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S. Krag, T.T. Andreassen, T. Olsen; Mechanical Strength of the Lens Capsule in Pseudoexfoliation Syndrome . Invest. Ophthalmol. Vis. Sci. 2003;44(13):201.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To investigate the mechanical strength of the lens capsule in patients with pseudoexfoliation (PEX) syndrome. Methods: 10 patients with PEX and 22 patients without PEX, who underwent cataract surgery, were included in the study. Age of the patients ranged from 65 to 85 years. During surgery, the capsulotomy specimens were withdrawn and stored at -80°C until mechanical testing. Test specimens were prepared as tissue rings using an excimer laser. The diameter of the capsular rings was 3.0 mm and the width was 100 µm. Capsular thickness was measured under microscope as the difference in focus between microspherules placed on the outer and inner surfaces of the capsule. The capsular rings were slipped over two pins connected to a motorized micropositioner and a force transducer, respectively, and stretched at constant rate with continuous recording of load and deformation. Results: Mean thickness (± SD) of lens capsules with PEX (+PEX) versus lens capsules without PEX (-PEX) was 24.4 µm ± 1.2 versus 22.9 µm ± 2.8. The difference in capsular thickness was not significant (p=0.06). Ultimate strain was 51.1% ± 9.4 (+PEX) versus 50.1% ± 13.4 (-PEX) (p=0.8). Ultimate load was 14.3 mN ± 5.5 (+PEX) versus 12.9 mN ± 7.1 (-PEX) (p=0.6). Ultimate stiffness was 47.2 mN ± 14.2 (+PEX) versus 42.8 mN ± 16.1 (-PEX) (p=0.5). Ultimate stress was 2.9 N/mm² ± 1.1 (+PEX) versus 2.7 N/mm² ± 1.5 (-PEX) (p=0.8). Ultimate elastic modulus was 9.5 N/mm² ± 2.8 (+PEX) versus 9.1 N/mm² ± 3.1 (-PEX) (p=0.8). Conclusions: The presence of pseudoexfoliation material on the lens capsule seems not to affect the mechanical strength of the lens capsule; neither seems the mechanical quality of the capsular tissue to be affected.
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