Research On Q-value Guided Customized LASIK

Part one Comparison of Q-value Guided Customized and Standardized LASIK for Myopia【Objective】To compare the clinical effect of Q-value guided customized LASIK (Q-LASIK) and standardized LASIK (S-LASIK) for myopia.【Methods】Fifty-one eyes of 28 patients were treated with Q-LASIK, and fifty-one eyes of 26 patients were treated with S-LASIK. Preoperative and postoperative 6 months, visual activity, refractions, Q-value and spherical aberration were evaluated in all cases.【Results】The evaluation at 6 months showed the following results for the S-LASIK group and Q-LASIK group: (1)Safety: No eye lost more than 1 line of the best corrected visual acuity (BCVA) in either group, safety indices were 1.006 and 1.012 respectively; (2)Efficacy: UCVA were 1.04±0.06 and 1.05±0.07, with 1.0 or better in 88.2% and 92.2%,1.2 or better in 49.0% and 54.9% respectively, efficacy indices were 0.99 equally; (3)Predictability: Postoperative mean spherical equivalent of the manifest refraction(SE) were (-0.11±0.44)D and (-0.07±0.45)D, 82.4% and 80.4% of eyes were within±0.5D of the intended correction, respectively, 56.9% of eyes were within±0.25D of the intended correction for both groups; (4)Stability: Spherical equivalents were -0.03±0.40D and 0.10±0.43D, -0.03±0.41D and 0.00±0.39D, -0.11±0.44D and -0.07±0.42D at 1, 3 and 6 months respectively, and the changes were less than 0.25 D over 6 months for both groups. There was no statistical difference between the two groups in terms of the above 4 indices (P>0.05); (5)Corneal Q value and spherical aberration had both increased after surgery. In Q-LASIK group, they were obviously lower than that in S-LASIK group, which had statistical significance (P<0.05); attempt refractions had a positive correlation with△Q and△spherical aberrations; (6)The incidence of vision quality's decrement in Q-LASIK group was lower than that in S-LASIK group (P<0.05);【Conclusion】Both Q-value guideded customized ablation and standard ablation LASIK surgeries show very good safety, efficacy, stability and predictability after 6 months of follow-up. Q-LASIK may maintain the asphericity of corneal surface, also help reduce the induction of spherical aberration in refractive surgical correction of myopia and myopic astigmatism, therefore, Q-LASIK is efficient in improving patients'vision quality.Part two Related factors and symmetry between right and left eyes of corneal Q-value in myopic eyes【Objective】To investigate the distribution characters and related factors of corneal Q-value in myopic eyes, and analyze the symmetry of Q-value between right and left eyes.【Methods】The K&Q calculator of Orbscan- IIz anterior segment System was used to obtain the Q-value of 6 mm optical zone in 305 cases (610 eyes), and statistical analysis was used to comprehend the distribution characters of Q-value and its relations with diopter, cornea curvature and lens thickness.【Results】The Q-value of 610 eyes (305 cases) were positive normal distribution with average as -0.16±0.11 (range-0.51～0.20). The Q-value showed positive line relation with cornea astigmatism and Z40, showed negative line relation with cornea curvature, lens thickness and Diff value of corneal anterior surface, but was not related with spherical lens, spherical equivalent, Diff value of corneal posterior surface, Irreg index of 3㎜ and 5㎜ zone, simulated keratometry, cornea diameter, central cornea thickness, intraocular pressure, anterior chamber depth, axis ocular length, sex and age. There was no significant difference between right and left eyes individually.【Conclusion】The cornea Q-value shows a significant individual variation, and it relates with many factors of eye. Both eyes exhibit marked symmetry in individual.