Dependence of dynamic contour and Goldmann applanation tonometries on peripheral corneal thickness

AIM：To determine the effects of peripheral corneal thickness（PCT）on dynamic contour tonometry（DCT）and Goldmann applanation tonometry（GAT）.METHODS：A cross-sectional study.We created a software which calculates the corneal contour（CC）as a function of the radius from the corneal apex to each pixel of the contour.The software generates a central circumference with a radius of 1 mm and the remainder of the cornea is segmented in 5 rings concentric with corneal apex being its diameter not constant around the corneal circumference as a consequence of the irregular CC but keeping constant the diameter of each ring in each direction of the contour.PCT was determined as the mean thickness of the most eccentric ring.Locally weighted scatterplot smoothing（LOWESS）regression was used to determine the pattern of the relationship between PCT and both DCT and GAT respectively.Thereafter,two multivariable linear regression models were constructed.In each of them,the dependant variable was intraocular pressure（IOP）as determined using GAT and DCT respectively.In both of the models the predictive variable was PCT though LOWESS regression pattern was used to model the relationship between the dependant variables and the predictor one.Age and sex were also introduced control variables along with their first-degree interactions with PCT.Main outcome measures include amount of IOP variation explained through regression models（R2）and regression coefficients（B）.RESULTS：Subjects included 109 eyes of 109 healthy individuals.LOWESS regression suggested that a 2nd-degree polynomial would be suitable to model the relationshipbetween both DCT and GAT with PCT.Hence PCT was introduced in both models as a linear and quadratic term.Neither age nor sex nor interactions were statistically significant in both models.For GAT model,R2was 17.14%（F=9.02;P=0.0002）,PCT linear term B was-1.163（95%CI：-1.163,-0.617）.PCT quadratic term B was 0.00081（95%CI：0.00043,0.00118）.For DCT model R2was 14.28%（F=9.29;P=0.0002）,PCT linear term B was-0.712（95%CI：-1.052,-0.372）,PCT quadratic term was B=0.0005（95%CI：0.0003,0.0007）.CONCLUSION：DCT and GAT measurements are conditioned by PCT though this effect,rather than linear,follows a2nd-degree polynomial pattern.

Comparison of central corneal thickness measurements with three new optical devices and a standard ultrasonic pachymeter

AIM:To compare the RTVue spectral optical coherence tomography(SD-OCT),Sirius Scheimpflug-Placido topographer,Lenstar optical low coherence reflectometry(OLCR)and ultrasound pachymetry(USP)devices in terms of their agreement and repeatability of measuring central corneal thickness(CCT).METHODS:In this prospective study,50 eyes of 50patients were included.Three repeated measures were obtained using SD-OCT,Scheimpflug-Placido topographer and USP and five measurements were determined with the OLCR.Bland-Altman plots were used to assess agreement among the instruments,and 95%limits of agreement(LoA)for each comparison were calculated.Intra-examiner repeatability was assessed using intraclass correlation coefficients(ICCs).RESULTS:The mean CCT by SD-OCT,ScheimpflugPlacido topographer,OLCR,and USP were 525.90±34.08μm,525.92±34.10μm,530.30±35.62μm,and543.50±37.11μm respectively.All 4 modalities of CCT measurements correlated closely with each other,with Pearson correlation coefficients ranging from 0.977 to0.995.The mean differences(and upper/lower LoA)for CCT measurements were-0.05±6.77μm(13.3/-13.3)between SD-OCT and Scheimpflug-Placido topographer,4.38±3.79μm(11.8/-3.1)between OLCR and SD-OCT,4.38±6.03μm(16.2/-7.5)between OLCR and ScheimpflugPlacido topographer,13.20±6.46μm(25.9/0.5)between USP and OLCR,17.59±6.76μm(30.8/4.3)between USP and SD-OCT,and 17.58±8.13μm(33.5/1.6)between USP and Scheimpflug-Placido topographer.Intra-examiner repeatability was excellent for all devices with ICCs】0.98.CONCLUSION:For most practical purposes,CCT measurements with the RTVue,Sirius and Lenstar can be used interchangeably.Although highly correlated,CCTmeasurement differences between USP and these 3optical instruments can be significant depending on the clinical situation.

