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Sue Shiao, Ashraf M. Mahmoud, Jun Liu, David Lee, Kimberly Metzler, Chris Minning, Cynthia J. Roberts; Influence of Internal Pressure and Distance from Air Nozzle on Maximum Deformation Depth under an Air Puff of Pig Corneas. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1512.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the effect of both internal pressure and distance from the air nozzle on maximum corneal deformation induced by an air puff in pig corneas with an artificial anterior chamber mount.
The CorVis ST (Oculus, Wetzlar, Germany) is a new device that captures approximately 140 Scheimpflug images in a single horizontal meridian during a 30ms air puff. Deformation data for 8 pig corneas mounted in a Barron disposable artificial anterior chamber were acquired and analyzed. Each cornea was tested at pressures of 10, 20, 30, and 40 mmHg, and each pressure setting was tested with distances of 0.5, 1.0, and 1.5 mm from the cornea to the air nozzle on the Corvis head. A 0mm distance was set as the distance at which the anterior cornea surface was captured just within the top border of the image window on the Corvis. One scan at each setting was acquired. A repeated measures Multivariate Analysis of Variance (MANOVA) on pressure and distance was performed to evaluate the dependent variable of maximum corneal deformation with a p value of 0.05 as the significance threshold.
At distances 0.5, 1.0, and 1.5 mm, the means of corneal deformation were 0.672 ± 0.198, 0.761 ± 0.267 , 0.660 ± 0.273 (at pressure 10 mmHg and), 0.791 ± 0.228, 0.676 ± 0.212, 0.660 ± 0.156 (at pressure 20 mmHg), 0.708 ± 0.232, 0.665 ± 0.169, 0.662 ± 0.186 (at pressure 30 mmHg), 0.634 ± 0.134, 0.624 ± 0.159, and 0.763 ± 0.244 mm (at pressure 40 mmHg), respectively. The MANOVA showed no pressure or distance effect as single variables, but a significant interaction effect of pressure and distance on maximum corneal deformation (p = 0.0179).
The internal pressure and distance of the cornea from the air nozzle affects the maximum corneal deformation in pig corneas mounted on a rigid artificial anterior chamber. Future studies will investigate the influence pressure and distance will have on maximum deformation in a whole globe mount.
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