A Comparison Of LASIK With And Without Iris Registration In Myopic Eyes With Astigmatism Greater Than 2.00 Diopters

Objective To compare the clinical outcomes of LASIK with and without iris registration to correct 2.00D or higher myopic astigmatism with or without myopia.Methods LASIK with or without iris registration (IR) was performed on 67 myopic eyes of 53 patients, with-2.00 diopters (D) astigmatism or higher. LASIK with the assist of iris registration technology was performed on 31 eyes (IR-LASIK group) while LASIK without iris registration was performed on 33 eyes (LASIK group). Uncorrected vision acuity (UCVA), best-spectacle corrected visual acuity (BSCVA),manifest refraction and higher order aberrations (HOAs) and contrast sensitivity were measured and recorded preoperatively and at two weeks, one month and three months postoperatively for each eye.Results The related results at 3 months were reported. The safety index (SI) in IR-LASIK group and LASIK group was 1.14 and 1.07. respectively (P=0.321).93.55% of eyes in the IR-LASIK group and 78.13%in the LASIK group gained UCVA of or above 1.0 (P=0.049).80.96% of eyes in total (30 eyes of IR-LASIK group and 23 eyes of LASIK group) were within±0.50 (D) of emmetropia. There was statistically significant difference between the two groups (P=0.009). The mean change of manifest refractive spherical equivalent (MRSE) between two weeks and one month, one month and three months were 0.12D,0.18D in the IR-LASIK group and 0.19D in the LASIK group (P=0.373). There was close correlation between attempted and achieved MRSE for both groups, but no statistically significant difference between the two groups (P=0.241). The mean values of total RMS higher order aberrations, coma, trefoil and spherical aberration in the IR group increased to 0.47μm,0.74μm,0.48μm,0.53μm, respectively. And the figures in the non-IR group were 0.54pμm,0.93μm,0.48μm. 0.73μm, respectively. There was no statistically significant difference between the two groups (P>0.05). Mean contrast sensitivity with glare reached a higher level than that of preoperative. Mean contrast sensitivity without glare was still at low levels at low spatial frequencies (1.0,1.7,2.6,4.2 cpd) but almost returned to preoperative levels at high spatial frequencies (6.6,10.4 cpd). There was no statistically significant difference between the two groups (P>0.05).Conclusion LASIK with the assist of iris registration technology was safe and effective for the treatment of moderate to high myopic astigmatism. It achieved reduced residual astigmatism, better UCVA. and improved visual quality compared to the conventional LASIK.