| Objective:To investigate the related factors affecting the effective optical zone after corneal refractive surgery and the related corneal injury repair mechanism by monitoring the changes of the effective optical zone 1 day after SMILE in different degrees of myopia with different designed optical zones,and to predict the safety,stability,predictability and accuracy of refractive surgery.Methods:Patients with myopia and myopic astigmatism who underwent SMILE surgery in Huaxia Eye Hospital of Lanzhou Province were divided into 6.0mm group(55 eyes),6.3mm group(52eyes)and 6.5mm group(48 eyes)according to the designed optical zone size.According to the spherical equivalent(SE),moderate myopia group:-3.00 D < SE ≤-6.00D;High myopia group:spherical equivalent >-6.00 D.All patients underwent non-contact intraocular pressure,refraction,medical optometry,slit lamp and Sirius three-dimensional corneal topography examination before surgery.Levofloxacin eye drops were routinely given 3 days before surgery for anti-inflammatory treatment to prevent postoperative eye infection.All operations were performed by the same experienced doctor using Visu Max 3.0 full femtosecond corneal refractive surgery system(Carl Zeiss,Germany).The laser energy was 130 n J,and the thickness of the corneal cap was set at 100-120 μm.The upper and lower surfaces of the lens were separated and the stromal layer lens was removed through a lateral incision 2mm above the cornea.All patients were treated with 0.5% levofloxacin eye drops,0.1% fluorometholone eye drops and 0.3% sodium hyaluronate eye drops after operation.The uncorrected visual acuity before surgery and the best corrected visual acuity at 1 day,1 week and 1 month after surgery were measured by comprehensive refractometer.The size of the effective optical zone was examined by Sirius topograph(CSO,Italy)at 1 day after surgery,and the diameter of the effective optical zone was measured using the tangential curvature difference map of the corneal topography.Result:The FOZ(functional optical zone)was(5.17±0.26)mm in the moderate myopia 6.0mm group and(4.91±0.34)mm in the moderate myopia 6.0mm group at 1 day after surgery.The transverse diameter of the moderate myopia 6.3mm group was(5.62±0.28)mm,the longitudinal diameter of the moderate myopia 6.3mm group was(5.36±0.31)mm,the transverse diameter of the moderate myopia 6.5mm group was(5.68±0.30)mm,and the longitudinal diameter of the moderate myopia 6.5mm group was(5.40±0.32)mm.The transverse diameter of the high myopia 6.0mm group was(5.12±0.28)mm,the longitudinal diameter of the high myopia 6.0mm group was(4.98±0.20)mm,the transverse diameter of the high myopia 6.3 mm group was(5.49±0.26)mm,and the longitudinal diameter of the high myopia 6.3 mm group was(5.37±0.25)mm.The transverse diameter of the high myopia 6.5 mm group was(5.45±0.21)mm,and the longitudinal diameter of the high myopia 6.5 mm group was(5.75±0.20)mm.In the three moderate myopia groups(6.0 mm,6.3 mm,6.5 mm),the postoperative FOZ values of transverse diameter were significantly greater than those of longitudinal diameter(p = 0.002,<0.001,< 0.001,respectively).In the high myopia group(6.0 mm,6.3 mm,6.5 mm),the FOZ values of transverse diameter and longitudinal diameter were similar(p = 0.050,0.311,0.072,respectively).In moderate myopia,the FOZ diameter of the 6.0mm group was smaller than that of the 6.3 mm and 6.5 mm groups(p < 0.001 and P < 0.001,respectively).There were significant differences between the 6.0mm group and the 6.3 mm group,and between the6.0mm group and the 6.5 mm group.However,there was no significant difference in FOZ diameter between the moderate myopia group of 6.3 mm and 6.5mm(p = 0.366).In high myopia,the FOZ diameter of the 6.0 mm group was smaller than that of the 6.3 mm and 6.5mm groups(p < 0.001,0.010,respectively).There were significant differences between the 6.0mm group and the 6.3 mm group,and between the 6.0 mm group and the 6.5 mm group.However,there was no significant difference in FOZ diameters between the 6.3 mm group and the 6.5 mm group(p = 0.811).In moderate myopia,the postoperative FOZ in the 6.0mm group was smaller than that in the 6.3 mm and 6.5 mm groups(p < 0.001 and P < 0.001,respectively).There was a significant difference between the groups.However,there was no significant difference in postoperative FOZ longitudinal diameter between the 6.3 mm group and the6.5mm group in moderate myopia(p = 0.470).In high myopia,the postoperative FOZ longitudinal diameter of the 6.0 mm group was smaller than that of the 6.3 mm and 6.5 mm groups(p < 0.001 and P < 0.001,respectively).There was a significant difference between the groups.In high myopia,the postoperative FOZ longitudinal diameter of the 6.3 mm group was smaller than that of the 6.5 mm group,and the p value was 0.008.Conclusion:(1)The effective optical zone after SMILE was lower than the preoperative predicted optical zone,but there were differences among different myopic degrees and different design sizes.(2)When the designed optical zone was 6.0 mm,6.3 mm and 6.5 mm,the FOZ of moderate myopia on the horizontal axis was larger than that of the vertical axis at 1 day after operation,and there was no significant difference in the FOZ of high myopia.(3)When the SMILE designed optical zone was greater than or equal to 6.3mm,the changes of FOZ in horizontal and vertical axis tended to be consistent among different designed optical zones in moderate myopia at 1 day after surgery,and only in horizontal axis tended to be consistent in high myopia.(4)When the designed optical zone size was the same,there was no significant difference in the changes of FOZ horizontal axis and vertical axis among different degrees of myopia at 1day after SMILE.(5)Within the allowable range of corneal thickness,the designed light zone of SMILE is recommended to be greater than or equal to 6.3mm,which has a good effect on the recovery of visual quality after surgery. |
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