July 2018
Volume 59, Issue 9
Open Access
ARVO Annual Meeting Abstract  |   July 2018
Assessment of macular and retinal nerve fiber layer thicknesses in patients with keratoconus using optical coherence tomography (OCT) and an adjunctive contact lens
Author Affiliations & Notes
  • Elena Zhu
    Melbourne Medical School, University of Melbourne, Parkville, Victoria, Australia
  • Laura Elizabeth Downie
    Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Allison M McKendrick
    Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Elaine W Chong
    Department of Ophthalmology, Royal Melbourne Hospital, Parkville, Victoria, Australia
    Centre for Eye Research Australia, Royal Victoria Eye and Ear Hospital, Department of Surgery (Ophthalmology), University of Melbourne, Parkville, Victoria, Australia
  • Robert Charles Andrew Symons
    Department of Ophthalmology, Royal Melbourne Hospital, Parkville, Victoria, Australia
    Department of Optometry and Vision Sciences, University of Melbourne, Parkville, Victoria, Australia
  • Footnotes
    Commercial Relationships   Elena Zhu, None; Laura Downie, None; Allison McKendrick, Heidelberg Engineering GmBH (F); Elaine Chong, None; Robert Symons, CSL Pty Ltd (I), Novartis (F), Psivida (I)
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science July 2018, Vol.59, 1108. doi:
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      Elena Zhu, Laura Elizabeth Downie, Allison M McKendrick, Elaine W Chong, Robert Charles Andrew Symons; Assessment of macular and retinal nerve fiber layer thicknesses in patients with keratoconus using optical coherence tomography (OCT) and an adjunctive contact lens. Invest. Ophthalmol. Vis. Sci. 2018;59(9):1108.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

Purpose : Prior work suggests that patients with keratoconus (KC) have abnormal macular and retinal nerve fiber layer thickness (RNFL). To assess whether these abnormalities may be artefactual, due to irregular astigmatism, we used a novel contact lens to reduce the corneal astigmatic error (OSIE, Ocular Instruments Inc., Bellvue WA), in conjunction with the Heidelberg Spectralis OCT.

Methods : 26 eyes of 13 subjects with KC and 30 eyes of 15 normal age-matched non-KC subjects underwent a comprehensive eye examination, corneal topography and axial length measurement. Macular and RNFL OCT imaging were performed. Scans were performed without the contact lens and were subsequently repeated with the OSIE lens in place. The image quality was automatically calculated by the Spectralis OCT using a signal-to noise estimate. Outcomes were analyzed using the Student’s t-test, either paired or unpaired accordingly.

Results : The Median (25%ile, 75%tile) age was 24 (23, 27) years for the control group and 26 (25, 30) years for the KC group(p=0.12). The mean (±SD) axial length of the control group was 22.76 (±0.98) mm and 23.86 (±0.83) mm for the KC group (p=0.18).
The OSIE lens significantly improved the image quality in KC group (p<0.0001), while having little effect on the controls.
In controls, use of the OSIE lens did not significantly alter central point thickness (CPT), central subfield thickness (CSFT), inner (IMT) and outer macular thickness (OMT), or RNFL thickness. In the KC group, CPT, CFST, temporal OMT, global average RNFL thickness, nasal and inferior RNFL thickness were significantly reduced when the lens was used (all p<0.05). With the OSIE lens, for the macula, there was no significant difference between the two groups concerning CPT, CSFT, IMT and OMT.
For RNFL, the KC group showed decreased temporal, temporal inferior and nasal superior RNFL thickness compared to the control group (all p<0.05).

Conclusions : Macular parameters, determined by OCT imaging in KC subjects, are comparable to those of aged-matched non-KC subjects when the OSIE lens is employed. Some of the RNFL parameters may be reduced in patient with KC than the controls. Irregular corneal astigmatism in KC patients may contribute to an artefactual increase in retinal thickness measures in the absence of the OSIE lens.

This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.

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