A small foveal avascular zone may be an historic mark of prematurity

Abstract

Objective: To compare in children the area and diameter of the foveal avascular zone (FAZ) of former preterm infants, when no significant retinopathy of prematurity (ROP) developed, to the area and diameter of the FAZ of former term infants.

Design: Retrospective observational case series and literature review.

Participants: Forty-nine children (39 former preterm infants and 10 former term infants) between the ages of 1 and 17 years had fluorescein angiograms. All of these children had been appropriate weight for gestational age at birth and had no genetic disorders. Neither eye of any of these children had any macular ectopia or vessel traction, had been treated for active ROP, had developed active ROP >stage 3 mild, or had any refractive error > +/- five diopters. Every child had a visual acuity of 20/40 or better in both eyes.

Methods: The area and greatest diameter of the FAZ were measured using digital image analysis of masked fundus fluorescein angiograms. Variables of gender, race, multiple birth, gestational age, birth weight, ROP stage, age, and refraction at the time of fluorescein angiography, and final visual acuity were recorded.

Results: Increasing FAZ area and greatest diameter correlated significantly with increasing gestational age and birth weight: FAZ area (microm2) versus gestational age (weeks) (R/F/P = 0.88/166.70/<0.0001); FAZ greatest diameter (microm) versus gestational age (weeks) (R/F/P = 0.87/151.10/<0.0001); FAZ area (micro/m2) versus birth weight (g) (R/F/P = 0.88/167.06/<0.0001); and FAZ greatest diameter (microm) versus birth weight (g) (R/F/P = 0.87/148.74/ <0.0001). A small or absent FAZ was found in all former preterm infants who had been < or = 30 weeks gestational age or had weighed < or = 1100 g at birth. A normal FAZ was present in all children who had been > or = 36 weeks gestational age or had weighed > or = 2650 g at birth. None of the other parameters studied correlated with FAZ area or greatest diameter.

Conclusion: This study provides evidence that the FAZ in developing humans is initially densely vascularized with a fine meshwork of inner retinal vessels during vasculogenesis. This vascular meshwork undergoes regression by apoptosis in all infants > or = 36 weeks gestational age at birth to form a normal FAZ, but apoptosis almost never occurs in preterm infants < or = 30 weeks gestational age at birth. Although there is no effect on final visual acuity, a small or absent FAZ may be an historic mark of prematurity.