Corneal endothelial cells and acoustic cavitation in phacoemulsification

Postoperative complications of phacoemulsification,such as corneal edema caused by human corneal endothelial cell(CEC)injury,are still a matter of concern.Although several factors are known to cause CEC damage,the influence of ultrasound on the formation of free radicals during surgery should be considered.Ultrasound in aqueous humor induces cavitation and promotes the formation of hydroxyl radicals or reactive oxygen species(ROS).ROS-induced apoptosis and autophagy in phacoemulsification have been suggested to significantly promote CEC injury.CEC cannot regenerate after injury,and measures must be taken to prevent the loss of CEC after phacoemulsification or other CEC injuries.Antioxidants can reduce the oxidative stress injury of CEC during phacoemulsification.Evidence from rabbit eye studies shows that ascorbic acid infusion during operation or local application of ascorbic acid during phacoemulsification has a protective effect by scavenging free radicals or reducing oxidative stress.Both in experiments and clinical practice,hydrogen dissolved in the irrigating solution can also prevent CEC damage during phacoemulsification surgery.Astaxanthin(AST)can inhibit oxidative damage,thereby protecting different cells from most pathological conditions,such as myocardial cells,luteinized granulosa cells of the ovary,umbilical vascular endothelial cells,and human retina pigment epithelium cell line(ARPE-19).However,existing research has not focused on the application of AST to prevent oxidative stress during phacoemulsification,and the related mechanisms need to be studied.The Rho related helical coil kinase inhibitor Y-27632 can inhibit CEC apoptosis after phacoemulsification.Rigorous experiments are required to confirm whether its effect is realized through improving the ROS clearance ability of CEC.

Cytotoxic effects of betaxolol on healthy corneal endothelial cells both in vitro and in vivo

AIM: To demonstrate the cytotoxic effect of betaxolol and its underlying mechanism on human corneal endothelial cells(HCE cells) in vitro and cat corneal endothelial cells(CCE cells) in vivo,providing experimental basis for safety anti-glaucoma drug usage in clinic of ophthalmology. ·METHODS: In vivo and in vitro experiments were conducted to explore whether and how betaxolol participates in corneal endothelial cell injury. The in vitro morphology,growth status,plasma membrane permeability,DNA fragmentation,and ultrastructure of HCE cells treated with 0.021875-0.28g/L betaxolol were examined by light microscope,3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide(MTT) assay,acridine orange(AO)/ethidium bromide(EB) double-fluorescent staining,DNA agarose gel electrophoresis,and transmission electron microscope(TEM). The in vivo density,morphology,and ultrastructure of CCE cells,corneal thickness,and eye pressure of cat eyes treated with 0.28g/L betaxolol were investigated by specular microscopy,applanation tonometer,alizarin red staining,scanning electron microscope(SEM),and TEM. · RESULTS: Exposure to betaxolol at doses from 0.0875g/L to 2.8g/L induced morphological and ultrastructural changes of in vitro cultured HCE cells such as cytoplasmic vacuolation,cellular shrinkage,structural disorganization,chromatin condensation,and apoptotic body appearance. Simultaneously,betaxolol elevated plasma membrane permeability and induced DNA fragmentation of these cells in a dose-dependent manner in AO/EB staining. Furthermore,betaxolol at adose of 2.8g/L also induced decrease of density of CCE cells in vivo,and non-hexagonal and shrunk apoptotic cells were also found in betaxolol-treated cat corneal endothelia. ·CONCLUSION: Betaxolol has significant cytotoxicity on HCE cells in vitro by inducing apoptosis of these cells,and induced apoptosis of CCE cells in vivo as well. The findings help provide new insight into the apoptosis-inducing effect of anti-glaucoma drugs in eye clinic.

