Normative dataset for retinal layers’ thickness maps automatically generated by spectral domain optical coherence tomography in a Caucasian population

Abstract

Purpose : To collect a dataset of normative ETDRS thickness maps values for each of the 7 retinal layers automatically generated by the Spectralis SD-OCT software (Heidelberg Engineering, Germany) in a healthy Caucasian population and to test the effect of age, sex and axial length (AXL) on such values.

Methods : 30x25 degrees volume scans centred on the fovea (61 b-scans, 120 mm inter-scan distance, 16 ART frames) were collected on healthy Caucasian subjects. Automatic segmentation of retinal layers was performed using the inbuilt software function. In one eye from each subject mean thickness values in the central subfield (C), inner ring (IR) and outer ring (OR) of the ETDRS grid were than calculated for each layer. A multivariate regression analysis was used to test the effect of age, sex and AXL on these values.

Results : 200 subjects (110 females) were enrolled. Mean age was 39.9±13.9 years (range 20-74). Mean AXL was 24.30±1.07 mm (range 22.23-27.14). Thickness values in the 3 main ETDRS subfield are reported for each retinal layer in Table 1. Nerve fiber layer thickness increased with age in the IR (p=0.006). Ganglion cells thickness was higher in males (p=0.009) in the IR and OR, it was also negatively correlated with AXL in the OR (p<0.0001) but positively correlated with the AXL in the C (p=0.001). Inner plexyform layer was thicker in males (p=0.0007) in the IR and thinner in longer eyes in the OR (p=0.0001). Inner Nuclear Layer was thicker in males in the C and IR (p<0.0001) and negatively correlated with age in the OR (p=0.008). Outer plexyform layer thickness didn’t change with age and gender but was positively correlated with AXL in the C (p=0.0004). Outer nuclear layer thickness was higher in males in all subfields (all p<0.0009) and decreased in with age in the OR (p=0.003). Retinal pigment epithelium increased in thickness with age (p=0.008) in the IR but wasn’t affected by sex or AXL in any of the subfields.

Conclusions : The thickness of each retinal layer in a large Caucasian population are provided. Age, sex and AXL have an influence on retinal layers thickness. The effect of these factors may vary according to the layer and the ETDRS subfield. Large datasets are needed to provide normative referring values.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

 

Thickness values in the 3 main ETDRS subfields and the effect of age, sex, axial length are reported for each retinal layer.