Diabetic corneal neuropathy and diabetic retinopathy are ocular complications occurring in the context of diabetes mellitus.Diabetic corneal neuropathy refers to the progressive damage of corneal nerves.Diabetic retin...Diabetic corneal neuropathy and diabetic retinopathy are ocular complications occurring in the context of diabetes mellitus.Diabetic corneal neuropathy refers to the progressive damage of corneal nerves.Diabetic retinopathy has traditionally been considered as damage to the retinal microvasculature.However,growing evidence suggests that diabetic retinopathy is a complex neurovascular disorder resulting from dysfunction of the neurovascular unit,which includes both the retinal vascular structures and neural tissues.Diabetic retinopathy is one of the leading causes of blindness and is frequently screened for as part of diabetic ocular screening.However,diabetic corneal neuropathy is commonly overlooked and underdiagnosed,leading to severe ocular surface impairment.Several studies have found that these two conditions tend to occur together,and they share similarities in their pathogenesis pathways,being triggered by a status of chronic hyperglycemia.This review aims to discuss the interconnection between diabetic corneal neuropathy and diabetic retinopathy,whether diabetic corneal neuropathy precedes diabetic retinopathy,as well as the relation between the stage of diabetic retinopathy and the severity of corneal neuropathy.We also endeavor to explore the relevance of a corneal screening in diabetic eyes and the possibility of using corneal nerve measurements to monitor the progression of diabetic retinopathy.展开更多
The cornea is a transparent tissue that serves as the main refractive element of the eye ball.Limbal epithelial stem cells(LESCs),residing in the basal epithelial layer of the Palisades of Vogt located in the corneal ...The cornea is a transparent tissue that serves as the main refractive element of the eye ball.Limbal epithelial stem cells(LESCs),residing in the basal epithelial layer of the Palisades of Vogt located in the corneal limbus between cornea and scleral,are believed to be crucial for the continuous turnover of the corneal epithelium.The proliferation,migration,and differentiation of the LESCs are modulated by unique physical and chemical futures contained within the microenvironment known as the limbal niche.This niche,composed of nerve terminals,cells,extracellular matrix,vasculature,and signaling molecules,is the home for processes such as proliferation,migration and differentiation.Corneal nerve terminals possess special anatomical structures in the limbal region and basal epithelial cells,and they demonstrate pivotal biological effects in the regulation of the LESC function and corneal epithelium homeostasis.Biological molecules such as neuropeptides,neurotransmitters,and neurotrophic factors play a crucial role in modulating the LESCs phenotype responsible for corneal epithelium homeostasis.This paper will review recent studies on how these nerve derived molecules function in this process and provide clear orientations for future research.展开更多
Background:Fluorescein is commonly used in ophthalmology for the assessment of ocular surface integrity.There have been limited studies on the effects of fluorescein on corneal endothelial cells.This study aims to ass...Background:Fluorescein is commonly used in ophthalmology for the assessment of ocular surface integrity.There have been limited studies on the effects of fluorescein on corneal endothelial cells.This study aims to assess the effect of the widely used fluorescein dye on human corneal endothelial cells(HCEnCs)in vitro at different concentrations and exposure times.Methods:B4G12,an immortalized human corneal endothelium cell line was cultured on pre-coated tissue culture flask with human endothelial-serum free medium(SFM)supplemented with 10 ng/mL basic fibroblast growth factor(bFGF).The fully confluent B4G12 cell monolayers in 96 well plates were treated with water as control,or fluorescein at various concentrations and exposure times.Cell viability was assessed using two techniques:Alamar Blue assay and cell morphology assessment with an inverted phase-contrast microscopy.Results:Short-term exposure to fluorescein(0.01-0.2%)for up to 30 minutes did not affect cell viability.Continuous fluorescein exposure however significantly reduced the viability of the cells with a notable reduction in cell metabolic activity with fluorescein treatments of 0.001%,0.01% and 0.05% for 1 day(and up to 4 days).Conclusions:Short-term exposure to fluorescein for up to 30 minutes in concentrations commonly used in clinical practice did not affect HCEnC viability.However,fluorescein exposure for longer durations can be detrimental to corneal endothelial cell health.Future studies should evaluate the effects of longer-term fluorescein exposure on endothelial function especially in susceptible patients including the elderly and patients with epithelial defects that enable diffusion of fluorescein towards the endothelium.展开更多
AIM:To assess early visual outcomes and corneal stability following small incision lenticule extraction(SMILE)in eyes with a pre-planned residual stromal thickness(RST)ranging from 280 to 300μm.METHODS:This retrospec...AIM:To assess early visual outcomes and corneal stability following small incision lenticule extraction(SMILE)in eyes with a pre-planned residual stromal thickness(RST)ranging from 280 to 300μm.METHODS:This retrospective study was designed to evaluate 82 eyes from 82 patients,all of whom had a pre-planned RST of 280 to 300μm and normal corneal topography prior to undergoing SMILE surgery.The mean preoperative spherical equivalent(SE)was-4.82±1.30 D.A standard follow-up protocol was conducted between 1 to 6mo postoperatively.Visual outcomes were recorded using uncorrected visual acuity(UCVA)and subjective refraction.The curvature of the anterior and posterior corneal surfaces,as well as the posterior elevation at the thinnest point(PTE)were derived from the Pentacam system.RESULTS:At the final follow-up,the efficacy index was 1.14±0.15,the safety index was 1.20±0.13.The mean preoperative UDVA was 0.78±0.16 logMAR,which improved significantly to-0.07±0.06 logMAR postoperatively(P<0.001).The preoperative mean SE was-4.82±1.30 D,which decreased to-0.14±0.30 D by the last visit.The curvature of the anterior cornea at the flat meridian(AK1)were 42.62±1.02 D preoperatively,38.56±1.37 D and 38.59±1.39 D at 1 and 6mo after operation,respectively.Corresponding measurements at the steep meridian(AK2)were 43.55±1.14 D preoperatively,39.18±1.46 D and 39.22±1.50 D at 1 and 6mo after operation,respectively.Both AK1 and AK2 remained stable at 1 and 6-mo postoperative intervals(P=0.126 and 0.082,respectively).There were no observed changes in the curvature of the posterior cornea at the flat meridian or at the steep meridian,or the PTE before and after surgery.CONCLUSION:SMILE represents a safe and effective procedure for the correction of myopia and astigmatism in eyes featuring a pre-planned RST ranging from 280 to 300μm accompanied by normal corneal topography,on the premise of strict control of surgical indications.展开更多
AIM:To assess tomographic changes and subclinical edema detection in Fuchs’endothelial corneal dystrophy(FECD)through Scheimpflug tomography in a group of phakic patients contemplating cataract surgery.METHODS:A retr...AIM:To assess tomographic changes and subclinical edema detection in Fuchs’endothelial corneal dystrophy(FECD)through Scheimpflug tomography in a group of phakic patients contemplating cataract surgery.METHODS:A retrospective study was conducted on 30 phakic eyes from patients diagnosed with FECD but without clinical edema,and 59 phakic eyes from a control group without corneal alterations.Comprehensive ophthalmic examinations were conducted,including slitlamp biomicroscopy,corneal specular microscopy(CSM),and Scheimpflug tomography.RESULTS:The study encompassed 30 phakic eyes with FECD(mean age 59.8±13.1y)and 59 control eyes(mean age 61.3±7.7y).The best-corrected visual acuity was higher in the control group compared to the FECD group[0(0,0.08)vs 0.05(0,0.15)logMAR;P=0.042].CSM revealed significant differences between the FECD and control groups in several parameters:number of analyzed cells(26±13 vs 135±42,P<0.001),cell density(2049±376 vs 2479±225 cells/mm2,P<0.001),mean cell area[463(434,544)vs 397(383,431)μm2;P<0.001],coefficient of variation(54.8%±18.7%vs 41.0%±7.2%,P<0.001),and hexagonal cells[0(0,47%)vs 47%(40%,53%),P<0.001].Although often used as a clinical parameter for detecting edema,central corneal thickness measured by CSM showed no significant difference between the FECD and control groups(530±57 vs 546±30μm,P=0.179).Significant differences were noted in various Pentacam measurements between the groups.Specifically,parameters like loss of parallel isopachs(13 vs 0 eyes,P<0.001),displacement of the thinnest point(11 vs 0 eyes,P<0.001),posterior focal depression(25 vs 7 eyes,P<0.001),and increased light scatter[21.4(17.6;23.9)vs 18.0(16.8,21.8),P=0.01]were significantly more prevalent in FECD eyes,reflecting the presence of subclinical edema and loss of corneal transparency.CONCLUSION:Scheimpflug tomography allows for an objective assessment of FECD,offering the capability to detect subclinical edema at an early stage,monitor disease progression,and serve as a predictor of corneal decompensation following cataract surgery.展开更多
