Corneal asphericity has been a topic in clinical ophthalmology. This article discusses a corneal surface model based on corneal topography height data， as well as the Q value calculated by tangential data and axial data. The method of using the tangential data， which can be used to calculate the Q-values of all the semi-meridians by coordinate circumrotation， solved the problem of the accuracy and positioning of calculated Q-value. Related firdings support the accuracy and stability of this method.

Objective  To calculate the Q-value of the anterior corneal surface of children by using the tangential radius of curvature； to analyze the distribution of horizontal Q-values and the relationship between Q-value and different refractions. The vertical Q-values were calculated by curve fitting， and the Q-values of the 360° semi-meridians were then obtained， to complete the mathematical model of the anterior corneal surface. Methods  The Ft-values of the 360 semi-meridians from the 84 right eyes of the children （12 cases of myopia， 45 cases of hyperopia， and 27 cases of emmetropia） were calculated by Orbscan Ⅱ topography using a linear regression equation to calculate the Q-values of the semi-meridians and analyze the nasal and temporal distribution of the Q-values and the effect of refractive state. MATLAB R2009b （Matrix Laboratory） was used for curve fitting calculations of the right eye data from 62 children （10 myopes， 25 hyperopes and 27 emmetropes） to obtain Q-values of 360 semi-meridians and to analyze the distribution of the Q-values. Results ①All of the coefficients of determination （R2） were greater than or equal to 0.5. The Q-values of the nasal and temporal distributions were between 1 and 0. The mean Q-values of the nasal distribution of 84 right eyes was -0.42±0.16， and the temporal distribution was -0.23±0.08. The difference was statistically significant （t=-9.527， P<0.05）. The mean r0 of the nasal distribution of 84 right eyes was 7.85±0.24 and the temporal distribution was 7.83±0.24. The difference was statistically significant （t=3.213， P<0.05）. No statistical correlation was found between Q-values and r0 in this study （nasal distribution r=-0.077， P=0.487， temporal distribution r=0.001， P=0.992）. ②The Q values of a one-way ANOVA analysis of emmetropes， myopes and hyperopes showed that the differences between the nasal corneas of myopes and emmetropes and of myopes and hyperopes were statistically significant （P<0.05）. No significant difference was found between the emmetropes and hyperopes （P>0.05）. The differences between the temporal distributions were not statistically significant （P>0.05）. ③The coefficient of determination （R2） of the curve fitting by MATLAB was greater than 0.9.④Fitting the vertical Q-values of the 48 eyes： the mean Q-values of the nasal distribution of the semi-meridian before and after curve fitting were -0.45±0.16 and -0.45±0.16 and the temporal distributions were -0.21±0.08 and -0.20±0.10. There were no significant differences before and after curve fittings （nasal distribution， t=2.009， P>0.05， temporal distribution， t=2.009， P>0.05）. The mean vertical Q-values of the superior and inferior distributions after curve fitting were -0.24±0.10 and -0.17±0.08. Conclusion ①The method of using linear regression to calculate the Q-value of the anterior corneal surface by the tangent radius of curvature proved to be stable and reliable. Corneal asphericity was represented by a prolate ellipse and a trend toward a more prolate Q-value was found in the nasal and horizontal distributions. The Q-value had a weak correlation to ametropia. ?②The distribution of 360 semi-meridians of the Q-value calculated from the curve fits were in the form of a double hump and the two peaks were above and below the vertical semi-meridinans. ③After curve fitting calculations， the horizontal semi-meridians had more asphericity than the vertical meridians， which were more round.④The method using the Curve Fitting Toolbox of the MATLAB System to fit the Q-values proved to be stable and reliable. It solves the problem of calculating Q-values， and enables the creation of a digital model of the corneal anterior surface to become a reality

