الفهرس 
Prenatal ultrasound diagnosis of fetal hyaloid artery changes and abnormalities with its effect on the neonatal APGAR score
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Abstract
Fetal eye development incorporates a cluster of processes beginning in the early first trimester. One of them is the proliferation of a vascular tree originating from the hyaloid artery (HA), enabling proper blood supply to the primary vitreous for normal retinal development. The hyaloid artery disappears between 23 and 28 weeks, and is normally not visible on ultrasound after 29 weeks of gestations (Bronshtein et al., 2017).
Later in pregnancy, a critical stage occurs with regression of the HA and its branches. This event starts at early second trimester and ends with full regression of the HA at mid–third trimester (Shastry et al., 2009). Failure of this stage to occur is known as persistent hyperplastic primary vitreous (PHPV). When bilateral, it is usually associated with extraocular anomalies and chromosomal abnormalities such as trisomy 13. However, in most cases, PHPV is unilateral and nonhereditary, with leukocoria as the first sign, appearing at early neonatal life (Balmer et al., 2007).
Persistent hyperplastic primary vitreous is a spectrum of congenital ocular abnormalities caused by the failure of in utero conversion of the primary vitreous to the secondary adult vitreous and regression of hyaloid vasculature (Bezuidenhout et al. 2014).
Clinical features of the classic persistent hyperplastic primary vitreous syndrome include leukocoria, microphthalmia, cataracts, extensive intravitreal hemorrhage, persistence of the hyaloid artery, secondary glaucoma caused by swelling of the lens or contracture of the retrolental tissue, and, occasionally, retinal detachment. It is typically unilateral and isolated; however, when it is bilateral, it is mostly accompanied by other ocular and systemic abnormalities and suggests congenital syndromes such as trisomy 13, Walker Warburg syndrome, and Norrie disease (Esmer et al., 2016). The natural course of the disease may result in early cataract and closed‐angle glaucoma. In the long term, enucleation may be inevitable as a result of terminal glaucoma, intraocular hemorrhage, retinal detachment, uveitis, or phthisis bulbi(Azrak et al., 2011)
The prenatal diagnosis of persistent hyperplastic primary vitreous is extremely rare. The most prominent sonographic findings include hyperechoic lenses and a hyperechoic mass between the posterior surface of the lens and posterior wall of the eye, representing hyaloid artery persistence and retinal detachment (Spaggiari et al., 2012).
Prenatal sonographic description of HA regression throughout pregnancy was first studied by Birnholz et al. (1988). They found that the presence of the HA in the mid–third trimester is uncommon in healthy fetuses (<1%), and when present it may be associated with chromosomal abnormalities and central nervous system anomalies. Abnormal appearance and non-regression of the HA was previously described in case reports, suggesting an association with postnatal ophthalmic diseases (Spaggiari et al., 2012).
In previous reports, fundus photography, fluorescein angiography (FAG), optical coherence tomography (OCT) and Doppler ultrasound were used to diagnose and to check the blood flow of the PHA (Sundararajan et al., 2018). OCT angiography can visualize peri-papillary vessels by detecting the movement of red-blood cells (Akil et al., 2017).