SURGICAL METHOD CORRECTING PRESBYOPIA COMBINED WITH SPHERICAL HYPERMETROPIA Russian patent published in 2007 - IPC A61F9/01 

FIELD: medicine.

SUBSTANCE: method involves exposing cornea to excimer laser radiation with optical surfaces and optical transition zone surfaces being formed by means of sequential layer-by-layer removal of cornea areas. Treatment parameters are as follows. Wavelength is 193-222 nm large, impulse power is equal to 0.8-2.1 mJ, laser spot diameter is 0.5-1.5 mm large, pulse duration is equal to 5-8 ns, pulse succession frequency is 30-500 Hz. The first optical surface is formed as convex spherical surface belonging to the whole optical zone and contains the optical zone center. The second optical zone surface is formed as convex spherical surface which has optical axis coinciding with the optical zone center. Ratio between second optical surface diameter and optical zone diameter belongs to interval from 0.28 to 0.55. The first transition zone surface is formed as a portion of convex external surface of the first ring-shaped toroid. External boundary of the first transition zone surface has smooth interface to untreatable cornea portion. The surface width is 0.04-0.2 times as large as the treatment zone diameter. The second surface of the transition zone of the same width is formed as a portion of the concave internal surface of the second ring-shaped toroid. Internal boundary of the second transition zone surface has smooth interface to external boundary of the first optical surface, the external one being conjugated with the internal boundary of the first transition zone surface.

EFFECT: improved vision function in near and far zone; minimized removed eye tissues volume.

22 dwg