Macular Optical Coherence Tomography Characteristics at 36 weeks Postmenstrual Age in Infants Examined for Retinopathy of Prematurity

Objective: To report our ability to capture, grade reliably and analyze bedside macular optical coherence tomography (OCT) images from preterm infants and relate OCT findings to biological factors and retinopathy of prematurity (ROP) status at a single time window in the STudy of Eye imaging in Preterm infantS (BabySTEPS).

Design: Prospective observational study PARTICIPANTS: Preterm infants eligible for ROP screening, with parental consent for research and a 36±1 weeks postmenstrual age (PMA) visit.

Methods: We imaged both eyes of preterm infants with an investigational non-contact, handheld swept-source OCT at the time of clinical ROP examinations. Macular OCT features and layer thicknesses for untreated eyes of infants at 36±1 weeks PMA were compared to demographic data and clinical ROP examination performed by experts. Statistical analyses accounted for the use of both eyes of infants.

Main outcome measures: Macular OCT features and layer thicknesses, gender, race/ethnicity, gestational age, birth weight, ROP stage, and plus disease.

Results: We captured macular OCT from 169 eyes (one eye excluded for prior ROP treatment) at 36±1 weeks PMA. The quality of OCT volumes was excellent in 33 eyes (19%), acceptable in 112 (67%), poor in 24 (14%) and unusable in 0 (0%). Macular edema was present in 60% of eyes and bilateral in 82% of infants with edema. At the fovea, retinal thickness and inner nuclear layer (INL) thickness increased with edema severity: 183±36μm and 51±27μm in mild edema (16% of eyes), 308±57μm and 163±53μm in moderate (25%) and 460±76μm and 280±83μm in severe (12%), respectively. With an increase in ROP stage from 0 to 2, the mean (standard deviation) retinal thickness at fovea increased from 227(124) to 297(99)μm, p<0.001. The choroid was thinner 155(72) with pre-plus/plus disease versus without 236 (79), p=0.04, while retinal thickness did not vary.

Conclusion: We demonstrate the reliability of methods and the prevalence of OCT findings in preterm infants enrolled in BabySTEPS, at a single time-point of 36±1 weeks PMA. The variations in layer thicknesses in infants at this time point may reflect abnormalities due to delay in foveal development that may be impacted by macular edema, ROP, or both.