Comparison of corneal flap thickness using a FS200femtosecond laser and a moria SBK microkeratome

AIMTo evaluate differences in flap thickness resulting from use of an Alcon Wavelight FS200 femtosecond laser and a MORIA SBK microkeratome when making a 110-µm-thick corneal flap and to identify the potential factors that affect corneal flap thickness.

Transplantation of tissue-engineered human corneal epithelium in limbal stem cell deficiency rabbit models

AIM: To evaluate the biological functions of tissue-engineered human corneal epithelium (TE-HCEP) by corneal transplantation in limbal stem cell deficiency (LSCD) rabbit models. METHODS: TE-HCEPs were reconstructed with DiI-labeled untransfected HCEP cells and denuded amniotic membrane (dAM) in air-liquid interface culture, and their morphology and structure were characterized by hematoxylin-eosin (HE) staining of paraffin-sections, immunohistochemistry and electron microscopy. LSCD models were established by mechanical and alcohol treatment of the left eyes of New Zealand white rabbits, and their eyes were transplanted with TE-HCEPs with dAM surface outside by lamellar keratoplasty (LKP). Corneal transparency, neovascularization, thickness, and epithelial integrality of both traumatic and post transplantation eyes were checked once a week by slit-lamp corneal microscopy, a corneal pachymeter, and periodic acid-Schiff (PAS) staining. At day 120 post surgery, the rabbits in each group were sacrificed and their corneas were examined by DiI label observation, HE staining, immunohistochemistry and electron microscopy. RESULTS: After cultured for 5 days on dAM, HCEP cells, maintaining keratin 3 expression, reconstructed a 6-7 layer TE-HCEP with normal morphology and structure. The traumatic rabbit corneas, entirely opaque, conjunctivalized and with invaded blood vessels, were used as LSCD models for TE-HCEP transplantation. After transplantation, obvious edema was not found in TE-HCEP-transplanted corneas which became more and more transparent, the invaded blood vessels reduced gradually throughout the monitoring period. The corneas decreased to normal thickness on day 25, while those of dAM eyes were over 575 mu m in thickness during the monitoring period. A 45 layer of epithelium consisting of TE-HCEP originated cells attached tightly to the anterior surface of stroma was reconstructed 120 days after TE-HCEP transplantation, which was similar to the normal control eye in morphology and structure. In contrast, intense corneal edema, turbid, invaded blood vessels were found in dAM eyes, and no multilayer epithelium was found but only a few scattered conjunctiva-like cells appeared. CONCLUSION: The TE-HCEP, with similar morphology and structure to those of innate HCEP, could reconstruct a multilayer corneal epithelium with normal functions in restoring corneal transparency and thickness of LSCD rabbits after transplantation. It may be a promising HCEP equivalent for clinical therapy of corneal epithelial disorders.

Eye rubbing-induced changes in intraocular pressure and corneal thickness measured at five locations, in subjects with ocular allergy

AIM: To assess the effects of eye rubbing on corneal thickness(CT) and intraocular pressure(IOP)measurements obtained 0-30 min after habitual eye rubbing in symptomatic patients.METHODS: Measurements of IOP and CT were obtained at five locations(central, temporal, superior,nasal and inferior) before, and every 5min for 30 min interval after 30 s of eye rubbing, for 25 randomly selected eyes of 14 subjects with ocular allergy and 11age-matched normals. Differences in measurements were calculated in each group [Baseline measurements minus measurements recorded at each time interval after eye rubbing(for IOP), and for each corneal location(for CT)]and comparison were then made between groups(allergic versus control) for differences in any observed effects.RESULTS: Within groups, baseline mean IOPs in the allergic patient-group(14.2 ±3.0 mm Hg) and in the control group(13.1±1.9 mm Hg) were similar at all times,after eye rubbing(P 】0.05, for all). The maximum reduction in IOP was 0.8 mm Hg in the control subjects and the maximum increase was also 0.8 mm Hg in the allergic subjects. Between groups(allergic versus control), the changes in IOP remained under 1 mm Hg at all times(P =0.2) after 30 min of eye rubbing. Between 0and 30 min of CT measurements after eye rubbing, the mean central CT(CCT), inferior CT(ICT), superior CT(SCT), temporal CT(TCT) and nasal CT(NCT) did not vary significantly from baseline values in the control and allergic-subject groups(P 】0.05, for both). Between both groups, changes in CT were similar at all locations(P 】0.05)except for the TC which was minimally thinner by about4.4 μm(P =0.001) in the allergic subjects than in the control subjects, 30 min following 30 s of eye rubbing.CONCLUSION: IOP measured in allergic subjects after30 s of habitual eye rubbing was comparable with that obtained in normal subjects at all times between 0 and30 min. Although, CT in the allergic subjects were similar to those of the control subjects at all times, it varied between +10 and-7.5 μm following eye rubbing, with the temporal cornea showing consistent reductions in thickness in the subjects with allergy. However, this reduction was minimal and was considered to not be clinically relevant.