AIM:To investigate the changes in posterior corneal elevation within 6mo after small incision lenticule extraction(SMILE)surgery for myopia and myopic astigmatism in patients with thin corneas.METHODS:A prospective st...AIM:To investigate the changes in posterior corneal elevation within 6mo after small incision lenticule extraction(SMILE)surgery for myopia and myopic astigmatism in patients with thin corneas.METHODS:A prospective study included patients with thin corneas(preoperative thinnest corneal thickness ranging from 480 to 520μm)who underwent SMILE for myopia or myopic astigmatism.Corneal topography and posterior corneal elevation were assessed using Pentacam HR at three time points:preoperatively,1mo,and 6mo postoperatively.The measured parameters included thinnest point elevation(PTE),posterior maximal elevation(PME),posterior central elevation(PCE),and 24 additional reference points.RESULTS:A total of 106 eyes from 106 patients(age range:18-34)were included in the study.Uncorrected distance visual acuity(UDVA)improved significantly,with a mean logMAR value of-0.07±0.06 at the final follow-up visit.Measurements of posterior corneal elevation showed no significant changes in most points,hemispheres,and meridians at 6mo postoperatively.Notably,only two points,ΔE_(2mm-45°)andΔE_(2mm-90°),exhibited statistically significant elevation changes:the elevation ofΔE_(2mm-45°)increased from-2.3±4.99 to-1.0±5.9μm(P=0.0037),and that ofΔE_(2mm-90°)increased from-16±7.53 to-15±7.4μm(P=0.016).However,these changes were within the measurement error range of the Pentacam HR(±5μm in a 5 mm area).CONCLUSION:SMILE surgery is a safe and stable procedure for correcting myopia or myopic astigmatism in patients with thin corneas,as evidenced by the stability of posterior corneal elevation.展开更多
Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to b...Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to be considered a gold standard.This study aims to introduce novel metrics to differentiate between KCN and healthy corneas using three-dimensional(3D)measurements of surface area and volume.Methods:This retrospective observational study examined KCN patients along with healthy control patients between the ages of 20 and 79 years old at the University of Maryland,Baltimore.The selected patients underwent a nine-line raster scan anterior segment optical coherence tomography(AS-OCT).ImageJ was used to determine the central 6 mm of each image and each corneal image was then divided into six 1 mm segments.Free-D software was then used to render the nine different images into a 3D model to calculate corneal surface area and volume.A two-tailed Mann-Whitney test was used to assess statistical significance when comparing these subsets.Results:Thirty-three eyes with KCN,along with 33 healthy control,were enrolled.There were statistically significant differences between the healthy and KCN groups in the metric of anterior corneal surface area(13.927 vs.13.991 mm^(2),P=0.046),posterior corneal surface area(14.045 vs.14.173 mm^(2),P<0.001),and volume(8.430 vs.7.773 mm3,P<0.001)within the central 6 mm.Conclusions:3D corneal models derived from AS-OCT can be used to measure anterior corneal surface area,posterior corneal surface area,and corneal volume.All three parameters are statistically different between corneas with KCN and healthy corneas.Further study and application of these parameters may yield new methodologies for the detection of KCN.展开更多
AIM:To evaluate the agreement of axial length(AL),anterior chamber parameters,and total cornea power obtained by swept-source optical coherence tomography(SS-OCT)-based and Scheimpflug-based optical biometers in myopi...AIM:To evaluate the agreement of axial length(AL),anterior chamber parameters,and total cornea power obtained by swept-source optical coherence tomography(SS-OCT)-based and Scheimpflug-based optical biometers in myopic children.METHODS:AL,steep keratometry(K),flat K,posterior corneal keratometry(PK),total keratometry(TK),anterior chamber depth(ACD),horizontal corneal diameter(CD),and central corneal thickness(CCT)were obtained using IOL Master 700 and Pentacam AXL.The agreement between the devices was evaluated using intraclass correlation coefficients(ICC),Bland-Altman plots,and astigmatism vector analysis.RESULTS:Totally 175 myopic children(48.5%male)with a mean age of 10.29±2.14y were enrolled.The ICC and Bland-Altman plots indicated a satisfactory agreement for AL,ACD,and CCT.The mean difference in CD of-0.31±0.30 mm was considered clinically significant(>0.2 mm).Additionally,measurements of K and TK obtained from the IOL Master 700 showed good agreement.Nevertheless,there were clinically significant differences observed in PK,simulated keratometry(simK),total cornea power,and astigmatism(at least 10%of the cases with a difference of>10 degrees in meridian)between the two devices.CONCLUSION:The study findings demonstrate a significant difference in K,PK,astigmatism,and CD,indicating that the two optical biometers cannot be considered interchangeable.Therefore,it is recommended to utilize one kind device for follow-up examinations in myopic children.展开更多
AIM:To develop a new decellularization method depended upon the natural corneal structure and to harvest an ideal scaffold with good biocompatibilities for corneal reconstruction.METHODS:The acellular cornea matrix (A...AIM:To develop a new decellularization method depended upon the natural corneal structure and to harvest an ideal scaffold with good biocompatibilities for corneal reconstruction.METHODS:The acellular cornea matrix (ACM) were prepared from de-epithelium fresh porcine corneas (DFPCs) by incubation with 100% fresh human sera and additional electrophoresis at 4℃. Human corneal epithelial cells (HCEs) were used for the cytotoxicity tests of ACM. ACM were implanted into the Enhanced Green Fluorecence Protein (eGFP) transgenic mouse anterior chamber for evaluation of histocompatibility.RESULTS:HE and GSIB4 results showed fresh porcine cornea matrix with 100% human sera and electrophoresis could entirely decellularize stromal cell without reducing its transparency. ACM has no cytotoxic effect ex vivo. Animal test showed there was no rejection for one month after surgery.CONCLUSION:These results provide a decellularizing approach for the study of corneal tissue engineering and had the broader implications for the field of biological tissue engineering in other engineered organ or tissue matrix.展开更多
·AIM: To investigate whether decellularization using different techniques can reduce immunogenicity of the cornea, and to explore the decellularized cornea as a scaffold for cultured corneal endothelial cells(CEC...·AIM: To investigate whether decellularization using different techniques can reduce immunogenicity of the cornea, and to explore the decellularized cornea as a scaffold for cultured corneal endothelial cells(CECs).Transplantation of decellularized porcine corneas increases graft transparency and survival for longer periods compared with fresh grafts.·METHODS: Six-month-old wild-type pig corneas were cut into 100-200 μm thickness, and then decellularized by three different methods: 1) 0.1% sodium dodecyl sulfate(SDS); 2) hypoxic nitrogen(N2); and 3) hypertonic NaCl. Thickness and transparency were assessed visually. Fresh and decellularized corneas were stained with hematoxylin/eosin(H&E), and for the presence of galactose-α1,3-galactose(Gal) and N-glycolylneuraminic acid(NeuGc, a nonGal antigen). Also, a human IgM/IgG binding assay was performed. Cultured porcine CECs were seeded on the surface of the decellularized cornea and examined after H&E staining.· RESULTS: All three methods of decellularization reduced the number of keratocytes in the stromal tissue by 】80% while the collagen structure remained preserved. No remaining nuclei stained positive for Gal or NeuGc, and expression of these oligosaccharides on collagen was also greatly decreased compared to expression on fresh corneas. Human IgM/IgG binding to decellularized corneal tissue was considerably reduced compared to fresh corneal tissue. The cultured CECs formed a confluent monolayer on the surface of decellularized tissue.· CONCLUSION: Though incomplete, the significant reduction in the cellular component of the decellularized cornea should be associated with a significantly reduced in vivo immune response compared to fresh corneas.展开更多