Nerve Growth Factor Modulate Proliferation of Cultured Rabbit Corneal Endothelial Cells and Epithelial Cells

Summary： In order to investigate the effect of nerve growth factor （NGF） on the proliferation of rabbit corneal endothelial cells and epithelial cells, the in vitro cultured rabbit corneal endothelial cells and epithelial cells were treated with different concentrations of NGF.MTT assay was used to examine the clonal growth and proliferation of the cells by determining the absorbency values at 570 nm. The results showed that NGF with three concentrations ranging from 5 U/mL to 500 U/mL enhanced the proliferation of rabbit corneal endothelial cells in a concentration-dependent manner. 50 U/mI. and 500 U/mI. NGF got more increase of proliferation than that of 5 U/mL NGF did. Meanwhile, 50 U/mL and 500 U/mL NGF could promote the proliferation of the rabbit corneal epithelial cells significantly in a concentration-dependent manner. However, 5 U/mL NGF did not enhance the proliferation of epithelial cells. It was suggested that exogenous NGF can stimulate the proliferation of both rabbit corneal endothelial and epithelial cells, but the extent of modulation is different.

Effect of p27Kip1 Inhibition on Proliferation of Bovine Corneal Endothelial Cells by RNA Interference

Three plasmids （pGenesil-P1, pGenesil-P2, pGenesil-P3） with different p27Kip1-shRNA sequences were designed and synthesized. Their effects on the proliferation of bovine corneal endothelial cells （bCEC） were investigated. Plasmid expressing irrelevant shRNA with a random combination was used as negative control （pGenesil-HK）. The recombination of four plamids was confirmed by restrictive enzyme digestion and sequence analysis. The expression of mRNA and protein of p27Kip1 was detected by RT-PCR and Western blotting after stable transfection. The expressions of p27Kip1 mRNA and p27Kip1 protein of pGenesil-P1 group, pGenesil-P2 group and pGenesil-P3 group were all lower than those in the pGenesil-HK group and the blank group （non-transfected group）, pGenesil-P3 had the strongest inhibitory effect and was selected for the next steps. The proliferation rates of the pGenesil-P3 group, the pGenesil-HK group and the blank group were assessed by MTT. The influence of shRNA-p27Kip1 on bCEC cell cycle was detected by flow cytometry （FCM）. Compared with the control groups, the proliferation rate of the pGenesil-P3 group was increased significantly, and the ratio of S-phase also increased. It is concluded that shRNA-p27Kip1 could down-regulate the expression of p27Kip1 effectively and increase the proliferation of bCEC. RNA interference （RNAi） may be an effective means to promote the proliferation of CEC.

Transforming growth factor-β2 induces morphological alteration of human corneal endothelial cells in vitro

AIM:To investigate the morphological altering effect of transforming growth factor-β2(TGF-β2) on untransfected human corneal endothelial cells(HCECs)in vitro.METHODS:After untransfected HCECs were treated with TGF-β2 at different concentrations, the morphology,cytoskeleton distribution, and type IV collagen expression of the cells were examined with inverted contrast light microscopy, fluorescence microscopy,immunofluorescence or Western Blot.RESULTS:TGF-β2 at the concentration of 3-15 μg/L had obviously alterative effects on HCECs morphology in dose and time-dependent manner, and 9 μg/L was the peak concentration. TGF-β2(9 μg/L) altered HCE cell morphology after treatment for 36 h, increased the mean optical density(P 【0.01) and the length of F-actin,reduced the mean optical density(P 【0.01) of the collagen type IV in extracellular matrix(ECM) and induced the rearrangement of F-actin, microtubule in cytoplasm and collagen type IV in ECM after treatment for 72 h.·CONCLUTION: TGF-β2 has obviously alterative effect on the morphology of HCECs from polygonal phenotype to enlarged spindle-shaped phenotype, in dose and time-dependence manner by inducing more, elongation and alignment of F-actin, rearrangement of microtubule and larger spread area of collagen type IV.

