December 2008
Volume 8, Issue 17
Free
OSA Fall Vision Meeting Abstract  |   December 2008
Transverse magnification in an Optovue Fourier-Domain OCT instrument
Author Affiliations
  • Lee Johnson
    New England College of Optometry, Boston MA
  • Nancy J. Coletta
    New England College of Optometry, Boston MA
Journal of Vision December 2008, Vol.8, 62. doi:10.1167/8.17.62
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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)

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Abstract

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.

Johnson, L. Coletta, N. J. (2008). Transverse magnification in an Optovue Fourier-Domain OCT instrument [Abstract]. Journal of Vision, 8(17):62, 62a, http://journalofvision.org/8/17/62/, doi:10.1167/8.17.62. [CrossRef]
Footnotes
 Supported by NIH grants R24 EY014817 and T35 EY007149.
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