membrane, vitreous hemorrhage, tractional retinal detachment, optic disc dysplasia, secondary glaucoma or pthisis. PHPV is often associated with leukocoria, microphthalmos, a shallow anterior chamber and elongated ciliary processes.
PHPV is rarely familial, but, rather, is typically sporadic and unilateral; some have suggested autosomal inheritance, but this has not been confirmed. Bilateral PHPV is rare and is often associated with systemic developmental anomalies such as trisomy 13, 15 or 18.
Treatment
The treatment for PHPV depends heavily on the severity. Severe anterioposterior PHPV where there is no useable vision may be treated with lensectomy to prevent angle closure. Glaucomatous or phthisical eyes may require enucleation. In anterior PHPV, membranectomy with or without lensectomy and anterior vitrectomy may be performed. Complete surgical vitrectomy may be completed as needed to salvage vision. This is often in conjunction with amblyopia therapy.
In the case of the patient described in this case, despite her interesting manifestation of PHPV, her vision was correctable to 20/40, and surgical intervention was deemed unnecessary. While reducing macular traction would likely improve her vision to some extent, her visual prognosis would be guarded with amblyopia likely contributing to her decreased vision; therefore, polycarbonate spectacles for full-time wear for protection were recommended, and ocular health monitoring without surgical treatment was planned.