Objective  To analyze the characteristics of corneal higher-order aberrations in myopia and the relationship between corneal and ocular higher-order aberrations. Methods  Two hundred sixteen eyes of 216 myopic subjects were included in this cross-sectional study. The SCHWIND corneal and ocular aberrometer was used to measure the higher-order aberrations of eyes at two pupil sizes （4 and 6 mm）. An independent-samples t test was used to analyze the difference between corneal and ocular higher-order aberrations. And a Pearson correlation analysis was used to assess the correlations between anterior corneal higher-order aberrations and age， myopia and astigmatism. The differences in corneal higher-order aberrations between subjects who had with-the-rule （WR） astigmatism and those with against-the-rule （AR） astigmatism were analyzed by one-way ANOVA. Results  There were differences between corneal and ocular total higher-order aberrations， total spherical aberrations， horizontal coma （C3+1）， and spherical aberration （C40） both at 4 mm and 6 mm pupils （4 mm： t=-2.364， -7.587， -2.197， -6.320， P＜0.05； 6 mm： t=-4.794， -7.631， -7.945， -7.413， P＜0.01）. A positive correlation was found between C40 （WR & AR） and myopia both at the 4 mm and 6 mm ranges（WR： r=0.211， 0.255， P＜0.01； AR： r=0.697， 0.562， P＜0.01）. Astigmatism was positively correlated with corneal C3+1 in the AR group at both pupil sizes （4 and 6 mm） （r=0.470， 0.429， P＜0.05）. There was a difference in vertical coma （C3-1） between the WR and AR groups at 6 mm （P＜0.05）. Conclusion  Under the same pupil diameter， the root mean square of corneal higher-order aberrations from high to low in turn is： C40， C3-1， C3+1， C3-3， C3+3. Ocular aberrations show a difference. There are differences between the distribution of corneal and ocular higher-order aberrations， which indicated that there is compensation and superposition between corneal and internal higher-order aberrations. There are some differences in corneal higher-order aberrations between the WR and AR groups， although ocular astigmatism is against the rule and corneal astigmatism is almost always with the rule. Corneal astigmatism has some correlation with corneal higher-order aberrations.

Objective  To compare the myopic anterior corneal surface measurements of the Q value and corneal power provided by Pentacam， iTrace and Orbscan Ⅱz and evaluate the agreement among the 3 methods. Methods  This was a cross-sectional study. One hundred eyes were chosen from 100 myopic patients and the Q value and mean Sim K of the anterior corneal surface was measured by Pentacam， iTrace and Orbscan Ⅱz in the same patient′s eye. Measurement results were compared using analysis of variance and agreement among the measurements was assessed using Bland-Altman plots. Results  The Q value measurements were -0.09±0.12， -0.09±0.09， and -0.18±0.10 with Pentacam， iTrace and Orbscan Ⅱz， respectively. The Q value measurements with Orbscan Ⅱz were lower than those with Pentacam and iTrace （F=43.06， P<0.01）. For the Q value measurements， the 95% limits of agreement （LoA） was small between iTrace and Orbscan Ⅱz （from -0.08 to 0.26） and the 95% LoA was large between iTrace and Pentacam （from -0.23 to 0.23）. The respective mean Sim K measurements were 43.34±1.37 D， 43.30±1.35 D and 43.56±1.36 D with Pentacam， iTrace and Orbscan Ⅱz. The mean Sim K measurements with Orbscan Ⅱz were greater than that with Pentacam and iTrace （F=23.25， P<0.01）. For the mean Sim K measurements， the 95% LoA was small between iTrace and Pentacam （from -0.68 to 0.59 D） and the 95% LoA was large between iTrace and Orbscan Ⅱz （from -1.15 D to 0.63 D）. Conclusion  Measurements of Q value and mean Sim K of the anterior corneal surface of myopes showed statistically significant differences among the 3 instruments. The agreement among the 3 instruments was not comparable for Q value measurements. The agreement between iTrace and Pentacam had comparable results for mean Sim K， and can refer to one another.

Objective To investigate the changes in ocular wavefront aberrations that were induced by physiological accommodation. Methods A descriptive study was adopted for this research and the different stages of ocular accommodation were induced by moving the visual target. At the same time， the value of wavefront aberrations was measured under different accommodative stages. These results were used to evaluate the induced amplitude and to compare the differences in higher-order aberrations for the groups with accommodative amplitudes greater than 3 D and less than 3 D under a relaxed state. In addition， the characteristic changes in wavefront aberrations for three different levels of accommodative demand （0 D， 1 D， 3 D） and between pupil diameters at 3.11 mm and 4.93 mm were evaluated and compared. The collected data was analyzed by independent t tests and an ANOVA. Results The induced accommodation was achieved under the present experimental conditions with a maximum amplitude up to 7.43 D. There was no statistical difference between the groups with amplitudes greater than or less than 3 D in terms of higher-order aberrations. With accommodation between the 0 D and 3 D range， the change in higher-order aberrations was not statistically significant. However， during the process of accommodation， the values of coefficients 12， 24 and 33 from the Zernike polynomial pyramid， which were all located on the axial of the pyramid， had statistically significant changes （Mini F=3.799， P<0.05）. Conclusion When the human eye is in the accommodative mode， there are structural changes in higher order aberrations that compensate for the change in defocus.

