Hyaloid Artery – Embryonic Eye Vessel
The hyaloid artery is a temporary embryonic blood vessel in the eye that supplies the developing lens and vitreous humor during fetal development, and normally disappears completely before birth.
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The hyaloid artery is a temporary embryonic blood vessel in the eye that supplies the developing lens and vitreous humor during fetal development, and normally disappears completely before birth.
What is the Hyaloid Artery?
The hyaloid artery (Latin: Arteria hyaloidea) is a transient blood vessel that exists only during the embryonic development of the eye. It arises from the central retinal artery, a branch of the ophthalmic artery, and travels through the vitreous humor (the gel-like substance filling the eye) to reach the back surface of the developing lens. Its primary function is to supply oxygen and nutrients to the embryonic lens and vitreous body during a stage when these structures cannot yet sustain independent metabolism.
Development and Regression
The hyaloid artery develops from approximately the 6th to 7th week of gestation and forms part of the tunica vasculosa lentis, a temporary vascular network surrounding the embryonic lens. It belongs to the primary vitreous system, which is progressively replaced by the avascular (vessel-free) secondary vitreous as fetal development continues.
Toward the end of pregnancy, typically between the 28th and 34th week of gestation, the hyaloid artery begins to regress through a process of programmed cell death known as apoptosis. In a healthy newborn, the vessel is fully obliterated and no longer functional. The only anatomical remnant is the Cloquet canal (canalis hyaloideus) – a fine, optically empty channel running through the vitreous from the optic disc to the back of the lens, which has no clinical significance in adults.
Persistent Hyaloid Artery
In rare cases, the hyaloid artery fails to regress fully after birth. This condition is known as a persistent hyaloid artery and may occur in isolation or as part of a more complex developmental disorder called PHPV (Persistent Hyperplastic Primary Vitreous), now more commonly referred to as Persistent Fetal Vasculature Syndrome (PFVS).
Clinical Presentations
- Isolated persistence: A thin vascular stalk or fibrous cord extends from the optic disc to the posterior lens capsule. This is often an incidental finding with no clinical consequence.
- PHPV / PFVS: A more complex malformation involving fibrovascular tissue behind the lens, possible lens opacification, microphthalmia (abnormally small eye), glaucoma, or retinal detachment.
Symptoms
- Leukocoria (white pupil reflex) – an important warning sign in newborns
- Reduced vision or amblyopia (lazy eye)
- Strabismus (squinting or crossed eyes)
- Elevated intraocular pressure (when glaucoma is present)
Diagnosis
Diagnosis of a persistent hyaloid artery or PFVS is made through ophthalmological examination, which may include:
- Slit-lamp examination to assess the lens and anterior segment of the eye
- Ophthalmoscopy (funduscopy) to visualize the vitreous and retina
- Ocular ultrasound (B-scan) when direct visualization is limited
- MRI of the eye for complex cases or to differentiate from other conditions (e.g., retinoblastoma)
Treatment
An isolated, asymptomatic persistent hyaloid artery typically requires no treatment. In cases of clinically significant PFVS, management depends on the severity:
- Vitrectomy: Surgical removal of the fibrovascular tissue and abnormal vitreous to improve visual outcomes
- Cataract surgery: Removal of the lens if it has become opacified (cloudy) due to the persistent tissue
- Amblyopia therapy: Patching of the unaffected eye to stimulate visual development in the affected eye
- Glaucoma management: Pressure-lowering medications or surgery if intraocular pressure is elevated
Early diagnosis and timely intervention are essential to prevent permanent visual impairment in affected individuals.
References
- Sadler TW. Langman's Medical Embryology. 14th edition. Wolters Kluwer, 2019.
- Goldberg MF. Persistent fetal vasculature (PFV): An integrated interpretation of signs and symptoms associated with persistent hyperplastic primary vitreous (PHPV). American Journal of Ophthalmology. 1997;124(5):587–626.
- Chung MM, Orlin A. Persistent Hyperplastic Primary Vitreous. American Academy of Ophthalmology – EyeWiki. Available at: https://eyewiki.aao.org (accessed 2024).
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