A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neova...A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neovascularization(CNV) by examining the mechanisms behind common CNV-related corneal pathologies, with a particular focus on herpes simplex stromal keratitis,contact lenses-induced keratitis and CNV secondary to keratoplasty. Moreover, we reviewed CNV in the context of different types of corneal transplantation and keratoprosthesis, and summarized the most relevant treatment available so far.展开更多
AIM:To reconstruct the lamellar cornea using human amniotic epithelial(HAE) cells and rabbit cornea stroma in vitro using tissue engineering technology.·METHODS:Human amnia taken from uncomplicated caesarean sect...AIM:To reconstruct the lamellar cornea using human amniotic epithelial(HAE) cells and rabbit cornea stroma in vitro using tissue engineering technology.·METHODS:Human amnia taken from uncomplicated caesarean sections were digested by collagenase to obtain HAE cells,and the cells were cultured to proliferate.Rabbit corneal epithelial cells were removed by n-heptanol to make lamellar matrix sheets.The second passage of HAE cells were cultured on the corneal stroma sheets for 1 or 2 days,then transferred to an air-liquid interface environment to culture for 2weeks.Tissue engineered lamellar cornea(TELC)morphology was observed by Hematoxylin-eosin(HE)staining;its ultrastructure was observed by transmission electron microscopy(TEM) and scanning electron microscopy(SEM);corneal epithelial cell-specific keratin3 and keratin 12 were detected with immunofluorescence microscopy.·RESULTS:HAE cells grew on the rabbit corneal stroma,forming a monolayer after 1-2 days.About 4-5 layers of epithelial cells developed after 2 weeks of air-liquid interface cultivation,a result similar to normal corneal epithelium.Rabbit corneal stromal cells were significantly reduced after one week,then almost completely disappeared after 2 weeks.TEM showed desmosomes between the epithelial cells;hemidesmosomes formed between the epithelial cells and the basement membrane.SEM revealed that the HAE cells which grew on the lamellar cornea had abundant microvilli.The tissue-engineered cornea expressed keratin 3 and keratin 12,as detected by immunofluorescence assay.·CONCLUSION:Functional tissue-engineered lamellar corneal grafts can be constructed in vitro using HAE cells and rabbit corneal stroma.展开更多
The cornea is the transparent connective tissue window at the front of the eye.The physiological role of the cornea is to conduct external light into the eye,focus it,together with the lens,onto the retina,and to prov...The cornea is the transparent connective tissue window at the front of the eye.The physiological role of the cornea is to conduct external light into the eye,focus it,together with the lens,onto the retina,and to provide rigidity to the entire eyeball.Therefore,good vision requires maintenance of the transparency and proper refractive shape of the cornea.The surface structures irregularities can be associated with wavefront aberrations and scattering errors.Light scattering in the human cornea causes a reduction of visual quality.In fact,the cornea must be transparent and maintain a smooth and stable curvature since it contributes to the major part of the focusing power of the eye.In most cases,a simple examination of visual acuity cannot demonstrate the reduction of visual quality secondary light scattering.In fact,clinical techniques for examining the human cornea in vivo have greatly expanded over the last few decades.The measurement of corneal back scattering qualifies the degree of corneal transparency.The measurement of corneal forward-scattering quantifies the amount of visual impairment that is produced by the alteration of transparency.The aim of this study was to review scattering in the human cornea and methods of measuring it.展开更多
AIM: To evaluate the relationship between contrast sensitivity(CS) and corneal shape following overnight orthokeratology(OK). METHODS: We conducted a retrospective clinical study of 80 lens-wearing myopia patients, al...AIM: To evaluate the relationship between contrast sensitivity(CS) and corneal shape following overnight orthokeratology(OK). METHODS: We conducted a retrospective clinical study of 80 lens-wearing myopia patients, all of whom had undergone OK and had been evaluated by Orbscan II topography. We measured the surface irregularity index(SIRI) of corneal topography at 3 and 5 mm, the size of the flattened central corneal curvature of OK lens(zone A), the size of the cornea altered by OK lens(zone B), the size of the pupillary area at the corneal level(zone C), the area of crossover between zones A and C(zone AC), the area of crossover between zones B and C(BC), the ratio of BC to B(BC/B), and the ratio of AC to C(AC/C). CS was evaluated using the CSV-1000 with spatial frequencies of 3, 6, 12, and 18 cycles/degree(CPD). RESULTS: Multiple correlation analyses indicated significant negative correlations between CS, zone C, BC/B, and 3-mm SIRI(all P<0.01). There were no significant differences between CS, zone B, AC/A, or 5-mm SIRI(P=0.60, 0.94 and 0.11, respectively). Zone C was negatively correlated with 3, 6, 12, and 18 CPD. 5-mm SIRI were negatively correlated with 6, 12, and 18 CPD. BC/C was negatively correlated with 6 and 18 CPD. AC/C was positively correlated with 3 CPD. CONCLUSION: Zone C, 3-mm SIRI and BC/B affect the CS following overnight OK.展开更多
In this review we evaluate evidence for three different hypotheses that explain how the corneal epithelium is maintained. The limbal epithelial stem cell(LESC)hypothesis is most widely accepted. This proposes that ste...In this review we evaluate evidence for three different hypotheses that explain how the corneal epithelium is maintained. The limbal epithelial stem cell(LESC)hypothesis is most widely accepted. This proposes that stem cells in the basal layer of the limbal epithelium, at the periphery of the cornea, maintain themselves and also produce transient(or transit) amplifying cells(TACs). TACs then move centripetally to the centre of the cornea in the basal layer of the corneal epithelium and also replenish cells in the overlying suprabasal layers. The LESCs maintain the corneal epithelium during normal homeostasis and become more active to repair significant wounds. Second, the corneal epithelial stem cell(CESC) hypothesis postulates that, during normal homeostasis, stem cells distributed throughout the basal corneal epithelium, maintain the tissue. According to this hypothesis, LESCs are present in the limbus but are only active during wound healing. We also consider a third possibility, that the corneal epithelium is maintained during normal homeostasis by proliferation of basal corneal epithelial cells without any input from stem cells. After reviewing the published evidence, we conclude that the LESC and CESC hypotheses are consistent with more of the evidence than the third hypothesis, so we do not consider this further. The LESC and CESC hypotheses each have difficulty accounting for one main type of evidence so we evaluate the two key lines of evidence that discriminate between them. Finally, we discuss how lineage-tracing experiments have begun to resolve the debate in favour of the LESC hypothesis. Nevertheless, it also seems likely that some basal corneal epithelial cells can act as long-term progenitors if limbal stem cell function is compromised. Thus, this aspect of the CESC hypothesis may have a lasting impact on our understanding of corneal epithelial maintenance, even if it is eventually shown that stem cells are restricted to the limbus as proposed by the LESC hypothesis.展开更多
