Clinical analysis of functional optical zone after transepithelial photorefractive keratectomy in patients with different degrees of myopic astigmatism

Abstract

AIM: To evaluate the effect of preoperative degrees of myopic astigmatism and anterior corneal curvature on the functional optical zone(FOZ)after transepithelial photorefractive keratectomy(TransPRK).METHODS: Retrospective study was conducted on 78 patients(130 eyes)with myopia and myopic astigmatism who underwent TransPRK, and they were divided into control group(cylinder 0D), moderate astigmatism group(-0.50～-2.00D)and high astigmatism group(>-2.00～<-6.00D). The FOZ was measured and compared among the three groups 6mo after operation. The correlations between attempted correction, anterior corneal curvature, corneal aberrations, Q value, and the FOZ were analyzed.RESULTS: At 6mo after operation, the mean FOZ was 5.16±0.12mm in the control group, 5.29±0.23mm in the moderate astigmatism group, and 5.49±0.23mm in the high astigmatism group(P<0.001), and the FOZ of the high astigmatism group was significantly higher than moderate astigmatism and control group(P<0.05, P<0.001); Pearson correlation analysis showed that the changes in spherical equivalent, total corneal higher-order aberrations(HOAs), coma, and spherical aberration were all negatively correlated with FOZ(all P<0.05); and FOZ positively correlated with changes in the steep curvature(K2), mean curvature(Km), corneal astigmatism, and Q value(all P<0.01). Multiple linear regression analysis showed that there was still positive correlation between preoperative K2 and FOZ after adjusting for other risk factors(P<0.001).CONCLUSION: Patients with high astigmatism can obtain a larger FOZ and less induced coma after TransPRK. A larger FOZ can be achieved in eyes with steeper keratometry.

Keywords

• functional optical zone
• transepithelial photorefractive keratectomy(transprk)
• myopic astigmatism
• anterior corneal curvature
• corneal aberrations