Corneal surface ablation using different techniques of epithelial removal with the VISX S4 IR platform

To compare corneal wound healing, post-operative pain, corneal haze and visual outcome after photorefractive keratectomy [PRK] using two different techniques of epithelial removal with the VISX S4 IR excimer laser system. Sixty-eight patients with low myopia and myopic astigmatism underwent conventional PRK using the VISX S4 IR platform were included in this study. Corneal epithelial removal has been done using 20% alcohol applied to the cornea for 20-30 seconds in the first eye and using laser-assisted transepithelial PRK technique in the second eye. Epithelial wound healing, post-operative pain, corneal haze and refractive outcome have been evaluated in all eyes over 6 months follow-up after the procedure. Although epithelial wound healing was faster and smoother in eyes underwent laser-assisted PRK [tPRK], immediate postoperative pain was marked in those eyes compared to eyes underwent alcohol-assisted PRK [aPRK]. NO eyes developed more than grade 2 haze with tPRK while 2 eyes developed grade 3 haze with aPRK. No eyes lost any line of BCVA. UCVA was similar in both groups despite mild overcorrection in the group of tPRK. both tPRK and aPRK have been found to be safe and effective in treating low myopia and myopic astigmatism. Despite the fact that tPRK was more painful than aPRK, tPRK produces a faster and smoother epithelial wound healing and less incidence of haze formation compared to aPRK. Both tPRK and aPRK have favorable refractive outcome, although tPRK produces mild overcorrection compared to aPRK

Comparative estimation of anterior chamber depth and axial length by ultrasonography and orbscan II

To assess and compare the degree of agreement of anterior chamber depth [ACD] and axial length [AL] measurements by optical devices [Orbscan II] and contact ultrasound A-scan. In this prospective study of 30 eyes of 25 consecutive patients, ACD and AL estimation were done by 2 methods-scanning slit topography [Orbscan II] and contact ultrasound A-scan. One observer performed all Orbscan measurements and another performed all the ultrasonic measurements. Repeated measures Analysis of Variance [ANOVA] was used to analyze difference between ACD and AL measurements by the 2 methods. Difference in measurements between methods was assessed using the paired t test. The mean ACD [SD] by the 2 methods was 3.658 mm [0.254], and 3.406 mm [0.348], respectively. There was a statistically significant difference between measurements recorded by the 2 methods [P>.01]. Mean contact A-scan measurements were 0.252 mm lower than by Orbscan II. The mean AL were 24.220 mm [0.851] and 23.897 [0.857] mm respectively. There was none statistically significant difference between measurements recorded by the 2 methods [P>.01]. Mean contact A-scan measurements were 0.323 mm lower than by Orbscan II. Applanation ultrasound gives consistently lower measurements for ACD as well as the AL compared to Orbscan II