March 2012
Volume 53, Issue 14
Free
ARVO Annual Meeting Abstract  |   March 2012
Treatment Zone Decentration During Orthokeratology On Eyes With Low And Moderate Amounts Of Corneal Toricity
Vinod K. Maseedupally; Paul Gifford; Edward Lum; Rajeev Naidu; Dyana Sidawi; Bingjie Wang; Helen A. Swarbrick
Author Affiliations & Notes
  • Vinod K. Maseedupally
    School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
  • Paul Gifford
    School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
  • Edward Lum
    School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
  • Rajeev Naidu
    School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
  • Dyana Sidawi
    School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
  • Bingjie Wang
    School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
  • Helen A. Swarbrick
    School of Optometry and Vision Science, The University of New South Wales, Sydney, Australia
  • Footnotes
    Commercial Relationships  Vinod K. Maseedupally, None; Paul Gifford, Bausch & Lomb Boston. (F), BE Enterprises, Capricornia Contact Lens. (F); Edward Lum, None; Rajeev Naidu, None; Dyana Sidawi, None; Bingjie Wang, None; Helen A. Swarbrick, Bausch & Lomb Boston. (F), BE Enterprises, Capricornia Contact Lens. (F)
  • Footnotes
    Support  Funded under Australian Government's ARC Linkage Scheme
Investigative Ophthalmology & Visual Science March 2012, Vol.53, 4714. doi:
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      Vinod K. Maseedupally, Paul Gifford, Edward Lum, Rajeev Naidu, Dyana Sidawi, Bingjie Wang, Helen A. Swarbrick; Treatment Zone Decentration During Orthokeratology On Eyes With Low And Moderate Amounts Of Corneal Toricity. Invest. Ophthalmol. Vis. Sci. 2012;53(14):4714.

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Abstract

Purpose: : To calculate the amount and direction of treatment zone (TZ) decentration in orthokeratology (OK) on eyes with low (≤1.50D) and moderate (>1.50D) amountsof corneal toricity, and correlate these with baseline corneal topography.

Methods: : Corneal topography data from 21 eyes with corneal toricity ≤1.50D (Group 1, 9M, 12F; age 29.2±6.2yrs) treated with OK were retrospectively analyzed. Corneal topography data from 10 eyes with corneal toricity between1.50 and 3.15D (Group 2, 3M, 7F; age 24.7±7.5yrs) were prospectively analysed. All participants wore BE reverse geometry lenses (Capricornia Contact Lens, Australia) in Boston XO material (Dk:100 ISO/Fatt) on an overnight schedule for one night in one eye. Corneal topography (Medmont E300, Australia) was captured at baseline and after one night of OK wear. A custom written Matlab program was used to determine the amount and direction of TZ decentration with respect to pupil centre based on subtraction of baseline corneal refractive power data from post wear data.

Results: : TZ was decentred in both groups, with greater decentration in group 2 (0.87±0.40mm, range: 0.31-1.50mm) than group 1 (0.58±0.26mm, range: 0.15-1.03mm, Student t-test: p=0.05). In group 1, TZ decentred supero-temporally in 8 (38%) eyes, infero-temporally in 7 (33%) eyes, infero-nasally in 3 (14%) eyes, and supero-nasally in 3 (14%) eyes. The magnitude of corneal toricity did not correlate with the amount of TZ decentration (p=0.69). No significant association was found between TZ decentration and baseline mean K (p=0.31), J180 (p=0.41) or J45 (p=0.76). In group 2, TZ decentred infero-temporally in 7 (70%) eyes, and infero-nasally in 3 (30%) eyes. The magnitude of corneal toricity did not correlate with the amount of TZ decentration (p=0.72). Significant association was found between TZ decentration and baseline mean K (r=-0.66, p<0.05), but no association was found with J180 (p=0.30) and J45 (p=0.65).

Conclusions: : The TZ in OK decentred by a greater amount in moderately toric corneas compared to those with low toricity. In moderately toric corneas, TZ decentration was reduced as mean K steepened. Studies are currently underway to determine the limits of corneal toricity for success in OK, and to develop strategies to minimize TZ decentration on toric corneas.

Keywords: contact lens • astigmatism • cornea: clinical science 
© 2012, The Association for Research in Vision and Ophthalmology, Inc., all rights reserved. Permission to republish any abstract or part of an abstract in any form must be obtained in writing from the ARVO Office prior to publication.
Copyright © 2024 Association for Research in Vision and Ophthalmology.
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