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The impact of repetitive and prolonged eye rubbing on corneal biomechanics

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First Author: H.Abdshahzadeh SWITZERLAND

Co Author(s):    R. Abrishamchi   E. A. Torres-Netto   F. Gilardoni   N. Hafezi   F. Hafezi        

Abstract Details

Purpose:

The general understanding is that keratoconus is a multifactorial disease with a genetic component. Repetitive and prolonged eye rubbing is considered a risk factor and trigger for the progression of keratoconus, rather than the cause of the disease. Little is known about the impact of repetitive mechanical stress on corneal biomechanics. The purpose of this study is to evaluate the effect of eye rubbing on the corneal biomechanical properties in an ex vivo model of eye rubbing.

Setting:

Laboratory for Ocular Cell Biology, Center for Applied Biotechnology and Molecular Medicine, University of Zurich, Zurich, Switzerland and ELZA Institute, Dietikon/Zurich, Switzerland

Methods:

In a first step, we determined the average force human keratoconus patients apply to their eyelids when rubbing. Then, porcine eyes were obtained from a local slaughterhouse and divided into 2 groups. Thirty-three eyes were rubbed over their own eyelids in a specially developed eye-rubbing device. Each eye underwent 10,500 eye-rubbing movements over the eyelid (corresponds to one year of eye-rubbing, 3 times daily, 10 movements each), using a force similar to the human condition. Thirty-seven eyes served as no-rub controls. The elastic modulus of 5-mm wide corneal strips was analyzed and used to determine corneal biomechanical properties.

Results:

Seventy porcine eyes were analyzed. The elastic modulus at the range of 1% and 5% of strain was 1.219 ± 0.284 and 1.218 ± 0.304 N/mm in the eye-rubbing group and the no-rub controls, respectively. Corneal stiffness was thus similar in both groups. (p=0.984)

Conclusions:

We did not observe significant corneal biomechanical changes in eyes subjected to repetitive and prolonged eye-rubbing under ex vivo conditions when compared to no-rub controls. The damage threshold level to induce biomechanical changes must be higher than 10’500 eye rubbing movements, suggesting that occasional eye rubbing should not impact corneal biomechanics. In conclusion, repetitive eye rubbing may indeed not be an etiological factor, but rather a risk factor and trigger for progression in predisposed corneas. Further in vivo studies would be needed to assess whether eye-rubbing would have an impact on inflammatory activity and possibly on biomechanical properties.

Financial Disclosure:

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