Hypoxia‐induced redox signalling in Müller cells

Cheong2014), theCTwas thickest in the superior and temporal sectors (inner superior: 328.5 lm; outer superior: 334.0 lm; inner temporal: 337.9 lm; outer temporal: 336.8 lm), followed by the central sector (324.9 lm), and thinnest in the nasal sectors. Studies have also demonstrated that the thickest region of the choroid varies with the spherical equivalent (SE) and axial length (AL) (Flores-Moreno et al. 2013; Tan et al. 2014). For those with spherical equivalent of 1.99 D to +0.50 D, the central and temporal regions were of similar thickness, whereas for those with spherical equivalent 2.0 D or worse, the superior and temporal sectorswere thicker (Tan et al. 2014). Differences in CT reported in different studies could also be due to the occurrence of diurnal variation, differences in age, interobserver variability, presence of systemic diseases or the type of OCT device used (Tan et al. 2015). Lee et al. also reported that the ratio of temporal CT to subfoveal CT (CTT/ CTF) positively correlated with AL and negatively correlated with refractive error, although CT at all locations did not correlate with AL and refractive error. This is interesting, as CT has been reported to vary with both AL and refractive error, and values of up to 58.2 lm/mm and 25.4 lm/D have been reported (Tan & Cheong 2014). In addition, it hasbeen reported thatCTexhibits different rates of change with AL and refractive error at different regions of the macula (Tan & Cheong 2014). Therefore, it may be useful to measure mean CT or choroidal volume at different predefined macular regions, for example using the Early Treatment Diabetic Retinopathy Study (ETDRS) grid (Tan et al. 2014). This will provide more accurate information of the relationship of choroidal topography with myopia than single point thickness measurements along horizontal and vertical OCT B-scans. In summary, we congratulate the authors on their study findings, and look forward to future studies which evaluate the choroid and myopia.