Age and location-specific norms of interocular retinal nerve fiber layer thickness asymmetry

Abstract

Purpose : To provide age-specific normative quantiles of pointwise interocular circumpapillary retinal nerve fiber layer thickness (RNFLT) asymmetry in healthy Caucasian eyes.

Methods : From the age and gender stratified population-based LIFE Adult study; we selected spectral domain optical coherence tomography (OCT) scans of circumpapillary RNFLT (768 A-scans, diameter: 12°) of participants with reliable measurements of both eyes (≥50 B-scan repetitions, quality ≥20 dB, ≤2.5% missing A-scans) with no clinically significant findings on fundus and/or OCT images in either eye. Interocular RNFLT differences of all 768 retinal locations per age decade were investigated for significant age effects (p<0.05 after adjustment for multiple comparisons) by linear regression. For each age decade, interocular RNFLT difference quantiles were calculated for all 768 locations.

Results : 8,966 RNFLT scans of 8,966 eyes of 4,483 subjects were selected (age range: 20 to 79 years, 2,466 female/2,017 male). Mean interocular RNFLT differences (OS–OD) for the full age range were significant for 95.4% of the 768 locations and ranged within [-11.9,+11.6] μm with predominantly thicker RNFLT for left eyes at superior and inferotemporal locations and for right eyes at nasal and inferonasal locations (Fig. 1A). Fig. 1B compares interocular mean RNFLT differences between the youngest (20 to 29 years) and oldest (70-79 years) age decade, which illustrates less interocular mean difference for elderly subjects comparing to younger subjects for most retinal locations. Fig. 1C shows the age slopes for absolute interocular RNFLT differences: For 7.3%/49.2% of the locations, absolute interocular differences significantly increase/decrease with age, ranging within [-0.20,+0.09]μm per year. This may justify the consideration of age and retinal location in interocular RNFLT difference norms. Fig. 2 provides normative quantiles (between 0.5% and 99.5%) of RNFLT difference between left and right eye for each of the 768 measured retinal locations, separately for each age decade.

Conclusions : Optic neuropathies may develop asymmetrically between the eyes, and abnormal interocular RNFLT differences might be relevant to detect disease onset or monitor progression. We demonstrate substantial age and location-specific interocular RNFLT differences and provide normative quantiles per age decade for 768 circumpapillary retinal locations.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

 

Fig.1

 

Fig.2