Refractive surgery has become a common technique for the correction of refractive error. The goal of modern refractive surgeries is not only to improve unaided vision， but also to attain natural and nearly perfect visual and optical quality. This article reviews the factors that degrade visual quality such as higher?鄄order aberrations and their optical characteristics after various corneal refractive surgeries and other procedures， risk factors for night vision complaints and for subjective satisfaction. The main approaches for acquiring better visual quality are introduced and described， including the choice of suitable surgical procedure （femtosecond laser and surface ablation）， better ablation algorithms， novel technologies， etc.

Objective  To evaluate the safety， efficacy， and predictability of mechanical automated microkeratome laser in situ keratomileusis(LASIK) in eyes underwent radial keratotomy (RK). Methods  In this retrospective case-series study， 38 eyes of 27 patients who had undergone RK were performed automated microkeratome One Use-Plus LASIK， including 20 myopic eyes and 18 hyperopic eyes， among them 22 eyes with irregular astigmatism. The patients were 11-24 years after RK， 38-53 years old， The mean spherical equivalent was -9.50-+4.25 D， the number of RK incisions was 8-32， the cornea thickness was 512-557 ?滋m. An Allegretto system was used.  Data were analyzed using a paired samples t test and a one-way ANOVA. Results  No free flap， incomplete flap and flap or eye ball broken  happened during the surgeries. The flap thickness was (102.0±7.7)?滋m. The stromal bed was smooth， 9 eyes with corneal epithelial border defect was found and 7 eyes with cornea bleeding. The percentage of uncorrected visual acuity equal to or better than preoperative best corrected visual acuity (BCVA) at 1 day， 1 week， 1 month and 6 months after surgery was 63%， 82%， 88% and 87%. Postoperative BCVA post surgery of all the 38 eyes were equal to or better than BCVA before surgery. Excursion or undersize of the operation field in 22 eyes which received corneal topography guided individual surgery was corrected in varying degree. The coma， total higher-order aberration were reduced obviously  after surgery (t=-3.70， 4.10， P<0.01). The significant difference of contrast sensitivity was found in the frequency of 3.0 c/d and 18.0 c/d(t=-2.45， -3.24， P<0.01). Conclusion  Automated microkeratome One Use-Plus LASIK is an effective and safe method to treat post-RK poor visual outcomes.

Objective  To analyze the clinical characteristics and effects of making thin corneal flaps using a modified oval ring in sub-Bowman′s keratomileusis (SBK). Methods  In this prospective case-series study， 36 patients (71 eyes) undergoing SBK had corneal flaps created with a modified oval ring and One Use-Plus （OUP） automatic microkeratome. The transverse diameter， longitudinal diameter， and pedicle width of the corneal flaps were recorded in surgery. Measurements of corneal flap thickness and stromal bed thickness were conducted after surgery using anterior segment optical coherence tomography （OCT）， recording intraoperative and postoperative complications. Data were analyzed with a paired samples t test and Pearson correlation. Results  The average transverse diameters and vertical diameters of the flap were （8.78±0.26）mm and （8.58±0.28）mm (t=－4.635， P<0.01)， respectively. The average pedicle width was （4.11±0.35）mm and the average corneal flap thickness was (111.1±7.6)μm. There were no significant differences between the two eyes of each patient. The corneal flaps were all made successfully on the first attempt and there was no bleeding or serious intraoperative or postoperative complications. All corneal flaps were in good alignment. Conclusion  A modified oval ring makes a cross-oval flap and reduces the incidence of bleeding from laser in situ keratomileusis. It is effective for correcting with-the-rule astigmatism， and has proven to be secure and stable.

