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Hosein Hoseini-Yazdi, Stephen Vincent, Michael J Collins, Scott A Read, David Alonso-Caneiro; Wide-field choroidal thickness in myopes and emmetropes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):1108.
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© ARVO (1962-2015); The Authors (2016-present)
There is limited information regarding the choroidal thickness (CT) characteristics beyond the central macular region (central 17°) and how the peripheral CT is affected by myopia. This prospective study examined the topographical CT profile over the central 55° of the retina in healthy myopic and emmetropic adults with enhanced depth imaging wide-field optical coherence tomography (WFOCT).
The right eye of 13 emmetropic and 11 myopic adults who were matched for age (mean age 27 ± 5 years) and sex (54% male) underwent WFOCT choroidal imaging using the Spectralis device (a 55° wide × 45° high horizontal volumetric protocol with 37 B-scans), controlling for the time of day. Using a semi-automated procedure, CT was measured over the macular region including the fovea (FCT), parafovea (PaFCT), and perifovea (PeFCT), and the peripheral region including the near-periphery (NPCT), mid-periphery (MPCT) and far-periphery (FPCT) across common points (Figure 1). The anatomical variation in the disc-fovea angle and variations in the transverse magnification of the B-scans due to individual ocular dimensions were taken into account.
°For both myopes and emmetropes, significant topographical variations in CT were observed, with the choroid progressively thinning beyond the parafovea (365 ± 80 µm) towards the far-periphery (257 ± 36 µm), and being thickest in the superior quadrant (361 ± 64 µm) and thinnest in the nasal quadrant (291 ± 71 µm) (all p < 0.05). The CT profile was also influenced significantly by refractive error (p < 0.05). While myopes exhibited a significantly thinner macular and near-peripheral choroid than emmetropes (FCT: 322 ± 81 v 422 ± 81 µm, PaFCT: 317 ± 81 v 413 ± 81 µm, PeFCT: 308 ± 74 v 390 ± 74 µm, NPCT: 290 ± 60 v 346 ± 60 µm) (all p < 0.05), there was no significant difference in CT associated with refractive error in the two outermost peripheral regions (all p > 0.05) (Figure 2). The meridional variations in CT were not associated with myopia (p > 0.05).
Across a 55° field, the choroid was thickest within the parafoveal zone and attenuated substantially towards the periphery. Significant differences in CT associated with myopia were found to be largely confined to the central 27 macular and near-peripheral zones.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
Illustration of the examined choroidal regions following the disc-foveal angle adjustment
Wide-field CT profile in myopes and emmetropes as a function of retinal eccentricity
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