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The importance of kappa distance and data alignment in the axis and value of anterior

Poster Details

First Author: C.Arce BRAZIL

Co Author(s):    A. Dos Santos Forseto   G. Pilau           

Abstract Details

Purpose:

To show the relation of kappa distance and the differences of axis and values of anterior, posterior and total corneal astigmatism presented when data is aligned to first Purkinje or pupil centroid.

Setting:

BOS-Eye Bank of Sorocaba, Sao Paulo, Brazil and Private Eye Clinic, Sousas, Campinas, Sao Paulo, Brazil

Methods:

Axis and value of anterior, posterior and total corneal astigmatism were recorded using dual Scheimpflug tomography and Placido topography in normal corneas that went to refractive and cataract surgery, corneas with suspected initial keratoconus and/or risk factors of postoperative ectasia that were rejected for surgery and corneas with established diagnosis of keratoconus.

Results:

Kappa is the distance between the 1st Purkinje and the pupil centroid on the anterior surface of the cornea. Anterior, posterior and total corneal astigmatisms may change according to the alignment of data and kappa distance. A shift in axis seems more frequent when small anterior or total corneal astigmatism is present. Although normal corneas may have different axis of anterior, posterior and total corneal astigmatisms, corneas with typical keratoconus seems to have the three cylinders in a close axis.

Conclusions:

Value and axis of anterior, posterior and total corneal astigmatisms may vary according to the kappa distance and the alignment of topographic/tomographic maps. Preoperative evaluation of cylinder should be made in the same alignment used to implant multifocal and/or toric IOLs and not in alignments like the apex of the cornea that are impossible to be recognized on the eye under the surgical microscope. Disagreement of alignment on the data used to plan refractive and cataract surgery and the final alignment used for toric IOLs seem to be an overlooked source of error that may be solved with appropriate technology.

Financial Disclosure:

One or more of the authors receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented, One or more of the authors travel has been funded, fully or partially, by a company producing, developing or supplying the product or procedure presented

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