The cornea is maintained in an avascular state by maintaining an environment whereby anti-angiogenic factors take the upper hand over factors promoting angiogenesis. Many of the common pathologies affecting the cornea...The cornea is maintained in an avascular state by maintaining an environment whereby anti-angiogenic factors take the upper hand over factors promoting angiogenesis. Many of the common pathologies affecting the cornea involve the disruption of such equilibrium and the shift towards new vessel formation, leading to corneal opacity and eventually-vision loss. Therefore it is of paramount importance that the molecular underpinnings of corneal neovascularization（CNV） be clearly understood, in order to develop better targeted treatments. This article is a review of the literature on the recent discoveries regarding pro-angiogenic factors of the cornea（such as vascular endothelial growth factors,fibroblast growth factor and matrix metalloproteinases）and anti-angiogenic factors of the cornea（such as endostatins and neostatins）. Further, we review the molecular underpinnings of lymphangiogenesis, a process now known to be almost separate from（yet related to） hemangiogenesis.展开更多
AIM： To assess acellular ostrich corneal matrix used as a scaffold to reconstruct a damaged cornea. METHODS： A hypertonic saline solution combined with a digestion method was used to decellularize the ostrich cornea...AIM： To assess acellular ostrich corneal matrix used as a scaffold to reconstruct a damaged cornea. METHODS： A hypertonic saline solution combined with a digestion method was used to decellularize the ostrich cornea. The microstructure of the acellular corneal matrix was observed by transmission electron microscopy （TEM） and hematoxylin and eosin （H＆E） staining. The mechanical properties were detected by a rheometer and a tension machine. The acellular corneal matrix was also transplanted into a rabbit cornea and cytokeratin 3 was used to check the immune phenotype, RESULTS： The microstructure and mechanical properties of the ostrich cornea were well preserved after the decellularization process, in vitro, the methyl thiazolyl tetrazoUum results revealed that extracts of the acellular ostrich corneas （AOCs） had no inhibitory effects on the proliferation of the corneal epithelial or endothelial cells or on the keratocytes, The rabbit lamellar keratoplasty showed that the transplanted AOCs were transparent and completely incorporated into the host cornea while corneal turbidity and graft dissolution occurred in the acellular porcine cornea （APC） transplantation, The phenotype of the reconstructed cornea was similar to a normal rabbit cornea with a high expression of cytokeratin 3 in the superficial epithelial cell layer, CONCLUSION： We first used AOCs as scaffolds to reconstruct damaged corneas. Compared with porcine corneas, the anatomical structures of ostrich corneas are closer to those of human corneas. In accordance with the principle that structure determines function, a xenograft lamellar keratoplasty also confirmed that the AOC transplantation generated a superior outcome compared to that of the APC graft.展开更多
AIM: To evaluate the efficacy and safety of corneal collagen crosslinking (01) to prevent the progression of post-laser in situ keratomileusis (LASIK) corneal ectasia. METHODS: In a prospective, nonrandomized, single-...AIM: To evaluate the efficacy and safety of corneal collagen crosslinking (01) to prevent the progression of post-laser in situ keratomileusis (LASIK) corneal ectasia. METHODS: In a prospective, nonrandomized, single-centre study, CXL was performed in 20 eyes of 11 patients who had LASIK for myopic astigmatism and subsequently developed keratectasia. The procedure included instillation of 0.1% riboflavin-20% dextrane solution 30 minutes before UVA irradiation and every 5 minutes for an additional 30 minutes during irradiation. The eyes were evaluated preoperatively and at 1-, 3-, 6-, and 12-month intervals. The complete ophthalmologic examination comprised uncorrected visual acuity, best spectacle-corrected visual acuity, endothelial cell count, ultrasound pachymetry, corneal topography, and in vivo confocal microscopy. RESULTS: CXL appeared to stabilise or partially reverse the progression of post-LASIK corneal ectasia without apparent complication in our cohort. UCVA and BCVA improvements were statistically significant (P<0.05)beyond 12 months after surgery (improvement of 0.07 and 0.13 logMAR at 1 year, respectively). Mean baseline flattest meridian keratometry and mean steepest meridian keratometry reduction (improvement of 2.00 and 1.50 diopters (D), respectively) were statistically significant (P < 0.05) at 12 months postoperatively. At 1 year after 01, mean endothelial cell count did not deteriorate. Mean thinnest cornea pachymetry increased significantly. CONCLUSION: The results of the study showed a long-term stability of post-LASIK corneal ectasia after crosslinking without relevant side effects. It seems to be a safe and promising procedure to stop the progression of post-LASIK keratectasia, thereby avoiding or delaying keratoplasty.展开更多
AIM： To evaluate the inhibitory effect of subconjunctival bevacizumab as single-and multiple-dose application, and compare their effects on corneal neovascularization in a rat model. METHODS： Thirty adult Sprague-Da...AIM： To evaluate the inhibitory effect of subconjunctival bevacizumab as single-and multiple-dose application, and compare their effects on corneal neovascularization in a rat model. METHODS： Thirty adult Sprague-Dawley rats were used in this experimental study. The central cornea of the rats was cauterized chemically. The rats were randomly enrolled into three groups. All groups received subconjunctival injections. In Group 1（control group, n=10）, 0.05 m L 0.9% Na Cl solution was injected on the first day. In Group 2（single-dose group, n=10）, 0.05 m L bevacizumab（1.25 mg） was injected on the first day. In Group 3（multiple-dose group, n=10）, four doses of 0.05 m L bevacizumab（1.25 mg） were injected on the first, third, fifth and seventh day. Slit-lamp examination of all rats was performed at the third and ninth day. Digital images of the corneas were taken and analyzed using image analysis software to calculate corneal neovascularization area. All rats were sacrificed on the tenth day. In corneal sections, the number of blood vessels, state of inflammation and collagen formation was evaluated histopathologically. RESULTS： In Group 3, corneal edema grades were significantly lower than Group 1 and Group 2（P=0.02, and P=0.035, respectively）. The mean percentage of neovascularized corneal area in Group 3 was significantly lower than Group 2（P=0.005）. On histopathological examination, Group 2 and Group 3 showed significantly less number of blood vessels than Group 1（P=0.005, and P=0.001, respectively）. Additionally, Group 3 showed significantly less number of blood vessels compared to Group 2（P=0.019）. Inflammation and edema grades were significantly lower in Group 3 compared to Group 1（P=0.001）. CONCLUSION： Subconjunctival bevacizumab injection is effective in inhibition of newly formed corneal neovascularization. The multiple-dose bevacizumab treatment seems to be more effective compared to single-dose treatment.展开更多
文摘Diabetic corneal neuropathy and diabetic retinopathy are ocular complications occurring in the context of diabetes mellitus.Diabetic corneal neuropathy refers to the progressive damage of corneal nerves.Diabetic retinopathy has traditionally been considered as damage to the retinal microvasculature.However,growing evidence suggests that diabetic retinopathy is a complex neurovascular disorder resulting from dysfunction of the neurovascular unit,which includes both the retinal vascular structures and neural tissues.Diabetic retinopathy is one of the leading causes of blindness and is frequently screened for as part of diabetic ocular screening.However,diabetic corneal neuropathy is commonly overlooked and underdiagnosed,leading to severe ocular surface impairment.Several studies have found that these two conditions tend to occur together,and they share similarities in their pathogenesis pathways,being triggered by a status of chronic hyperglycemia.This review aims to discuss the interconnection between diabetic corneal neuropathy and diabetic retinopathy,whether diabetic corneal neuropathy precedes diabetic retinopathy,as well as the relation between the stage of diabetic retinopathy and the severity of corneal neuropathy.We also endeavor to explore the relevance of a corneal screening in diabetic eyes and the possibility of using corneal nerve measurements to monitor the progression of diabetic retinopathy.
