Risk factors of refractive regression after 1 year femtosecond laser assisted in situ keratomileusis correction of moderate and high myopia and its prediction model construction / 国际眼科杂志(Guoji Yanke Zazhi)

AIM: To investigate the risk factors of refractive regression after correction of moderate and high myopia by femtosecond laser assisted in situ keratomileusis(FS-LASIK)for 1 a, and construct prediction model.METHODS: A retrospective analysis was performed on the clinical data of 400 patients(800 eyes)with moderate and high myopia undergoing FS-LASIK correction in Xi'an Gaoxin Hospital from June 2017 to November 2018, and the patients were randomly divided into modeling group(n=300)and verification group(n=100)according to a ratio of 3:1. The modeling group was divided into regression group and non-regression group according to the occurrence of refractive regression at 1 a after surgery. The changes of corneal curvature and corneal thickness were observed. Logistic regression analysis was used to screen the risk factors of refractive regression in patients with moderate and high myopia at 1 a after FS-LASIK correction, and the prediction model was built based on the regression coefficient. Receiver operating curve(ROC)was used to evaluate model differentiation.RESULTS:Refractive regression occurred in 44 eyes of the modeling group and 15 eyes of the verification group at 1 a after surgery. The anterior corneal surface curvature in the modeling group was lower than that in the regression group at 6 and 12 mo after surgery(all P<0.05). The degree of corneal hyperplasia in the regression group was greater than that in the non-regression group at 1, 3, 6 and 12 mo after surgery(all P<0.05). The regression equation of the probability value of refractive regression in patients with moderate and high myopia corrected by FS-LASIK at 1 a after surgery is as follows:P=1/[1+e-(-5.989+0.127×age+2.019×preoperative diopter-0.022×preoperative central corneal thickness+0.043×depth of cutting-1.569×diameter of cutting optical region)], Hosmer-Lemeshow detected the goodness of fit of the regression equation(P=0.818). Internal verification using the modeling group data showed that the area under ROC curve was 0.890(95%CI: 0.843-0.937), the sensitivity was 81.82%, and the specificity was 84.71%. The area under ROC curve was 0.838(95%CI: 0.717-0.959), the sensitivity was 80.00%, and the specificity was 87.57%.CONCLUSIONS:The established risk model has good discriminating validity and can be used to identify the high-risk group of refractive regression at 1 a after FS-LASIK in patients with moderate and high myopia.

Research progress on mechanism and medical prevention of refractive regression after laser myopia corneal refractive surgery / 国际眼科杂志(Guoji Yanke Zazhi)

Laser corneal refractive surgery is an effective way for the correction of myopia, and its long-term stability is a common concern of surgeons and patients. However, refractive regression is still one of the most common postoperative long-term complications, which has a great impact on postoperative refractive state and visual quality. Refractive regression may be related to many factors, such as the remodeling of corneal epithelium and stroma, and the imbalance between corneal biomechanics and intraocular pressure. Although enhancement surgery could be a useful way to correct refractive regression, there is a risk of corneal ectasia and other complications. Some intraocular pressure lowering medications can be used to rebuild the balance of intraocular pressure and corneal biomechanics, and to prevent postoperative refractive regression by affecting the thickness of corneal epithelium. To a certain extent, the type, the timing and the way of intraocular pressure lowering medications application may have an impact on the prevention and treatment effect of refractive regression.

Refractive regression after corneal refractive surgery / 国际眼科杂志(Guoji Yanke Zazhi)

@#Corneal refractive surgery is a method of correcting refractive errors such as myopia, hyperopia and astigmatism through corneal surgery. Refractive regression can often be seen in clinical practice, that is, refractive errors occur again after surgery. Refractive regression and the consequent poor visual quality often trouble patients. So far, different types and methods of corneal refractive surgery have the problem of refractive regression. It is believed that refractive regression is mainly related with epithelium thickening and change of corneal biomechanics. Refractive regression could be predicted and avoided by preoperative risk factors such as preoperative conditions and operative parameters, and can also be prevented by selecting appropriate refractive surgery and using medicine. Non-operative and enhancement surgery can be used to treat refractive regression that has occurred.