The study of human PDGF-B gene transferred to cat corneal endothelial cells

AIM: To demonstrate that human platelet-derived growth factor-B (PDGF-B) cDNA could be Expressed in primary cultured cat corneal endothelia cells by using gene transfer techniques; to explore a useful tool for the further studies of the molecular mechanisms of corneal endothelium failure and provide a potential effective genetic therapy for the blind patients. ' METHODS: Human PDGF-B cDNA was isolated from human placent by RT-PCR and inserted into pcDNA(4) vector to construct recombinant eukaryotic expression plasmid pcDNA(4)-PDGF-B. The full length was confirmed by the DNA sequencing analysis. By tearing endothelium technique we obtained pure single layer of cat corneal endothelial cells. The pcDNA(4)-PDGF-B eukaryotic Expression vector was transferred into cat corneal endothelial cells by Effectene (TM) lipofectine. The transfection efficiency of Effectene (TM) lipofectine in pcDNA(4)-B was detected with pcDNA(4)-GFP. 5 days later, RT-PCR was used to check the PDGF-B expression. Cell viability was tested by modified tertrozalium salt (MU) method. Cell morphology was observed under inverted phase contrast microscope. RESULTS: The human PDGF-B cDNA was isolated successfully from healthy parturien placent tissue and the sequence was confirmed by computer automatic sequence and PCR analysis. Pure single layer cat corneal endothelial cells were successfully cultured by tearing endothelium technique. Effectene (TM) lipofectine transfection technique could be effectively used to transfer pcDNA(4)-PDGF-B into cat corneal endothelial cells in vitro, the transfection efficiency was 30%. RT-PCR result showed that human PDGF-B gene was highly expressed in transfected cat corneal endothelial cells. The expressed PDGF-BB protein promoted the viability of cat corneal endothelial cells. CONCLUSION: Human platelet-derived growth factor-B (PDGF-B) cDNA could be highly Expressed in cultured cat corneal endothelial cells by gene transfection techniques. Expressed PDGF-BB protein significantly promoted the viability of cat corneal endothelial cells, thus provided a potential effective method for corneal endothelium blindness genetic therapy.

Effect of mechanical stretching and substrate stiffness on the morphology,cytoskeleton and nuclear shape of corneal endothelial cells

Due to the limited capacity of corneal endothelial cells(CECs)division,corneal endothelial diseases have become a great challenge.The cornea is subjected to various mechanical stimuli in vivo,which may have a positive or negative influence.Thus,it is significant to gain an insight into the mechanism of mechanobiology of CECs for seeking more possible treatment.The purpose of this study was to determine the impacts of mechanical stretch and substrate stiffness on the morphology and fundamental cell behavior of CECs.Rabbit corneal endothelial cells(RCECs)were subjected to a 5%mechanical stretch or cultured on substrates of different stiffness.The impacts of mechanical stimulus on cell area,aspect ratio,circularity,cell density,nuclear shape,cytoskeleton,and cell viability were investigated.The expressions of the corneal endothelium-related markers ZO-1 and Na^(+)/K^(+) ATPase were also evaluated by confocal immunofluorescence microscopy in the stiffness group.Our results suggested that mechanical stretch promoted the rearrangement of the cytoskeleton while decreasing the cell circularity,nuclear area,and cell density as well as cell viability.RCECs cultured on 10 kPa substrates,which was close to the physiological stiffness of rabbit Descemet's membrane(DM),showed better cell morphology,more stable actin cytoskeleton assembly,and more robust expression of the functional marker compared with other softer or stiffer substrates.In summary,mechanical stretch and substrate stiffness have profound influences on the morphology and function of CECs,which may have implications for the understanding and possible treatment of corneal endothelial diseases.

Manifestations of type 2 diabetes in corneal endothelial cell density,corneal thickness and intraocular pressure

We sought to evaluate central corneal thickness（CCT）,corneal endothelial cell density（ECD）and intraocular pressure（IOP）in patients with type 2 diabetes mellitus（DM）and to associate potential differences with diabetes duration and treatment modality in a prospective,randomized study.We measured ECD,CCT and IOP of125 patients with type 2 DM（mean age 57.1±11.5 years）and compared them with 90 age-matched controls.Measured parameters were analyzed for association with diabetes duration and glucose control modalities（insulin injection or oral medication）while controlling for age.In the diabetic group,the mean ECD（2511±252 cells/mm^2）,mean CCT（539.7±33.6μm）and mean IOP（18.3±2.5 mmHg）varied significantly from those the control group[ECD：2713±132 cells/mm^2（P〈0.0001）,CCT：525.0±45.3μm（P=0.003）and IOP：16.7±1.8 mmHg（P〈0.0001）].ECD was significantly reduced by about 32 cell/mm^2 for diabetics with duration of〉10 years when compared with those with duration of〈10 years（P〈0.05）.CCT was thicker and IOP was higher for diabetics with duration of〉10 years than those with duration of〈10 years（P〉0.05）.None of the measured parameters was significantly associated with diabetes duration and treatment modality（P〉0.05）.In conclusion,subjects with type 2DM exhibit significant changes in ECD,IOP and CCT,which,however,are not correlated with disease duration or if the patients receive on insulin injection or oral medications.

