Treatment of astigmatism associated with myopia or hyperopia with the holmium laser: second year follow-up

In 1993, the Summit Technology apogee system for treating astigmatism was not available, so (to avoid the deep cuts of astigmatic keratotomy) the Summit Holmium: YAG laser was used to treat astigmatism associated with myopia; an excimer laser photorefractive keratectomy was to be performed when the keratometry readings had stabilized. The holmium:YAG laser also was utilized to concurrently treat hyperopia and astigmatism.

For myopic astigmatism, four holmium spots were administered, two on either side of the optical zone. An optical zone of 6.5 mm was used for keratometric astigmatism of 4.00 diopters (D) or greater; 7.0 mm for 3.00 to 3.90 D; 7.5 mm for 1.50 to 2.90 D. For hyperopic astigmatism, two extra spots were placed in the inner treatment ring, one on either side of the flattest meridian for 1.50 to 2.90 D of keratometric astigmatism. By omitting the outer ring treatments in the steeper meridian and using four extra spots, two on either side of the flattest meridian in the inner ring, 3.00 D or more was treated.

Thirty-one myopic eyes were treated; five were lost to follow-up; 12 have subsequently had a photoastigmatic refractive keratectomy (PARK); six have had a PRK; eight had had no further procedures. Seven eyes now have 18 months of follow-up or more (and have not had a PARK); the four successes are presented in detail and it appears that their keratometry readings are nearly stable.

Four of 7 (57%) myopic eyes, which had holmium laser treatment of associated astigmatism, can be considered as successes after 18 months or more follow-up. Keratometry readings are nearly stable; further follow-up is required to determine if regression continues. The treatment of astigmatism simultaneously with hyperopia treatment with the holmium laser was not successful.