Final answer:
Persistent hyperplastic primary vitreous (PHPV) or persistent fetal vasculature (PFV) is a congenital condition where the hyaloid artery fails to regress during gestation, potentially leading to various eye abnormalities.
Step-by-step explanation:
The condition in which the hyaloid artery does not regress is known as persistent hyperplastic primary vitreous (PHPV) or persistent fetal vasculature (PFV). This is a rare congenital eye anomaly where the hyaloid artery which typically disappears during the later stages of fetal development remains and may cause structural and functional abnormalities in the eye. The normal regression occurs between the 4th to 6th gestational months, but in cases of PHPV, the artery persists beyond birth, potentially leading to complications such as cataracts, retinal detachment or microphthalmia (abnormally small eyes). PHPV is usually unilateral, affecting only one eye.