文摘The cornea is a transparent tissue that serves as the main refractive element of the eye ball.Limbal epithelial stem cells(LESCs),residing in the basal epithelial layer of the Palisades of Vogt located in the corneal limbus between cornea and scleral,are believed to be crucial for the continuous turnover of the corneal epithelium.The proliferation,migration,and differentiation of the LESCs are modulated by unique physical and chemical futures contained within the microenvironment known as the limbal niche.This niche,composed of nerve terminals,cells,extracellular matrix,vasculature,and signaling molecules,is the home for processes such as proliferation,migration and differentiation.Corneal nerve terminals possess special anatomical structures in the limbal region and basal epithelial cells,and they demonstrate pivotal biological effects in the regulation of the LESC function and corneal epithelium homeostasis.Biological molecules such as neuropeptides,neurotransmitters,and neurotrophic factors play a crucial role in modulating the LESCs phenotype responsible for corneal epithelium homeostasis.This paper will review recent studies on how these nerve derived molecules function in this process and provide clear orientations for future research.
文摘Background:Fluorescein is commonly used in ophthalmology for the assessment of ocular surface integrity.There have been limited studies on the effects of fluorescein on corneal endothelial cells.This study aims to assess the effect of the widely used fluorescein dye on human corneal endothelial cells(HCEnCs)in vitro at different concentrations and exposure times.Methods:B4G12,an immortalized human corneal endothelium cell line was cultured on pre-coated tissue culture flask with human endothelial-serum free medium(SFM)supplemented with 10 ng/mL basic fibroblast growth factor(bFGF).The fully confluent B4G12 cell monolayers in 96 well plates were treated with water as control,or fluorescein at various concentrations and exposure times.Cell viability was assessed using two techniques:Alamar Blue assay and cell morphology assessment with an inverted phase-contrast microscopy.Results:Short-term exposure to fluorescein(0.01-0.2%)for up to 30 minutes did not affect cell viability.Continuous fluorescein exposure however significantly reduced the viability of the cells with a notable reduction in cell metabolic activity with fluorescein treatments of 0.001%,0.01% and 0.05% for 1 day(and up to 4 days).Conclusions:Short-term exposure to fluorescein for up to 30 minutes in concentrations commonly used in clinical practice did not affect HCEnC viability.However,fluorescein exposure for longer durations can be detrimental to corneal endothelial cell health.Future studies should evaluate the effects of longer-term fluorescein exposure on endothelial function especially in susceptible patients including the elderly and patients with epithelial defects that enable diffusion of fluorescein towards the endothelium.
文摘AIM:To assess early visual outcomes and corneal stability following small incision lenticule extraction(SMILE)in eyes with a pre-planned residual stromal thickness(RST)ranging from 280 to 300μm.METHODS:This retrospective study was designed to evaluate 82 eyes from 82 patients,all of whom had a pre-planned RST of 280 to 300μm and normal corneal topography prior to undergoing SMILE surgery.The mean preoperative spherical equivalent(SE)was-4.82±1.30 D.A standard follow-up protocol was conducted between 1 to 6mo postoperatively.Visual outcomes were recorded using uncorrected visual acuity(UCVA)and subjective refraction.The curvature of the anterior and posterior corneal surfaces,as well as the posterior elevation at the thinnest point(PTE)were derived from the Pentacam system.RESULTS:At the final follow-up,the efficacy index was 1.14±0.15,the safety index was 1.20±0.13.The mean preoperative UDVA was 0.78±0.16 logMAR,which improved significantly to-0.07±0.06 logMAR postoperatively(P<0.001).The preoperative mean SE was-4.82±1.30 D,which decreased to-0.14±0.30 D by the last visit.The curvature of the anterior cornea at the flat meridian(AK1)were 42.62±1.02 D preoperatively,38.56±1.37 D and 38.59±1.39 D at 1 and 6mo after operation,respectively.Corresponding measurements at the steep meridian(AK2)were 43.55±1.14 D preoperatively,39.18±1.46 D and 39.22±1.50 D at 1 and 6mo after operation,respectively.Both AK1 and AK2 remained stable at 1 and 6-mo postoperative intervals(P=0.126 and 0.082,respectively).There were no observed changes in the curvature of the posterior cornea at the flat meridian or at the steep meridian,or the PTE before and after surgery.CONCLUSION:SMILE represents a safe and effective procedure for the correction of myopia and astigmatism in eyes featuring a pre-planned RST ranging from 280 to 300μm accompanied by normal corneal topography,on the premise of strict control of surgical indications.