Objective  To evaluate the repeatability and accuracy of corneal parameters in post-laser in situ keratomileusis （LASIK） eyes obtained by RTVue Fourier-domain optical coherence topography （FD-OCT）. Methods  In this prospective study， 58 right eyes of 58 persons who agreed to undergo LASIK were included. Subjective refractions were performed before LASIK and 3 months after LASIK. IOL Master was used to evaluate corneal power before LASIK. Three months after LASIK， RTVue FD-OCT was used to evaluate the anterior corneal curvature in a 3 mm central zone （Ranterior）， posterior corneal curvature in a 3 mm zone （Rposterior）， the ratio of posterior and anterior curvature （Rposterior/ Ranterior）， central corneal thickness （CCT）， total corneal power （Knet）， simulated corneal power （SimK）， anterior corneal power （Kanterior）， and posterior corneal power （Kposterior）. Km was obtained with IOL Master 3 months after the surgery. Kchm was calculated from the patient′s clinical history. Repeatability of corneal parameters was assessed using the coefficient of variation （CV）， Cronbach′s alpha， and intra-class correlation coefficient （ICC）. Bonferroni corrected multiple comparisons analyzed the differences between SimK， Knet， Km and Kchm. A Pearson correlation analyzed the correlations between SimK， Knet， Km and Kchm. Bland-Altman plots analyzed the agreements between SimK and Kchm， Knet and Kchm， Km and Kchm， SimK and Knet， and SimK and Km. Results  The Ranterior， Rposterior， Rposterior/Ranterior， Kanterior， Kposterior， SimK， Knet and CCT were （8.560±0.292）mm， （6.525±0.159）mm， 0.763±0.024， （43.98±1.48）D， （-6.13±0.15）D， （39.47±1.33）D， （37.93±1.42）D and （451.81±33.91）μm， respectively. The CVs of all parameters were lower than 1%. Cronbach′s alpha and ICC were both higher than 0.9. SimK was （0.434±0.433）D higher than Kchm， Knet was （1.112±0.471）D lower than Kchm， Km was （0.334±0.379）D higher than Kchm， and SimK was （1.546±0.162）D higher than Kchm. All the differences were statistically significant （P<0.01）. SimK was （0.100±0.287）D higher than Km but the difference was not statistically significant. There were close correlations among SimK， Knet， Km and Kchm （r≥0.944， P<0.01）. The Bland-Altman analysis showed that the 95% limit of agreements between SimK and Kchm， Knet and Kchm， Km and Kchm， SimK and Knet， and SimK and Km were -0.41～1.28 D， -2.04～-1.11 D， -0.41～1.08 D， 1.23～1.86 D， -0.46～0.66 D， respectively. Conclusion  The RTVue Fourier-domain OCT had high repeatability on corneal curvature and CCT measurements in post-LASIK eyes. The SimK obtained by RTVue Fourier-domain OCT and IOL Master were 0.3 to 0.4 D higher than those obtained by clinical history. Knet may be a more accurate method to assess corneal power in post-LASIK eyes， but further clinical studies are needed for the prediction of post-LASIK intraocular lens power.

Objective  To investigate the effects of signal strength （SS） on the measurement of macular thickness and volume in normal volunteers with spectral-domain optical coherence tomography （OCT）. Methods  This was a retrospective cohort study. The retinal thickness of 109 normal volunteers was measured by a cubic scan of the macular， Cirrus OCT. All eyes were divided into subgroups： group A1 （identical SS ≥7 in both eyes）， group A2 （identical SS ＜7 in both eyes）， group B1 （different SS≥7 in both eyes）， group B2 （different SS＜7 in both eyes） and group B3 （SS≥7 in one eye， SS＜7 in the other eye）. Macular thickness and volume were measured in the subgroups. ANOVA and paired t test were used to analyze. Results  There were no differences in macular thickness and volume for both eyes in group A1， group A2 and group B1. There was a significant positive correlation between SS and macular cubic volume in group B2 （t=-2.776， P<0.05）. However， there was a significant negative correlation between SS and macular cubic volume and average macular thickness in group B3 （t=2.871， P＜0.05； t=3.210， P＜0.05）. Conclusion  Signal strength is one of the determi-nants of macular thickness measurement with spectral-domain optical coherence tomography.

