Age-related changes in the peripheral retinal nerve fiber layer thickness

Abstract

Purpose: This pilot cross-sectional study aimed to determine age-related changes of the retinal nerve fiber layer (RNFL) thickness in retinal periphery by swept-source optical coherence tomography-based analysis.

Methods: Forty eyes of 40 healthy subjects were studied in three age groups, group 1 (20-40 years, n=15), group 2 (41-60 years, n=14), and group 3 (≥61 years, n=11). Wide-angle swept-source optical coherence tomography scans, including the optic disc and macula, were montaged with the nasal peripheral optical coherence tomography images acquired with a contralateral gaze. The peripapillary and peripheral RNFL thickness values were obtained for nasal and temporal sides. The ratio of peripheral-to-peripapillary RNFL thickness was also calculated for these sectors.

Results: We detected a significantly thinner RNFL in older than younger subjects at a distance of 6 mm from the optic disc on nasal and temporal sides (P<0.001). An age-related reduction in peripheral-to-peripapillary RNFL thickness ratios (P<0.001 and P<0.02 for nasal and temporal sides, respectively) was also detected.

Conclusion: The age-related decline should be taken into consideration when determining the glaucoma-related alterations in peripheral RNFL thickness. Continued analysis in patients with ocular hypertension and glaucoma should help determine whether RNFL in the periphery with lower nerve tissue reserve might be more susceptible to injury, whether injury to the peripheral RNFL might be easier to detect, and/or whether analysis of the peripheral RNFL thickness could improve clinical diagnosis and follow-up of glaucoma.

Keywords: age; glaucoma; retinal nerve fiber layer thickness; swept-source optical coherence tomography.

Figure 1

Retinal images were acquired using the swept-source Deep Range Imaging-OCT (DRI-OCT-1, Topcon, Tokyo, Japan). Note: Montaging the routine wide-angle OCT image with the nasal peripheral OCT image (acquired with a contralateral gaze) yielded the composite image with a larger field, including up to 10 mm nasal and 8 mm temporal to the optic disc, and 3 mm superior and inferior to the optic disc. Abbreviation: OCT, optical coherence tomography.

Figure 2

The Deep Range Imaging-OCT segmentation software (Topcon, Tokyo, Japan) was used to identify the limits of the retinal nerve fiber layer as the area expanding from the internal limiting membrane to the inner boundary of the retinal ganglion cell layer. Abbreviation: OCT, optical coherence tomography.

Figure 3

The representative composite images obtained from different age groups containing the retinal nerve fiber layer thickness data: (A) Group 1, (B) Group 2, and (C) Group 3.

Figure 4

The peripheral RNFL thickness in different age groups. Abbreviation: RNFL, retinal nerve fiber layer.

Figure 5

The peripheral-to-peripapillary RNFL thickness ratio in different age groups. Abbreviation: RNFL, retinal nerve fiber layer.

Figure 6

Scatterplots of the relationship between the peripheral RNFL thickness and age. Notes: Linear regression analysis detected a negative correlation between the peripheral RNFL thickness and age (R=0.549, P<0.001; and R=0.612, P<0.001 for nasal and temporal sides, respectively) and the peripheral-to-peripapillary RNFL thickness ratio obtained for nasal (R=0.542; P<0.001) and temporal sides (R=0.362; P=0.02). Abbreviation: RNFL, retinal nerve fiber layer.