Human vision for spatial pattern depends on information processes in the visual system for several basic physical variables, such as luminance, spatial frequency (or size), contrast and orientation, which determine characteristics of the pattern. Therefore, assessment of visual performance or visual quality needs to systematically measure the ability of the visual system in response to these variables. Because visual acuity only tests the resolution power under high luminance and high contrast, techniques capable of comprehensively assessing visual ability, such as the contrast sensitivity and contrast visual acuity tests, have been developed and widely applied in both eye research and clinical practice. Studies have shown that visual test under varied contrasts could be effectively used to ①diagnose many common eye diseases in the early stage and monitor effects of ophthalmic intervention and treatment; ②diagnose some specific visual disorders; and ③assess problems in daily performances which are associated with visual defects. Due to its highly standardization, and superior reliability, repeatability and accuracy in visual measurement,computerized technique will be the method for assessing visual performance in the future.

Objective To analyze the changes of the modulation transfer function (MTF) with or without different mode higher order aberration in normal myopic eyes. Methods Two hundred and fifty-five patients (255 eyes) were included. An aberrometer with Hartmann-Shack sensor was used to measure the monochromatic aberration of eyes. MTF of optical system were calculated at various pupil sizes (3 and 6 mm) respectively and the difference between MTF with whole high order aberrations and MTF without different Zernike mode (C3-3-C33,C40) and different mode of higher-order aberration (S3, S4, S5, S6) with paired-t test. Results The MTF values improved at all spatial frequency [5-60 cycles per degree, (c/d)] without C3-3-C33, C40 respectively both at 3 mm and 6 mm pupil (P＜0.01). As for the effect of each Zernike mode, for a 3 mm pupil, MTF values got the most improvement without C3-1 and C3-3, following with without C31 and C33, and least without C40; for a 6 mm pupil, the improvement of the MTF without C40 was the most, secondly without C3-1 and C3-3,and thirdly without C31 and C33. As for the effects of each order aberrations, for a 3 mm pupil, MTFvalues got significantly improvement without S3 and S4 at all spatial frequency (5-60 c/d) (P＜0.01);for a 6 mm pupil, all MTF values got significantly improvement without S3, S4, S5 and S6 respectively at all spatial frequency (5-60 c/d) (P＜0.01), and without S3 and S4, MTF value increased more than without S5 and S6. Without S3, MTF value increased more than without S4 when the spatial frequency was 20 c/d or lower, and there were no significantly differences between MTF values without S3 and without S4 when the spatial frequency was higher than 20 c/d. MTF value decreased by a constant speed with the spatial frequency increasing at a 3 mm pupil, while at 6 mm pupil, MTF value decreased sharply below 30 c/d, and keep relative stable more than 30 c/d.Conclusion ①The MTF values improve at all spatial frequency (5-60 c/d ) without C3-3-C33 and C40 respectively at different pupil size.

Objective To investigate the influence of intraocular lens (IOL) decentration and tilt on high-order aberrations in pseudophakic eyes. Methods Sixty-six patients (84 eyes) with senile cataract were scheduled to have phacoemulsification and IOL implantation. Foldable IOL were implanted, which included Acrysof SA60AT (Alcon), Sensar AR40e (AMO), XLSTABI (IOLTECH)and QUATTRO SE (Corneal). The patients were examined 3 months after surgery. The decentration and tilt of the IOL were quantitated using Scheimpflug videophotography system (Pentacam, Oculus)and image-analyzing approaches. The high-order aberrations were measured using a Hartmann-Shack aberrometer (WASCA Analyzer, Zeiss) over a 3 mm or 5 mm pupil diameter. The correlations between high-order aberrations and IOL decentration or tilt were tested using Pearson's correlation coefficient. Moreover, the relationship between IOL decentration, tilt and high-order aberrations were assessed with stepwise multiple linear regression model. The correlations between Snellen visual acuity and IOL decentration or tilt were tested using Spearman rank correlation coefficient. Results For a 3 mm aperture diameter, the correlations between IOL tilt and total high-order aberrations (r=0.3488,P=0.0022) or coma-like aberrations (r=0.3880, P=0.0006) were positive, while the correlations between IOL tilt and spherical-like aberrations (r=0.0800, P=0.4951), secondary coma-like aberrations (r=0.2045, P=0.0784) or secondary spherical-like aberrations (r=0.1110, P=0.3431) were not significant.For a 5 mm aperture diameter, the correlations between IOL tilt and total high-order aberrations (r=0.2861, P=0.0128), coma-like aberrations (r=0.3298, P=0.0039) or secondary coma-like aberrations (r=0.2704, P=0.0190) were positive, while the correlations between IOL tilt and spherical-like aberrations (r=0.1482, P=0.2045) or secondary spherical-like aberrations (r=0.1460, P=0.2114) were not significant. For a 3 mm or 5 mm aperture diameter, the correlations between IOL decentration and total hig

