Induced Refractive error changes Optical Coherence Tomograph
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A Study was conducted to assess the effect of changing anterior eye refractive power with contact lenses on the transverse magnification of enface images and associated vascular indices from optical coherence tomography angiography (OCT-A).

In 11 healthy young adults, spherical soft contact lenses (-6D to +6D in 2D steps) were used to cause anterior eye refractive power changes, and 3 x 3mm macular scans were captured using OCT-A. Based on refraction and biometry measurements, image transverse magnification was predicted and compared to empirical changes in the enface images measured with image analysis. The relationship between induced refractive ametropia and the location, perimeter, circularity, vessel density, and perfusion density of the foveal avascular zone (FAZ) was investigated using linear regression analysis.

Results:
--The predicted transverse magnification was linearly related to induced refractive ametropia and to the empirical transverse magnification changes (average slope:1.02).

--All the OCT-A indices showed linear relationships with induced refractive ametropia with the 12D tested range altering the indices by 7-12%.

--After correcting for transverse magnification, all OCT-A indices except FAZ area were linearly related to induced refractive ametropia and were reduced to 1-9%.

To summarize, this is the first research to show that induced refractive ametropia has an effect on OCT-A image magnification and indices. These improvements are clinically significant and must be taken into account when analyzing OCT-A indices, along with biometry effects. OCT-ability A's to accurately calculate linear measurements of blood vessels may be harmed by changes in transverse magnification.

Source: https://www.sciencedirect.com/science/article/abs/pii/S0002939421002038?dgcid=rss_sd_all
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