Distribution of central corneal thickness and intraocular pressure in emmetropic eyes of healthy children of Palestine: a representative cross-sectional study

AIM: To determine the distributions of central corneal thickness(CCT) and intraocular pressure(IOP) in emmetropic eyes of healthy children of Palestine.METHODS: This representative cross sectional study included a total of 1156 eyes from 578 healthy school children aged 7-15 y. Inclusion criteria included emmetropia, no previous history of ocular or systemic diseases, no previous history of contact lens use, and the availability of both eyes. CCT and IOP were measured using ultrasound pachymeter and Goldmann applanation tonometer, respectively. The relationship of the results with age and gender was investigated.RESULTS: The mean age of school children was 11.13±2.8 y. Mean CCT was 542.2±37.4 and 544.3±39.2 μm for right and left eyes, respectively. Mean IOP was 12.5±2.2 and 12.3±2.2 mm Hg for right and left eyes, respectively. A positive correlation was observed between CCT and IOP of the right eye(P<0.001, R=0.358) and CCT and IOP of the left eye(P<0.001, R=0.324). No significant differences were observed in CCT and IOP due to age or gender(P>0.05). There were significant differences in mean CCT and IOP between right and left eyes(P=0.004, P=0.001, respectively).CONCLUSION: A population profile of CCT and IOP is established in Palestinian children for the first time. Mean CCT is comparable to some studies but differ from others. Mean IOP is considerably lower than that of majority children of other ethnic groups. Intereye difference of more than 36 μm in CCT, and 5 mm Hg in IOP should prompt evaluation for potential ocular disorders.

In vitro reconstruction and characterization of tissue-engineered human corneal epithelium with seeder cells from an untransfected human corneal epithelial cell line

AIM: To demonstrate the morphology and structure of in vitro reconstructed tissue-engineered human corneal epithelium (TE-HCEP) with seeder cells from an untransfected HCEP cell line. METHODS: The TE-HCEPs were reconstructed in vitro with seeder cells from an untransfected HCEP cell line, and scaffold carriers of denuded amniotic membrane (dAM) in air-liquid interface culture for 3, 5, 7 and 9 days, respectively. The specimens were examined with hematoxylin-eosin (HE) staining of paraffin-section, immunocytochemical staining, scanning and transmission electron microscopy. RESULTS: During in vitro reconstruction of TE-HCEP, HCEP cells formed a 3-4, 6-7 and 8-10 layers of an HCEP-like structure on dAMs in air-liquid interface culture for 3, 5 and 7 days, respectively. But the cells deceased to 5-6 layers and the structure of straified epithelium became loose at day 9. And the cells maintained positive expression of marker proteins (keratin 3 and keratin 12), cell-junction proteins (zonula occludens-1, E-cadherin, connexin 43 and integrin beta 1) and membrane transport protein of Na+-K+ ATPase. The HCEP cells in TE-HCEP were rich in microvilli on apical surface and established numerous cell-cell and cell-dAM junctions at day 5. CONCLUSION: The morphology and structure of the reconstructed TE-HCEP were similar to those of HCEP in vivo. The HCEP cells in the reconstructed TE-HCEP maintained the properties of HCEP cells, including abilities of forming intercellular and cell-extracellular matrix junctions and abilities of performing membrane transportation. The untransfected HCEP cells and dAMs could promisingly be used in reconstruction HCEP equivalent for clinical corneal epithelium transplantation.