Objective To discuss the visual function and subjective parameters in patients who underwent implantation of ReSTOR apodized diffractive multifocal intraocular lens on both eyes.Methods This was a retrospective study. Forty eyes of 20 patients received implantation of ReSTOR multifocal intraocular lens (observe group) and 40 eyes of 20 patients received implantation of IQ monofocal intraocular lens (control group) participated in the study. All patients were assessed at 3 months postoperatively under the same luminance conditions, far, intermediate and near uncorrected and corrected visual acuity, near stereoacuity were observed, a questionnaire survey was conducted.Data was examined by rank sum test. Results At 3 months postoperation, uncorrected intermediate visual acuity, intermediate visual acuity after distant correction, uncorrected near visual acuity and near visual acuity after distant correction in observe group were significantly higher than those of control group (Z=2.978, P＜0.01; Z=3.040, P＜0.01; Z=3.471, P＜0.01; Z=3.098, P＜0.01).The stereoacuity of the observe group was much better than that of the control group, which had significant meaning (Z=2.264, P＜0.05) and patients in the observe group had higher satisfaction in near and intermediate visual acuity. Conclusion Binocular implantation of multifocal intraocular lens could provide patients with good vision, as well as good stereoacuity.

Objective To evaluate and compare the methods of measurement and statistical analysis of visual acuity (VA) in articles published in the Chinese Journal of Ophthalmology (CJO)and the American Journal of Ophthalmology (AJO). Methods The full text of articles published in CJO and AJO from 2003 to 2005 were obtained. Data were collected including if type of VA chart used was mentioned, the unit of VA, whether the unit of VA was converted into a logarithmic unit,descriptive and inference statistics of VA, and whether figures describing VA and tables listing VA data were used. The proportion of every method used in the articles of either journal were calculated and compared. Results There were 400 papers published in CJO during the three years, 132 (33.0%)mentioned VA; 616 papers published in AJO, 358 (58.1%) mentioned VA. Seventy-seven point three percent and 50.8% of the articles in CJO and AJO, respectively, did not describe the type of VA chart. 91.7% of the articles in CJO used a decimal unit for VA, including 2.6% of which were converted into a logarithmic unit, and 3.8% of the articles used a logarithmic unit directly. In comparison, 74.9% of the articles in AJO used a fraction unit for VA, including 29.4% of which were converted into a logarithmic unit, and 14.0% of the articles used a logarithmic unit directly.The proportions of mean, standard deviation and median used in CJO articles were 8.3%, 6.1% and 0%, respectively, compared to 31.0%, 16.8% and 14.0%, respectively, of AJO articles. Analysis of variance or t-test appeared in 5.3% of CJO articles, and 19.0% in AJO articles. Descriptive figures and tables listing all cases of VA data were found in 2.3% and 6.8% of CJO articles, respectively,compared to 14.2% and 24.9% of A JO articles, respectively. Conclusion Decimal units for VA were used in the majority of CJO articles, while both fraction and logarithmic units were used in AJO articles. More statistical analysis was used in AJO articles than those in CJO, such as mean,standard deviation, median, t-tes