Therapeutic potential of Rho-associated kinase inhibitor Y27632 in corneal endothelial dysfunction:an in vitro and in vivo study

AIM:To investigate the effects of a selective inhibitor of Rho-associated kinase(ROCK),Y-27632,on inbred Wuzhishan porcine corneal endothelial cells(PCECs)in vitro and in vivo studies.METHODS:Primary PCECs were trypsinized from Wuzhishan miniature porcine corneal tissues.The optimal concentration of Y-27632 on PCECs was determined through MTT and 5-ethynyl-2'-deoxyuridine(EdU)-labeling assays.Seven New Zealand rabbits were used as a corneal endothelial dysfunction model,and a PCECs suspension supplemented with Y-27632 was injected into the anterior chamber of the rabbits.The progression of rabbit corneal opacity and edema were observed by slit lamp examination.The rabbits were sacrificed,and rabbit globes were enucleated for trypan blue-alizarin red staining,hematoxylineosin staining,and immunofluorescence analysis.RESULTS:Administration of 100μmol/L Y-27632 facilitated PCECs'proliferation obviously.The rabbit corneas injected with PCECs suspension and 100μmol/L Y-27632 were restored to transparency significantly after 14d.CONCLUSION:The 100μmol/L Y-27632 treatment improves PCECs'proliferation significantly.And our results suggest that Y-27632 and PCECs can be used to treat corneal endothelial dysfunction.

AB027.Varying pattern of proteases secretion in Fuchs corneal endothelial dystrophy

Background:The goal of this project was to analyze the relationship between cell morphology and proteases/proteases inhibitors(PIs)secretion profile in fuchs endothelial corneal dystrophy(FECD)corneal endothelial cells(CECs).Methods:Cell morphology was determined using a circularity index(4π×area/perimeter2)for each CECs population extracted from surgical FECD specimens(N=2)and healthy Eye bank corneas(N=3).CECs were cultured 28 days post-confluency.Supernatant was collected and analysed using Proteome Profiler Array detecting 35 proteases and 32 PIs(R&D Systems).Proteome signal was analyzed using Image Studio Lite and correlated with the population’s circularity index.Results:Calculation of circularity index reported different morphologies among FECD populations(0.59±0.18 and 0.64±0.17)and healthy populations(0.44±0.18,0.66±0.13 and 0.71±0.11).Proteome arrays revealed the presence of 10 proteases(ADAMTS1,Cathepsin A,B,D,and X/Z/P,DPPIV/CD26,MMP-2,3 and 12,uPA/Urokinase)and 10 PIs(Protease Nexin II,Cystatin B and C,EMMPRIN/CD147,Latexin,Lipocalin-1,Serpin E1,TFPI,TFPI-2,TIMP-1,2 and 4).Healthy and FECD specimens showed similar variation patterns according to morphology for secretion of ADAMTS1,MMP-3 and 12.However,opposing patterns between healthy and FECD populations were observed for Cathepsin B and D.Moreover,some proteins did not show variation according to phenotype in healthy CECs,but did in FECD CECs:Cathepsin A,Cystatin C,TFPI-2 and total TIMPs.For the other proteins,secretion did not vary according to morphology or no specific pattern was distinguishable.Conclusions:To conclude,our results suggest that cell phenotype is linked to the secretion of certain proteases/PIs in both groups.However,there seems to be differences in secretion of particular proteases and PIs between FECD and healthy specimens as morphology did not have a similar influence.These differences might initiate an imbalance between proteases and PIs explaining the irregular thickening of the Descemet membrane seen in FECD.