Objective  To investigate the change in morphologic parameters using the Pentacam to discriminate between clinical keratoconus eyes， subclinical keratoconus eyes and normal eyes for early diagnosis. Methods  This was a case control study. Adopting the Rabinowitz diagnosis standards， we divided 35 patients with keratoconus into 2 subgroups： 16 patients （16 eyes） with clinical keratoconus and 19 patients （19 eyes） with subclinical keratoconus. Twenty-nine patients （29 eyes） with myopic astigmatism were used as a control group. The following morphologic parameters of the anterior corneal surface provided by Pentacam in the clinical keratoconus group， subclinical keratoconus group and control group were recorded： index of surface variance （ISV）， index of vertical asymmetry （IVA）， keratoconus index （KI）， central keratoconus index （CKI）， index of highest asymmetry （IHA）， index of highest decentration （IHD）， minimum sagittal curvature （Rmin） and aberration coefficient （ABR）. An analysis of variance， Dunnett-t test and receiver operating characteristic （ROC） curves were used for analysis and partial least squares （PLS） was used to construct models with corneal morphologic parameters of the anterior corneal surface for early diagnosis. Results  There were significant differences between the clinical keratoconus group， subclinical keratoconus group and control group. The values of the area under the curve （AUC） were all close to 1， and the diagnosis accuracy was high. The optimum cutoff points of the ISV for clinical keratoconus and subclinical keratoconus were 39 and 22.4， Rmin was 6.765 and 7.11， and KI was 1.085 and 1.045. The PLS model of clinical keratoconus was Yhat=8.231+0.006×ISV+ 0.843×IVA+ 0.869×KI－ 3.186×CKI－ 0.010×IHA+ 0.679×IHD－ 0.649×Rmin－ 0.057×ABR，and the PLS model of subclinical keratoconus was Yhat=7.861－0.563×Rmin+ 0.018× ISV+ 0.390×IVA－ 3.281×KI+ 0.571×CKI－ 0.010×IHA+ 0.727×IHD－ 0.009×ABR. Conclusion  Pentacam is important in the early diagnosis of clinical keratoconus eyes and subclinical keratoconus.

Objective  To evaluate the long-term efficacy of intravitreal Bevacizumab （IVB） combined with trabeculectomy and panretinal photocoagulation （PRP） in the management of neovascular glaucoma. Methods  It was a retrospective case series study. Eighteen eyes of 17 patients with neovascular glaucoma were included. Patients first received an intravitreal injection of Bevacizumab （1.25 mg in 0.05 ml）. Trabeculectomy with intraoperative mitomycin C was then performed after the complete regression of neovascularization of the iris （NVI）. PRP or supplementary photocoagulation was performed postoperatively. Compare the intraocular pressure （IOP） pre-IVB， pre-trabeculectomy and 1 week， 1 month， 3 months， 6 months， 12 months after trabeculectomy and the final visit. In addition， pre-ＩＶＢ visual acuity （VA） was compared to VA at the final visit. The follow-up period ranged from 12 to 32 months， mean 20.5±7.4 months. Data were analyzed with paired t test and one-way ANOVA. Results  NVI completely regressed in 18 of the eyes after IVB. The mean time for regression was 3.7±1.4 days （range from 2 to 7 days）. Pre-ＩＶＢ mean IOP was 51.9±10.9 mmHg， with 3.9±0.7 anti-glaucoma medications， and the mean logMAR VA was 2.26±0.43. Mean IOPs were 45.2±7.1， 8.6±2.1， 13.9±6.3， 16.5±6.9， 17.7±7.2， 19.2±7.8， 16.1±3.7 mmHg before trabeculectomy and at postoperative 1 week， 1 month， 3 months， 6 months， 12 months and the final visit， respectively. The reduction between pre-trabeculectomy IOP and pre-IVB IOP was statistically significant （t=5.437， P<0.05）. The reduction between post-trabeculectomy IOPs and pre-trabeculectomy IOP was statistically significant （F=64.79， P<0.05）. At the final visit， only 3 eyes were using anti-glaucoma medications， and the mean LogMAR VA was 2.1±0.6. The change in the mean LogMAR VA was not statistically significant. Recurrence of NVI occurred in 4 eyes， two of which received ciliary photocoagulation. The complete success， qualified success and failure at the final visit was 13 eyes， 3 eyes and 2 eyes， respectively. Conclusion  IVB combined with trabeculectomy and PRP is an effective method for controlling intraocular pressure in NVG over the long term.

