| Femtosecond small incision lenticule extraction for the correction of myopia and myopic astigmatism has good effectiveness,safety,predictability and stability,become more and more popular in clinical.In the treatment of myopia and myopic astigmatism,more attention should be paid to the possible problems during the operation and after the operation.In the past,there have been a lot of research and clinical study on the changes of corneal biomechanics,corneal sensitivity,corneal nerve fiber,corneal Bowman membrane and posterior cornea surface height after femtosecond laser corneal small incision lenticule extraction(SMILE),However,these studies are mostly confined to the anterior segment and the corneal morphological changes,rarely involving the posterior segment of the eye,and there is a lack of systematic research and clear conclusions about the effects of the vitreous and retina after SMILE.The retina is the first stop to receive light and form vision,especially the macula is the most sensitive part of the human central vision.If the retina,macular damage,it will have a serious impact on vision.However,the visual recovery in SMILE is slower than after LASIK.As the procedure is relatively new,the corneal wound healing response is not well documented,and the reason for delayed recovery is not clear.In the SMILE procedure,the mean IOP are 65±20mm Hg,the maximum IOP values of 105 mm Hg.The average duration of suction to be 39.20 ±1.030 s with a range from 38 to 43 s.The short-term increase in IOP may cause significant enlargement in optic disc cupping in emmetropic and myopic eyes.This acute increase in IOP during surgery is certainly sufficient to reduce or stop blood flow within the retinal vessels,and could induce reversible visual field(VF)depression in normal and glaucomatous eyes.Few studies exist in the literature investigating the visual field after SMILE.The purpose of this study was to prospectively evaluate changes in threshold automated perimetry using a Humphrey perimrter(30-2 program)caused by transient IOP peaks during SMILE surgery on myopes.MethodsChoose 41 eyes(41 cases)undergoing SMILE for myopia and myopic astigmatism between June 2016 and September 2016 in our hospital excimer laser room.All 41 patients’ left eyes were selected as the research object,the male 31 eyes(31cases),the female 10 eyes(10 cases).Aged 18 ~ 30,average(21.50±3.31).The intraocular pressure are 10.40~19.20 mm Hg,average(15.46±2.15)mm Hg(1 mm Hg= 0.133 KPa).The preoperative spherical equivalent(SE)are-1.75~-7.50 D,average(-5.14±1.51)D.Central corneal thickness(CCT)are 489 ~ 573μm,average(539.46±20.81)μm.The corneal curvature are 40.60 ~ 46.25 D,average(43.30±1.27)D.Patients preoperative are tested by preoperative main optometry,computer optometry,comprehensive optometry,intraocular pressure,Orbscan Ⅱ corneal topography,anterior segment of ocular,fundus oculi.The Visu Max(Carl Zeiss,Germany)femtosecond laser system was used to perform surgical refractive corrections for the patients.Recording visual field values of preoperative and postoperative 1day、7day、1month,including mean deviation(MD)and the pattern standard deviation(PSD)by Humphrey field analyzer Ⅱ-i 750 i analyze.Statistical analysisSPSS 21.0 statistical software for data statistics analysis,measurement data using mean ± standard deviation,continuous variables were compared using repeated-measures analysis of variance(ANOVA).Afterwards,statistical correlations between parameters were assessed using the Pearson correlation.P<0.05 was considered statistically significant.Results1 postoperative uncorrected visual acuity and residual diopter at 1day,7day and 1 monthPostoperative 1day,3 eyes(7.32%)uncorrected visual acuity declined≥ 2 lines,22 eyes(53.66%)uncorrected visual acuity decreased by 1 line;Postoperative 7 days,there are still 7 eyes(17.07%)uncorrected visual acuity fall 1 line;after1 months,all postoperative naked eyesight visual acuity was better than or equal to the preoperative best corrected visual acuity;Postoperative 1day,the average residual diopter was(0.32±0.27)D,within±0.5 D(80.49%);Postoperative 7 days,the average residual diopter was(0.29±0.20)D,within ± 0.5 D(92.68%);after 1 months,the average residual diopter was(0.24± 0.19)D,within±0.5 D(95.12%).2 Preoperative and postoperative 1 day,7 days,1 months the comparison of the mean deviation,the pattern standard deviation value.After 1day,7days and 1 month,41 eyes’ mean deviation value are compared with preoperative,the difference was statistically significant(F=220.586,P=0.000).Preoperative average MD were(-3.26 ± 1.48)d B,postoperative 1day,7days and 1month the average MD were(-3.68±1.18)d B、(-2.71±1.17)d B、(-2.73±0.93)d B.Postoperative 1day MD value increased,after 7 days and 1 months MD value gradually decreased,but lower than preoperative level at last.After 1day,7days and 1 month,41 eyes’ the pattern standard deviation value are compared with preoperative,there was no statistically significant difference(F=10.206,P=0.310).Preoperative average PSD were(1.77±0.43)d B,postoperative1 