| PurposeAt present,corneal refractive surgery is one of the important correction methods for refractive error,which involves a wide range of people.It has a great clinical significance for the control of surgical complications and the clinical observation of relatively few hyperopic surgeries.This subject was mainly divided into two parts: myopic surgery and hyperopic surgery.The study of myopic surgery was mainly based on the complications.Firstly,this study focused on the intraoperative complications of opaque bubble layer,which explored whether the energy setting had an effect on it,and further studied the effects of energy setting on postoperative visual acuity.The main purpose of this part is to explore the optimal energy setting clinically.Then the study mainly revolved around the postoperative complications of corneal Haze,describing the current use of mitomycin-C in patients with low to moderate myopia.The main purpose of this part is to explore the effects of prophylactic MMC on Haze and further explored the optimal MMC duration clinically.The subject of hyperopic surgery mainly focused on the refractions,visual quality and dry eye condition after hyperopic corneal refractive surgery.This part explored whether there were differences between the two main operations,and tried to find relevant interactions.The main purpose of this part was to provide the appropriate surgery for different groups of people.Methods1.The study of opaque bubble layer on myopic SMILE surgeryThe retrospective cohort was from April 2015 to July 2016 in the refractive surgery center of Tianjin Eye Hospital.For patients with myopia and myopic astigmatism underwent SMILE surgery,a total of 1130 eyes were included.The whole cohort was used for the study of the effects of energy on visual acuity,and all OBL analyses were performed in a nested case-control study.The relationship between energy and postoperative visual acuity,preoperative refeactions and the risk of intraoperative OBL was explored by multiple regression analysis after adjusting for confounding factors.The effect of energy on postoperative visual recovery was analyzed by a generalized additive model.2.The study of Haze on myopic PRK surgeryThe retrospective cohort was from January 2013 to December 2017 in the Refractive Surgery Center of Optical Express,Glasgow,UK.A total 7252 eyes of low to moderate myopia were included which were consistent with the inclusion criteria in this study.The effect of corneal Haze on postoperative visual acuity and refractions,and the relationship between MMC and the risk of postoperative Haze in patients with different diopters,were analized by multiple regression analysis after adjusting for the confounding factors.3.The study of postoperative refractions,dry eye and visual quality between hyperopic LASIK and PRK.The retrospective cohort was from January 2008 to April 2015 in the refractive surgery center of Optical Express,Glasgow,UK.A total of 58562 eyes of patients receiving hyperopic laser vision correction were included.The relationship between the main variables was analized by multiple regression analysis after adjusting for confounding factors.In order to explore the interactions of preoperative population characteristics between operations and postoperative refractions,preoperative features were stratified according to clinical criteria and multiple regression statistics were performed while adjusting for confounding factors in each layer.In addition,the changes in dry eye and visual symptoms were analyzed by a generalized additive model.ResultsIn the first part,a total of 22 eyes(1.95%)in the 1130 eyes of this cohort developed OBL.The multivariate regression analysis of the energy setting for the risk of intraoperative OBL in SMILE was OR=0.90(95% CI =0.60,1.37),p=0.64.The effect of energy setting on postoperative UDVA(log MAR)was β=0.01(95% CI = 0.00,0.01),p=0.003.There was no significant difference in the change of UDVA between the two groups at 1 day postoperatively(difference,-0.03;SE,0.02;p = 0.09).However,the changes at 1 week,1 month,and 3 months after surgery were statistically different(1 week: difference,-0.05;SE,0.02;p = 0.01.1 month: difference,-0.06;SE,0.02;p < 0.01.3 months: difference,-0.08;SE,0.02;p <0.01).In the second part,3.6% of the patients in the study cohort(263 eyes)had a record of corneal Haze.In patients with-5D ≤ sph <-4D,OR = 0.17,95% CI = 0.06,0.46,p < 0.001.In patients with-4D≤ sph <-1 D,the results were OR = 0.58,95% CI = 0.28,1.22,p = 0.15;OR = 0.90,95% CI = 0.48,1.69,p = 0.75;OR = 0.75,95% CI = 0.34,1.66,p = 0.47,respectively.For patients with-1D≤ sph <0D,OR = 1.84,95% CI = 0.89,3.83,p = 0.10.For MMC duration,when the application duration was in the range of 1-20 seconds,OR=0.52,95% CI = 0.35,0.77,p<0.001.When the application duration was 20-35 seconds,OR=0.59,95% CI = 0.19,1.83,p=0.36,but after 35 seconds,OR=1.69,95% CI = 1.05,2.74,p= 0.032.In the third part,for LASIK,there were 37,647 eyes(69.1%)in the ±0.5D at the final follow-up and 2,773 eyes(67.7%)in the PRK group(p = 0.052).Compared with LASIK in hyperopia,the OR of the SE within ±0.5D was 0.85(95% CI = 0.78-0.92,p < 0.001).Central corneal thickness may be an interaction between operations and refractions(p interaction = 0.036).The degree of dry eye was not statistically different at all follow-up time points.There was a slight statistical difference in dry eye frequency between 1 week and 12 months after surgery.In terms of visual quality symptoms,glare,starburst and night driving were statistically different at 1 week after surgery.At 1 month after surgery,there were statistical differences in the five items.However,there were no statistical differences between the two operations at 3,6,and 12 months postoperatively.Conclusions1.Low energy settings ranging from 125 n J to 160 n J were associated with better postoperative vision and vision recovery.A 4.5μm spot-track-distance and a 125 n J energy setting were the best combination of this energy setting range.Low myopia and low astigmatism were independent risk factors for OBL in SMILE surgery.The effect of astigmatism on the risk of OBL may be greater than the degree of myopia.These results may suggest that the surgeons can reduce the risk of OBL by appropriately deepening the intraoperative laser scan depth,especially for patients with lower pre-correction.2.Overall,the risk of postoperative Haze in patients with low to moderate myopia applying prophylactic MMC did not decrease.For patients with-5D ≤ sph <-4D,intraoperative prophylactic application of MMC can significantly reduce the risk of postoperative corneal Haze.For patients with-4D ≤ sph <-1D,MMC may have a protective effect on postoperative corneal Haze also.However,for patients with-1D ≤ sph <0D,MMC may even have a promoting effect on the occurrence of haze.In terms of MMC duration,for the characteristic population in this study,the optimal duration may be 20 seconds to 35 seconds,and the risk of postoperative Haze increased no matter the duration too low or too high.3.Both hyperopic LASIK and PRK can basically achieve the expected corrected refractive power of the patient.The possibility of hyperopic LASIK surgery to achieve the expected corrected refractions is slightly higher than that of hyperopic PRK surgery,especially for patients with thicker cornea.Hyperopia may be overcorrected after PRK surgery,especially in patients with thicker corneas also.In addition,the degree of dry eye and dry eye frequency postoperatively were increased compared with preoperative,but the degree of increase was relative small,and there was no significant difference between the operations.The visual quality also was lower than that before surgery,but the reduction was small also and the subjective feelings gradually improved over time. |
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