June 2020
Volume 61, Issue 7
ARVO Annual Meeting Abstract  |   June 2020
The effects of corneal edema on intra-operative aberrometry to determine toric intraocular lens cylindrical power and axis.
Author Affiliations & Notes
  • Karalee Corley
    Claremont McKenna College, Saint Petersburg, Florida, United States
  • Brent Carmack
    St. Petersburg Institute of Opthamology, Saint Petersburg, Florida, United States
  • Footnotes
    Commercial Relationships   Karalee Corley, None; Brent Carmack, None
  • Footnotes
    Support  None
Investigative Ophthalmology & Visual Science June 2020, Vol.61, 4754. doi:
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      Karalee Corley, Brent Carmack; The effects of corneal edema on intra-operative aberrometry to determine toric intraocular lens cylindrical power and axis.. Invest. Ophthalmol. Vis. Sci. 2020;61(7):4754.

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

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Purpose : Intra-operative aberrometry for determining intraocular lens (IOL) power often differs from that predicted by pre-operative optical biometry. The main explanation has been that aphakic optical power measurements include posterior corneal curvature. In our research, we theorized that intra-operative corneal edema at the primary incision could affect the aberrometry, thus having an affect on the power and axis of astigmatism.

Methods : Images of 12 eyes receiving a toric IOL , excluding any with refractive surgery or corneal dystrophy were retrospectively analyzed. Pre-operative measurements with Lenstar (Haag-Streit USA) biometry were compared to intra-operative measurements using ORA (Alcon, Inc). The area of any edema extending anterior to 2.4mm keratome or 2.6mm femto primary incision, was quantified from the aphakic raw images. The results were analyzed with non-parametric statistics (Spearman correlation) due to small sample size.

Results : The mean difference in astigmatic power measurement was 0.344D (diopters) (SD = 0.246), and not found to be signficiant (r = -0.007, p = 0.983). The mean difference in the axis of astigmatism was 11.67 degrees (SD = 11.44 degrees), and not significant (r = -0.159, p = 0.622) Despite using a bubble level in pre-op with the patient upright, the exact magnitude of excyclotorsion when supine can vary widely. The ORA reticules were calibrated to these pre-operative marks but we believe the 11.44 degrees difference was artifactitious related to eye positioning rather than due to edema given the insignificant effect on power.

Conclusions : Though a small sample size and lacking pachymetry to quantify volume of edema, small areas of edema do not seem to have significant affect on ORA readings. Resolving to add the aforementioned and looking at anterior/posterior cornea to determine net keratometric power with a Pentacam (Ocular) will further our goal of helping surgeons refine IOL selection. The question remains, should intra-operative aberrometry regularly supercede pre-operative optical biometry in determining IOL selection if edema is noted at the primary incision. In this case, we do not know yet, but it is reassuring to surgeons that our theory has not been proven. Even so, this subject warrants further investigation which the authors are already planning.

This is a 2020 ARVO Annual Meeting abstract.


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