Objective To compare visual acuity (VA) related issues in Chinese ophthalmological journals by analyzing papers published in 4 journals during 2008. Methods Papers published in the Chinese Journal of Ophthalmology, the Chinese Journal of Practical Ophthalmology, the Chinese Journal of Ocular Fundus Disease, and the Chinese Journal of Optometry and Ophthalmology were surveyed. The characteristics of each paper were recorded, including whether the paper mentioned VA, whether the VA mentioned was the result of the paper, the kind of visual acuity chart used,details of the VA test, distance and near VA, correction methods, VA score, and descriptive statistics of the VA. Excel 2003 software was used for data sorting and percentage calculations.Results A total of 1111 papers were published in these 4 journals in 2008, 476 papers mentioned VA, 237 papers had VA as the result. In these 237 papers, 51 mentioned the type of visual acuity chart, 43.1% used the International Standard Visual Acuity chart, 29.4% used the Standard Logarithmic Visual Acuity Chart; 155 papers specified correction methods, best correction predominated; 213 papers specified VA score, 75.1% used a decimal notation, 10.1% used a 5-grade notation; descriptive statistics of the VA data was presented in 216 papers, VA was graded in 66.7% papers, 24.5% were expressed in mean± standard deviation. Conclusion After statistical analysis, papers published in domestic ophthalmology journals have some deficiencies in presenting details of the VA test, especially descriptive statistics, and some mistakes are found. Basic knowledge of optometry and ophthalmology training should be emphasized and enhanced, and editors of ophthalmological journals should also pay attention to these aspects.

Objective To evaluate the differences in contrast visual acuity (VA) under different background illuminations in patients who had been implanted with the ReSTOR aspheric multifocal intraocular lens (MIOL)(SN6AD3). Methods This was a prospective study. Forty-two eyes of 26 patients who had received ReSTOR MIOL (SN6AD3) implantation after cataract extraction were enrolled. Six months postoperatively, best corrected distance VA was measured at 4 contrast levels (100%, 25%, 10%, 5%) under 3 background illumination levels (250 cd/m2, 85 cd/m2, 25 cd/m2)using a multi-functional visual acuity tester (MFVA-100). Dunnett's T3 multiple comparison was used for statistical anaylysis. Results The mean VA at the 4 contrast levels (100%, 25%, 10%, 5%)under 250 cd/m2 background illumination were 0.01, 0.23, 0.40 and 0.62; under 85 cd/m2, the mean VA were 0.02, 0.26, 0.46 and 0.74; under 25 cd/m2, the mean VA were 0.08, 0.32, 0.49 and 0.63. At the same background illumination level, there was a statistically significant decrease in VA with a decrease in contrast level (P＜0.05). While at the same contrast level, there were no statistically significant differences in VA at different background illuminations (250 cd/m2, 85 cd/m2,25 cd/m2)(P＞0.05). Conclusion Implantation of the ReSTOR MIOL (SN6AD3) offers excellent VA under high luminance (250 cd/m2), normal luminance (85 cd/m2) and moderate luminance (25 cd/m2).VA is affected much more by the contrast of the visual target rather than background illumination.

Objective To evaluate the biological response of biodegradable scaffold material porcine type Ⅰ atelocollagen in rabbit cornea in order to study the feasibility of corneal reconstruction using this material. Methods Forty rabbits were divided into 5 groups based on observation time with 8 rabbits in each group. One eye was used as the experimental eye, the other eye was used as the normal control eye. Scaffold material was transplanted into the anterior lamellar of rabbit corneas.Observations were performed with the naked eye and slit lamp biomicroscopy twice a week after the operation within 1 month, and after then, observations were performed once a month. Transparency and neovascularization scores of the cornea were recorded. HE histological examinations were done on the day 3, day 14 and the 1st, 3rd and 6th month, and the immunohistochemistry of the epithelial cell marker protein K3 was assessed. Statistical methods were used to test for related samples and to test for two comparison samples. Results The transparency of the cornea gradually increased (P＜0.05). The extent of corneal neovascularizazion gradually increased, reached a peak in the 1st month,and then gradually decreased (P＜0.05). The difference was not statistically significant when the transparency and neovascularization of the cornea 6 months postoperatively were compared to normal eyes (P＞0.05). Conclusion The scaffold material has better biocompatibility, and will become a new scaffold material for corneal transplants after further improvement.

