Treatment of myopic astigmatism with the 193 nm excimer laser utilizing aperture elements.

In this paper, we examine the 193 nm excimer laser's efficacy and safety in treating myopic astigmatism. The VISX Twenty/Twenty excimer laser uses aperture elements to effect astigmatic photorefractive keratectomy. In 70 patients with six months follow-up, the average postoperative sphere was -0.14 and the average postoperative cylinder was -0.54. Seventy-one percent of these patients had uncorrected visual acuity of 20/40 or better at six months. In 12 patients with one year follow-up, the average postoperative sphere was -0.05 and the average postoperative cylinder was -0.59. Eighty-three percent of these patients had uncorrected acuities of 20/40 or better; none had a clinically significant loss of best corrected acuity. This investigation demonstrates that the excimer laser can be used to treat myopic astigmatism successfully.

Photorefractive keratectomy for myopic astigmatism: phase IIA of the Federal Drug Administration study (12 to 18 months follow-up). Excimer Laser Study Group.

Excimer laser photorefractive keratectomy was performed on eight eyes to investigate toric ablation of naturally occurring compound myopic astigmatism. Follow-up ranged from 12 to 18 months. In each surgical case, the spherical component was reduced. The cylindrical component was reduced or eliminated in seven of eight eyes and remained unchanged in one eye. However, six of eight eyes had some residual astigmatism and three had 0.75 diopters of cylinder or more. In six of eight eyes the change in axis in the postoperative cylinder varied between 5 and 10 degrees of the preoperative cylinder axis. In one eye with an eccentric ablation, the axis changed by 40 degrees. In two eyes with loss of best corrected visual acuity of one line each, from 20/20 to 20/25, irregular astigmatism and subepithelial haze persisted 18 months after treatment. One eye gained a line of best corrected visual acuity from 20/20 to 20/15. Two eyes were overcorrected. Twenty-five percent of patients achieved 20/20 or better uncorrected visual acuity, 62.5% achieved 20/40 or better uncorrected acuity, and 100% achieved 20/50 or better uncorrected acuity. These preliminary results of excimer laser photoastigmatic keratectomy compare favorably with reports of photorefractive keratectomy for myopia alone. There were no adverse reactions to treatment. The procedure was effective although some residual astigmatism was found in most patients.

The effects of panretinal photocoagulation on dark adaptation in diabetics with proliferative retinopathy.

The dark adaptation of 14 diabetic patients was measured before and after panretinal photocoagulation (PRP). The rod-cone break of diabetics prior to PRP was delayed 1.7 minutes compared to normal controls and the final rod threshold was elevated 0.7 log units. After PRP, the rod-cone break was delayed 2.9 minutes and the final rod threshold was elevated 1.1 log units.