Changes in posterior corneal elevation after small incision lenticule extraction for different myopic diopters

●AIM:To study the changes and effect factors of posterior corneal surface after small incision lenticule extraction(SMILE)with different myopic diopters.●METHODS:Ninety eyes of 90 patients who underwent SMILE were included in this retrospective study.Patients were allocated into three groups based on the preoperative spherical equivalent(SE):low myopia(SE≥-3.00 D),moderate myopia(-3.00 D>SE>-6.00 D)and high myopia(SE≤-6.00 D).Posterior corneal surfaces were measured by a Scheimpflug camera preoperatively and different postoperative times(1wk,1,3,6mo,and 1y).Posterior mean elevation(PME)at 25 predetermined points of 3 concentric circles(2-,4-,and 6-mm diameter)above the best fit sphere was analyzed.●RESULTS:All surgeries were completed uneventfully and no ectasia was found through the observation.The difference of myopia group was significant at the 2-mm ring at 1 and 3mo postoperatively(1mo:P=0.017;3mo:P=0.018).The effect of time onΔPME was statistically significant(2-mm ring:P=0.001;4-mm ring:P<0.001;6-mm ring:P<0.001).The effect of different corneal locations onΔPME was significant except 1wk postoperatively(1mo:P=0.000;3mo:P=0.000;6mo:P=0.001;1y:P=0.001).Posterior corneal stability was linearly correlated with SE,central corneal thickness,ablation depth,residual bed thickness,percent ablation depth and percent stromal bed thickness.●CONCLUSION:The posterior corneal surface changes dynamically after SMILE.No protrusion is observed on the posterior corneal surface in patients with different degrees of myopia within one year after surgery.SMILE has good stability,accuracy,safety and predictability.

Morphological and cytological changes of meibomian glands in patients with type 2 diabetes mellitus

AIM: To observe the changes of microcellular structure of meibomian glands(MGs) in type 2 diabetes mellitus(DM), and to explore its correlation with the duration of diabetes.METHODS: The study assessed 132 eyes of 132 patients with type 2 diabetes mellitus(DM group) and 100 eyes of 100 non-diabetic participants(NDM group). All patients underwent the examination of the Keratograph 5 M system to obtain the meibography which were used to evaluate the structure dropout of the MGs. And then laser scanning confocal microscopy(LSCM) was performed for observing the acinar cells and ducts of the MGs to obtain the following parameters: the MG acinar unit density(MGAUD), MG acinar longest diameter(MGALD) and MG acinar shortest diameter(MGASD). The examination results of the right eye were selected for analysis.RESULTS: Compared with that in NDM group, the meiboscore was significantly higher(Z=-4.057, P<0.001), and there were more MGs dropout in DM group. With the prolongation of the course of diabetes, the absence of MGs aggravated and the MGs dropout score increased(r=0.596;P<0.001). LSCM showed that there were various cytological alterations in acinar cells of MGs with the progress of diabetes duration, such as expansion, atrophy or fibrosis of MG acinar units, decreased density of MG acinar units, deposition of lipid substances, infiltration of inflammatory cells, proliferation of fibrous tissues, etc. And the opening of the glandular duct changed from smooth at the beginning to narrow, blocked, fibrotic and so on. Compared with that in NDM group, the MGAUD in DM group was significantly lower(Z=-9.713;P<0.001), the MGALD and MGASD were significantly larger(Z=-9.751,-6.416;P<0.001). With the duration of diabetes, the MGAUD reduced, the MGASD increased(r=0.860, 0.364, P<0.001);but the MGALD had no correlation with diabetic duration(r=0.133, P=0.151).CONCLUSION: With the progress of diabetes, the meibomian glandular acinar cells of diabetic patients show various manifestations. Those changes may result in the dysfuction of the MGs, tear film instability and dry eye symptoms in patients with type 2 DM.

