| Objective To observe the changes of contrast sensitivity after LASIK for high myopia,and to explore the influence of the relationship between optical ablation diameter and scotopic pupil diameter on contrast sensitivity.Methods 70 patients(140 eyes)with high myopia who underwent LASIK in our hospital from June 2019 to June 2020 were selected.Patients with scotopic pupil diameter≤optical ablation diameter were divided into group A,and patients with scotopic pupil diameter>optical ablation diameter were classified as group B,each group with 35 cases(70 eyes).According to the difference(ΔR)between the diameter of pupil and optical ablation diameter,group B were divided into three subgroups: B1(0.1≤ΔR≤0.5mm,28 eyes),B2(0.6≤ΔR≤1.0mm,24 eyes),B3(ΔR≥1.1mm,18 eyes).The photopic CS,mesopic CS and GS were measured for 70 patients before LASIK and 1 week,1 month,3 months and 6 months postoperatively,also check the dominant eye.Collect data and make statistical analysis.Results 1.Photopic CS: One week after operation,the photopic CS of two groups was significantly lower than that before operation(P<0.05);At 3 months after operation,photopic CS returned to the preoperative level,and there was no significant difference between two groups(P>0.05);6 months after operation,photopic CS in both groups were higher than that before operation(P<0.05);There was no significant difference in photopic CS between group A and group B at different time(P>0.05);And there was no significant difference among B1,B2,B3 groups(P>0.05).Photopic CS of dominant eye was better than that of non-dominant eye(P<0.05);Photopic CS of binocular eye was better than that of monocular eye(P<0.05).2.Mesopic CS: One week after operation,the number of failed cases of mesopic CS in each grade in group A and group B was higher than that before operation(P<0.05);At 3months and 6 months after operation,there was no difference in the number of failed cases of mesopic CS in each grade compared with that before operation(P>0.05);The comparison of the mesopic CS of group A and B at each time shows that the number of failed cases in group B is higher than that in group A,and there is a statistical difference(P<0.05);The B1,B2,and B3 groups were compared at each time before and after the operation.The results showed that there was no difference in the number of failed cases between the B2 and B1 groups(P>0.05),while the number of failed cases in the B3 group was higher than that in B1 and B2 groups,with statistical difference(P<0.05).3.GS:One week after operation,the number of failed cases of GS in each grade in group A and group B was higher than that before operation(P<0.05);At 3 months after operation,the number of failed cases in group A decreased to the preoperative level,and there was no difference compared with that before operation(P>0.05),in group B,the number of 1:2(Grade 8)failed cases at 6 months after operation was still higher than that before operation(P<0.05);Comparison between two groups,the number of GS failed cases in group B was higher than that in group A(P<0.05);Comparison of B1,B2,and B3 subgroups showed that the number of failed cases in group B2 was higher than that in group B1(P<0.05),and the number of failed cases in subgroup B3 was higher than that in subgroup B2(P<0.05).4.At 6 months after the operation,the number of failed cases in group A,B1,B2 and B3 with glare in 1:2.7(Grade 7)was higher than that without glare in 1:2.7(grade 3),the difference was statistically significant(P<0.05).Conclusion 1.In the early stage after LASIK surgery,the contrast sensitivity decreased,and then gradually recovered.The relationship between optical ablation diameter and scotopic pupil diameter had little effect on the photopic CS,but when the optical ablation diameter is smaller than the scotopic pupil diameter,the effect on the change of the mesopic CS is obvious,which can reduce the mesopic CS of the patients.When the difference≥1.1 mm,the mesopic CS decreases more obviously;Under glare condition,the contrast sensitivity of patients was further reduced.2.In order to ensure satisfactory visual quality,the optical ablation diameter of LASIK should be larger than or equal to the scotopic pupil diameter. |
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