Objective To investigate the protective effect of erythropoietin (EPO) encapsulated in poly (L-lactic-co-glycolic acid) (PLGA) microspheres on damaged retinal ganglion cell (RGC) by intravitreal injection after optic nerve crush. Methods Adult SD rats were selected to establish an optic nerve crush model. Immediately after the crush, the animals received intravitreal doses of 10 IU EPO of EPO-PLGA microspheres (EPO-PLGA group), 10 IU EPO (EPO group), blank PLGA microshperes (PLGA group), and PBS (PBS group) or untreated (untreated group). Five days and 2 weeks after crush, apoptotic RGC were detected with TUNEL labeling in frozen retinal sections.Twenty-three days after optic nerve crush, retinal ganglion cells were retrogradely labeled by injecting DiI into the superior colliculi of the brain. The animals were scarificed 4 weeks after the crush. Mounted retinal photographs were assessed for the number of surviving RGC. Six rats were prepared from each group at every time point. Results TUNEL-positive cells could be identified in all groups 5 days and 2 weeks after the operation. However, there were fewer in both the EPO-PLGA and EPO groups. Retinal mounts revealed that the density of RGC was (2387.7±164.9)cells/mm2 in normal adult rats, and (748.3±58.8)cells/mm2 in the untreated group, (1296.7±157.6)cells/mm2 in the EPO-PLGA group, (1418.5±154.9)cells/mm2 in the EPO group, (821.7±52.1)cells/mm2 in the PLGA group, and (804.4±86.4)cells/mm2 in the PBS group 4 weeks after the operation. Compared to the untreated group, the EPO-PLGA and EPO groups showed a significant neuroprotective effect on RGC (P＜0.01), and no significant differences were found between these two groups (P=0.065).Conclusion The protective effect of EPO-PLGA microspheres on RGC is equal to EPO, which provides evidence for further study on the long-term neuroprotective effect of EPO-PLGA microspheres.

Objective To construct and express the prokaryotic recombinant vectors for rat oncomodulin gene, and to identify their expression. Methods Peritoneal macrophages were extracted from six selected SD rats and activated. Total RNA was extracted from activated rat macrophages,and design primers to obtain whole length of oncomodulin gene by RT-PCR. The oncomodulin gene was cloned into pUC57 vector. Then the gene was inserted into pET-22b(+) expression vector and and the inserting plasmid was transformed into Escherichia coli. host DH5α. The positive clone was characterized by PCR examination of bacterium liquid pET-22b(+)/OM and DNA sequence analysis.Then the recombinant plasmids were transformed into E. coli BL21 and the expressions of recombinant plasmids were induced by adding isopropylthiogalactoside (IPTG). The expression product was identified by Western blot assay. Results The target DNA sequence of oncomodulin was obtained by RT-PCR which was about 350 bp length, exactly in accordance with prospective. The positive clones about 500 bp length were obtained by PCR examination of bacterial colony pET-22b(+)/OM plasmid, which were consistent with the expected size. The result of DNA sequence analysis for recombinant plasmids extraction revealed that the gene encoding oncomodulin was coloned into vector pET-22b(+)accurately. The protein bands with the molecular weight of about 11.7 kD were induced by IPTG in the recombinant plasmids. Western blot assay revealed that the protein was OM. Conclusion The prokaryotic recombinant vectors for rat oncomodulin gene is successfully constructed and expressed. It might provide a foundation for further study on the functional test of oncomodulin that can promote regeneration of damaged optic nerve.

Objective To investigate the changes in tear film and ocular surface after epipolis laser in situ keratomileusis (Epi-LASIK), and to evaluate the relationship with haze and refractive regression. Methods Epi-LASIK was performed on 214 eyes with low and moderate myopia and 154 eyes with high myopia. Tear film break up time (BUT), Schirmer Ⅰ test and corneal fluorescence staining were observed before and after the operation. Corneal haze and refractive regression were also examined. The results were analyzed with t test and correlation analysis. Results Haze was found in 87 eyes (23.6%) 1 month after the operation, in 69 eyes (18.8%) 3 months after the operation, and in 48 eyes (13.0%) 6 months after the operation. Refractive regression was found in 37 eyes (10.1%) 6 months after the operation. Haze and refractive regression were only found in high myopia. The values of BUT decreased in all eyes after Epi-LASIK. There was a significant decrease in eyes with high myopia 1 month, 3 months and 6 months after the operation (t=6.82, 7.51,6.73, P＜0.05). The Schirmer Ⅰ test showed no differences when all eyes were compared before and after the operation, and there were no differences between the two groups after the operation (P＞0.05). There was more fluorescence staining on the corneas of eyes with high myopia compared to eyes with low and moderate myopia (t=5.48, 5.23, 7.67, P＜0.05). There was a positive correlation between the occurrence of haze and a decrease in the scope of BUT (r=0.892), and there was a positive correlation between the occurrence of haze and the amount of fluorescence staining on the cornea after the operation (r=0.881). There was a greater decrease in tear film stability in eyes with refractive regression 6 months after the operation (t=5.50, P＜0.05). Theamount of fluorescence staining on the cornea was also greater in eyes with refractive regression 6 months after the operation (t=5.27, P＜0.05). Conclusion The changes in tear film and the ocular surface are associated with haze and refractive reg

