Abstract
Purpose :
To characterize infant macaque macular development longitudinally in vivo by measuring the thickness of retinal layers with spectral domain ocular coherence tomography (sdOCT) over the first six postnatal months.
Methods :
Eight breastfed, mother-reared rhesus macaque infants were imaged by sdOCT (Heidelberg Spectralis) at 2, 4, 8, 16 and 24 weeks postnatal age. After sedation and placement of a speculum and contact lens, macular scans were acquired as averages of 20 B-scans with 37 slices. Eleven retinal layers were segmented by Spectralis software (Viewing Module 6.3.2, 2014) with manual correction of each slice. Layer thicknesses were measured at the foveal center, and average thicknesses were determined for the central 1 mm and for the superior, nasal, inferior and temporal quadrants of 1-2 and 2-3 mm diameter annuli. Values were compared with those for 25 rhesus adults (5-24 years of age).
Results :
A foveal pit was present in all animals at 2 weeks of age, and each of the 11 layers could be resolved at all ages. In all regions, total retinal thickness was approximately 75% of adult values at 2 weeks and increased to 89-96% of adult thickness by 24 weeks. The thickness of the photoreceptor inner/outer segment layer (IS/OS) and outer nuclear layer (ONL) increased progressively with age, while the outer plexiform layer (OPL), inner nuclear layer (INL), inner plexiform layer (IPL) and ganglion cell layer (GCL) decreased, reflecting the characteristic pattern of foveal maturation. In the foveal center and central 1 mm, IS/OS thickness increased from 73-75% of the adult value at 2 weeks to 94-96% by 16 weeks, and ONL thickness from 59-68% of the adult value to 88-95% by 24 weeks. In the 1-2 and 2-3 diameter annuli, IS/OS thickness was 74-76% of adult values at 2 weeks, increasing to 89-92% at 24 weeks, while the ONL increased from 78-85% to attain adult thickness by 16 weeks.
Conclusions :
This study provides the first quantitative longitudinal measurement of macaque macular development. Retinal layer thicknesses in the infant macula are nearly comparable to the adult pattern by 24 weeks of age. This set of normative data will serve as the basis for evaluation of alterations in macular development due to nutritional and other factors.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.