Changes of meibomian glands in patients with type 2diabetes mellitus

AIM： To investigate the morphological changes of meibomian glands in patients with type 2 diabetes mellitus （DM）.METHODS： Of 118 eyes （118 patients） with type 2 DM （DM group） and 100 eyes of 100 control subjects （control group） were enrolled. After completing an ocular surface disease index （OSDI） questionnaire, the non-invasive tear film break-up time （NI-BUT） and the structure of the meibomian glands （MGs, meibography） were assessed by the Keratograph 5M system. Partial or complete loss of MG was scored for each eyelid from grade 0 （no loss） to grade 3 （lost area was 〉2/3 of the total MG area）, which were also examined by laser scanning confocal microscopy （LSCM）. The primary outcomes were meibomian gland acinar unit density （MGAUD）, meibomian gland acinar longest diameter （MGALD） and meibomian gland acinar shortest diameter （MGASD）.RESULTS： Compared with control group, the OSDI was significantly higher in DM group （Z=-5.916; P〈0.001）, while the NI-BUT was significantly lower （Z=-7.765; P〈0.001）. Keratograph showed that there were more MGs dropout in DM group than that in control group. The meiboscore was significantly higher in DM group compared with control group （Z=-3.937; P〈0.001）. LSCM revealed that there were cytological alterations of MGs in DM group compared with control group, which included enlargement of MG acinar units and decreased in density of MG acinar units. Specifically, there were lower MGAUD, larger MGALD and MGASD in DM group than control group （Z=-10.120, -9.4442, -7.771; P〈0.001）.CONCLUSION： Compared with the normal control participants, the patients with type 2 DM had more unstable tear films and severe symptoms of dry eye. Using Keratograph 5M system and LSCM, we found that the patients with type 2 DM had more significant morphological and cytological changes and dysfunction in MGs.

Measurement of retinal thickness in macular region of high myopic eyes using spectral domain OCT

AIM: To investigate the changes of retinal thickness in macula of high myopic eyes using spectral domain optical coherence tomography(OCT). ·METHODS: Middle-aged and young myopic patients were divided into three groups according to their refractive error/axial length: low and medium myopia group(LMMG),high myopia group(HMG) and super high myopia group(SHMG). Cirrus HD-OCT was used to evaluate total average macular thickness,central subfield thickness,inner/outer macular thickness and macular volume. The differences among experimental groups were analyzed by one-factor analysis of variance. Associations between macular thickness and refractive error/axial length were analyzed by Pearson correlation analysis. ·RESULTS: There was no significant difference in age among the three groups(P =0.2789). The mean refraction error in the LMMG,HMG,and SHMG groups was-2.49 ± 1.38D,-8.53 ±1.95D and-13.88 ±1.76D,respectively(P 【 0.001). The central subfield thickness of three groups was 244.56 ±12.19μm,254.33 ±11.61μm and 261.75 ± 11.83μm,respectively,and there were statistically significance between random two groups. The total average macular thickness,inner/outer macular thickness,and macular volume decreased with increased myopia/axial length. Average foveal thickness had negative correlations with refractive error(P 【0.001),and positive correlations with axial length. The inferior and temporal inner macular thickness,all the quadrants of outer ring,total average macular thickness and macular volume featured positive correlations with refractive error,and negative correlations with axial length. Average foveal thickness,superior and temporal innermacular thicknesses,and temporal outer macular thickness was lower in females compared to males. ·CONCLUSION: With an increase in myopia degree/axial length,the average foveal thickness increased and the inner/outer macular thickness decreased. Females featured thicker average foveal thickness,and thinner macular thickness compared to males.

Multifocal electroretinogram in non-pathological myopic subjects:correlation with optical coherence tomography