Objective  To observe the changes in visual function after photodynamic therapy （PDT） and PDT combined with an intravitreal injection of Avastin for macular choroidal neovascularization （CNV） secondary to pathological myopia （PM）. Methods  Thirty-eight patients （38 eyes） with active CNV secondary to PM were included in a retrospective case series study. Twenty-one patients （21 eyes） were treated with PDT （PDT group）， while 17 patients （17 eyes） were treated with PDT combined with an intravitreal injection of Avastin （1.25 mg） （combination group）. All patients were assessed by an early treatment of diabetic retinopathy study （ETDRS） chart， optical coherence tomography （OCT） and MP-1 microperimetry before and 1， 3， and 6 months after treatment. Results were recorded and compared for the number of recognized letters， foveal nerve fiber layer thickness and macular median sensitivity （MS） within a central 20° area. Treatments were repeated if CNV leaked again. Data were analyzed using independent samples t test and paired t test. Results  Six months after treatments， the numbers of recognized letters had increased， foveal retinal thickness had decreased and MS had increased in both the PDT group and combination group， and the differences were statistically significant （PDT group： t=-4.45， 10.72， -8.62， P<0.01； combination group： t=-9.28， 8.72， -11.54， P<0.01）. In the following month （7 months after treatment）， the differences in the number of recognized letters and foveal nerve fiber layer thickness were not statistically significant between the PDT group and combination group （P>0.05）， while the differences in MS were statistically significant （t=-2.86， -2.15， -2.50， P<0.05）. Conclusion  PDT combined with an intravitreal injection of Avastin could effectively stabilize and improve the macular median sensitivity for CNV secondary to PM.

Objective  To explore the effect and mechanism of vascular endothelial cadherin （VE-cadherin） on the development of experimental corneal neovascularization. Methods  This was an animal experimental study. Mouse corneas were burned by NaOH to induce corneal neovascularization. The gene expression of VE-cadherin in burned corneas was examined by RT-PCR. The neutralizing anti-VE-cadherin antibody was locally administrated 1 week after the alkali injury and the formation of corneal neovascularization was examined 3 weeks after the injury by corneal whole mount staining with CD31. The mRNA expression of caspase-3 in burned corneas was detected by RT-PCR and the number of apoptosis neovascular endothelial cells in corneas was examined by FCS （flow cytometry）. The effect of VE-cadherin on human retinal endothelial cells （HRECs） tube formation was detected in vitro. Data were analyzed statistically with a two-tailed Student′s t-test. Results  Compared to the control group， the group treated with the neutralizing anti-VE-cadherin antibody showed significantly decreased corneal neovascularization. RT-PCR confirmed that neutralizing anti-VE-cadherin antibody treatment resulted in an increase of caspase-3 expression in corneal tissue. FCS revealed that antibody treatment resulted in increased intracorneal apoptosis neovascular endothelial cells. In addition， the tube formation ability of HRECs was found to be significantly inhibited by neutralizing antibody in vitro. Conclusion  VE-cadherin plays vital roles in experimental corneal neovascularization by down-regulating caspase-3 mRNA expression， reducing the number of apoptic cells and promoting cell-cell adhesion.

