METHOD OF SURGICAL CORRECTION OF PRESBIOPIA IN COMBINATION WITH MYOPIC ASTIGMATISM Russian patent published in 2009 - IPC A61F9/01 B82B3/00 

FIELD: medicine.

SUBSTANCE: invention relates to field of medicine, namely to ophthalmosurgery. Cornea is influenced by layer-by-layer ablation with pulse irradiation of non-scanning excimer laser with Gauss radial distribution of energy density in transversal section of ray and formation of concave relative to anterior cornea surface surfaces. Exposure is carried out by successive reduction of parametre of mean-square deviation of energy density distribution in each of following pulse series within the interval from 2.7 mm to 1.6 mm. Value of energy density amplitude in centre of pulse symmetry, which is within the interval from 175 mJ/sq.cm to 100 mJ/sq.cm is also successively reduced with each following pulse series. Within each pulse series values of parametres of mean-square deviation of energy density distribution and energy density amplitude are constant. Each pulse series forms concave relative to initial cornea surface ellipsoidal surfaces, located on one axis, and zone of exposure is symmetrical relative to optic centre of cornea symmetry. Primarily location of wealk astigmatism axis is determined, and larger axis of formed ellipsoidal surfaces is superposed with it; then first concave ellipsoidal surface is formed, ratio of length of large axis of first concave ellipsoidal surface to cornea diametre being within the interval from 0.6 to 0.8. Further second concave ellipsoidal surface is formed, ratio of large axis of second ellipsoidal surface to diametre of optic zone being in interval from 1.0 to 1.1. Then third concave ellipsoidal surface is formed, ratio of large axis of third ellipsoidal surface to diametre of optic zone being in interval from 0.28 to 0.55. Wavelength of laser irradiation is 193-250 nm, diametre of laser impact zone is from 5 to 9 mm, pulse duration 15-30 ns, pulse recurrence rate from 5 to 15 Hz.

EFFECT: method ensures reduction of operation traumaticity due to reduction of volume of removed eye tissues, increase of optic surfaces number with simultaneous simplification of technical method realisation.

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