文摘AIM:To assess tomographic changes and subclinical edema detection in Fuchs’endothelial corneal dystrophy(FECD)through Scheimpflug tomography in a group of phakic patients contemplating cataract surgery.METHODS:A retrospective study was conducted on 30 phakic eyes from patients diagnosed with FECD but without clinical edema,and 59 phakic eyes from a control group without corneal alterations.Comprehensive ophthalmic examinations were conducted,including slitlamp biomicroscopy,corneal specular microscopy(CSM),and Scheimpflug tomography.RESULTS:The study encompassed 30 phakic eyes with FECD(mean age 59.8±13.1y)and 59 control eyes(mean age 61.3±7.7y).The best-corrected visual acuity was higher in the control group compared to the FECD group[0(0,0.08)vs 0.05(0,0.15)logMAR;P=0.042].CSM revealed significant differences between the FECD and control groups in several parameters:number of analyzed cells(26±13 vs 135±42,P<0.001),cell density(2049±376 vs 2479±225 cells/mm2,P<0.001),mean cell area[463(434,544)vs 397(383,431)μm2;P<0.001],coefficient of variation(54.8%±18.7%vs 41.0%±7.2%,P<0.001),and hexagonal cells[0(0,47%)vs 47%(40%,53%),P<0.001].Although often used as a clinical parameter for detecting edema,central corneal thickness measured by CSM showed no significant difference between the FECD and control groups(530±57 vs 546±30μm,P=0.179).Significant differences were noted in various Pentacam measurements between the groups.Specifically,parameters like loss of parallel isopachs(13 vs 0 eyes,P<0.001),displacement of the thinnest point(11 vs 0 eyes,P<0.001),posterior focal depression(25 vs 7 eyes,P<0.001),and increased light scatter[21.4(17.6;23.9)vs 18.0(16.8,21.8),P=0.01]were significantly more prevalent in FECD eyes,reflecting the presence of subclinical edema and loss of corneal transparency.CONCLUSION:Scheimpflug tomography allows for an objective assessment of FECD,offering the capability to detect subclinical edema at an early stage,monitor disease progression,and serve as a predictor of corneal decompensation following cataract surgery.
文摘AIM:To investigate the changes in posterior corneal elevation within 6mo after small incision lenticule extraction(SMILE)surgery for myopia and myopic astigmatism in patients with thin corneas.METHODS:A prospective study included patients with thin corneas(preoperative thinnest corneal thickness ranging from 480 to 520μm)who underwent SMILE for myopia or myopic astigmatism.Corneal topography and posterior corneal elevation were assessed using Pentacam HR at three time points:preoperatively,1mo,and 6mo postoperatively.The measured parameters included thinnest point elevation(PTE),posterior maximal elevation(PME),posterior central elevation(PCE),and 24 additional reference points.RESULTS:A total of 106 eyes from 106 patients(age range:18-34)were included in the study.Uncorrected distance visual acuity(UDVA)improved significantly,with a mean logMAR value of-0.07±0.06 at the final follow-up visit.Measurements of posterior corneal elevation showed no significant changes in most points,hemispheres,and meridians at 6mo postoperatively.Notably,only two points,ΔE_(2mm-45°)andΔE_(2mm-90°),exhibited statistically significant elevation changes:the elevation ofΔE_(2mm-45°)increased from-2.3±4.99 to-1.0±5.9μm(P=0.0037),and that ofΔE_(2mm-90°)increased from-16±7.53 to-15±7.4μm(P=0.016).However,these changes were within the measurement error range of the Pentacam HR(±5μm in a 5 mm area).CONCLUSION:SMILE surgery is a safe and stable procedure for correcting myopia or myopic astigmatism in patients with thin corneas,as evidenced by the stability of posterior corneal elevation.
文摘Background:Traditional imaging approaches to keratoconus(KCN)have thus far failed to produce a standardized approach for diagnosis.While many diagnostic modalities and metrics exist,none have proven robust enough to be considered a gold standard.This study aims to introduce novel metrics to differentiate between KCN and healthy corneas using three-dimensional(3D)measurements of surface area and volume.Methods:This retrospective observational study examined KCN patients along with healthy control patients between the ages of 20 and 79 years old at the University of Maryland,Baltimore.The selected patients underwent a nine-line raster scan anterior segment optical coherence tomography(AS-OCT).ImageJ was used to determine the central 6 mm of each image and each corneal image was then divided into six 1 mm segments.Free-D software was then used to render the nine different images into a 3D model to calculate corneal surface area and volume.A two-tailed Mann-Whitney test was used to assess statistical significance when comparing these subsets.Results:Thirty-three eyes with KCN,along with 33 healthy control,were enrolled.There were statistically significant differences between the healthy and KCN groups in the metric of anterior corneal surface area(13.927 vs.13.991 mm^(2),P=0.046),posterior corneal surface area(14.045 vs.14.173 mm^(2),P<0.001),and volume(8.430 vs.7.773 mm3,P<0.001)within the central 6 mm.Conclusions:3D corneal models derived from AS-OCT can be used to measure anterior corneal surface area,posterior corneal surface area,and corneal volume.All three parameters are statistically different between corneas with KCN and healthy corneas.Further study and application of these parameters may yield new methodologies for the detection of KCN.
基金Supported by National Natural Science Foundation of Guangdong,China(No.2020A1515010829,No.2023A1515011652,No.2025A1515012389)Science and Technology Program of Guangzhou,China(No.2025A03J4033).
文摘AIM:To evaluate the agreement of axial length(AL),anterior chamber parameters,and total cornea power obtained by swept-source optical coherence tomography(SS-OCT)-based and Scheimpflug-based optical biometers in myopic children.METHODS:AL,steep keratometry(K),flat K,posterior corneal keratometry(PK),total keratometry(TK),anterior chamber depth(ACD),horizontal corneal diameter(CD),and central corneal thickness(CCT)were obtained using IOL Master 700 and Pentacam AXL.The agreement between the devices was evaluated using intraclass correlation coefficients(ICC),Bland-Altman plots,and astigmatism vector analysis.RESULTS:Totally 175 myopic children(48.5%male)with a mean age of 10.29±2.14y were enrolled.The ICC and Bland-Altman plots indicated a satisfactory agreement for AL,ACD,and CCT.The mean difference in CD of-0.31±0.30 mm was considered clinically significant(>0.2 mm).Additionally,measurements of K and TK obtained from the IOL Master 700 showed good agreement.Nevertheless,there were clinically significant differences observed in PK,simulated keratometry(simK),total cornea power,and astigmatism(at least 10%of the cases with a difference of>10 degrees in meridian)between the two devices.CONCLUSION:The study findings demonstrate a significant difference in K,PK,astigmatism,and CD,indicating that the two optical biometers cannot be considered interchangeable.Therefore,it is recommended to utilize one kind device for follow-up examinations in myopic children.
基金National Natural Science Foundation of China (No.81160118,81100648,81101858,81100649)Natural Science Foundation of Jiangxi Province,China (No.20114BAB215029)+3 种基金Technology Foundation of Jiangxi Province,China (No.20111BBG70026-2)Health Department Science and Technology Foundation,China (No.20121026)Education Department Youth Scientific Research Foundation,China (No.JJJ12158)National High Technology Research of China (863 project)(No.2006AA02A131)
文摘AIM:To develop a new decellularization method depended upon the natural corneal structure and to harvest an ideal scaffold with good biocompatibilities for corneal reconstruction.METHODS:The acellular cornea matrix (ACM) were prepared from de-epithelium fresh porcine corneas (DFPCs) by incubation with 100% fresh human sera and additional electrophoresis at 4℃. Human corneal epithelial cells (HCEs) were used for the cytotoxicity tests of ACM. ACM were implanted into the Enhanced Green Fluorecence Protein (eGFP) transgenic mouse anterior chamber for evaluation of histocompatibility.RESULTS:HE and GSIB4 results showed fresh porcine cornea matrix with 100% human sera and electrophoresis could entirely decellularize stromal cell without reducing its transparency. ACM has no cytotoxic effect ex vivo. Animal test showed there was no rejection for one month after surgery.CONCLUSION:These results provide a decellularizing approach for the study of corneal tissue engineering and had the broader implications for the field of biological tissue engineering in other engineered organ or tissue matrix.