Objective  To observe the changes in oculomotor parameters after vision therapy and assess the vision therapy effect on relieving the symptoms of asthenopia and improving binocular vision function. Methods  In a retrospective case series study， 121 asthenopic patients aged 8 to 27 years （average 15.5±5.2 years） were recruited from the Optical Center of Tianjin Eye Hospital. Sixty-two of them were males and 59 were females. All patients had routine eye examinations to exclude eye disease. Personalized vision therapy was performed based on the results of binocular vision examination and refraction with a phoropter. The oculomotor parameters were assessed after 9 weeks′ vision therapy. All data were statistically analyzed by a paired samples t test. Results  The accommodative amplitude (t=-9.015， P＜0.01)， positive relative accommodation (PRA， t=9.569， P＜0.01)， negative relative accommodation （NRA， t=-6.719， P＜0.01) and accommodative convergence/accommodation （AC/A ratio， t=-3.716， P＜0.01) were significantly improved. There was no difference in far exophoria before and after therapy， while near exophoria was significantly reduced (t=-3.716， P＜0.01). There was no difference in accommodative lag after therapy. Conclusion  The oculomotor parameters accommodative amplitude， NRA， PRA， near phoria and AC/A ratio improved after reasonable vision therapy. Visual fatigue symptoms were relieved remarkably.

Objective To explore the differences and agreements between Sirius corneal topography and a keratometer in the measurement of corneal curvature before laser in situ keratomileusis （LASIK） in patients with myopia. Methods This was a prospective control study. One hundred and seventy eyes of 85 patients with myopia were selected at The People′s Hospital of Shaoxing. Measurements of corneal curvature were taken with both Sirius corneal topography and a keratometer. A paired samples t-test and Pearson linear correlation were used for statistical analysis， and a Bland-Altman analysis was used to evaluate the consistency of the two methods of measurement. Results The corneal curvature K1 values measured by Sirius corneal topography and a keratometer were 42.41±1.25 D and 42.33±1.28 D， K2 values were 43.36±1.38 D and 43.56±1.38 D， and （K1+K2）/2 values were 42.88±1.28 D and 42.92±1.29 D， respectively， indicating significant differences （t1=5.241， P＜0.01； t2=-9.936， P＜0.01； taverage=-3.021， P＜0.01） and significant linear correlations between K1 and K2 （r1=0.989， P＜0.01；r2=0.981， P＜0.01； raverage=0.990， P＜0.01）. The differences between Sirius corneal topography and keratometry measurements of corneal curvature for K1 and K2 values and the differences in average corneal curvature （K1+K2）/2 were 0.08 D， -0.20 D and -0.04 D， respectively. The differences between standard deviations were 0.1897 D， 0.2644 D and 0.1790 D and the 95% limits of agreement were （0.45 D， -0.30 D）， （0.32 D， -0.72 D） and （0.31 D， -0.39 D）. There were 2.4%（4/170）， 3.5（6/170） and 4.7%（8/170） points for the 95% limits of agreement， and consistency within the bounds of the maximum differences were 0.44 D， 0.68 D and 0.38 D， respectively. Conclusion Sirius corneal topography and keratometry show good agreement in the measurement of corneal curvature in patients with myopia. The values can be used interchangeably.

Objective  To evaluate toric intraocular lens （IOL） implantation as a treatment for regular corneal astigmatism during phacoemulsification. Methods  This was a retrospective analysis of a series of cases. Twenty-one eyes of 20 patients with both cataract and corneal astigmatism were implanted with toric IOLs after phacoemulsification. Outcome measures were uncorrected distance visual acuity （UDVA）， postoperative refractive cylinder， toric IOL axis rotational stability and complications. A paired t-test was used for data analysis. Results  The patients were followed up for 12 to 24 months （average 15.5±2.3） postoperatively， mean UDVA （logMAR） was 0.20±0.08 （1 week）， 0.19±0.06 （1 month）， 0.17±0.07 （12 months）， which represented a significant increase. The UDVA was better than 0.1 in 5 eyes （24%） and 0.3 in 18 eyes （86%）. Twelve months after surgery， the mean IOL misalignment was 4.31°±1.57°. IOL misalignment was less than 5°in 18 eyes （86%） at last observation. Conclusion  Implantation of a toric IOL during cataract surgery is effective， predictable and safe for correcting corneal astigmatism.

The increasing high prevalence of myopia has become a global risk factor for ocular disease in youths. However， the pathological mechanism inducing myopia is still unclear. Most research focuses on genetic and environmental factors. In this paper， the environmental factors involved in myopia are reviewed. These factors can provide a new target for controlling the development of myopia.