Objective  To investigate the characteristics and relevant factors of intraocular straylight before and after sub-Bowman′s keratomileusis (SBK). Methods  This was a prospective clinical study. Straylight measurement was performed on 46 myopic and myopic astigmatism patients (92 eyes) before SBK surgery and 1 day， 1 week， and 1 month after surgery using Oculus C-Quant straylight meter. In 46 patients， there were 29 males and 17 females， the mean age was (24.0±5.4)years (range： 18 to 39 years)， and the mean preoperative spherical equivalent (SE) of refraction was (-6.70±1.50)D (range： -11.13 to -4.75 D)， with mean astigmatism of (0.68±0.58)D (range： 0 to 2.50 D). The mean keratometric value and central corneal thickness (CCT) were tested by Pentacam device. The data was analyzed for statistical significance by repeated measure ANOVA， paired t tests and Pearson correlation using SPSS 13.0 software. Results  Patients had a mean straylight of logarithmic value of the straylight parameter [log(s)]=(0.90±0.13) before surgery， which showed no significant correlation with spherical equivalent (SE)， keratometric (K) value， and CCT. After surgery， the mean straylight of [log(s)]=0.96±0.13， 0.98±0.10， and 0.99±0.09 at 1 day， 1 week， and 1 month postoperatively respectively. When comparing with preoperative straylight values， the difference did reach a statistical significance increase for various time points after SBK (F=24.94， P＜0.05). The individual postop-preop changes in straylight showed significant negative correlation with the preoperative values (r=-0.47， -0.67， -0.78， P<0.05)， and showed no significant relationship with intended refractive correction and ablation depth. Conclusion  Straylight values increases significantly at early time after SBK， which maybe influence visual performance at this time. Patients with lower preoperative straylight values present exacerbated elevation after SBK.

Objective  To investigate the distribution of the eye′s higher order aberrations in post-laser in situ keratomileusis (LASIK) patients with visual complaints， excluding patients whose complaints were due to overcorrection， undercorrection and eye disease. Methods  Refractive surgery was performed on 17 625 eyes of 8848 patients from January 1， 2006 to March 31， 2010 in Beijing Military General Hospital. In this retrospective case-control study， a total of 48 eyes of 40 cases with double vision， glare and other visual symptoms after LASIK (including the traditional group and wavefront-guided group)， excluding cases of overcorrection， undercorrection and eye disease were reviewed. As a result， there were 23 eyes of 18 cases in the traditional LASIK group and 25 eyes of 22 cases in the wavefront-guided LASIK group. Patients were observed for more than 3 months and refractive power stability was within the ±1.00 D range in both groups. The observation period for the wavefront-guided group was 10 months （4-26 months） and was 23 months for the traditional group (5-72 months). All patients were measured using a Hartmann-Shack wavefront sensor. The results for higher-order aberrations with 4-mm pupils were analyzed. The preoperative and postoperative results of the wavefront-guided LASIK group were compared (using a paired samples t test and Wilcoxon signed ranks test). The results between the wavefront-guided LASIK and traditional LASIK groups were also compared (using independent samples t tests and the Mann-Whitney test) to test for higher-order aberration root mean square （RMS） values， the distribution ratio of different aberration types in total higher-order aberrations and the dominant aberration changes （chi-square test）. Results  There were significant differences in higher-order aberrations in the wavefront-guided LASIK group when aberrations were compared before and after surgery： there was an 118% increase in total higher order aberrations (t=-11.485， P<0.01)； there was a 125% increase in third order aberration RMS values (Z=-6.125， P<0.01)； there was a 93% increase in fourth order aberration RMS values (Z=-6.154， P<0.01)； there was a 135% increase in fifth order aberrations (Z=-6.154， P<0.01)； there was a 114% increase in sixth order aberrations (t=-21.080， P<0.01). Vertical coma increased by 143% (Z=-6.154， P<0.01)， horizontal coma increased by 93% (Z=-6.154， P<0.01)， and spherical aberrations increased by 89% (t=-19.659， P<0.01). Trefoil varied less than the other types. 30° trefoil increased by 5% (Z=-6.154， P<0.01) and 0° trefoil increased by 35% (Z=-6.154， P<0.01). The results for the wavefront-guided LASIK group and the traditional LASIK group were also compared. Differences in total higer-order aberrations， third order aberrations， fourth order aberrations， vertical coma， horizontal coma， spherical aberration， 30° trefoil and 0° trefoilwere not statistically significant. But the postoperative fifth order aberrations (Z=-2.033， P=0.042) and sixth order aberrations (Z=-2.631， P=0.009) showed statistically significant differences when the two groups were compared. In addition， the proportion of third order aberrations was the highest among total higher-order aberrations and fourth order aberrations were second after LASIK. The differences between the two groups were not significant. But the differences in the proportion of fifth order aberrations (Z=-2.053， P=0.040) and sixth order aberrations (Z=-2.012， P=0.044) were statistically significant between the two groups. Coma aberrations accounted for 56% of the third order aberrations and spherical aberration accounted for 78% of the fourth order aberrations before and after wavefront-guided LASIK. But trefoil decreased significantly from 43% to 36% of the third order aberrations after wavefront-guided LASIK (t=2.285， P=0.027). The proportion of vertical coma was 44%， horizontal coma was 12% and spherical aberration was 40% among the dominant aberrations after wavefront-guided LASIK and the differences between preoperative and postoperative levels were statistically significant (χ2=7.891， P=0.048). The proportion of vertical coma was 30%， horizontal coma was 34% and spherical aberration was 21% among the dominant aberrations after traditional LASIK. There were no statistically significant differences between the two groups. Conclusion  Visual complaints after LASIK are closely related to the increase in higher-order aberrations. The RMS values of higher-order aberrations are generally higher than preoperative levels except for trefoil aberrations. The third order aberrations and the fourth order aberrations account for a large proportion of the higher-order aberrations. Coma and spherical aberration are especially important. Trefoil varis less than other types. Traditional LASIK is superior to wavefront-guided LASIK on the ablation of fifth order and sixth order aberrations. Coma and spherical aberration are the dominant aberrations in patients with visual symptoms after LASIK.

