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Rhett Stroupe, Nancy Coletta; Foveal Pit Dimensions in Myopia. Invest. Ophthalmol. Vis. Sci. 2013;54(15):3610.
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© ARVO (1962-2015); The Authors (2016-present)
The effects of myopia on macular retinal thickness have been examined in several studies but few have examined how myopia affects the dimensions of the foveal pit. The purpose of this study was to examine how foveal pit dimensions vary with axial length and refractive error.
Data are reported for both eyes of 25 subjects (average age 24.8 years +/- 3.8 s.d.) with refractions ranging from plano to -9.90 D (mean -3.70 D) and axial lengths ranging from 21.8 to 26.6 mm (mean 24.7 mm) as measured with an IOL Master. Retinal thickness was measured with an Optovue RTVue spectral domain OCT using the MM6 scan protocol consisting of twelve 6-mm scans centered on the fovea. For each scan orientation, we computed the minimum thickness, maximum thickness on either side of the foveal pit, pit depth, pit width across the maxima (FWFM), pit width at half the pit depth (FWHM), and pit slope. Lateral dimensions were corrected for the variation in transverse magnification of the OCT scan vs. axial length.
Minimum foveal thickness increased with increasing myopia (p=0.007) and foveal pit depth became shallower with increasing myopia (p = 0.0005). The pit width across the maxima (FWFM) significantly decreased with increasing axial length (p = 0.027) and increasing myopia (p = 0.017); the FWHM also decreased with increasing myopia but not significantly (p>0.05). FWFM increased as the foveal pit became deeper (p = 0.014). The pit was wider in the horizontal than vertical direction by an average ratio of 1.09; this ratio decreased with increasing myopia. Foveal pit dimensions in fellow eyes were well correlated (r ranging from 0.78 for FWFM to 0.93 pit depth).
Myopes have shallower, narrower foveal pits that become more circular in shape with increasing myopia. Our results differ from those of Dubis et al. (BJO, 2008) who reported no significant difference between the foveal parameters of myopes and emmetropes. This discrepancy may be due to the range of refractions in each study.
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