Changes of corneal central thickness of aphakia following congenital cataract surgery under the first six months of life

AIM: To observe the central corneal thickness (CCT) changes in infants and young children who had been undergone bilateral congenital cataract surgery, and to compare the changes with normal control group which was selected from healthy population. METHODS: A cross section case-control study contained 28 cases (56 eyes) of bilateral aphakia (aphakic group) due to congenital cataract surgery combining with posterior continuous curvilinear capsulorhexis and with anterior vitrectomy during 2-6 months after birth. Fourteen children (28 eyes) of age-sex matched with the aphalic group were selected as normal control group. CCT and intraocular pressure (TOP) were measured postoperatively and the results were compared between groups. RESULTS: The mean CCT was 653.5 +/- 82.4 mu m in the aphakic group and 579.6 +/- 39.2 mu m in the control group, with a significant difference (P=0.000). The mean value of TOP in aphakic group (22.0 +/- 1.6mmHg) was greater than that of control group (16.9 +/- 2.1mmHg), P=0.023. There was a negative correlation between age and CCT in normal control group (r=-0.531, P=0.026), and there was no correlation in bilateral aphakia group (r=-0.324, P=0.165). CONCLUSION: Aphakic children due to congenital cataract surgery have a greater CCT than normal children. It is necessary to consider CCT in evaluating IOP for children after congenital cataract surgery.

Changes in intraocular pressure and central corneal thickness during pregnancy:a systematic review and Meta-analysis

AIM：To conduct a Meta-analysis for investigating the variations in intraocular pressure（IOP）and central corneal thickness（CCT）during normal pregnancy.METHODS：We searched for clinical trials published up to November 2015 without language or region restrictions in Pub Med,EMBASE,Web of Science,the Cochrane Central Register of Controlled Trials,Ovid,EBSCO,Elsevier,the Chinese Biomedicine Database,Wan Fang,CNKI,CQVIP and Google Scholar.Studies of the ocular changes observed in pregnant women were selected.The main outcomes were assessed by changes in IOP and CCT.RESULTS：Fifteen studies were included.In subgroup analyses,IOP was significantly decreased during the second MD=-1.53,95%CI（-2.19,-0.87）;P〈0.00001,and third MD=-2.91,95%CI（-3.74,-2.08）;P〈0.00001 trimesters of pregnancy.CCT was increased during the second MD=10.12,95%CI（2.01,18.22）;P=0.01,trimester of pregnancy;moreover,during the third trimester of pregnancy,the CCT displayed an increasing trend,but the difference was not significant MD=5.98,95%CI（-1.11,13.07）;P=0.1.CONCLUSION：A decrease in IOP is accompanied by an increase in CCT in the second and third trimesters of a normal pregnancy in women.

Corneal endothelial cell density and morphology and central corneal thickness in Guangxi Maonan and Han adolescent students of China

AIM: To investigate the corneal endothelial cell density and morphology and central corneal thickness in the Guangxi Maonan and Han adolescent students of China.METHODS: Noncontact specular microscope(Topcon SP3000 P, Tokyo, Japan) was performed in 133 adolescent students of Maonan nationality(M:F 54:79)and 105 adolescent students of Han nationality(M:F 50:55),5 to 20 y of age, who were randomly selected from 3schools in Huanjiang Maonan Autonomous County of Guangxi Zhuang Autonomous Region of China.Parameters studied included endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness. RESULTS: Endothelial cell density, mean cell area,coefficient of variation in cell size, percentage hexagonality and central corneal thickness in the study population were(2969.50 ±253.93) cells/mm2,(339.23 ±29.44) μm2,(29.96 ±4.07) %,(64.58 ±9.41) % and(523.71 ±32.82) μm in Maonan and(2998.26 ±262.65) cells/mm2,(336.11±30.07) μm2,(29.89±5.03) %,(64.91±11.64) % and(524.39 ±33.15) μm in Han, respectively. No significant differences were observed in endothelial cell density,mean cell area, coefficient of variation in cell size,percentage hexagonality and central corneal thickness between Maonan and Han(P =0.615, 0.659, 0.528, 0.551,0.999). In Maonan and Han, we found age was negatively correlated with endothelial cell density and percentagehexagonality and positively correlated with mean cell area and coefficient of variation in cell size. Negative correlation was also found between central corneal thickness and age in Han, whereas no correlation was found in Maonan. CONCLUSION: There were no differences between Maonan and Han in corneal endothelial cell density and morphology and central corneal thickness. In these two nationalities, there were statistically significant decrease in endothelial cell density and percentage hexagonality with increasing age and statistically significant increase in cell area and coefficient of variation in cell size with increasing age. Central corneal thinned with increasing age in Han, whereas difference did not attain statistical significance in Maonan.

