SURGICAL CORRECTION METHOD FOR TREATING PRESBIOPIA CASES AGGRAVATED WITH SIMPLE MYOPIC ASTIGMATISM Russian patent published in 2008 - IPC A61F9/01 

FIELD: medicine.

SUBSTANCE: method involves treating eye cornea with excimer laser radiation with optical surfaces and transition zone surface being formed by sequentially layer-by-layer removing cornea segments. Action parameters are wavelength of 193-222 nm pulse power of 0.8-2.1 mJ, laser spot diameter of 0.5-1.5 mm, pulse duration of 5-8 ns, frequency of 30-500 Hz. The first optical surface is concave cylindrical surface arranged within the whole optical zone. When forming it, central internal segment to be withdrawn is traced. Central internal segment symmetry center is made coincide with the optical zone center, and central internal segment symmetry axis is made coincide with the weak astigmatism axis. The second optical surface is formed as spherical convex surface which optical axis coincides with the optical zone center. The second optical surface diameter is 0.28-0.55 times as large as the optical zone diameter. The transition zone surface is formed as a part of convex external surface of annular toroid. The transition zone surface is coupled with its internal edge to external edge of the first optical surface and with its external edge to cornea portion that is not to be subjected to treatment. Transition zone surface width is 0.04-0.2 times as large as action zone diameter.

EFFECT: improved visual function in long and short distance; reduced luminous halation; minimized volume of withdrawn eye tissues.

15 dwg