day,7day and 1 month the mean PSD were(1.76±0.47)d B、(1.72±0.46)d B、(1.73±0.45)d B.3 Visual field index changes relationship with preoperative equivalent sphericalPreoperative spherical equivalent were range from-1.75 to-7.50 D,the average were(-5.14±1.51)D,the average preoperative MD were(-3.26±1.48)d B,At1 day,7day and 1month postoperatively,the MD were(-3.68±1.18)d B,(-2.71±1.17)d B,(-2.73±0.93)d B respectively.The preoperative average MD positively correlated with preoperative spherical equivalent(r=0.532,p=0.000).The MD in 1day,7day and1 month after operation had no correlation with preoperative spherical equivalent(r=0.284,P=0.072;r=0.115,P=0.474;r=0.036,P=0.823).Preoperative spherical equivalent were range from-1.75 to-7.50 D,the average were(-5.14±1.51)D,the average preoperative PSD were(1.77 ± 0.43)d B,At1 day,7day and 1month postoperatively,the PSD were(1.76±0.47)d B,(1.72±0.46)d B,(1.73 ± 0.45)d B respectively.Preoperative and postoperative PSD had no correlation with preoperative spherical equivalent(r=0.230,p=0.149;r=0.197,P=0.217;r=0.246,P=0.122;r=0.239,P=0.132).4 Visual field index changes relationship with postoperative residual diopterPostoperative 1 day、7days、1month the residual diopter average were(0.32±0.27)D,(0.29±0.20)D,(0.24±0.19)D respectively.The average preoperative MD were(-3.26±1.48)d B,At 1day,7days and 1month postoperatively,the MD were(-3.68±1.18)d B,(-2.71±1.17)d B,(-2.73±0.93)d B respectively.Preoperative and postoperative MD had no correlation with postoperative 1 day residual diopter(r=-0.079,p=0.622;r=0.051,P=0.749;r=0.004,P=0.982;r=-0.140,P=0.384).Preoperative and postoperative MD had no correlation with postoperative 7 days residual diopter(r=-0.026,p=0.870;r=0.068,P=0.671;r=0.131,P=0.416;r=-0.137,P=0.391).Preoperative and postoperative MD had no correlation with postoperative 1 month residual diopter(r=0.004,p=0.978;r=-0.021,P=0.897;r=-0.037,P=0.819;r=-0.182,P=0.255).The average preoperative PSD were(1.77±0.43)dB,At 1day,7days and 1month postoperatively,the PSD were(1.76±0.47)d B ?(1.72±0.46)d B ?(1.73±0.45)d B respectively.Preoperative and postoperative PSD had no correlation with postoperative 1 day residual diopter(r=-0.127,p=0.427;r=-0.105,P=0.514;r=-0.177,P=0.269;r=-0.143,P=0.372).Preoperative and postoperative PSD had no correlation with postoperative 7days residual diopter(r=-0.206,p=0.197;r=-0.105,P=0.516;r=-0.181,P=0.258;r=-0.136,P=0.396).Preoperative and postoperative PSD had no correlation with postoperative 1month residual diopter(r=-0.082,p=0.608;r=0.004,P=0.978;r=-0.022,P=0.890;r=-0.014,P=0.929).5 Visual field index changes relationship with postoperative uncorrected visual acuityPreoperative and postoperative MD had no correlation with postoperative 1 day uncorrected visual acuity(r=-0.036,p=0.822;r=-0.301,P=0.056;r=-0.216,P=0.175;r=0.002,P=0.988).Preoperative and postoperative MD had no correlation with postoperative 7days uncorrected visual acuity(r=-0.003,p=0.985;r=-0.165,P=0.301;r=0.048,P=0.766;r=0.131,P=0.414).Preoperative and postoperative PSD had no correlation with postoperative 1day uncorrected visual acuity(r=-0.010,p=0.951;r=-0.053,P=0.742;r=0.139,P=0.387;r=0.071,P=0.658).Preoperative and postoperative PSD had no correlation with postoperative 7days uncorrected visual acuity(r=0.055,p=0.735;r=0.048,P=0.765;r=0.176,P=0.271;r=0.140,P=0.382).6 Visual field index changes relationship with removed tissue thicknessRemoved tissue thickness average were(102.512±22.342)μm,range from 53.0 to 139.0μm,the average preoperative MD were(-3.26±1.48)d B,At 1day,7days and1 month postoperatively,the MD were(-3.68±1.18)d B,(-2.71±1.17)d B,(-2.73±0.93)d B respectively.The preoperative average MD negatively correlated with removed tissue thickness(r=-0.479,p=0.002).The MD in 1day,7days and 1month after operation had no correlation with the removed tissue thickness(r=-0.271,P=0.086;r=-0.124,P=0.440;r=-0.029,P=0.855).Removed tissue thickness average were(102.512±22.342)μm,range 53.0 to139.0μm,the average preoperative PSD were(1.77±0.43)d B,At 1day,7days and1 month postoperatively,the PSD were(1.76±0.47)d B,(1.72±0.46)d B,(1.73±0.45)d B respectively.Preoperative and postoperative PSD had no correlation with the removed tissue thickness(r=-0.207,p=0.195;r=-0.174,P=0.276;r=-0.224,P=0.159;r=-0.208,P=0.192).7 Visual field index changes relationship with the duration of suctionThe duration of suction average were(39.200±1.030s),range from 38 to43 s,Preoperative and postoperative MD had no correlation with the duration of suction(r=0.2106,p=0.188;r=0.191,P=0.231;r=0.231,P=0.147;r=0.248,P=0.118).Preoperative and postoperative PSD had no correlation with the duration of suction(r=0.114,p=0.479;r=0.180,P=0.261;r=0.171,P=0.285;r=0.115,P=0.475).ConclusionAfter SMILE,the visual threshold decreased and gradually recovered over time.The study suggests that SMILE did not render the optic nerve more vulnerable to damage and cause visual field defects,which has no significant effect on the normal physiological function of retina. |
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