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Optics of Refractive Surgery

James Schwiegerling, PhD

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	Slide 1A. The effects of radial keratotomy. Incisions are placed in a spoke-like pattern on the cornea. The central uncut hub is the optical zone.
	Slide 1B. The effects of radial keratotomy. The cornea sags following radial keratotomy so that the radii of curvature become longer and the corneal power is reduced.
	Slide 2A. Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) modify the corneal radius of curvature. (A) Myopic case.
	Slide 2B. Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) modify the corneal radius of curvature. (B) Hyperopic case. Rpre is the preoperative corneal radius of curvature. Rpost is the postoperative radius of curvature, and D is the optical zone diameter.