Comparing corneal outcome between femtosecond laser-assisted cataract surgery and conventional phaco surgery in Fuchs’endothelial dystrophy patients:a randomized pilot study with 6mo follow up

AIM:To compare the corneal outcome in Fuchs’endothelial dystrophy(FED)patients between femtosecond laser-assisted cataract surgery(FLACS)and conventional phaco surgery(CPS).METHODS:This was a randomized controlled study comparing one eye surgery by FLACS and the contralateral eye operated by CPS(stop and chop technique)in FED patients.Central corneal thickness,corneal light backscatter,corneal densitometry,and central corneal endothelial cell count and hexagonality(noncontact endothelial cell microscope),and corrected distance visual acuity(CDVA)were assessed preoperatively and at day 1,40,and 180 postoperatively.RESULTS:Totally 31 patients(16 women)were included.At day 40 postoperatively,the mean endothelial cell loss(ECL)was 23.67%by FLACS and 17.30%by CPS(P=0.53).At day 180 postoperatively,ECL was 25.58%in FLACS and 21.32%in CPS(P=0.69).Densitometry data in all layers and all annuli from anterior layer to posterior layer in annuli 0-2,2-6,6-10 and 10-12,total densitometry with all layers and all annuli was performed.A significant difference was found in 6-10(posterior layer)at day 1 with-1.42 grayscale units(GSU;95%CI:-2.66 to-0.19,P=0.02).In 10-12(anterior layer,central layer and all layers)at day 40 were significant different with 7.7(95%CI:1.89 to 13.50,P=0.009),3.97(95%CI:0.23 to 7.71,P=0.03),4.73 GSU(95%CI:0.71 to 8.75,P=0.02),respectively.In the remaining parameters we found no difference between the two groups(P>0.05).Three CPS eyes suffered from corneal decompensation.CONCLUSION:There is no significant difference in corneal outcome between FLACS and CPS.Endothelial cell density and pentacam corneal outcome may be inadequate as outcome parameters in FED patients.

Corneal endothelial cell density and morphology in Chinese patients with pseudoexfoliation syndrome

AIM: To evaluate the corneal endothelial cell density and morphology in Chinese patients with pseudoexfoliation syndrome (PEX). METHODS: Medical records of 16 patients (20 eyes) with PEX who presented to our institution between July 2008 and June 2010 were retrospectively reviewed. Thirteen eyes had combined glaucoma. The information of five apparently normal fellow eyes in these patients was also recorded. Left eyes of 20 patients with bilateral senile cataracts but no other eye disease were included as controls. Specular microscopy was performed in all eyes to analyze for corneal endothelial cell density and morphology. Cell density, coefficient of variation in cell size, and percentage of hexagonal cells in corneal endothelium were evaluated. RESULTS: The mean corneal endothelial cell density in the PEX eyes was 2298+/- 239 cells/mm(2), significantly lower than that in the cataract eyes (2652+/- 18 cells/mm(2), P=0.026), but there were no significant differences in coefficient of variation of cell size and frequency of hexagonality between these two groups. No significant differences in the three parameters were found between the apparently normal fellow eyes and the PEX eyes or the cataract eyes, or between the PEX eyes with and without glaucoma. CONCLUSION: Corneal endothelial cell density may decrease in Chinese patients with PEX. The development of glaucoma in PEX eyes does not seem to be related with the change in corneal endothelial cell density or morphology.

Effect of recombinant human platelet-derived growth factor B on cat corneal endothelial cell viability mediated by adeno-associated virus

