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Ryan Eyn Kidd Man, Ecosse L. Lamoureux, Yamna Taouk, Jing Xie, Muhammad Bayu Sasongko, William J. Best, Jonathan E. Noonan, Ryo Kawasaki, Jie Jin Wang, Chi D. Luu; Axial Length, Retinal Function, and Oxygen Consumption: A Potential Mechanism for a Lower Risk of Diabetic Retinopathy in Longer Eyes. Invest. Ophthalmol. Vis. Sci. 2013;54(12):7691-7698. doi: https://doi.org/10.1167/iovs.13-12412.
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© ARVO (1962-2015); The Authors (2016-present)
To determine the relationship between axial length (AL), retinal function, and relative oxygen (O2) consumption to better understand the protective effect of axial elongation on diabetic retinopathy development.
Measurements of AL, multifocal electroretinogram (mfERG), and relative O2 consumption (difference between arteriolar and venular O2 saturation levels or A-V difference) were performed on 50 healthy individuals. The relationships between AL, mfERG amplitude, and A-V difference were analyzed using linear regression models. Path analysis was performed to determine the direct and indirect effects (via mfERG amplitude) of AL on A-V difference.
mfERG P1 amplitude was positively associated with A-V difference ( β = 0.33; 95% confidence interval [CI]: 0.23–0.42). Increased AL was significantly associated with a decrease in A-V difference (β = −1.08; 95% CI: −1.52 to −0.65) as well as a decrease in retinal function (β = −3.14, 95% CI: −4.07 to −2.20). Path analysis models including AL (study factor), retinal function (intermediate variable), and A-V difference (outcome variable) showed that AL had little direct association with A-V difference (β p = −0.002), while the indirect effect of AL on A-V difference via changes in retinal function were substantial (β p = −0.51).
In eyes with longer AL, the reduction in A-V difference is explained by the parallel reduction in retinal function. These findings suggest that longer eyes have decreased retinal function and O2 consumption, and thus are relatively less hypoxic in the presence of diabetes, which may partly explain the reduced risk of DR in these eyes.
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