Publications by authors named "Imre Kovats"

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Axis-free correction of astigmatism using bifocal soft contact lenses.

Cont Lens Anterior Eye 2017 Dec 19;40(6):394-400. Epub 2017 Sep 19.

Department of Optometry and Vision Science, Ernst Abbe University of Applied Science Jena, Carl-Zeiss-Promenade 2, 07745 Jena, Germany. Electronic address:

Purpose: Pilot study to investigate the feasibility of an axis-free correction approach of regular astigmatism using soft, bifocal contact lenses (CL).

Methods: The investigation covers an optical simulation and a pilot study for the assessment of visual performance (over refraction OR, monocular visual acuity VA). The power of the two zones was adjusted according to the power of the astigmatic meridians, individually. Subjective performance was assessed in 30 participants with a mean horizontal cylindrical component of J=- 0.65±1.29 D (cylinder from -0.75 to -4.00 DC). OR and VA were measured directly after fitting the CL, after one hour and after 5days (3FUP).

Results: Evaluating the modulation transfer function, CL increased the Strehl ratio by 10% and the transferred spatial frequency was improved from 6.6 cpd to 21.3 cpd. Analysis of Sturm's interval revealed a residual astigmatism of D=0.73 D. OR revealed a statistically significant reduction of spherical error between baseline and all follow up (ΔM=-2.14 D, p<0.001) and between the J from baseline to 3FUP (ΔJ=-0.46 D, p=0.04). Wearing the CL for 5days did not result in a significant difference of VA (ΔVA=+0.01 logMAR, p=0.99).

Conclusion: Axis-free correction of astigmatism using bifocal CL resulted in reasonable performance based on computer simulation. Participants showed no clinically reduced visual acuity or contrast sensitivity. Further clinical studies are needed to show if this approach provides a good alternative to conventional astigmatic correction.
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December 2017