TREM-1 expression in rat corneal epithelium with Aspergillus fumigatus infection

AIM: To investigate the expression of triggering receptor expressed on myeloid cells-1(TREM-1) in the aberrant inflammation within the corneal epithelium at early period of fungal infection.METHODS: A total of 65 Wistar rats were randomly divided into control group, sham group and fungal keratitis(FK) group, in which the cornea was infected by Aspergillus fumigatus(A. fumigatus). After executed randomly at 8, 16, 24, 48 and 72 h after experimental model being established, the severity of keratomycosis in rats was scored visually with the aid of a dissecting microscope and slit lamp. Then corneas in three groups were collected to assess the expression of TREM-1through quantitative reverse transcription-polymerase chain reaction(RT-PCR), immunofluorescence technique and Western blot analysis. The correlation between FK inflammation and expression of TREM-1 was also analyzed.RESULTS: Corneal inflammation scores increased with time after fungal infection(F =49.74, P =0.000). The inflammation scores in FK group were obviously higher than those in sham group on the whole(F =137.78, P =0.000). Levels of TREM-1 in the infected rat corneal epithelium had elevated at 8h and peaked at 48h(P 【0.001,compared with control group). Western blot analysis also showed an obviously elevated TREM-1 level in rat corneal epithelium at 24 h and 48 h after fungal infection.Immunofluorescence technique showed that TREM-1mainly existed in corneal epithelium and infected corneal stoma of rat. TREM-1 protein expression was enhanced after fungal infection. Moreover, severity of FK inflammation was significantly related to TREM-1expression in FK(r =0.942, P =0.000).CONCLUSION: TREM-1 may contribute to amplify theinflammation in the cornea infected with A. fumigatus and play critical roles in the battle against A. fumigatus in the innate immune responses.

Corneal epithelial thickness analysis of forme fruste keratoconus with optical coherence tomography

AIM:To explore the significance of corneal epithelial thickness analysis in diagnosing early keratoconus.METHODS:There were 26 clinical keratoconus,21 forme fruste keratoconus,40 high corneal astigmatism(ΔK)and 40 low ΔK eyes involved in the study.Fourierdomain optical coherence tomography was used to measure the corneal epithelial thickness of four groups.The morphological features of topographic map and the thickness of corneal epithelial thinnest point were analyzed.The distribution curve of corneal epithelial thickness at 45°,90°,and 135° axial directions that are through the pupil center was also analyzed.One-way ANOVA was performed to compare the data.RESULTS:The topographic map of forme fruste keratoconus corneal epithelial thickness was uniformity shape;crater shape existed only in clinical keratoconus group;and central island shape mainly existed in highΔK group.The thinnest point of corneal epithelial thickness of forme fruste keratoconus group was significantly lower than that of low ΔK group(P=0.022).The thickness of corneal epithelium in the forme fruste keratoconus at 90°was thinner than that in the low astigmatism group at -1,and -2 mm points(P_(-1mm)=0.015,P_(-2mm)=0.036).CONCLUSION:The analysis of the thinnest point in forme fruste keratoconus corneal epithelium appears earlier than corneal epithelial remodeling.The topographic map of corneal epithelium in high ΔK eyes appears in central island shape,and can be used for the differential diagnosis of early keratoconus.

Anti-inflammatory and anti-apoptotic effects of N-acetylcysteine in diabetic rat corneal epithelium

