Reasons for remaining astigmatism in cataract patient after implanting toric intraocular lenses

Session Details

Session Title: Pseudophakic IOLs: Toric

Session Date/Time: Tuesday 10/10/2017 | 08:30-10:30

Paper Time: 08:42

Venue: Room 4.4

First Author: : J.Hienert AUSTRIA

Co Author(s): :    N. Hirnschall   N. Bayer   S. Norrby   C. Leisser   E. Zimper   O. Findl     

Abstract Details

Purpose:

To detect the sources of remaining astigmatism after implanting a toric intraocular lens (IOL) during cataract surgery using Gaussian error propagation.

Setting:

Vienna Institute for Research in Ocular Surgery, Hanusch Hospital, Vienna, Austria

Methods:

Consecutive cataract patients that received toric IOLs were included as well as data from the literature used. In a first step, all parameters that could have an influence on the post-operative remaining astigmatism were detected by screening the recent literature. In a next step, mean and standard deviation as well as reproducibility of pre-operative measurements were taken from our data set, or from the recent literature. Then thick lens ray tracing and Gaussian error propagation analysis was used to evaluate the influence of different parameters on the remaining post-operative astigmatism.

Results:

In total, 235 eyes of 200 patients were included and 42 papers from the literature were screened. Mean corneal astigmatism measured pre-operatively with an optical biometry device was -2.24 D (SD: 0.87; -5.75 D to -1.00D). Mean absolute and vector differences between the aimed and the post-operatively measured astigmatism were 0.48D (SD: 0.37; 0.00 to 2.05D) and 0.73D (SD: 0.46, 0.031 to -2.20), respectively (p=0.576).

Conclusions:

The main reason for error when using toric IOLs are inaccuracies in the pre-operative measurement of corneal astigmatism. In eyes with low astigmatism this error was seen be higher. The influence of the post-operative anterior chamber depth on the cylindrical power of toric IOLs and the effect of misalignment on the reduction of the astigmatism reducing effect can be easily calculated.

Financial Disclosure:

NONE