Objective To evaluate the differences in central corneal thickness, curvature and endothelium between patients wearing soft contact lenses (SCL) and those wearing rigid gas permeable contact lenses (RGPCL). Methods Three hundred eyes of 172 patients with no eye disorders except ametropia were divided into two groups: SCL group and RGPCL group. All patients had to wear contact lenses at least 6 hours a day. Corneal thickness, corneal endothelium, corneal curvature and topography were measured and comparisons were made between baseline measurements and the measurements taken at various intervals: before wearing, 6 months, and 3 years after wearing the contact lenses. Results Central corneal thickness after 3 years of SCL wear was (27.1±-0.8)mm less than before wearing the SCL (P＜0.05); central corneal thickness after 3 years of RGPCL wear was (3.1±2.2)mm less than before wearing the RGPCL (P＞0.05), but there were no differences between the SCL and RGPCL groups prior to and 6 months after the lenses wear (P＞0.05). However, there were obvious differences at 3 years (P＜0.05). There were no obvious differences in corneal curvature in the SCL group (P＞0.05). But more differences betweeen wearing before and 3 years after in RGPCL group. The corneal endothelium in the SCL group was partially reduced (368.5±31.5)cells/mm2 and (140.2±5.6)cells/mm2 was reduced in the RGPCL group, there was a significant differencesbetween the 2 groups (P＜0.05). Conclusion This study shows that RGPCL affect the corneal endothelium less. Therefore, RGPCL can be worn safely over the long term.

Objective To analyze the results from ophthalmic B-scan ultrasonography for consistency, sensitivity and specificity in the diagnosis of fundus disease. All data from clinical analysis and ultrasonography were compared to support the use of B-scan as a reference for assessing refractive media opacity in fundus disease. Methods One thousand ninety-two eyes with refractive media opacity were examined with conventional B-scan ultrasonography from June 2006 to September 2008, and the data were reviewed and analyzed to evaluate for consistency, sensitivity, specificity,and the positive and negative predictive values between the B-scan ultrasonography results and the final diagnosis of fundus disease. The results of the B-scan ultrasonography were evaluated for consistency, reliability, and authentic assessment. Results The coincidence rate of B-scan ultrasonography for fundus disease was 85.07%, and the adjusted agreement was 84.15%; the Kappa index was 0.6802; The sensitivity was 84.51%, the specificity was 85.37%, and the Youden index was 0.70; the positive likelihood ratio was 5.78, and the negative likelihood ratio was 0.18. Fundus disease found out by B-scan most were diabetic retinopathy, trauma, and age related degeneration;the disease misdiagnosed easiest were retinopathy, optic neuropathy, and retina edema; the disease missed diagnosed easiest were age related degeneration and diabetic retinopathy. Conclusion Ophthalmic B-scan ultrasonography used in eyes with refractive media opacity has a high clinical coincidence rate in diagnosing fundus disease, and can be used as a guide for therapy and prognosis.

