| abstract |
Laser and non-laser means for selective thermal shrinkage of ocular tissue (including cornea, sclera, choroids and ciliary-body) for the treatment of hyperopia, presbyopia and glaucoma are disclosed. The preferred system includes lasers in visible (0.48 to 0.78 micron) and IR (1.4 to 2.2 micron), and non-laser device of radio frequency wave including electrode device, bipolar device and plasma-assisted device. Two predetermined treated area having a circle diameter of about (6 to 8) mm and about (10 to 14) mm are defined. A revised Beer's law is introduced, Bexp(−dA), to relate the focusing factor (B), penetration depth (d) and the absorption coefficient (A) at a given laser spectra. An optimal focal length about 0.8 to 1.4 times of (InB*)/A is formulated for lens design. The effective thermal penetration depth, d*=(0.3−1.0) mm, may be achieved by choosing an optimal focal length laser, or by the length of the conductor tip (about 0.45 to 1.2 mm) of the radio frequency device. |