Objective  To investigate the predictability of ultra-thin corneal flap thickness created with VisuMax femtosecond laser in high myopia and to identify the factors affecting flap thickness. Methods  A prospective clinical study involved 21 eyes of 11 high myopia patients who underwent femtosecond laser in situ keratomileusis （LASIK）. The VisuMax femtosecond laser was used to create ultra-thin corneal flaps with an intended central flap thickness of 85 μm. The preoperative central corneal thickness (CCT) and residual stromal bed thickness (RST) after corneal flap lift were measured by ultrasound pachymetry. The actual flap thickness was calculated as the difference between preoperative CCT and intraoperative RST after flap lift. Pearson correlation analysis was used to compare actual flap thickness and data that included preoperative intraocular pressure， spherical equivalent refractive error (SE)， keratometry， horizontal corneal diameter and preoperative CCT. Results  The mean intraoperative corneal flap thickness was (96.0±10.5)μm for all eyes. Corneal flap thickness was not significantly correlated to preoperative SE， intraocular pressure， keratometry or horizontal corneal diameter， but was significantly correlated to preoperative CCT （r＝0.512， P=0.018). Conclusion  The thickness of ultra-thin corneal flaps created with VisuMax femtosecond laser in high myopia is essentially predictable. The intended 85 μm corneal flap thickness yields an actual flap thickness that is significantly correlated to preoperative CCT.

Objective  To evaluate the clinical effect and safety of esculin and digitalisglycosides eye drops in patients with asthenopia after laser in situ keratomileusis (LASIK) surgery. Methods  This was an open， multicenter， random and antithetical prospective clinical trial. Post-LASIK surgery patients were chosen from seven hospitals across China from July 2008 to January 2009. Some patients received esculin and digitalisglycosides eye drops and others served as controls. Symptoms of asthenopia， uncorrected visual acuity (UCVA)， refraction， amplitude of accommodation， lag of accommodation， accommodative sensitivity and positive/negative relative accommodation were compared between the two groups at different time points. A total of 195 patients (88 males and 107 females) were included in the study with a mean age of (25.4±5.9)years. Among the 195 patients， 109 were in the treatment group and 86 were in the control group. Data were analyzed using a nested ANOVA. Results  Blurred vision after reading (F=4.099， P<0.05) and headache or sickness following near work (F=4.344， P<0.05) improved in the treatment group compared to the control group. Accommodative sensitivity (left eye： F=5.895， P<0.05； right eye： F=7.440， P<0.05； both eyes： F=5.323， P<0.05) and negative relative accommodation (F=5.561， P<0.05) were also better in the treatment group. Conclusion  Esculin and digitalisglycosides eye drops can significantly alleviate the symptoms of asthenopia in patients following LASIK surgery. It can also improve the accommodative sensitivity and negative relative accommodation in post-LASIK surgery patients.

