RNFL Thinning Linked to Poorer Visual Acuity in Preterm Infants

Cynthia A. Toth, MD

Findings from a recent observational study suggest the evaluation of retinal nerve fiber layer (RNFL) thickness using optical coherence tomography (OCT) may help identify preterm infants at risk for poor vision outcomes.

Data show the thinning of the RNFL across the papillomacular bundle (PMB) had associations with poorer 9-month visual acuity, found independent of birth weight, gestational age, need for retinopathy of prematurity (ROP) treatment, and macular microanatomy.

“Our findings suggest that RNFL thinning across the PMB may be an early biomarker of global disruptions in neurodevelopment that put preterm infants at risk for poorer vision outcomes,” wrote study author Cynthia A. Toth, MD, Department of Ophthalmology, Duke University School of Medicine.

Previous research using investigational bedside OCT revealed subclinical microanatomic features in preterm infants, which carried into school age, which investigators noted may suggest that preterm birth may have continual impact on retinal microanatomy.

This prospective, observational study investigated retinal microanatomy in preterm infants vs their subsequent grating VA as part of Study of Eye Imaging in Preterm Infants (BabySTEPS). Infants were eligible for enrollment in BabySTEPS if they met criteria for ROP screening, were 35 weeks’ postmenstrual age (PMA) or older at the time of first OCT imaging, and a parent or guardian provided written informed consent.

The primary outcome of BabySTEPS was the analysis of infant retinal microanatomy and VA at 9 months’ corrected age. The outcome consisted of measuring the presence and severity of macular edema and presence of ellipsoid zone at the fovea, choroid across foveal 1 mm, and RNFL across the PMB.

Moreover, associations between retinal microantomy and normal (3.70 cycles/degree or greater) vs subnormal grating VA at 9 months’ corrected age using logistic regression and with logMAR VA using linear regression.

Infants were included in the analysis if they had bedside OCT imaging of both eyes at 38 to 42 weeks’ postmenstrual age (primary analysis) or 35 to 37 weeks’ postmenstrual age (secondary analysis).

Thus, a total of 61 infants were included in the study with a mean gestational age of 27.6 weeks and mean birth weight of 958.2 grams, according to investigators. Within the 122 eyes of this population, investigators found the correlation between retinal layer thickness and logMAR VA to be:

• r, 0.01 (95% CI, -0.07 to -0.27) for inner nuclear layer
• r, 0.19 (95% CI, 0.01 to 0.35) for inner retina
• r, 0.15 (95% CI, -0.02 to 0.31) for total retina
• r, -0.22 (95% CI, -0.38 to -0.03) for choroid
• r, -0.27 (95% CI, -0.45 to 0.10) for RNFL across the PMB

Using a multivariable linear regression model, investigators then observed RNFL thickness across the PMB (adjusted β, −0.05 per 10-μm increase in RNFL thickness; 95% CI, −0.10 to −0.01; P = .046) and ROP treatment prior to OCT imaging (adjusted β, 0.33 for ROP treat- ment; 95% CI, 0.11 to 0.56; P = .003) had an association with VA.

Toth noted this meant “thinner RNFL across the PMB and prior ROP treatment were associated with poorer VA.”

The study, “Association Between Retinal Microanatomy in Preterm Infants and 9-Month Visual Acuity,” was published in JAMA Ophthalmology.