Postnatal regression of the tunica vasculosa lentis.

Previous studies have shown a good correlation between appearance of the tunica vasculosa lentis (TVL) at birth and gestational age in 27-34 week premature infants. We studied the effect of postnatal age on the rate of regression of the TVL in premature infants to assess whether this occurred at a similar rate to that in utero. Fifty-eight premature infants were enrolled into the study. Gestational age was assessed using the method described by Ballard. Lens examination was by direct ophthalmoscopy within 36 hours of birth and then on a weekly basis. Regression of the TVL was graded according to the system described by Hittner; grade IV being the most immature (vascularity covering virtually the entire anterior surface of the lens) to grade I (vascular regression to a point at which only occasional vessels are visualized). Results were analyzed and compared according to postconceptional age. No significant differences were found in the rate of disappearance of the TVL when infants were studied at equivalent postconceptional ages irrespective of postnatal age. Thus, premature delivery was not associated with accelerated regression of the TVL. These findings may be useful in assessing gestational age of a preterm infant who has not had an assessment of gestational age within the first days after birth or who is transferred to a high-care centre beyond the stage when other gestational aging systems are considered reliable.