| 摘要 |
FIELD: medicine. ^ SUBSTANCE: invention relates to field of medicine, namely to ophthalmic surgery. Cornea is exposed to pulse radiation of non-scanning excimer laser with Gauss radial space distribution of energy density in transverse section of ray in mode of layer-by-layer ablation. Exposure is performed by successive reduction of parametre of mean square deviation of energy density distribution in each of next pulse series within the interval from 2.7 mm to 1.8 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 and is successively reduced with each next 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 with respect to initial cornea surface ellipsoidal surfaces located on one axis. Zone of exposure is symmetrical relative to optic centre of cornea symmetry; first position of weak axis of astigmatism is determined, and large axis of formed ellipsoidal surfaces is superimposed with it. Ratio of length of large axis of concave ellipsoidal surface to cornea diametre is within the interval from 0.6 to 0.8. Ratio of length of large axis of second ellipsoidal surface to length of large axis of first ellipsoidal surface is within the interval from 0.8 to 0.95. Ratio of length of large axis of third ellipsoidal surface to length of large axis of second ellipsoidal surface is within the interval from 0.8 to 0.95. Parametres of laser irradiation: wave length 193-250 nm, diametre of laser exposure zone from 5 to 9 mm, pulse duration 15-30 ns, pulse repetition rate from 5 to 15 HZ. ^ EFFECT: method ensures reduction of eye tissue trauma with simultaneous reduction of post-operation complications and volume of ablated eye tissues. ^ 2 tbl, 3 dwg, 2 ex |
