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Monika P. Reder, Marcus Blum, Stefan Schramm, Bernd U. Seifert, Roland Ackermann, Robert Kammel, Stefan Nolte, Kathleen S. Kunert; Analysis of Optical Side Effects of fs-Laser Therapy in the Human Presbyopic Lens Simulated With Modified Contact Lenses. Invest. Ophthalmol. Vis. Sci. 2011;52(14):6215.
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In a single-blinded study, the optical side effects of a potential fs-laser therapy in presbyopic human lenses were tested. The simulation of this therapy was carried out by creating four different laser-patterns into standard contact lenses (CL).
Comparative examinations between modified and standard contact lenses were performed on 28 subjects. The 56 eyes were divided into four groups according to the modification of the CL: ‘G1-LASIK-Simulation’, ‘G2-Presbyopia-Therapy-Simulation’, ‘G3-grid-without-variation’ and ‘G4-grid-with-variation’. Parameters differed in spot size, pulse energy and grid pattern. Visual acuity was measured with EDTRS-charts, contrast sensitivity with F.A.C.T.-charts and night vision with Mesotest II with/without glare. Forward scattered light was subjectively measured with the C-Quant (both instruments: Oculus Optikgeräte GmbH, Germany) and objectively with a modified wavefront-analyser WASCA-MOD (Carl Zeiss Meditec AG, Germany). A questionnaire detected subjective quality of vision during contact lens wear. Differences between modified and standard contact lenses as well as differences among the modifications were analysed.
The modified and standard contact lenses indicated no significant difference in visual acuity, contrast sensitivity and mesopic vision without glare. While wearing modified lenses with a regular grid (G1-G3), quality of vision decreased significantly by means of mesopic vision with glare and subjective/objective straylight. These three modifications also caused an impairment of the subjective quality of vision. In contrast, there was no significant difference between G4 (randomised grid) and standard CL’s.
The increase of optical side effects was reproducibly dependent on the geometry of the laser-structure. A randomised grid induced the least limitation of vision. The study results are useful for planning possible laser-patterns in fs-laser therapy of the presbyopic lens.
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