Abstract
Purpose:
In some studies, premature infants have worse visual acuities than full-term infants at the same chronological age. We hypothesize that foveal anatomy specifically photoreceptor inner segment (IS) band maturation can predict function; and consequently, photoreceptor maturation is likely to be linked to visual acuity development. We believe that Spectral Domain Optical Coherence Tomography (SDOCT) has the level of resolution to identify photoreceptor IS band development and maturation, and therefore, this may predict function.
Methods:
We compared microanatomy of preterm and term infants between 37 to 42 weeks (wks) post-menstruation age (PMA). 86 preterm and 60 term infants were enrolled in an IRB approved study from 2009 to 2012. Foveal SDOCT images were obtained at bedside and graded by a masked observer. Qualitative and quantitative analysis of IS band and retinal layers at the foveal center and outside of the foveal center was performed. Presence of IS band at the foveal center was considered a sign of maturity.
Results:
SDOCT images of 50 of 86 preterm infants born between 23 and 35 (median 25) wks PMA, and 47 of 60 term infants born between 37 and 42 (median 39) wks PMA were included after excluding poor quality images. At the time of imaging between 37 to 42 wks, the median PMA was 40 wks in preterm and 39 wks in term infants. The incidence of developed IS band at the foveal center was higher in term than preterm infants. In preterm infants, 0 of 37 infants at 37 to 41 wks PMA, and 3 of 13 at 42 wks PMA had IS band developed at the foveal center. In term infants, 0 of 3 infants at 37 wks PMA, 1 of 5 at 38 wks PMA, 3 of 19 at 39 wks PMA, 8 of 15 at 40 wks PMA, 2 of 4 at 41 wks PMA, and 0 of 1 at 42 wks PMA had IS band present at the foveal center. The average proximity of the developed IS band to the foveal center was 1094 (±433) µm in preterm, and 767 (±568) µm in term infants with statistically significant difference, p=0.00185 (T-test).
Conclusions:
We define photoreceptor development and maturation in infants as visualized by in-vivo SDOCT imaging. We describe immaturity of photoreceptors in preterm when compared to term infants at same chronological age. This delayed maturation of photoreceptors may explain the lower visual acuities in preterm infants born between 23 to 35 wks PMA. Therefore, SDOCT may serve as an imaging tool that helps identify those infants in need of an early intervention.
Keywords: 698 retinal development •
648 photoreceptors •
757 visual development: infancy and childhood