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E. Gross; Decreasing the duration of refractive laser ablations : without increasing thermal effects on the corneal surface . Invest. Ophthalmol. Vis. Sci. 2004;45(13):177.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: To decrease the treatment time needed for a scanning refractive laser ablation without increasing the thermal surface effects. Methods: A series of experiments was conducted to determine the temperature effects of excimer laser ablations on enucleated porcine eyes. The temperature response of the eyes to various pulse sizes and frequency rates was used to create a thermal model of laser–tissue interactions, and the thermal model was used to predict localized corneal temperature increase at any point during or after a corneal ablation. The thermal model was combined with an adaptive optimization method, which selectively added or removed milliseconds of delay between each pair of sequential laser pulses. Optimization criteria were balanced between minimizing the treatment time and limiting the induced rise in temperature. The optimized treatments were tested on enucleated porcine eyes, and recorded with a thermal imaging camera. Results: The new algorithm shortened all of the laser treatment times. The thermal model indicated that all optimized tables resulted in safe corneal temperatures. Thermally imaged treatments showed that temperature changes agreed with the model. Myopic treatment times were shortened from 3% – 47%. Treatments with high astigmatism benefited the most. Hyperopic treatment times were all shortened by 50%. Mixed astigmatism treatments were shortened by an average of 48%. In many cases, the accelerated table resulted in a cooler eye than the original table. Conclusions: This technique decreases the time needed to perform refractive laser surgery without substantially raising the maximum corneal temperature.
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