Figure 23-5 Persistent fetal vasculature (PFV). A, Mild variant with central retrolental membrane. B, Elongated ciliary processes are adherent to lens. Note the dense fibrous plaque on the posterior lens capsule. C, Ultrasonogram of eye with PFV. Note the dense stalk arising from the optic nerve and attaching to the posterior lens. (Part A courtesy of David A. Plager, MD;

part C courtesy of Edward L. Raab, MD.)

The natural history of more severely affected eyes is usually one of progressive cataract formation and anterior chamber shallowing, causing secondary glaucoma. The glaucoma can occur acutely because of rapid, total lens opacification and swelling that develop over a few days, or it may develop gradually, over years. Congenital retinal nonattachment, ciliary body detachment, vitreous hemorrhage, and optic nerve dysmorphism are other features of severe PFV.

Retinoblastoma may be part of the initial differential diagnosis of PFV. The presence of microphthalmos and cataract are important factors in the differentiation of these disorders, as retinoblastoma is rarely found in microphthalmic eyes, and cataracts are very unusual in retinoblastoma.

Evaluation

All newborns should have a screening eye examination, including an evaluation of the red reflex (see Chapter 1). Retinoscopy through an undilated pupil is helpful for assessing the potential visual significance of an axial lens opacity in a preverbal child. Any central opacity or surrounding cortical distortion measuring 3 mm or more in diameter is usually visually significant.

History

The clinician should obtain a detailed history of the child’s growth, development, and systemic disorders, in addition to a family history. A slit-lamp examination of immediate family members can reveal previously undiagnosed lens opacities that are visually insignificant but that may indicate an inherited cause for the child’s cataracts. Congenital posterior sutural cataracts, for example, develop in female carriers of X-linked Nance-Horan syndrome, and mild lenticular opacities develop in female carriers of Lowe syndrome by puberty.

Examination

Visual function

The mere presence of a cataract does not suggest that surgical removal is necessary. That determination requires assessment of the visual significance of the lens opacity.

In healthy infants aged 2 months or younger, the fixation reflex may not be fully developed; thus, its absence in this group of patients is not necessarily abnormal. In general, anterior capsule opacities are not visually significant unless they occlude the entire pupil. Central or posterior lens opacities of sufficient density that are greater than 3 mm in diameter are usually visually significant. Opacities that have a large area of surrounding normal red reflex or that have clear areas within them may allow for good visual development. Strabismus associated with a unilateral cataract and nystagmus associated with bilateral cataracts indicate that the opacities are visually significant. Although these signs may also indicate that the optimal time for treatment has passed, cataract surgery can still result in improvement of visual function.

In preverbal children older than 2 months, standard clinical assessment of fixation behavior, fixation preference, and objection to occlusion provide additional evidence of the visual significance of the cataract(s). For bilateral cataracts, assessment of the child’s visual behavior and the family’s observations of the child at home help determine the level of visual function. Preferential looking