ATARACT PHPV
Transparency at Risk Neovascularization of the Lens by Olawale Salami
Family history can be an important diagnostic tool.
T
he human lens and cornea are transparent tissues. In intrauterine life, the lens is nourished by a generous network of fetal capillaries which regress completely by the late fetal period, before birth. The avascular nature of the human lens is an important anatomical feature needed to maintain its optimal transparency. The invasion of the lens by abnormal or leaky vessels — or neovascularization — may occur in response to several types of insult and is a significant cause of opacity and/or blindness.
Blood vessels that just won’t go away Persistent hyperplastic primary vitreous (PHPV) is a failure of the regression of a component of fetal blood vessels within the eye. It remains an important cause of amblyopia and visual disabilities in children1 and should be suspected in any child with leukocoria. Affected eyes may develop complications including glaucoma, cataracts, intraocular hemorrhages, retinal detachments and/or phthisis, that will further affect the child’s vision.2
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Although the majority of cases are both unilateral and non-hereditary, the occurrence of some familial clinical patterns points to genetic factors and can be inherited as an autosomal dominant or recessive trait.3 Neovascularization of cornea, iris, optic disc and retina is well-documented. However, the adult human lens and its capsule are avascular and resistant to neovascularization. Latest research findings in the field suggest that the underlying mechanisms that drive neovascularization in the intraocular lens after cataract extraction may be related to diabetes and ischemic central retinal vein occlusion (CRVO), leading to chronic hypoxia and high levels of vascular endothelial growth factors (VEGF) in anterior chamber.4 Furthermore, anatomical proximity of the intraocular lens (IOL) with pupillary margin and loss of vitreous and its antiangiogenic factors, like opticin have been implicated.5
A family-centered approach to diagnosis According to Dr. Manoharan Shunmugam, director of clinical
| Sept/Oct 2020
services at the flagship branch of OasisEye Specialists in Kuala Lumpur, during the diagnostic work-up of a patient, it would be helpful to examine parents and siblings, as many genetic conditions — though they may have variable penetrance and expressivity — may have some detectable clinical manifestations. “For patients with hereditary conditions, it is imperative that the parents receive genetic counseling so that they are aware of the possibilities of these conditions affecting any other children,” Dr. Shunmugam emphasized. “It would also be prudent to ensure that siblings or extended family have a routine eye examination.” In addition, he advised that “a thorough social and dietary history is necessary, as some modern dietary restrictions have been shown to have an impact on even normal individuals, let alone those with an underlying genetic condition.”
Look out for leukocoria Early PHPV typically presents with leukocoria in the smaller eye of an infant within one to two weeks of birth.