AIM:To characterize the anti-inflammatory and antiapoptotic effects of N-acetylcysteine(NAC)in streptozotocin(STZ)-induced diabetic rat corneal epithelium and human corneal epithelial cells(HCECs)exposed to a high-glucose environment.METHODS:HCECs were incubated in 0,5,50 mmol/L glucose medium,or 50 mmol/L glucose medium with NAC for 24h.Diabetes was induced in rats by intraperitoneal injection of 65 mg/kg STZ and some of these rats were topically administered NAC to corneas with 3 mice per group.We characterized receptor for advanced glycation end-products(RAGE)expression using immunofluorescence,and interleukin(IL)-1βand cleaved caspase-3(CCAP-3)expression using immunohistochemistry.Circulating tumor necrosis factor(TNF)-αconcentration was measured by ELISA and cleaved poly-ADP ribose polymerase(PARP)concentration was quantified by Western blotting.Apoptotic cells were detected using TUNEL assay and annexin V and propidium iodide staining.RESULTS:Diabetic rats had higher expression of RAGE(2.46±0.13 fold),IL-1β,and CCAP-3 in apoptotic cells of their corneas than control rats.The expression of RAGE(1.83±0.11 fold),IL-1β,and CCAP-3,and the number of apoptotic cells,were reduced by topical NAC treatment.HCECs incubated in 50 mmol/L glucose medium showed high concentrations of TNF-α(310±2.00 pg/mL)and cleaved PARP(7.43±0.56 fold),and more extensive apoptosis than cells in 50 mmol/L glucose medium.However,the addition of NAC reduced the concentrations of TNF-α(153.67±2.31 pg/mL)and cleaved PARP(5.55±0.31 fold)and the number of apoptotic cells.CONCLUSION:NAC inhibits inflammation and apoptosis in the corneas of diabetic rats and HCECs maintained in a high-glucose environment.

Expression of vitamin D receptor and cathelicidin in human corneal epithelium cells during fusarium solani infection

AIMTo observe the expression of vitamin D receptor (VDR) in human specimen and immortalized human corneal epithelium cells (HCEC) when challenged with fusarium solani. Moreover, we decided to discover the pathway of VDR expression. Also, we would like to detect the expression of cathelicidin antimicrobial peptide (CAMP) in the downstream pathway of VDR.METHODSImmunohistochemistry was used to examine the VDR expression in HCEC from healthy and fungal keratitis patients. Real time quantitative polymerase chain reaction (qPCR) was performed to observe the messenger ribonucleic acid (mRNA) change of VDR when immortalized HCEC were challenged with fusarium solani for different hours. CAMP was detected at both mRNA and protein levels.RESULTSWe found out that the VDR expression in fusarium solani keratitis patients' specimen was much more than that in healthy people. The mRNA and protein expression of VDR increased when we stimulated HCEC with fusarium solani antigen (P&#x0003c;0.01) and it could be inhibited by toll like receptor 2 (TLR2) monoclonal antibody. The CAMP expression was decreased because of fusarium solani antigen stimulation (P&#x0003c;0.01).CONCLUSIONThe VDR expression can be increased via TLR2/1-VDR pathway while the CAMP expression is decreased by the stimulation of fusarium solani antigen.

Central corneal epithelium self-healing after ring-shaped glycerin-cryopreserved lamellar keratoplasty in Terrien marginal degeneration

Dear Sir, I am Dr Yan-Long Bi, from the Department of Ophthalmology, Tongji University Affiliated to Tongji University School of Medicine, Shanghai, China. I write to present a case report of total limbal stem cells deficiency after treatment with ring-shaped lamellar keratoplasty secondary to Terrien marginal degeneration. During 3 years

Difference in normal corneal thickness and curvature between Mongolian and Han nationalities

AIM: To investigate the differences in central corneal thickness(CCT) and curvature in myopic patients with different genders between Mongolian and Han nationalities in the Inner Mongolia region.METHODS: Patients with myopia, among whom 122cases(244 eyes) were Mongolian and 150 cases(300eyes) were Han, were selected. Pentacam was used to measure the corneal curvature, whereas CCT was determined by Pentacam, Orbscan and ultrasound pachymetry.RESULTS: Comparisons of the curvature of men and women in Mongolia showed a significant difference(P 【0.05) by comparing of the CCT values measured by three methods in Han and Mongolian in Inner Mongolia, we can draw a conclusion that the CCT values measured by Pentacam are less than the values by Orbscan and ultrasound pachymetry, and there are statistically significant difference in CCT measurement among the instruments except between the Orbscan and ultrasound pachymetry. The CCT values of Mongolians are more than Han people, and the analysis exhibited statistical significance. The CCT values measured by Orbscan in Mongolia of women are more than men, the difference showed statistical significance.CONCLUSION: Corneal curvature in Mongolian females was significantly higher than that in males. However, no significant difference was observed among Han males and females. The CCT values of Mongolian females were higher than those of males. The normal CCT values measured by Pentacam in Mongolian myopic patients were smaller than those obtained by Orbscan or ultrasound. The normal CCT values of Mongolian patients with myopia were higher than those reported for domestic people.

