Abstract
Purpose: :
To explore the effect of axial length (AL) on retinal nerve fiber layer (RNFL) and macular measurements in different ethnic groups.
Methods: :
As part of the Sydney Childhood Eye Study, 2367 year 7 students were examined in 2004 - 2005. AL measurement (IOLMaster) and StratusOCT scans of the macula and RNFL were acquired. The RNFL was scanned as a circle of 3.4mm diameter centered on the optic disc and divided into quadrants for analysis. The macula was divided into three concentric zones with outer radii of 0.5mm (central macula), 1.5mm (inner macula) and 3.0mm (outer macula). Pearson correlation coefficients (r) between AL and retinal parameters were calculated. The Bonferroni correction was applied to adjust for multiple comparisons.
Results: :
For the whole sample average, inferior, nasal and superior RNFL were negatively correlated with AL (r = -0.16, -0.22, -0.17, -0.08 respectively; P≤0.001), while the temporal RNFL was positively correlated with AL (r = 0.12, P<0.001). Average inner macula, average outer macula and macular volume were also negatively correlated with AL (r = -0.14, -0.25, -0.22 respectively; P<0.001). Although these patterns were also reflected in the Caucasian and East Asian subgroups, East Asian children displayed stronger correlations for average RNFL, inferior RNFL, nasal RNFL, temporal RNFL average outer macula and macular volume (r = -0.25, -0.36, -0.31, 0.28, -0.35 and -0.31 respectively, P<0.001) compared with Caucasian children (r = -0.14, -0.20, -0.12, 0.08, -0.17 and -0.13 respectively, P<0.05). In Caucasian children, both foveal minimum thickness and central macular thickness were positively correlated with AL (r = 0.11 and 0.13, respectively, P≤0.001).
Conclusions: :
The strength of AL correlations with retinal parameters varied according to ethnicity, with East Asian children displaying the strongest correlations. Ethnicity may be a consideration when interpreting OCT scans on individuals with atypical AL.
Keywords: imaging/image analysis: clinical • retina • clinical (human) or epidemiologic studies: systems/equipment/techniques