Abstract
Purpose:
To evaluate the effect of prematurity on optic nerve development by comparing optic nerve parameters and morphology in premature and term infants at 37-42 weeks postmenstrual age (PMA) using SDOCT.
Methods:
Images were obtained in 60 preterm infants and 60 term infants at 37-42 weeks PMA using a portable SDOCT system (Bioptigen Inc., Research Triangle Park, NC). For each subject, the highest quality image from either eye was selected for quantitative analysis based on a subjective assessment of image clarity, ability to identify lateral edges of the retinal pigmented epithelium and lamina cribrosa, centering of the optic nerve, and lack of tilt. Quantitative analysis included measurement of vertical cup diameter (vCuD), disc diameter (vDD), cup-to-disc ratio (vC:D), and cup depth, using a defined protocol. Images were masked, and measurements made using a custom MATLAB (MathWorks, Natick, MA) program. Statistical analyses compared measures by term status, race, and gender.
Results:
vCuD (µm), vDD (µm), vC:D, and cup depth (µm) were measured in 44/60 preterm and 52/60 term infants. Sixteen preterm and 8 term subjects were excluded due to lack of adequate optic nerve images. Preterm infants had a mean gestational age (GA) of 26 weeks, birth weight of 872g, and included 18 subjects who were treated for ROP or had Stage 3 disease; term infants had a mean GA of 39 weeks and birth weight of 3345g. In comparing preterm vs. term infants, preterms had significantly larger vCuD (µm) and vC:D (871 vs. 687, p<0.001; 0.66 vs. 0.52, p<0.001, resp.); no significant difference was found for vDD and cup depth (also after adjusting for gender and race). In comparing non-Hispanic Whites vs. African Americans, the latter had significantly larger vCuD (µm), vDD (µm), and cup depth (µm), but not vC:D, after adjusting for term status (716 vs. 829, p=0.032; 1267 vs. 1332, p=0.046; 377 vs. 489, p=0.01; 0.57 vs. 0.62, p=0.18, resp.). In comparing genders, no significant differences in optic nerve parameters were found after adjusting for term status.
Conclusions:
This is the first study using SDOCT to show a significantly larger vC:D in preterm compared to term infants at 37-42 weeks PMA, in contrast to prior papers that have reported similar findings in school-aged children with a history of low birth weight. The data show that prematurity impacts optic nerve development at a very early stage.
Keywords: 629 optic nerve •
497 development