Central corneal thickness measurements in premature infants

AIM:To evaluate the central corneal thickness(CCT)measurements of premature infantsMETHODS:The premature infants who were born between 25-34wk of gestational age(GA)were retrieved for the study.All CCT measurements were performed within the first 2d of their life under topical anesthesia by using an ultrasonic pachymeter.RESULTS:The mean CCT of 200 eyes was 647.79±63.94μm.The mean CCT of the right and left eyes were similar(647.30±64.72μm and 648.29±63.47μm consecutively).The mean CCT of the girls was 642.08±54.89μm and the boys was 653.07±71.14μm,with no statistically significant difference(P】0.05).But there was a negative correlation of the CCT with GA and birth weight(BW)(P【0.01).CONCLUSION:The CCT values of premature babies were negatively correlated with GA and BW.

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.

Construction of a full-thickness human corneal substitute from anterior acellular porcine corneal matrix and human corneal cells

AIM: To construct functional human full-thickness corneal replacements.METHODS: Acellular porcine corneal matrix(APCM) was developed from porcine cornea by decellulariztion. The biomechanical properties of anterior-APCM(AAPCM) and posterior-APCM(PAPCM) were checked using uniaxial tensile testing. Human corneal cells were obtained by cell culture. Suspending ring was designed by deformation of an acupuncture needle. MTT cytotoxicity assay was used to check the cytotoxicity of suspending ring soaking solutions. A new three-dimensional organ culture system was established by combination of suspending ring, 48-well plate and medium together. A human full-thickness corneal substitute was constructed from human corneal cells with AAPCM in an organ coculture system. Biochemical marker expression of the construct was measured by immunofluorescent staining and morphological structures were observed using scanning electron microscopy. Pump function and biophysical properties were examined by penetrating keratoplasty and follow-up clinical observations.RESULTS: There were no cells in the AAPCM or PAPCM, whereas collagen fibers, Bowman's membrane, and Descemet's membrane were retained. The biomechanical property of AAPCM was better than PAPCM. Human corneal cells grew better on the AAPCM than on the PAPCM.There was no cytotoxicity for the suspending ring soaking solutions. For the constructed full-depth human corneal replacements keratocytes scattered uniformly throughout the AAPCM and expressed vimentin. The epithelial layer was located on the surface of Bowman's membrane and composed of three or four layers of epithelial cells expressing cytokeratin 3. One layer of endothelial cells covered the stromal surface of AAPCM, expressed Na+/K+ATPase and formed the endothelial layer. The construct was similar to normal human corneas, with many microvilli on the epithelial cell surface, stromal cells with a long shuttle shape, and zonula occludens on the interface of endothelial cells. The construct withstood surgical procedures during penetrating keratoplasty. The corneal transparency increased gradually and was almost completely restored 7 d after surgery.CONCLUSION: AAPCM is an ideal scaffold for constructing full-thickness corneal replacement, and functional human full-thickness corneal replacements are successfully constructed using AAPCM and human corneal cells.

Monitoring of central corneal thickness after phacoemulsification—comparison of statical and rotating Scheimpflug pachymetry,and spectral-domain OCT

AIM:To explore the possibility of deploying three contactless devices(static and rotating Scheimpflug technology,spectral domain optical coherence tomography)for measuring central corneal thickness(CCT)in preoperative and postoperative examinations of cataract patients.METHODS:Totally 72 patients who had undergone surgery without complications were selected.The CCT was measured prior to the operation,as well as on the first,5th-7th and 28th day following the operation using the Nidek NT 530-P,Sirius?,and Topcon OCT-2000 devices.RESULTS:A significant postoperative increase and subsequent decrease in CCT was identified with all three devices.The correlations were highly significant and thus reflect a very good degree of comparability at all times with the exception of the rotating Scheimpflug camera.The postoperative results from the latter differed significantly from the other devices.The correlations were Sirius/Topcon(P=0.010)and Sirius/Nidek(P<0.0005).No statistically significant difference could be identified in the comparison between Topcon and Nidek(P=0.056).CONCLUSION:All three devices are suitable for postoperative monitoring of CCT.The measurement results are only comparable to a limited extent and not interchangeable in the course of treating a single patient.This is due to the different imaging technology used in the devices and the resulting modalities for conducting the measurements.