Abstract

P 223

Estrogen-induced changes of biomechanics of the cornea as a possible reason for keratectasia

Zubaty V., Spoerl E., Raiskup-Wolf F., Pillunat L. E.
Department of Ophthalmology, University of Dresden

Objective: The risk for regression after PRK or for the development of a keratectasia after lasik is higher in women. Actually an important interest consists in the influence of estrogen on the corneal stability after cornea-refractive surgery. The aim of the experimental study was to investigate the change of biomechanical properties of the cornea induced by estrogen.
Methods: The influence of estrogen was investigated at 12 fresh porcine corneas incubated in culture medium with 10 µm estradiol for 7 days. A group of 12 porcine corneas incubated in culture medium without estradiol for the same time serves as control. Strips of 10x4 mm were cut and the stress-strain was measured in a biomaterial tester. The Young’s modulus was calculated.
Results: During incubation the thickness changes in the control group only by 5.9% and in the estradiol group by 12%. However, the difference in the biomechanical stress values at 10% strain is important larger. In the control group the stress is 120.18±28.93 MPa and in the estradiol group 76.87±34.63 MPa (P=0.002).This is a reduction of the stiffness by 36% due to the estradiol treatment.
Conclusions: Estrogen is a modulating factor of the biomechanical properties of the cornea which is not only explainable by an increased swelling. Therefore the hormone status has a not to unterestimated influence on the biomechanical stability of the cornea and on the results after refractive surgery and may contribute to the development of keratectasia.

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