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Olivier Richoz, Farhad Hafezi; A Simple, Inexpensive And Efficient Method To Measure Changes In Biomechanics Of The Entire Globe. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6802.
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Some ocular diseases (i.e. malignant myopia) are linked to abnormal scleral biomechanical properties. A weakened sclera subjected to constant intraocular pressure (IOP) may lead to progressive elongation of the eye and some glaucoma diseases could be caused by a excessive scleral rigidity mainly in the optic nerve head. We developed an easy-to-use, inexpensive and sensible system to measure changes in the biomechanical properties of the globe.
After extracting the lens and vitreous with a cannula via the optic nerve head, the cannula is placed in the vitreous cavity and is connected to a manometer to control IOP. The globe is then placed in a paraffin seal chamber to measure volume changes via fluid displacement (Fig. 1). We analyzed the volume modification in five globes by changing the IOP. Compliance was calculated by dividing the volume modification through the pressure modification by averaging 5 measurements and performing a trendline calculation.
All eyes showed distinct volume expansion for low pressure modifications (first 10 mmHg). Volume expansion slowed down when IOP was raised by up to 20 mmHg. The mathematical model confirms our observation (ΔV/ΔP = 0 when P >20) (Fig. 2).
This method shows promising results but needs further experimentation to better investigate its reliability.
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