Objective  To compare postoperative visual function and quality after 3 different multifocal intraocular lenses （MIOLs） were implanted： REZOOM (refractive MIOL)， Tecnis ZMA00 (all optical diffractive MIOL) and Acri.Lisa 366D (refractive diffractive MIOL). Methods  This was a prospective case-control study. Forty eyes of 29 patients who underwent cataract phacoemulsification and MIOL implantation in Tianjin Eye Hospital cataract center were selected from September 2008 to March 2010. Fifteen eyes were implanted with REZOOM， 12 eyes with Tecnis ZMA00， and 13 eyes with Acri.Lisa 366D. Patients were reviewed after 3 months or more following surgery. Colenbrander Mixed Contrast Card Set vision test cards were used to measure intermediate and near visual acuity under the best corrected distance visual acuity. Then iTrace visual function analyzer checks were used to plot 5， 10， 15， 20， 25， and 30 c/d for modulation transfer function (MTF) and to measure intraocular aberrations as well as pupil diameter. Data were analyzed using a one-way ANOVA. Results  The differences in best corrected distance， intermediate， near visual acuity among the 3 groups were not statistically significant. Three months or more after MIOL implantation， all examined patients from the 3 groups had best corrected distance visual acuity with 20/25 or better visual acuity. Forty-seven percent， 42% and 54% patients in REZOOM， ZMA00 and Acri.Lisa 366D groups had intermediate visual acuities with 20/25 or better under the best corrected distance visual acuity. In corresponding group， 13%， 31% and 50% with 20/25 or better best corrected near visual acuity. Exccept for trefoil， There were statistically significant differences among the 3 groups in spherical and coma aberrations compared with the spherical intraocular lens （IOL） (Ar40e) and Tetraflex IOL. There were no statistically significant differences in MTF among the 3 groups except at 5 c/d. Conclusion  The differences among the 3 MIOLs for far visual acuity after surgery are not substantial. Performance for middle distance vision and near vision is good. The aspheric MIOLs， Tecnis ZMA00 and Acri.Lisa 366D， perform better with fewer aberrations and better MTF than the spherical design of the REZOOM.

Objective  To investigate the long-term surgical outcome of unilateral lateral rectus recession for small-to-moderate angle intermittent exotropia in children. Methods  Sixty-nine children with intermittent exotropia (15△-35△) who underwent unilateral lateral rectus recession during April 2009 to March 2010 were retrospectively reviewed. The exodeviations were measured by the alternate prism cover test at both distance (6 m) and near (33 cm) with fixation on accommodative targets. An amount of 7-10 mm unilateral lateral rectus recession was performed according to the quantity of distance deviation. The Worth 4-Dot test was employed both at distance and near fixation to assess central and peripheral fusion， respectively. The Titmus stereo test was used to assess stereoacuity. A successful alignment was defined as -8△-0△ in primary gaze while viewing distant and near targets. There was a minimum of 6 months follow-up period. Incomitance was defined as a change of more than 10△ from primary to lateral gaze. The data were analyzed with a chi-square test. Results  The successful rates in alignment at 1-3 days postoperative and final follow-up periods were 81% and 62%， and the undercorrection rates were 12% and 36%， respectively. The patients who underwent an amount of 9.5 mm and 10 mm unilateral lateral rectus recession had a higher undercorrection rate at the final followup. The number of patients with normal central fusion， peripheral fusion and stereoacuity at final examination increased statistically compared to the preoperative number (χ2=21.9， 14.0， 15.0， P<0.01). None of the patients had clinically significant lateral incomitance at the final followup. Conclusion  Unilateral lateral rectus recession is a safe and effective treatment for intermittent exotropia in children with exodeviation measuring 15△ to 25△.

Objective  To investigate the characteristics of the dark-adapted electroretinography (ERG) a-wave during development in normal rats. Methods  In this experimental study， the dark-adapted ERG of eight groups of Rcs-rdy+-p+rats at different ages (21， 25， 32， 35， 37， 46， 60 and 90 d)were recorded by a series of flashes (0.03， 0.95， 3 and 9.5 cd•s•m-2) using a RETI-scan system and gold-foil ring form corneal recording electrode and a stainless steel needle electrode custom made in the lab. Data were exported to the computer and processing by a Matlab 7.4 software， then were modeled with the solver model of Excel and two parameters of the a-wave were analyzed： the saturation a-wave amplitude (Rmp3) and sensitivity (S). Results  The minimum Rmp3 appeared at 25 days old group. When the intensity of light was 0.03 cd•s•m-2， the maximum of Rmp3 appeared at 60 days old group， under other intensity of light， it appeared at 46 days old group. It showed that there was a linear relationship between the sensitivity of the 8 groups and intensity of the light (S=ks•I+bs). Excluding the 60 days old group， the effects of age was mainly on the constant—bs but not the slope of the curve—ks， ks was equal to 0.09. Conclusion  The Rmp3 and sensitivity of a-wave of the ERG can be affected by age with vary degrees.

