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A. Barsam, A. Patmore, J. Marshall; Microwave Keratoplasty: An Experimental Study on Porcine and Human Corneas to Determine the Keratorefractive Effect. Invest. Ophthalmol. Vis. Sci. 2009;50(13):2221.
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© ARVO (1962-2015); The Authors (2016-present)
Microwave keratoplasty (MK) is a novel experimental technique. Microwave energy applied to corneal stroma results in elevation of temperature, shrinking of collagen and alteration of corneal curvature. The primary aim of this study was to determine the change in radius of curvature on excised porcine and human corneoscleral buttons after MK application.
Six excised human corneoscleral buttons from six separate donors (n=6) were treated with a prototype MK ring applicator. A 28.12 Watt, 1 second application was performed on the corneas using a 6mm diameter inner conductor and an 8.4mm diameter outer conductor. Ten enucleated porcine eyes (n=10) were treated with the same prototype MK ring applicator. A 25.21 Watt, 1 second application was performed on 5 of the eyes and a 28.12 Watt, 1 second application was perfomed on the other 5 eyes. Video keratography was performed with the Tomey TMS-1 topographic modelling system before and after MK application. The induced change in corneal curvature was calculated using the mean dioptric (D) power of rings situated 2 to 6mm from the geometrical apex of the cornea. Scanning electron microsocopy and blue light microscopy of semithin (1µm) sections stained with 1% Toluidine blue was carried out in order to qualify the effect on corneal stroma.
In the human corneas there was a 3.03 D mean reduction in curvature after MK application (range 0.18 to 7.16 D). In the porcine corneas there was a 3.10 D mean reduction in curvature after MK application in all eyes (range 1.09 to 4.63 D). In the 25.21 Watt treated group the mean reduction of curvature was 2.59 D (range 1.09 to 4.30 D) and in the 28.12 Watt treated group the mean reduction of curvature was 3.61D (range 2.57 to 4.63 D). Scanning and light microscopy examination demonstrated microwave induced shrinkage of corneal stromal collagen with minimal disturbance to the overlying epithelium.
MK is a novel technique for the reduction of corneal curvature. There is therapeutic potential for MK as a non-invasive alternative to excimer laser surgical correction of myopia. There may also be a role for MK in the treatment of corneal ectasia.
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