Posters

Surgically-induced astigmatism (SIA) after myopic LASIK in eyes with prior plano refractive cylinder using nasal- versus superior-hinged microkeratomes

Poster Details

First Author: A.Frings GERMANY

Co Author(s):    T. Katz   M. Casagrande   J. Steinberg   V. Druchkiv   S. Linke  

Abstract Details

Purpose:

Creating the corneal flap is one of the crucial steps in LASIK surgery. The aim of the current study was to assess the impact of superior (M2) versus nasal (SBK) hinge position on the change in the astigmatic component in eyes with preoperative plano refractive cylinder.

Setting:

University Medical Centre Hamburg-Eppendorf, Germany.

Methods:

This study included 1088 consecutive myopic eyes. Excimer ablation for all eyes was performed using an Allegretto excimer laser platform. The LASIK procedure included mechanical flap preparation using one of three automated MKs (nasal hinge: SBK with a single-use 90-μm head; superior hinge: M2 with a single-use 90-μm head or 130-μm head; all Moria, France). The Alpins vector method was applied to describe the effects of LASIK on refractive cylinder.

Results:

Although the median overall efficacy and safety indices indicate a highly precise, safe and efficient procedure, there were statistically significant differences (P=0.002) in SIA. In 124 (11.4%) of 1088 eyes, the postoperative refractive cylinder (= SIA) was 0.75 D or more. This was observed in 44 (12.8%) of 344 (SBK), 8 (18.6%) of 43 (M130) and 72 (10.3%) of 701 (M90) cases. Independent of the type of MK employed, SIA was slightly higher in eyes that were treated first (right eyes). No more than a mean magnitude of 0.35 D astigmatism was induced and that was independent of the type of MK.

Conclusions:

The current data support our previous studies showing that a certain proportion of eyes with low preoperative refractive cylinder tend to be overcorrected in terms of astigmatic component correction. The current study shows that this finding also applies to eyes with preoperative plano refractive cylinder. Nevertheless, it should be noted that - independent of the type of MK - no more than a mean magnitude of 0.35 D of refractive cylinder was documented after LASIK. FINANCIAL INTEREST: NONE