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Safety and efficacy of laser correction of hypermetropia: early results in a retrospective study comparing VISX Star S4 and SCHWIND Amaris

Poster Details

First Author: M.Litev BULGARIA

Co Author(s):    D. Mitova              

Abstract Details



Purpose:

1. To assess efficacy of hyperopia laser correction by measuring the change in UCVA before and after the procedure done with either VISX Star S4 or Schwind Amaris excimer laser systems. 2. To assess safety by measuring the rate of non-microkeratomic complications and adverse events with these different excimer systems. 3. To detect any post-keratorefractive regression and to determine the relative risk ratio of the excimer system type.

Setting:

A longitudinal retrospective study of medical records was performed in Sveta Petka Eyeclinic, Varna,Bulgaria. We selected a diverse demographic group of 17 patients (31 eyes) that had presented any regression of hyperopia post-LASIK. We project to extend this survey to 1000 patients by the end of 2015. The VISX STAR S4 is regarded as group A and consists of 15 eyes. The Shwind Amaris group B consists of 16 eyes. A rigorous study protocol for patient selection was perceived. Patient inclusion criteria consisted of ability to sign an informed consent, at least two follow-up visits, signs of hyperopic regression, no ocular comorbidity (apart from amblyopia and esotropia). No finacial interest was perceived in this study.

Methods:

Visual acuity by logMAR-scaled subjective refraction. Wavescan® and autorefractometer objective refaction readings to detect refractive regression. A meticulous search for complications was essential. Orbscan® topographies performed to prove regression and discontinue it from accommodative changes. We regard that keratometry readings tend to regress back to the presurgical values in all cases of regression. We regard that the two excimer systems have a similar tissue effect but differ by the laser beam structure and by the ablation profile. Hyperopic keratorefractive correction was performed by a single surgeon on any of the excimer systems.

Results:

Fig. 1 - UCVA before and after the procedure has improved by 29% in group A and by 42% in group B. Fig. 2 - The change in average keratometry (3mm) may indicate postkeratorefractive regression of hyperopia Fig. 3 - Interval of postkeratorefractive regression Fig.4 - Postsurgical complication structure - haze formation 3%, epithelial invasion 3%

Conclusions:

Keratorefractive laser correction of hyperopia on any of the two laser systems proves to be an efficient and effective treatment method. We still need to study and prove is this true about its repeatability for the cases of recorrection after refractive regression. Despite refractive regression performing laser correction on any of the two laser systems is a safe and well tolerated procedure that does not increment the incidence in side effects when compared to other keratorefractive procedures. Yet we need to come with improved criteria to detect any complications and especially of the regression. The sample size at this study phase is too small to determine whether the different laser beam structure in the two systems is influential to the regression rate. FINANCIAL INTEREST: NONE

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