Persistent fetal vasculature and minimal fetal vascular remnants: a frequent cause of unilateral congenital cataracts.

Purpose: To determine the significance of persistent fetal vasculature (PFV) and remnants of fetal vessels in the pathogenesis of pediatric unilateral cataracts.
Study Design: Prospective observational case series.
Participants: Thirty-one children with unilateral cataract aged between 2 weeks and 15 years.
Methods: As part of an ongoing prospective clinical trial concerning treatment and etiology of pediatric cataracts, a subgroup of 31 children with unilateral cataracts was defined. The affected eyes received preoperative and intraoperative biomicroscopic examinations to identify characteristic features of PFV and even minimal fetal vascular remnants (MFVRs) at the level of the posterior lens capsule and anterior hyaloid face. In eyes with MFVRs, 3 different severity degrees were assumed, according to different posterior capsule abnormalities: mild, A; moderate, B; and severe, C. All observations were documented on video and analyzed in relation to age (group I, infants between 0 and 1.5 years; group II, preschool children between 1.6 and 5.9 years; group III, schoolchildren between 6 and 16 years).
Main Outcome Measures: Frequency and morphology of characteristic features of PFV and MFVRs of the posterior lens capsule/anterior hyaloid face, lens clouding, and microphthalmos.
Results: All 31 eyes with unilateral congenital cataracts showed signs of PFV syndrome (100%). Characteristic features of PFV were found in 75% of group I eyes, in 8% of group II eyes, and in 67% of group III eyes. Minimal fetal vascular remnants were found in 25% of group I eyes (severity degree C in all eyes), in 92% of group II eyes (severity degree A in 36.4%, B in 27.2%, and C in 36.4%), and in 33% of group III eyes (severity degree A). Associated microphthalmos was found in all eyes in groups I and III and in 73% of group II, whereas axial lengths were equal in both eyes in 27% of group II children with MFVRs.
Conclusions: Varying degrees of PFV seem to be a frequent cause of unilateral congenital cataracts. Although characteristic features of PFV occurred mainly in infants, eyes of preschool children were usually very mildly affected, showing MFVRs that were detected only by careful observation during surgery. Abnormalities of the central part of the posterior capsule, such as a translucent opacity or a lenticonic area leading to a spontaneous hole during lens aspiration, may be caused by minimal remnants of PFV.