The importance of kappa distance and data alignment in the axis and value of anterior, posterior and total corneal astigmatism used for toric IOL planning

Session Details

Session Title: Pseudophakic IOLs: Toric & Multifocal

Session Date/Time: Tuesday 08/09/2015 | 08:00-10:30

Paper Time: 08:12

Venue: Room 11

First Author: : C.Arce BRAZIL

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

Abstract Details

Purpose:

To assess the value and axis of anterior, posterior, and total corneal astigmatism according to the alignment of data, Kappa distance, amount of astigmatism and steepening in keratoconus.

Setting:

Hospital Banco de Olhos of Sorocaba, Brazil

Methods:

Retrospective review of Galilei G4 SW 6.1.4 exams done in 163 normal corneas for preoperative refractive or cataract surgery and 127 with keratoconus (22 KC1; 39 KC2; 17 KC3 and 49 KC4). Data was collected aligned to the 1st Purkinje (system default) and to the pupil center

Results:

Anterior, posterior and total corneal astigmatism and axis may vary in normal corneas when data is aligned to the pupil center or to the 1st Purkinje. Kappa distance correlated with changes on the axis and amount of anterior, posterior and total corneal astigmatisms. Around 5% of normal corneas, 24% with KC, 12.8% with less than 3D cylinder and 15.6% with more than 3D cylinder had astigmatism axis switched more than 10° between both alignments.

Conclusions:

More corneas with KC than normals had a switch on axis larger than 10° in both alignments. Higher anterior astigmatism correlated with higher changes in the amount and axis of cylinder. Our results supports the concept that alignment of preoperative data should be done to the same referential point used in IOL implantation, corneal implants and refractive surgery. There is a potential source of error in toric IOL implantation when alignment of preoperative data is not the same than what is finally used in surgery.

Financial Interest:

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