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[Analysis of light scatter changes and relevant factors after laser refractive surgery]
1Tianjin Eye Hospital, Tianjin Institute of Ophthalmology, Tianjin Ophthalmology and Visual Development Key Laboratory, Tianjin Medical University, Tianjin 300020, China.
Objective:
To investigate the changes and relevant factors of forward scatter after Epipolis laser in situ keratomileusis (Epi-LASIK)and laser in situ keratomileusis (LASIK).
Methods:
It was a prospective clinical comparative study. 45 patients (45 eyes) were scheduled for Epi-LASIK and 42 patients (42 eyes) for LASIK. Straylight examinations were performed using the C-Quant straylight meter before and 1, 4, 10 months after surgery. The data was analyzed for statistical significance by one-way ANOVA and the correlation was tested by Pearson's test by using SPSS 13.0 software.
Results:
The straylight values were (0.91 ± 0.17), (1.03 ± 0.15), (1.11 ± 0.13), (1.01 ± 0.16) of Epi-LASIK group and (0.96 ± 0.14), (1.05 ± 0.12), (1.10 ± 0.12), (0.98 ± 0.15) of LASIK group preoperatively and 1, 4, 10 months postoperatively respectively, which there were significant increase postoperatively in both groups (F = 12.29, 8.11; P < 0.05). Compared with preoperative values, the changes in straylight values at 1, 4 and 10 months postoperatively were (0.12 ± 0.18), (0.19 ± 0.20), (0.08 ± 0.16) of Epi-LASIK group and (0.09 ± 0.13), (0.15 ± 0.17), (-0.01 ± 0.17) of LASIK group. In Epi-LASIK group, the preoperative refractive error, RBT/CCT, and ablation ratio have significant relevance with straylight values at 4 months postoperatively (r = -0.344, -0.361, 0.361; P < 0.05), no such correlation was found in LASIK group (r = 0.186, 0.162, -0.206; P > 0.05). For corneal haze which was found from 1 to 4 months after Epi-LASIK, grade 2, 1, 0.5 appeared in 1, 2, 4 eyes respectively and the changes of straylight values were 0.52, (0.37, 0.42), (0.06, 0.09, 0.07, 0.17) at 4 months postoperatively. 10 months postoperatively, the increases of straylight values for the eye with grade 2 haze declined from 0.52 to 0.11 after the haze disappeared.
Conclusion:
Straylight values increase significantly at early time after Epi-LASIK and LASIK, but decrease partially as time going. Corneal wound healing response may be the reasons induced the increases of light scatter after Epi-LASIK. For LASIK, flap interface factors may be the reasons. Corneal haze especially above mild grade, can affect the straylight obviously.