基金Supported in part by NIH Grants#1RO3A 1096296-01 (HH), #IU19A1090959-01 (DKCC), #U01A 1066331 (DKCC), and #5P01 HL107152-02 (DKCC)Ocular Tissue Engineering and Regenerative Ophthalmology (OTERO) Postdoctoral Fellowship (WL)Sponsored Research Agreements Between the University of Pittsburgh and Revivicor, Blacksburg, VA
文摘·AIM: To investigate whether decellularization using different techniques can reduce immunogenicity of the cornea, and to explore the decellularized cornea as a scaffold for cultured corneal endothelial cells(CECs).Transplantation of decellularized porcine corneas increases graft transparency and survival for longer periods compared with fresh grafts.·METHODS: Six-month-old wild-type pig corneas were cut into 100-200 μm thickness, and then decellularized by three different methods: 1) 0.1% sodium dodecyl sulfate(SDS); 2) hypoxic nitrogen(N2); and 3) hypertonic NaCl. Thickness and transparency were assessed visually. Fresh and decellularized corneas were stained with hematoxylin/eosin(H&E), and for the presence of galactose-α1,3-galactose(Gal) and N-glycolylneuraminic acid(NeuGc, a nonGal antigen). Also, a human IgM/IgG binding assay was performed. Cultured porcine CECs were seeded on the surface of the decellularized cornea and examined after H&E staining.· RESULTS: All three methods of decellularization reduced the number of keratocytes in the stromal tissue by 】80% while the collagen structure remained preserved. No remaining nuclei stained positive for Gal or NeuGc, and expression of these oligosaccharides on collagen was also greatly decreased compared to expression on fresh corneas. Human IgM/IgG binding to decellularized corneal tissue was considerably reduced compared to fresh corneal tissue. The cultured CECs formed a confluent monolayer on the surface of decellularized tissue.· CONCLUSION: Though incomplete, the significant reduction in the cellular component of the decellularized cornea should be associated with a significantly reduced in vivo immune response compared to fresh corneas.
文摘A large subset of corneal pathologies involves the formation of new vessels(neovascularization), leading to compromised visual acuity. This article aims to review the clinical causes and presentations of corneal neovascularization(CNV) by examining the mechanisms behind common CNV-related corneal pathologies, with a particular focus on herpes simplex stromal keratitis,contact lenses-induced keratitis and CNV secondary to keratoplasty. Moreover, we reviewed CNV in the context of different types of corneal transplantation and keratoprosthesis, and summarized the most relevant treatment available so far.
基金National Natural Science Foundation of China (No.30872808No.81100637)
文摘AIM:To reconstruct the lamellar cornea using human amniotic epithelial(HAE) cells and rabbit cornea stroma in vitro using tissue engineering technology.·METHODS:Human amnia taken from uncomplicated caesarean sections were digested by collagenase to obtain HAE cells,and the cells were cultured to proliferate.Rabbit corneal epithelial cells were removed by n-heptanol to make lamellar matrix sheets.The second passage of HAE cells were cultured on the corneal stroma sheets for 1 or 2 days,then transferred to an air-liquid interface environment to culture for 2weeks.Tissue engineered lamellar cornea(TELC)morphology was observed by Hematoxylin-eosin(HE)staining;its ultrastructure was observed by transmission electron microscopy(TEM) and scanning electron microscopy(SEM);corneal epithelial cell-specific keratin3 and keratin 12 were detected with immunofluorescence microscopy.·RESULTS:HAE cells grew on the rabbit corneal stroma,forming a monolayer after 1-2 days.About 4-5 layers of epithelial cells developed after 2 weeks of air-liquid interface cultivation,a result similar to normal corneal epithelium.Rabbit corneal stromal cells were significantly reduced after one week,then almost completely disappeared after 2 weeks.TEM showed desmosomes between the epithelial cells;hemidesmosomes formed between the epithelial cells and the basement membrane.SEM revealed that the HAE cells which grew on the lamellar cornea had abundant microvilli.The tissue-engineered cornea expressed keratin 3 and keratin 12,as detected by immunofluorescence assay.·CONCLUSION:Functional tissue-engineered lamellar corneal grafts can be constructed in vitro using HAE cells and rabbit corneal stroma.
文摘The cornea is the transparent connective tissue window at the front of the eye.The physiological role of the cornea is to conduct external light into the eye,focus it,together with the lens,onto the retina,and to provide rigidity to the entire eyeball.Therefore,good vision requires maintenance of the transparency and proper refractive shape of the cornea.The surface structures irregularities can be associated with wavefront aberrations and scattering errors.Light scattering in the human cornea causes a reduction of visual quality.In fact,the cornea must be transparent and maintain a smooth and stable curvature since it contributes to the major part of the focusing power of the eye.In most cases,a simple examination of visual acuity cannot demonstrate the reduction of visual quality secondary light scattering.In fact,clinical techniques for examining the human cornea in vivo have greatly expanded over the last few decades.The measurement of corneal back scattering qualifies the degree of corneal transparency.The measurement of corneal forward-scattering quantifies the amount of visual impairment that is produced by the alteration of transparency.The aim of this study was to review scattering in the human cornea and methods of measuring it.
文摘AIM: To evaluate the relationship between contrast sensitivity(CS) and corneal shape following overnight orthokeratology(OK). METHODS: We conducted a retrospective clinical study of 80 lens-wearing myopia patients, all of whom had undergone OK and had been evaluated by Orbscan II topography. We measured the surface irregularity index(SIRI) of corneal topography at 3 and 5 mm, the size of the flattened central corneal curvature of OK lens(zone A), the size of the cornea altered by OK lens(zone B), the size of the pupillary area at the corneal level(zone C), the area of crossover between zones A and C(zone AC), the area of crossover between zones B and C(BC), the ratio of BC to B(BC/B), and the ratio of AC to C(AC/C). CS was evaluated using the CSV-1000 with spatial frequencies of 3, 6, 12, and 18 cycles/degree(CPD). RESULTS: Multiple correlation analyses indicated significant negative correlations between CS, zone C, BC/B, and 3-mm SIRI(all P<0.01). There were no significant differences between CS, zone B, AC/A, or 5-mm SIRI(P=0.60, 0.94 and 0.11, respectively). Zone C was negatively correlated with 3, 6, 12, and 18 CPD. 5-mm SIRI were negatively correlated with 6, 12, and 18 CPD. BC/C was negatively correlated with 6 and 18 CPD. AC/C was positively correlated with 3 CPD. CONCLUSION: Zone C, 3-mm SIRI and BC/B affect the CS following overnight OK.
