Prediction of axial IOL position in femtosecond laser-assisted (FLACS) and conventional phacoemulsification

Session Details

Session Title: Presented Poster Session: FLACS

Session Date/Time: Monday 07/09/2015 | 15:00-16:30

Paper Time: 15:00

Venue: Poster Village: Pod 1

First Author: : P.Hoffmann GERMANY

Co Author(s): :    M. Abraham              

Abstract Details

Purpose:

Refractive precision is allegedly better in FLACS than in manual phaco. Main reason for this should be better placement of the IOL. If an indirect parameter like manifest refraction is used, too many variables come into play and many hundreds of eyes would be needed. Therefore, we directly evaluated the axial IOL position measured by optical low coherence reflectometry .

Setting:

Private eye clinic in Germany

Methods:

424 pseudophacic eyes were measured with the Haag-Streit Lenstar 6-12 months after surgery. 197 had been operated with the B&L Technolas Victus laser, 227 manually by a single surgeon. The axial position of the IOL (= distance from corneal endothelium to anterior IOL surface) was recorded and compared to the position predicted by preoperative parameters (axial length, anterior chamber depth, lens thickness) by a self-developed algorithm that we use for raytracing calculations.

Results:

In the femtolaser group, the measured IOL position was 0.08±0.17 mm deeper than predicted, in the manual group it was 0.06±0.23 mm flatter than predicted. This is highly significant (unpaired t-test 2-tailed P< 0.0001). Mean absolute error was 0.15 mm in the femto group and 0.18 mm in the manual group.

Conclusions:

The femtolaser capsulotomy seems to improve the predictability of axial IOL position. Our population is sufficiently large to prove this statistically. Axial IOL position is the single largest error of IOL calculation. The standard deviation of its predicition error can be improved by ≈ 20% by using the femtosecond laser. Using error propagation techniques, the impact on refractive predictability can be estimated as 7-10% depending on the algorithm used. This is very consistent with our actual long-term refractive results.

Financial Interest:

NONE