METHOD FOR SURGICAL CORRECTION OF PRESBYOPY COMBINED WITH SIMPLE MYOPIC ASTIGMATISM WITH PRESERVING CORNEAL SURFACE ASPHERICITY

摘要

FIELD: medicine.;SUBSTANCE: eye cornea is exposed to an eximer laser light at wave length 193-222 nm, pulse energy 0.8-2.1 mJ, laser spot diameter 0.5-1.5 mm, pulse length 5-8 nm, pulse repetition frequency 30 to 500 Hz. This exposure aiming at a sequential corneal abrasion is combined with forming optical surfaces and transition surfaces. A first cylindrical convex optical surface is formed within the entire optical cornea (OC). When forming the same, an ablated inner central segment (ICS) is marked. The centre of ICS symmetry matches with the OC centre. An axis of ICS symmetry matches with a weak axis of astigmatism. A second optical surface is formed as a convex ellipsoid of rotation with a negative conic constant within -0.1 to -0.4. An optical axis of the second optical surface matches with the OC centre. A diameter of the second optical surface is related to an OC diameter as a value within the range of 0.85 to 0.95. Then, the transitions surfaces (TS) are formed as a convex outer surface of an O-toroid. The transition surface is formed so that its inner border is coupled with an outer border of the first optical surface, and its outer border - with an intact cornea. A TS width makes 0.04 to 0.2 diameters of the exposure.;EFFECT: method enables minimising the amount of the resected eye tissue, provides the high far and near visual functions with no additional spectacle correction with a decreased light cap.;15 dwg, 3 ex