Objective  To investigate the anti-hypoxia and anti-oxidation effect of Fufang Xueshuantong capsule on the retina of rats with diabetic retinopathy and explore its mechanism. Methods  It was an experimental study． One hundred and ten male SPF Sprague Dawley rats were raised for 7 days and 30 of them were randomized as the normal group. And the other 80 rats were induced by Streptozotocin， randomized 60 successfully induced diabetic rats， which were divided into two groups： 30 STZ-diabetic rats without treatment as the diabetic rat control group； 30 STZ-diabetic rats treated with Fufang Xueshuantong capsule at a dose of 900 mg/kg/day as the treatment group. After the animals were raised for 4 weeks， 12 weeks， 20 weeks， use immunohistochemistry method and RT-PCR to detect the expression levels of hypoxia inducible factor-1α (HIF-1α) and CuZn super oxide dismutase (CuZn-SOD) proteins and mRNAs in the retina； determining the activities of T-SOD and CuZn proteins in the retina of rats in each group by a spectrophotometric method seperately. Data were analyzed using randomized block analysis of variance. Results  ①At 4， 12 and 20 weeks after treatment， the expression of HIF-1α protein were founded in the purkinje layer and inner nuclear layer of diabetic rats， and decreased in the treatment group （P＜0.05). The expression level of HIF-1α mRNAs was also lower in the retina of diabetic rats than in the treatment group （P＜0.05）. ②At 4， 12 weeks and 20 weeks after treatment， the expression of CuZn-SOD protein in the purkinje layer and inner nuclear layer of diabetic rats was obviously lower than the normal group′s， and was higer than the treatment group′s （P＜0.05）. The expression of CuZn-SOD mRNA was also higer in treatment group than in control group （P＜0.05）. ③At 4 weeks and 12 weeks， the activities of T-SOD and CuZn-SOD were decreased in diabetic rats compared with normal groups， but obviously increased in the treatment group （P＜0.05）. Conclusion  The anti-oxidation and anti-hypoxia effect of Fufang Xueshuantong capsule on the retina of rats with early diabetes maybe mediated by ameliorating the state of ischemia and hypoxic， downregulating the expression of HIF-1α， enhancing the activity of SOD and upregulating the expression of CuZn-SOD.

Objective  To investigate the inhibitory effect of vascular endothelial growth factor（VEGF）-targeted RNA interference on the retinal neovascularization of mice with oxygen-induced retinopathy (OIR). Methods  This was an experimental study. OIR mice models were induced by exposing mice to a 75% concentration of oxygen from postnatal day 7 (P7) to P12 and then returned to room air from P12 to P17. VEGF-siRNA was designed， screened and packaged in 293T cells to produce VEGF-RNAi-lentivirus. Sixty C57BL/6J mice were divided into 4 groups (every group n=15)： normal control group， OIR group， OIR+lentivirus (OIR-K-virus) group， and OIR+VEGF-RNAi-lentivirus (OIR-Ri-virus) group. Intravitreal injection of lentivirus was performed at P5 in the OIR-K-virus group and OIR-Ri-virus group. After FITC-Dextran perfusion， a retinal flat-mount was used to observe the area of retinal neovascularization. The distribution of Claudin-5 and Occludin was detected by double immunofluorescence staining of the retinal flat-mount. The expression of VEGF， phosphotylinosital 3 kinase （PI3K）， tyrosine kinase SRC， extracellular signal-regulated kinase (ERK) and phosphorylation ERK （p-ERK） proteins was analyzed by Western blot. Data were analyzed with a one-way ANOVA. Results  A study of the retinal flat-mounts after FITC-Dextran perfusion showed that the distribution of retinal vessels was uniform and there was no neovascularization in the normal group. The area of retinal neovascularization in the OIR group was 1.212 782 mm2， OIR-K-virus group was 1.152 504 mm2， and OIR-Ri-virus group was 0.271 399 mm2， the difference between groups was significant (F=449.924， P<0.01). There was no significant difference in the areas of retinal neovascularization between the OIR group and OIR-K-virus group. The areas of retinal neovascularization in the OIR-Ri-virus group were reduced significantly (P＜0.01) compared to the OIR group or the OIR-K-virus group. The distribution of Claudin-5 and Occludin in the retinal vessels of the OIR-Ri-virus group was more uniform and smoother than distribution in the OIR group or OIR-K-virus group. The expression of VEGF， PI3K， tyrosine kinase SRC and p-ERK protein in the OIR-Ri-virus group was significantly decreased compared to expression in the OIR and OIR-K-virus groups and was similar to the  expression of the normal group. Conclusion  The expression of VEGF and its signal pathway and development of retinal neovascularization in the OIR mice model were significantly inhibited by the intravitreal injection of lentivirus-mediated VEGF RNA interference， which may provide a new approach for the treatment of retinopathy of prematurity (ROP) in the clinic.

