Changes of corneal curvature and astigmatism and anterior chamber depth after FS-LASIK / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM: To observe the changes of corneal curvature and astigmatism and anterior chamber depth after femtosecond laser-assisted LASIK for myopic astigmatism.<p>METHODS: One hundred and thirty-four cases(212 eyes)undergone femtosecond laser-assisted LASIK in our hospital were included. They were selected and divided into two groups based on astigmatism. The group A:astigmatism -2.00D to -5.00D, spherical equivalent -6.15±1.74D. The group B:astigmatism -0.25D to -1.00D, spherical equivalent-6.67±1.04D. Patients were examined 1wk, 1mo and 3mo. Visual acuity, intraocular pressure, refraction, corneal curvature and anterior chamber depth were recorded. The changes of corneal curvature and astigmatism and anterior chamber depth were compared. Spearman correlation analysis and independent <i>t</i>-test were used for statistical analysis.<p>RESULTS: No statistically significant difference was found in posterior corneal curvature and astigmatism and anterior chamber depth of the groups A and B at preoperative, postoperative 1wk, 1mo and 3mo(<i>P</i>>0.05). No statistically significant difference was found in anterior corneal curvature of the groups A and B at postoperation 1wk, 1mo and 3mo(<i>P</i>>0.05). One week postoperative, the anterior corneal astigmatism of the group A was statistically significant from that of 1mo and 3mo postoperative(<i>P</i><0.05), there were no significant differences at 1mo, 3mo after operation(<i>P</i>>0.05). No statistically significant difference was found in anterior corneal astigmatism of the group Bat postoperation 1wk, 1mo and 3mo(<i>P</i>>0.05).<p>CONCLUSION: When correct high astigmatism, no significant changes of posterior corneal curvature and anterior chamber depth was found after femtosecond laser-assisted LASIK for correct myopic astigmatism. The anterior corneal curvature was stable from 1wk to 3mo.The astigmatism was stable from 1mo to 3mo.

Central Corneal Thickness Measured by Four Different Methods in Normal and Post-Femtosecond Laser-Assisted LASIK Eyes

PURPOSE: To compare corneal pachymetry assessment using four measurement methods in normal and post-femtosecond laserassisted LASIK eyes. METHODS: Central corneal thickness was measured sequentially using Orbscan II, Pentacam, Galilei and ultrasonic pachymetry in 30 normal, non-surgical eyes (Group I), 30 eyes one to six months after femtosecond laser-assisted LASIK (Group II), and 30 eyes six months or longer after femtosecond laser-assisted LASIK (Group III). RESULTS: In Group I, corneal thickness measurements were similar for all four methods (P=0.202, one way ANOVA). In Groups II and III, corneal thickness measurements were significantly different (P=0.000, respectively, one way ANOVA). Compared to the Pentacam, Galilei and ultrasonic pachymetry, Orbscan significantly underestimated the corneal thicknesses in Groups II and III (P<0.005, respectively, one way ANOVA). CONCLUSIONS: Central corneal thicknesses of normal eyes were similar for all four measurements, therefore corneal thickness measurements before refractive surgery using all four measurements is suitable. However measurements obtained with the Orbscan II were thinner than those obtained with the Pentacam, Galilei or ultrasonic pachymetry in post femtosecond laserassisted LASIK eyes. Further studies are needed to determine which instrument is more accurate in measuring central corneal thickness before and after refractive surgery.