Effect of timolol on refractive regression after high myopia surgery at different time points in LASIK operation / 国际眼科杂志(Guoji Yanke Zazhi)

@#AIM:To observe the effect of timolol on refractive regression after high myopia surgery at different time points in LASIK operation.<p>METHODS: Prospective study. Totally 180 eyes of 90 patients with high myopia who were admitted to our hospital from August 2015 to August 2016 were randomly divided into control group and observation group. Each group had 45 cases and 90 eyes. Both groups were treated with loxacin eye drops and tobramycin dexamethasone eye drops for 1wk. The control group was treated with timolol eye drops 7d after operation, and the observation group was treated with timolol eye drops 1d after operation. The uncorrected visual acuity, spherical equivalent, intraocular pressure, corneal surface curvature and corneal stroma thickness were measured and compared before and 7d, 1, 3 and 6mo after operation.<p>RESULTS: There were differences in naked vision and spherical equivalent between the two groups at different time points after operation(<i>P</i><0.05). At 6mo after operation, the naked vision and spherical equivalent of the observation group were better than those of the control group(0.03±0.01 <i>vs</i> 0.08±0.01; 0.15±0.33D <i>vs</i> -0.17±0.36D; all <i>P</i><0.05). There was no difference in corneal stroma thickness and corneal surface curvature between the two groups at different time points(<i>P</i>>0.05). The intraocular pressure of the observation group was significantly lower than that of the control group at 7d, 1 and 3mo after operation(all <i>P</i><0.05). The intraocular pressure of the two groups tended to be stable at 6mo after operation.<p>CONCLUSION: Early application of timolol after LASIK can effectively reduce intraocular pressure, maintain relatively long-term stability of intraocular pressure, prevent corneal swelling, and thus prevent refractive regression.

Factors Affecting Long-term Myopic Regression after Laser In Situ Keratomileusis and Laser-assisted Subepithelial Keratectomy for Moderate Myopia

PURPOSE: High myopia is known to be a risk factor for long-term regression after laser refractive surgery. There have been few studies about the correction of moderate myopias that did not need retreatment after long-term follow-up. We evaluated 10 years of change in visual acuity and refractive power in eyes with moderate myopia after laser refractive surgery. METHODS: We included patients that had undergone laser in situ keratomileusis (LASIK) or laser-assisted subepithelial keratectomy (LASEK) to correct their myopia and that had at least 10 years of follow-up. We evaluated the stability of visual acuity in terms of safety, efficacy, and refractive changes at examinations 6 months and 1, 2, 5, 7, and 10 years after surgery. RESULTS: The study evaluated 62 eyes (36 eyes in LASIK patients and 26 eyes in LASEK patients). In both groups, the efficacy index tended to decrease, and it was consistently higher in the LASEK group compared to the LASIK group over the 10 years of follow-up. The safety index improved over 10 years and was always higher than 0.9 in both groups. The difference between the spherical equivalent at 6 months postoperatively and later periods was statistically significant after 5, 7, and 10 years in both groups (LASIK, p = 0.036, p = 0.003, and p < 0.001, respectively; LASEK, p = 0.006, p = 0.002, and p = 0.001, respectively). Ten years after surgery,26 eyes (66.7%) in the LASIK group and 19 eyes (73.1%) in the LASEK group had myopia greater than 1 diopter. In comparison with the thickness at 6 months postoperatively, central corneal thickness was significantly increased after 5, 7, and 10 years in both LASIK and LASEK groups (LASIK, p < 0.001, p < 0.001, and p < 0.001, respectively; LASEK, p = 0.01, p < 0.001, and p < 0.001, respectively). CONCLUSIONS: Moderately myopic eyes showed progressive myopic shifting and corneal thickening after LASIK and LASEK during 10 years of follow-up. We also found that early refractive regression may indicate the long-term refractive outcome.

Correlation between dry eye and refractive regression after laser in situ keratomileusis / 国际眼科杂志(Guoji Yanke Zazhi)

AIM:To investigate the correlation between chronic dry eye and refractive regression after laser in situ keratomileusis (LASIK)for myopia.METHODS:Two hundred and twenty-five eyes of 225 patients were enrolled in this study.Examinations including Schirmer test,tear break-up time(BUT),corneal sensation,and ocular surface staining were performed before and 6 months after LASIK.Dry eye symptoms were assessed using the McMonnies Dry Eye Symptom Survey.Data were analyzed on history and treatment response.RESULTS:Refractive regression after LASIK was related to chronic dry eye.It occurred in 8(25.0%)of 32 patients with chronic dry eye and in 18(9.3%)of 193 patients without dry eye(P＜0.01).CONCLUSION:The risk of refractive regression was increased in patients with chronic dry eye.