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

Objective: To compare in children the area and diameter of the foveal avasc ular zone (FAZ) of farmer preterm infants, when no significant retinopathy of prematurity (ROP) developed, to the area and diameter of the FAZ of form er 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 ha d any macular ectopia or vessel traction, had been treated for active ROP, had developed active ROP >stage 3 mild, or had any refractive error >+/- fi ve diopters. Every child had a visual acuity of 20/40 or better in both eye s. Methods: The area and greatest diameter of the FAZ were measured using digi tal image analysis of masked fundus fluorescein angiograms. Variables of ge nder, race, multiple birth, gestational age, birth weight, ROP stage, age, and refraction at the time of fluorescein angiography, and final visual acu ity were recorded. Results: Increasing FAZ area and greatest diameter correlated significantly with increasing gestational age and birth weight: FAZ area (mu m(2)) versu s gestational age (weeks) (R/F/P = 0.88/166.70/<0.0001); FAZ greatest diame ter (mu m) versus gestational age (weeks) (R/F/P = 0.87/151.10/<0.0001); FA Z area (mu m(2)) versus birth weight (g) (R/F/P = 0.88/167.06/<0.0001); and FAZ greatest diameter (mu m) 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 wh o had been less than or equal to 30 weeks gestational age or had weighed le ss than or equal to 1100 g at birth. A normal FAZ was present in all childr en who had been greater than or equal to 36 weeks gestational age or had we ighed greater than or equal to 2650 g at birth. None of the other parameter s 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 ves sels during vasculogenesis. This; vascular meshwork undergoes regression by apoptosis in all infants greater than or equal to 36 weeks gestational age at birth to form a normal FAZ, but apoptosis almost never occurs in preter m infants less than or equal to 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.