Retinal Nerve Fiber Layer Thinning Associated With Poorer Visual Acuity, Study Finds

A study published in Jama Ophthalmology found that preterm infants had poorer visual acuity (VA) when they had retinal nerve fiber layer (RNFL) thinning across the papillomacular bundle (PMB), independent of birth weight, gestational age, need for retinopathy of prematurity (ROP) treatment, and macular microanatomy.

The study was part of the Study of Eye Imaging in Preterm Infants (BabySTEPS). Infants were eligible for this study if they met criteria for a ROP screening, were 35 weeks’ postmenstrual age (PMA) or older at time of first optical coherence tomography (OCT) imaging, and a parent or guardian provided written consent. Infants were excluded if they had eye pathology that precluded OCT imaging or retinal examination or a health condition with an impact on brain development.

Infants were included in this subanalysis if they had OCT imaging of both eyes at 38-42 or 35-37 weeks PMA. If an infant had more than 1 imaging session in the time intervals, the researchers selected images closest to 40 and 36 weeks PMA.

Sixty-one infants were included in the study with a mean (SD) age of 27.6 (2.8) weeks and birth weight of 958.2 (293.7) grams. The infants were enrolled between November 2016 and December 2019.

Monocular grating acuity of both eyes was successfully collected in 67 of the 118 infants who were enrolled in BabySTEPS. The monocular grating acuity of both eyes was imaged with bedside OCT in 91% of infants at a mean of 39.85 (0.79) weeks PMA. Ninety-seven percent of the infants were imaged at a mean of 36.03 (0.58) weeks PMA and were included in the secondary analysis.

There were 16 eyes of 8 infants who underwent ROP treatment prior to 40 weeks PMA; 4 eyes of 2 infants also underwent treatment after 40 weeks PMA and were included in the post hoc analysis in the treatment cohort. Seventy-one (58%) eyes had subnormal grating VA at 9 months' corrected age: 34% had normal VA in both eyes, 51% had subnormal VA in both eyes, and 15% had normal VA in 1 eye and subnormal in the other. The median (IQR) VA was 0.99 (95% CI, 0.81-1.10) logMAR.

Seventy-six (62%) eyes had macular edema in this study. Correlations between retinal layer thicknesses and logMAR VA were seen for the inner retina (r, 0.19; 95% CI, 0.01-0.35), total retina (r, 0.15; 95% CI, –0.02 to 0.31), choroid (r, –0.22; 95% CI, ­–0.38 to –0.03), RNFL across the PMB (r, –0.27; 95% CI, –0.45 to –0.10), and the inner nuclear layer (r, 0.01; 95% CI, –0.07 to 0.27).

In the univariable linear regression analysis, inner retinal thickness, total retinal thickness, choroidal thickness, and RNFL thickness across the PMB were associated with logMAR VA. ROP treatment prior to OCT imaging, gestational age, and birth weight was associated with logMAR VA in the univariable regression analysis. RNFL thickness across the PMB and ROP treatment prior to OCT imaging was associated with VA in the multivariable linear regression model.

There were some limitations to this study. The study was observational, which prevented the researchers from inferring causal relations between retinal microanatomy and VA outcomes, and relatively few eyes had ROP treatment, which prevented subanalysis of associations with laser ablation and bevacizumab injection.

The researchers concluded that the research demonstrated that RNFL thinning across the PMB near term was associated with poorer VA at 9 months corrected age that was independent of birth weight, gestational age, need for ROP treatment, and macular microanatomy.

“Our findings suggest that RNFL thinning across PMB may be an early biomarker of global disruptions in neurodevelopment that put preterm infants at risk for poorer vision outcomes,” the authors wrote.

Reference

Seely KR, Mangalesh S, Shen LL, et al. Association between retinal microanatomy in preterm infants and 9-month visual acuity. JAMA Ophthalmol. Published online June 2, 2022. doi:10.1001/jamaophthalmol.2022.1643