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Lee Johnson, Nancy J. Coletta; Transverse magnification in an Optovue Fourier-Domain OCT instrument. Journal of Vision 2008;8(17):62. doi: 10.1167/8.17.62.
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© ARVO (1962-2015); The Authors (2016-present)
Introduction: Clinical optical coherence tomography (OCT) software typically reports central retinal thickness over a 1 mm diameter area, but this data maybe affected by transverse magnification that varies with eye length.1–2 Such a magnification effect would cause thicker regions surrounding the fovea to be included in the ‘1 mm’ scan in longer myopic eyes.
Methods: An artificial eye with adjustable retinal position was used to record the magnification of the Optovue FD-OCT images of a calibrated scale. Fundus images were also taken for 20 human subjects. The full width of the foveal pit at half its maximum depth (FWHM) was examined as a function of refractive error and axial length.
Results: The artificial eye showed a large decrease in transverse magnification as axial length increased (p[[lt]]0.0001). This effect was reduced when a trial lens corrected the axial ametropia. When the eye was made a refractive ametrope, with a fixed axial length, myopia again resulted in decreased magnification (p[[lt]]0.0001). However, changes in the OCT focus setting alone did not result in magnification changes for a fixed axial length and power of the artificial eye. In human eyes, the foveal pit FWHM decreased significantly as myopia (p=0.004) and axial length increased (p=0.027).
Conclusions: Model eye data suggests a large transverse magnification effect that is reduced when the light entering the OCT is collimated. In real eyes, the correlation of foveal pit width with myopia implies a transverse magnification effect.
WakitaniY.SasohM.SugimotoM.ItoY.IdoM.UjiY. (2003). Macular thickness measurements in healthy subjects with different axial lengths using optical coherence tomography. Retina, 23(2), 177–182.
Sanchez-CanoA.BaraibarB.PabloL. E.HonrubiaF. M. (2008). Magnification characteristics of the Optical Coherence Tomograph STRATUS OCT 3000. Ophthalmic Physiol Opt., 28(1), 21–28.
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