Measurement of Ex Vivo Porcine Lens Shape During Simulated Accommodation, Before and After fs-Laser Treatment.
OBJECTIVE
According to Helmholtz, accommodation is based on the flexibility of the crystalline lens, which decreases with age, causing presbyopia. With femtosecond (fs)-lentotomy treatment, it is possible to restore the flexibility of presbyopic lenses. The efficiency of the treatment can be systematically evaluated using the finite element method based on experimental data. The purpose of this study was to quantify the shape change of ex vivo lenses in different accommodation states according to the fs-lentotomy treatment.


METHODS
Five lenses with ciliary body excised from ex vivo porcine eyes (age: approximately 6 months, exact age unknown) were stretched in an accommodation device before and after laser treatment. Depending on the accommodation state, the lens shape, reconstructed from lens thickness, diameter, and anterior and posterior curvature, was measured using optical coherence tomography (OCT). The complete lens shape was parameterized and each measured parameter was compared to the results of a control group (n = 5, age: approximately 6 months, exact age unknown) without treatment.


RESULTS
The amplitudes of the parameters thickness (+140%), diameter (+54%), and anterior radius of curvature (+57%) significantly increased after treatment (P < 0.05), and showed no significant change for the control group. By contrast, the amplitude of the posterior radius of curvature showed no change after treatment (P > 0.05).


CONCLUSIONS
Measurement of the lens shape in different accommodation states was successful and showed significant changes after the treatment. The resulting data will be utilized as input for a finite element model to systematically evaluate the effect of fs-lentotomy treatment in future work.
Laser Zentrum Hannover e.V. Hanover, Germany.
Jan
J
Hahn
Laser Zentrum Hannover e.V. Hanover, Germany 2ROWIAK GmbH, Hanover, Germany.
Michael
M
Fromm
Laser Zentrum Hannover e.V. Hanover, Germany.
Fedaa
F
Al Halabi
Institute of Continuum Mechanics, Leibniz Universität Hannover, Hanover, Germany.
Silke
S
Besdo
ROWIAK GmbH, Hanover, Germany.
Holger
H
Lubatschowski
Laser Zentrum Hannover e.V. Hanover, Germany.
Tammo
T
Ripken
Laser Zentrum Hannover e.V. Hanover, Germany.
Alexander
A
Krüger
D000065:Accommodation, Ocular / Q000502:physiology*; D000818:Animals; D004195:Disease Models, Animal; D004548:Elasticity; D053685:Laser Therapy; D007908:Lens, Crystalline / Q000473:pathology* / Q000503:physiopathology / Q000601:surgery; D010812:Physical Stimulation / Q000379:methods*; D011184:Postoperative Period; D057234:Preoperative Period; D011305:Presbyopia / Q000503:physiopathology* / Q000601:surgery; D013552:Swine; D041623:Tomography, Optical Coherence / Q000379:methods*