AIM： To investigate the changes of retinal function in non-pathological myopic subjects using multifocal electroretinography （mfERG） and to correlate the data with the central macular thickness obtained using optical coherence tomography （OCT）. ~ METHODS： One hundred and thirteen subjects （113 eyes） with age range from 18 to 35y were enrolled in the study. The subjects were divided into four groups according to spherical equivalent （SE） and axial length （AL）： emmetropia group （EG, n=31; SE： ＋0.75 to -0.50 D; AL： 22 to 24 mm）, low and medium myopia group （LMMG, n=26; SE： 〉-0.50 to -6.00 D; AL： 〉24 to 26 ram）, high myopia group （HMG, n--34; SE： 〉-6.00 to -10.00 D; AL： 〉26 to 28 mm） and super high myopia group （SHMG, n =22; SE： 〉-10.00 D; AL： 〉28 mm）. The P1 amplitude density, P1 amplitude, and P1 implicit time of the first- order kernel mfERG responses were obtained and grouped into five rings. The central subfield macular thickness （CST） was obtained using macular cube 512x218 scan of Cirrus HD-OCT. RESULTS： With the increasing of eccentricity, the first positive peak （P1） amplitude density （P=0.0000, 0.0001, 0.0021 in ring 1-3 respectively） and P1 amplitude （all P= 0.0000 in ring 1-5） of each group decreased. With the increasing of myopia, P1 implicit time gradually extended （all P=0.0000 in ring 1-3）. The average CST in four diagnostic groups was 241.56±12.72um, 244.56±12.19um, 254.33±11.61um, 261.75±11.83um respectively. With the increasing of myopia, CST increased （P〈0.001）. There was negative relationship between CST and P1 amplitude, P1 amplitude density （r =-0.402, P〈0.001; r= -0.261, P =0.003）. There was positive relationship between CST and P1 implicit time （r=0.34, P〈0.001）.~ CONCLUSION： With the increasing of myopia, P1 amplitude density and P1 amplitude of the first-order reaction gradually reduced. This showed potential decline in retinal function in myopia. To some extent it may reflect the functional disorder or depression of the visual cells, The exact mechanism needs further study,

氧化锌纳米颗粒在体内和体外对角膜的毒性评估

目的:通过构建体内和体外染毒模型,观察氧化锌纳米颗粒(ZnO NPs)对角膜的毒性影响。方法:体外培养原代人角膜上皮细胞(HCEpiC),暴露于0.5、5、12.5、25、50、100、250μg/mL氧化锌纳米颗粒24h,设不含纳米溶液的细胞培养液为空白对照组。采用MTT比色法评估细胞的活性。三种不同浓度(25、50和100μg/mL)的氧化锌纳米颗粒分散液暴露于麻醉后小鼠结膜囊内,磷酸盐平衡缓冲液(PBS)点眼为PBS对照组,每天3次,连续7d,第1、3、5、7d观察角膜形态,第8d取出眼球,观察角膜病理改变和炎症因子(TNF-α,IL-6)表达水平情况。结果:不同浓度的氧化锌纳米颗粒处理原代人角膜上皮细胞24h后,MTT结果显示,与空白对照组相比,氧化锌纳米颗粒在0.5μg/mL即对细胞有损伤作用,细胞存活率约80%(P<0.05),5μg/mL剂量时可致半数细胞死亡,在5~250μg/mL浓度范围对细胞的损伤作用具有浓度依赖性(P<0.0001)。不同浓度的氧化锌纳米颗粒暴露小鼠结膜囊,点眼7d后,25μg/mL和50μg/mL氧化锌纳米颗粒组可见部分角膜上荧光素的点状着染,100μg/mL氧化锌纳米颗粒组角膜见局部圆形荧光素着染区。HE染色结果显示,25μg/mL和50μg/mL氧化锌纳米颗粒组的角膜上皮层、基质层厚度、基质层免疫细胞数目无明显改变(均P>0.05),而100μg/mL氧化锌纳米颗粒组角膜上皮层变薄、角膜基质层变厚、基质层免疫细胞明显增多(均P<0.05)。免疫组织化学染色结果显示,100μg/mL氧化锌纳米颗粒组产生TNF-α、IL-6的角膜基质免疫细胞数及TNF-α、IL-6的平均光密度(IOD)值均明显高于PBS对照组(P<0.05),且炎症反应程度具有浓度依赖性,25μg/mL氧化锌纳米颗粒和50μg/mL氧化锌纳米颗粒组免疫细胞数和IOD值与PBS对照组相比均无明显增高(P>0.05)。结论:氧化锌纳米颗粒在体外和体内均对角膜具有毒性损伤作用,为氧化锌纳米颗粒眼部安全性评价提供了一定的理论依据。