Objective  To evaluate the effect of vitrectomy for ocular perforating wounds caused by foreign bodies； to investigate the surgical approach for removing foreign bodies and the timing of the vitrectomy. Methods  This was a retrospective case-series study. Fifty-six cases （56 eyes） of ocular perforating wounds were analyzed. Patients were divided into an eye-wall foreign body group (24 cases) and an intraorbital foreign body group (32 cases) based on the results of computer tomography (CT) and ultrasonography positioning. Twenty-four cases with eye-wall foreign bodies underwent vitrectomy within 1 week after the injury. Twenty-two cases of intraorbital foreign bodies underwent orbital foreign body removal combined with scleral wound closure. The other 10 cases were not candidates for foreign body removal because the foreign bodies were located in the posterior pole or deep orbit. All eyes with intraorbital foreign bodies underwent vitreoretinal surgery about 2 weeks after injury. Patients were followed up for 3 to 12 months， visual acuity (VA) was evaluated and complications were noted. The factors affecting visual acuity were analyzed using Chi-square tests. Results  Postoperative VA improved in 50 patients (89%). The VA of 34 patients (61%) was greater or equal to 0.05. The factors that influenced VA included the position of the anterior （χ2=7.69， P=0.01） and posterior wound （χ2=21.83， P＜0.01）， retinal （χ2=16.64， P＜0.01） and choroidal detachment （χ2=7.73， P=0.01） and endophthalmitis （χ2=6.89， P=0.01）. After surgery， retinal detachment occured in 6 cases， hypotension in 2 cases and macular preretinal membrane or macular pucker in 12 cases. Conclusion  The following factors are crucial in successfully dealing with ocular perforating wounds caused by foreign bodies： choose the right surgical approach and the timing of the vitrectomy based on the position of the foreign body and intraocular conditions， minimize the damage to the retina and prevent proliferative vitreoretinopathy.

Objective  To study the efficacy of retrobulbar anesthesia in nonquantitative strabismus surgery. Methods  A prospective， case-control study was performed on 85 patients who were presented for nonquantitative strabismus surgery. Retrobulbar anesthesia （61 eyes of 50 cases） and local infiltration anesthesia （40 eyes of 35 cases） was performed before operation respectively. Intraoperative and postoperative pain was assessed by using verbal rating scales， and anesthesia efficiency and operation efficiency were recorded. Data were analyzed with χ² test. Results  Operation was well tolerated with no complication in patients with retrobulbar anesthesia. 54% patients showed no pain and 46% patients showed mild pain according to verbal rating scales， and this was significantly better than that of the control group （χ²=13.833， P<0.01）. The success rate of surgery was 100%. Conclusion  Retrobulbar anesthesia proves to be an efficient and safe procedure for nonquantitative strabismus surgery.

Customized corneal refractive surgery has been an exciting research area in recent years. This article summarizes the advantages and the latest studies on customized corneal refractive surgery for reducing higher-order aberrations before， during and after surgery， and for trying to improve visual quality. Therefore， customized corneal refractive surgery should be encouraged more often.