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Analysis of optical side effects of fs-laser therapy in human presbyopic lens simulated with modified contact lenses

: Peter, Monika; Kammel, Robert; Ackermann, Roland; Bühren, Stephanie; Schramm, Stefan; Seifert, Bernd-Ulrich; Frey, Katharina; Kunert, Kathleen


Graefe's archive for clinical and experimental ophthalmology 250 (2012), Nr.12, S.1813-1825
ISSN: 0721-832X
Fraunhofer IOF ()
Presbyopia; lens; fs-Laser; visual quality; straylight

Background In a single-blinded study, optical side-effects of a potential femtosecond (fs)-laser therapy in presbyopic
human lenses were tested. Simulation of this therapy was carried out by applying fs-laser patterns into standard contact lenses (CL).
Methods In the first part of the study, the influence of the numerical aperture on optical side-effects was investigated
by comparing a typical fs-LASIK configuration to a fs-presbyopia treatment (n 0 11). The second part focused on
a possible improvement of visual performance by comparing a regular grid pattern to a randomly chosen spacing of
the laser spots (n 0 16). Visual acuity was measured with ETDRS charts, contrast sensitivity with F.A.C.T. charts and
mesopic vision with Mesotest II. Forward scattered light was measured with the C-Quant (both instruments: Oculus
Optikgeräte GmbH, Germany). A questionnaire detected subjective quality of vision. Differences between laser-
treated and untreated CL and among the modifications were analyzed.
Results The laser-treated and standard CL indicated no significant difference in visual acuity, contrast sensitivity and
mesopic vision without glare. While wearing modified lenses with a regular grid, quality of vision decreased sig-
nificantly by means of mesopic vision with glare and subjective straylight. These modifications also caused an
impairment of subjective quality of vision. In contrast, there was no significant difference between the random pattern
and standard CL.
Conclusion The increase of optical side-effects was reproducibly dependent on the geometry of the laser-structure. A randomized grid induced the least limitation. The study results are useful for planning possible laser-patterns in fs-laser therapy of the presbyopic lens.