Objective To observe the clinical results of Akreos adaptable foldable intraocular lens (IOL) implantation when the posterior capsule has a large rupture. Methods Thirty-one cataract cases (31 eyes) with a large rupture in the posterior capsule underwent Akreos adaptable foldable IOL implantation with crossed bag/sulcus fixation. Of these, 9 had traumatic cataracts and 22 had age-related cataracts. A continuous curvilinear capsulorhexis (CCC) technique was used and the diameters were about 5.0-5.5 mm. When the posterior capsule rupture was found during the operation, after the cortex or vitreous loss was cleanly managed with a vitreous cutter, the IOL was first implanted into the anterior chamber, the two haptics from the opposite angles were then pressed into the capsular bag. The remaining haptics were left on the surface of the anterior capsule. Thus,the IOL was implanted with crossed bag/sulcus fixation. Visual acuity, visual symptoms, the position and fixation of the IOL, inflammatory reaction and posterior capsule opacity were assessed postoperatively. All cases were followed up for at least 3 months. Results The visual acuity of all surgical eyes was improved after the operation. The best corrected visual acuity was 0.1-0.2 in 4eyes, 0.3-0.4 in 5 eyes, and ≥0.5 in 22 eyes. The implanted IOL remained centered and stable in all surgical eyes and no displacement was observed. The optics of the IOL and the posterior capsule holes were clear without fibroplasias. The pupils were centered and no posterior synechia, severe inflammation, IOL-related complications or glare occurred. Conclusion While a posterior capsule with a large rupture appeared, good CCC is still possible during the operation. The use of crossed bag/sulcus fixation to implant the Akreos adaptable foldable IOL is easy and safe. The IOL position is centered and no displacement occurred after the implantation. The results show good biocompatibility and stability with low postoperative inflammation and low posterior capsule opacity (PCO) due to it

Objectivt To study the value of the application of artificial iris recognition for laser in situ keratomileusis (LASIK). Methods A total of 314 patients with myopic astigmatism were recruited for the study. The patients was divided into 2 groups by whether or not artificial iris recognition was taken during the operation. The patients with artificial iris recognition were group Ⅰ,and the others were group Ⅱ. There were 162 patients (205 eyes) in group Ⅰ, astigmatism range -1.0- -3.0(-1.56±0.79)D, 110 males (141 eyes), 52 females (64 eyes), and mean age (22.6±5.2)years. There were 152 patients (205 eyes) in group Ⅱ, astigmatism range -1.0--3.0(-1.48±0.65)D, 101 males (135 eyes), 51 females (70 eyes), mean age (23.4±5.8)years. Astigmatism and axial direction were measured 6 months postoperatively. The differences between the two techniques were compared based on astigmatism and its axis. Results Postoperative astigmatism in group Ⅰwas (-0.73±0.34)D, and in group Ⅱ was (-0.68±0.53)D. There were no significant differences between the two groups (t=-1.200, P=0.231). Postoperative axial direction in group Ⅰ was (13.25±13.09)° and in group Ⅱ was (17.48±17.93)°. There were significant differences between the two groups (t=2.755, P=0.006). Conclusion Artificial iris recognition can help to correct astigmatism and axial direction in LASIK, and it can be applied to refractive surgery in general.

Objective To investigate pseudoptosis with a vertical deviation of the extraocular muscles and to evaluate different outcomes based on imaging and clinical findings. Methods This was a retrospective study that included 12 patients who were treated between August 2007 and October 2009. Preoperative ophthalmologic examination and orbital CT scan were performed. The choice of surgical procedure was based on the results of the clinical evaluation and CT imaging.Results Of the patients, 75%(8/12) showed significant changes in their extraocular muscles. In patients' coronal images, the maximum cross-sectional area of the superior rectus-levator complex in the affected eyes became thinner than that of the contralateral eyes [(15.11±7.11)mm2 vs (24.93±6.43)mm2, P＜0.01]. The vertical misalignment was completely corrected in all patients. Pseudoptosis totally disappeared in 10 patients and partially improved in 2 patients. Conclusion Either congenital hypoplasia or paresis of the superior rectus-levator complex in the affected eye may be the main cause of pseudoptosis with vertical deviation. Surgical procedures for pseudoptosis with vertical deviation must be individualized according to the clinical evaluation and imaging. CT imaging of the extraocular muscles may provide clinically valuable information for choosing the appropriate surgical procedure.

With the development of intraocular lens (IOL) design, patients ask for better visual quality after cataract surgery. Now we have achieved some improvement in design of achieving full range vision: the first is Monovision program posed at early stage, which the two eyes are implanted with monofocal IOL; with the development of multifocal IOL, bilateral implantation with multifocal IOL of the same size or with multifocal IOL of the different size; with the coming up of accommodating IOL, bilateral implantation with accommodating IOL becomes popular. The present paper is a review of the design of achieving full range vision after cataract surgery, and its development history, design principle, and its advantage and limitation.