The Effect of Topical Corticosteroid Treatment On Myopic Regression after Photorefractive keratectomy: Long-term Follow-up

To evaluate the long-term effect of topical corticosteroid treatment on reversing myopic regression after excimer laser potorefractive keratectomy(PRK), 118 eyes of 103 patients demonstrating myopic regression of more than-1.00D were treated with 0.1% dexamethasone eye solution, and the changes in visual acuity, refraction and corneal haze after treatment were assessed. The mean preoperative refraction was -6.89D. The mean myopic regression was -1.72D which improved to +0.12D after treatment and the mean uncorrected visual acuity also improved from 0.51 to 0.92. Corneal haze of Grade 1.04 at the time of regression decreased to Grade 0.61 after treatment. All eyes showed improvement after dexamethasone treatment but among 88 eyes which underwent long-term follow-up f the average 21.2 months(6~24 months), 48.9%(43 eyes) showed at least one 1episode of repeated regression while 51%(45 eyes) remained stable. Whether regression developed again depended on the changes of corneal haze(p<0.05). This study suggest that the effect of topical corticosteroid on reversing myopic regression after PRK lasted long in a significant number of eyes, retreat mint which also would have some complications.

The Central Island Occurrence Rate and Correlation between the Central Island and Corrected Visual Acuity after Excimer Photorefractive Keratectomy According to the Myopia Degree

We examined 60 eyes of 60 patients after excimer photorefractive keratectomy(PRK) for myopia and analyzed the changes of central island on corneal topography for 6 months prospectively. These patients were divided into two groups according to the degree of myopia, group 1(26 eyes, 6 diopters or below by spherical equivalent) and group 2 (34 eyes, over 6 diopters). The occurrence rate of central island was 76.4% collectively, 87.5% in group 1, 67.7% in group 2 at 2 weeks after PRK. It decreased to 30.4%, 43.5%, and 21.1% respectively at 6 months after PRK and was lower in group 2 than group 1. However there was no statistically significant correlation between the reduction of central island size and improvement of corrected visual acuity in both groups. In conclusion, the central island disappeared and decreased the amount for six months follow-up period after PRK and seems to be no effect on the corrected visual acuity.

Topographic Central Island after Excimer Photorefractive Keratectomy

We analyzed the topographic findings of central islands following excimer photorefractive keratectomies(VISX Twenty/Twenty, Inc, Santa Clara, CA) for myopia to evaluate whether the size of the central island was significantly different betwaen 1 week and 6months postoperatively and whether central island at postoperative 6months affected the decrease of corrected visual acuity from preoperative level. There were statistically significant differences in the indices related to the size of central island(peak, height, area) between 1 week(40 patients, 41 eyes) and 6 months(55 patients, 64 eyes) follow-up groups. In 64 eyes of 6months follow-up group, we could not find any statistically significant effect of the indices related to the size of central island on the decrease of corrected visual acuity, except SAI.