AIM: To transduce recombinant human platelet-derived growth factor B (PDGF-B) gene adeno-associated virus(AAV) to in vitro cultured cat corneal endothelial cell (CEC) and observe the effect of the expressed PDGF-BB protein on the viability of cat CEC. METHODS: Cat cornea endothelium was torn under microscope and rapidly cultivated in DMEM to form single layer CEC and the passage 2 endothelial cells were used in this study. The recombinant human PDGF-B gene AAV was constructed and transduced into cat CEC directly. Three groups were as following: blank control group, AAV control group and recombinant AAV group. At 24 hours, 48 hours, and 5 days after transduction, total RNA was extracted from the CEC by Trizol and the expression of PDGF-B gene was detected by fluorescence quantitative polymerase chain reaction. Viability of the transduced CEC was detected at 48 hours after transduction by MTT assay. Cell morphology was observed under inverted phase contrast microscope. RESULTS: With the torn endothelium culture technique, we rapidly got single layer cat CEC. At 24 hours, 48 hours and 5 days after transduction, fluorescence quantitative polymerase chain reaction showed there was no significant difference of the expressed PDGF-B gene mRNA between blank control group and AAV control group (P>0.05). In contrast, there were significant differences between two control groups and recombinant AAV group (P<0.05). MTT assay showed that in recombinant AAV group, the expressed PDGF-BB protein could promote the viability of cat CEC. Morphology observation showed at 48 hours after transduction, cells in CEC-AAV-PDGF-B group proliferated into bigger scales in regular triangle to hexagon shape with distinct boundary, while the number of cells was significantly less in the two control groups. CONCLUSION: The recombinant AAV-PDGF-B expresses biological active PDGF-BB protein in cat CEC, which promotes the viability and proliferation of cells.

The Corneal Endothelium in Children after Congenital Cataract Surgery--A Comparison of Pre- and Post-Operative Results

Three months after surgery, the research group showed significantly statistical improvement in visual acuity, a statistically significant decrease in corneal endothelial cell density, a statistically significant increase in the percentage of 5 and 8 sided cells and a statistically significant decrease in the percentage of six sided cells. Central corneal thickness and the percentage of 4 and 7 and more than 8 sided did not change in a statistically significant way. Comparing the test group and control group, no statistically significant differences were detected in the examined parameters. The present study also shows that the cornea in the eyes with congenital cataract does not show statistically significant changes in the density and the morphology of the corneal endothelial cells and the thickness of the cornea and in terms of corneal thickness in comparison to the corneas of healthy eyes. Although in corneas undergoing cataract occurs statistically significant changes, the influence of the cornea does not affect the improvement in visual acuity which was also demonstrated in this study.

Visual acuity and endothelial cell density with respect to the graft thickness in Descemet's stripping automated endothelial keratoplasty: one year results

AIM: To evaluate the visual acuity and endothelial cell density according to the thickness in Descemet’s stripping automated endothelial keratoplasty(DSAEK)one year after surgery.METHODS: DSAEK patients’ data were reviewed. Thirty seven eyes of 37 patients who underwent DSAEK for pseudophakic bullous keratopathy(PBK) were included in this study. Graft thickness was measured with optical coherence tomography(OCT) 12 mo after DSAEK. Eyes were divided into 3 groups based on the graft thickness:thick(】200 μm), medium-thick(150-200 μm) and thin(【150 μm). Best corrected visual acuity(BCVA),endothelial cells density(ECD) and complications were assessed and comparisons were done between groups.RESULTS: Median thickness of postoperative grafts was 188(range 73-317 μm). There was no significant difference in age, sex, preoperative BCVA, or follow-up period between DSAEK groups. At postoperative 12 mo,mean BCVA was 0.28±0.10 in thick graft group, 0.52±0.08 in medium-thick graft group, and 0.72 ±0.06 in thin graft group. Thin grafts showed better postoperative BCVA as compared with the medium-thick and thick grafts(P =0.001). Thick graft group had 1637.44 ±88.19-mm2,medium thick graft had 1764.50±34.28-mm2 and thin graft group had 1845.30 ±65.62-mm2. Thin graft group had better ECD at 12 mo after surgery(P =0.001).CONCLUSION: Thin grafts after DSAEK ensure better visual rehabilitation. Eyes with thin grafts had significantly lesser loss of ECD compared to eyes withmedium-thick and thick grafts one year after surgery.

A comparison of surgical efficacy between a 1.8-mm microincision and 3.2-mm and 5.5-mm incisions for phacoemulsification

Phacoemulsification is a commonly used surgical method in cataract surgery. This paper observes and compares the surgical efficacy of three incisions of different length for phacoemulsification to identify the optimal method for cataract surgery. Ninety patients were enrolled in the present study and divided into three groups. The 1.8-mm group received Bausch ＆ Lomb MI60 foldable intraocular lens （IOL） implantation （n=30）, 3.2-mm group received Bausch ＆ Lomb Akreos AO foldable lens implantation （n=30）, and 5.5-mm group received Alcon TYPE 05 rigid IOL implantation （n=30）. Visual acuity, Oculyzer-based anterior segment analysis, and corneal endothelial cell count before surgery, and 3, 7, 30, and 90d after surgery were recorded and compared. Pseudophakic accommodation three days, one week, one month, and three months after surgery was determined. Intraoperative ultrasound time and ultrasonic energy were recorded. It was finally concluded that for phacoemulsification with the same phaco tip, a 1.8-mm microincision can lead to quicker recovery of visual acuity, more stable astigmatism, and higher pseudophakic accommodation than conventional incision.