基金Supported by Grants from the Wellcome Trust,No.088876/Z/09/Zthe UK Biotechnology and Biological Sciences Research Council,No.BB/J015172/1 and No.BB/J015237/1
文摘In this review we evaluate evidence for three different hypotheses that explain how the corneal epithelium is maintained. The limbal epithelial stem cell(LESC)hypothesis is most widely accepted. This proposes that stem cells in the basal layer of the limbal epithelium, at the periphery of the cornea, maintain themselves and also produce transient(or transit) amplifying cells(TACs). TACs then move centripetally to the centre of the cornea in the basal layer of the corneal epithelium and also replenish cells in the overlying suprabasal layers. The LESCs maintain the corneal epithelium during normal homeostasis and become more active to repair significant wounds. Second, the corneal epithelial stem cell(CESC) hypothesis postulates that, during normal homeostasis, stem cells distributed throughout the basal corneal epithelium, maintain the tissue. According to this hypothesis, LESCs are present in the limbus but are only active during wound healing. We also consider a third possibility, that the corneal epithelium is maintained during normal homeostasis by proliferation of basal corneal epithelial cells without any input from stem cells. After reviewing the published evidence, we conclude that the LESC and CESC hypotheses are consistent with more of the evidence than the third hypothesis, so we do not consider this further. The LESC and CESC hypotheses each have difficulty accounting for one main type of evidence so we evaluate the two key lines of evidence that discriminate between them. Finally, we discuss how lineage-tracing experiments have begun to resolve the debate in favour of the LESC hypothesis. Nevertheless, it also seems likely that some basal corneal epithelial cells can act as long-term progenitors if limbal stem cell function is compromised. Thus, this aspect of the CESC hypothesis may have a lasting impact on our understanding of corneal epithelial maintenance, even if it is eventually shown that stem cells are restricted to the limbus as proposed by the LESC hypothesis.
文摘The cornea is maintained in an avascular state by maintaining an environment whereby anti-angiogenic factors take the upper hand over factors promoting angiogenesis. Many of the common pathologies affecting the cornea involve the disruption of such equilibrium and the shift towards new vessel formation, leading to corneal opacity and eventually-vision loss. Therefore it is of paramount importance that the molecular underpinnings of corneal neovascularization（CNV） be clearly understood, in order to develop better targeted treatments. This article is a review of the literature on the recent discoveries regarding pro-angiogenic factors of the cornea（such as vascular endothelial growth factors,fibroblast growth factor and matrix metalloproteinases）and anti-angiogenic factors of the cornea（such as endostatins and neostatins）. Further, we review the molecular underpinnings of lymphangiogenesis, a process now known to be almost separate from（yet related to） hemangiogenesis.
基金Supported by National Natural Science Foundation of China(No.31200724)Key Innovation Project of Shaanxi Science and Technology Plan(No. 2012KTCQ03-11)+1 种基金Shenzhen Peacock Plan(No. KQCX20130628155525051)Projects of Basic Research of Shenzhen(No.JCYJ20120614193611639,No.JCYJ 20140509172959988)
文摘AIM： To assess acellular ostrich corneal matrix used as a scaffold to reconstruct a damaged cornea. METHODS： A hypertonic saline solution combined with a digestion method was used to decellularize the ostrich cornea. The microstructure of the acellular corneal matrix was observed by transmission electron microscopy （TEM） and hematoxylin and eosin （H＆E） staining. The mechanical properties were detected by a rheometer and a tension machine. The acellular corneal matrix was also transplanted into a rabbit cornea and cytokeratin 3 was used to check the immune phenotype, RESULTS： The microstructure and mechanical properties of the ostrich cornea were well preserved after the decellularization process, in vitro, the methyl thiazolyl tetrazoUum results revealed that extracts of the acellular ostrich corneas （AOCs） had no inhibitory effects on the proliferation of the corneal epithelial or endothelial cells or on the keratocytes, The rabbit lamellar keratoplasty showed that the transplanted AOCs were transparent and completely incorporated into the host cornea while corneal turbidity and graft dissolution occurred in the acellular porcine cornea （APC） transplantation, The phenotype of the reconstructed cornea was similar to a normal rabbit cornea with a high expression of cytokeratin 3 in the superficial epithelial cell layer, CONCLUSION： We first used AOCs as scaffolds to reconstruct damaged corneas. Compared with porcine corneas, the anatomical structures of ostrich corneas are closer to those of human corneas. In accordance with the principle that structure determines function, a xenograft lamellar keratoplasty also confirmed that the AOC transplantation generated a superior outcome compared to that of the APC graft.
文摘AIM: To evaluate the efficacy and safety of corneal collagen crosslinking (01) to prevent the progression of post-laser in situ keratomileusis (LASIK) corneal ectasia. METHODS: In a prospective, nonrandomized, single-centre study, CXL was performed in 20 eyes of 11 patients who had LASIK for myopic astigmatism and subsequently developed keratectasia. The procedure included instillation of 0.1% riboflavin-20% dextrane solution 30 minutes before UVA irradiation and every 5 minutes for an additional 30 minutes during irradiation. The eyes were evaluated preoperatively and at 1-, 3-, 6-, and 12-month intervals. The complete ophthalmologic examination comprised uncorrected visual acuity, best spectacle-corrected visual acuity, endothelial cell count, ultrasound pachymetry, corneal topography, and in vivo confocal microscopy. RESULTS: CXL appeared to stabilise or partially reverse the progression of post-LASIK corneal ectasia without apparent complication in our cohort. UCVA and BCVA improvements were statistically significant (P<0.05)beyond 12 months after surgery (improvement of 0.07 and 0.13 logMAR at 1 year, respectively). Mean baseline flattest meridian keratometry and mean steepest meridian keratometry reduction (improvement of 2.00 and 1.50 diopters (D), respectively) were statistically significant (P < 0.05) at 12 months postoperatively. At 1 year after 01, mean endothelial cell count did not deteriorate. Mean thinnest cornea pachymetry increased significantly. CONCLUSION: The results of the study showed a long-term stability of post-LASIK corneal ectasia after crosslinking without relevant side effects. It seems to be a safe and promising procedure to stop the progression of post-LASIK keratectasia, thereby avoiding or delaying keratoplasty.
文摘AIM： To evaluate the inhibitory effect of subconjunctival bevacizumab as single-and multiple-dose application, and compare their effects on corneal neovascularization in a rat model. METHODS： Thirty adult Sprague-Dawley rats were used in this experimental study. The central cornea of the rats was cauterized chemically. The rats were randomly enrolled into three groups. All groups received subconjunctival injections. In Group 1（control group, n=10）, 0.05 m L 0.9% Na Cl solution was injected on the first day. In Group 2（single-dose group, n=10）, 0.05 m L bevacizumab（1.25 mg） was injected on the first day. In Group 3（multiple-dose group, n=10）, four doses of 0.05 m L bevacizumab（1.25 mg） were injected on the first, third, fifth and seventh day. Slit-lamp examination of all rats was performed at the third and ninth day. Digital images of the corneas were taken and analyzed using image analysis software to calculate corneal neovascularization area. All rats were sacrificed on the tenth day. In corneal sections, the number of blood vessels, state of inflammation and collagen formation was evaluated histopathologically. RESULTS： In Group 3, corneal edema grades were significantly lower than Group 1 and Group 2（P=0.02, and P=0.035, respectively）. The mean percentage of neovascularized corneal area in Group 3 was significantly lower than Group 2（P=0.005）. On histopathological examination, Group 2 and Group 3 showed significantly less number of blood vessels than Group 1（P=0.005, and P=0.001, respectively）. Additionally, Group 3 showed significantly less number of blood vessels compared to Group 2（P=0.019）. Inflammation and edema grades were significantly lower in Group 3 compared to Group 1（P=0.001）. CONCLUSION： Subconjunctival bevacizumab injection is effective in inhibition of newly formed corneal neovascularization. The multiple-dose bevacizumab treatment seems to be more effective compared to single-dose treatment.