One-step viscoelastic agent technique for ICL V4c implantation for myopia

AIM:To investigate the safety and efficacy of using a onestep viscoelastic agent technique for posterior chamber phakic implantable collamer lens with a central hole(ICL V4 c)implantation for myopia correction.METHODS:The one-step viscoelastic agent technique for ICL V4 c implantation was used in 100 eyes of 52 patients.Refractive outcomes,intraocular pressure(IOP),corneal endothelial cell,and corneal densitometry values were evaluated at 1 d,1 wk,1 and 3 mo postoperatively.RESULTS:All the surgeries were uneventful.No corrected distance visual acuity was lost after 3 mo.IOP was 16.12±3.18 mm Hg before surgery,and 14.74±3.08 mm Hg at 1d and 14.50±2.56 mm Hg at 3 mo after surgery(P<0.05).Corneal endothelial cell density was 2580±242 cell/mm^(2),the coefficient of variation in cell size was 42.11%±7.92%,and the percentage of hexagonal cells was 40.98%±9.46%before surgery.No significant difference was found when these outcomes were compared between the studied time points(P>0.05).The corneal densitometry values of the central 2 mm and 2 to 6 mm areas showed similar regularities.After surgery,the values significantly increased at 1 d,then decreased to the preoperative values at 1 wk,and then continued to decrease at 3 mo(P<0.05).CONCLUSION:The one-step viscoelastic agent technique for ICL V4c implantation is found to be safe and effective for myopia correction and causes little disturbance to the cornea.

Effects of Cataract Surgery on Endothelium in Transplanted Corneal Grafts： Comparison of Extracapsular Cataract Extraction and Phacoemulsification for Complicated Cataract after Penetrating Keratoplasty

Background： The endothelium should be carefully evaluated when choosing a surgical technique for cataract removal. Therefore, we aimed to study the effects of different cataract surgery techniques on endothelial cell loss in transplanted corneal grafts. Methods： A total of 54 patients who received complicated cataract surgery in post-penetrating keratoplasty （PKP） eyes at the Shandong Eye Institute between February 2001 and June 2014 were included, and clinical records were reviewed. Baseline demographic details, clinical characteristics, endothelial cell density （ECD）, and best-corrected visual acuity （BCVA） were recorded. Wilcoxon rank-sum test and Wilcoxon signed-rank test were used to test the equality of medians. A regression model was constructed to compare the reduced rate of ECD. Results： Of the 54 eyes included in this study, extracapsular cataract extraction （ECCE） was performed in 34 eyes of 33 patients （ECCE group） whereas phacoemulsification was performed in 20 eyes of 20 patients （phacoemulsification group）. There was no signifcant difference in the median age （P = 0.081） or preoperative ECD （P = 0.585） between the two groups. At 6 months after cataract surgery, ECD in ECCE group was significantly higher than that in phacoemulsification group （P = 0.043）. In addition, the endothelial cell loss rate in ECCE group was significantly lower than that in phacoemulsification group at 2 months （P = 0.018）, 4 months （P 〈 0.001）, and 6 months （P 〈 0.001） after cataract surgery. Endothelial cell loss rate after cataract surgery increased over the 6-month study duration in both ECCE group （P 〈 0.001） and phacoemulsification group （P 〈 0.001）, but phacoemulsification resulted in a greater reduction in ECD than that of ECCE in transplanted corneal grafts （P 〈 0.001）. There was no signifcant difference in postoperative BCVA between the two groups （P = 0.065）. Conclusion： ECCE is more suitable than phacoemulsification in cataract surgery in complicated cataract after PKP.