In recent years， the all-in-one femtosecond laser technology， one of the latest ophthalmic developments， has shown a tendency for rapid expansion in ophthalmology and has drawn extensive attention from ophthalmologists. The small incision lenticule extraction （SMILE） procedure is the representative surgery of the all-in-one femtosecond laser technology and has advanced corneal refractive surgery into an era of microinvasive and flapless techniques. This article reviews the generation and significance of all-in-one femtosecond laser technology and the clinical applications， potential superiority and advancements of the SMILE procedure.

Objective  To investigate the characteristics and relevant factors of intraocular stray light before and after small incision lenticular extraction （SMILE）. Methods  In a prospective case study， 67 myopic and myopic astigmatism patients （67 eyes） underwent SMILE surgery in Tianjin Eye Hospital. Stray light measurements were taken before SMILE surgery and 1 week， 1 month， 3 months and 6 months after surgery using an Oculus C-Quant stray light meter. Pearson correlation was used to identify correlations in stray light values for such factors as age， spherical equivalent refractive error， central corneal thickness （CCT）， mean keratometric value， and corneal curvature radius as well as for surgical factors such as cap diameter， hinge width， ablation depth， ablation ratio， residual bed thickness， RBT/CCT and energy. Results  The stray light values preoperatively， and 1 week， 1 month， 3 months and 6 months after SMILE surgery were 0.93±0.16， 0.97±0.14， 0.94±0.17， 0.94±0.17， and 0.90±0.17， respectively. The mean stray light value was slightly higher 1 week after surgery but no significant differences were found. There were no significant differences when the various time points were compared （F=2.253， P>0.05）. While the changes in stray light values after surgery were not correlated with surgical parameters， there was a slight positive correlation with hinge width at 3 months after surgery （r=0.356， P<0.01）. Conclusion  There are no significant differences in stray light between pre- and post-SMILE surgery. It may be possible that a change in stray light could cause a decrease in visual quality.

Objective  To evaluate the predictability and efficacy of femtosecond small incision lenticule extraction （SMILE） with different refractive targets in order to provide data for the clinic. Methods  This was retrospective clinical study that included 207 eyes from 104 patients who were treated for myopia or myopic astigmatism with SMILE surgery. The spherical equivalent （SE） of subjective manifest refraction less than -8.25 diopters （D） and astigmatism less than -3.25 D. SMILE surgery was performed on all eyes and patients were followed for 3 months. Patients were divided into three groups based on target refractions： group Ⅰ（target refraction was 0.00 D）， group Ⅱ（target +0.25 D） and group Ⅲ（target +0.50 D）. Preoperative mean SE refraction for group Ⅰ was -6.26±1.47 D， group Ⅱ was -5.62±1.43 D and group Ⅲ was -4.31±2.75 D. All surgeries were performed by the same doctor and uncorrected visual acuity （UCVA）， refraction and residual astigmatism were measured 1 day， 7 days， 1 month and 3 months postoperatively. An analysis of variance was used to analyze the changes in visual acuity and refraction at the different time points. Results  ①Differences in postoperative uncorrected visual acuity （UCVA） at the different time points were insignificant for the 3 groups （F=2.67， 0.82， 0.62， 0.25， P＞0.05）. ②The differences in target refraction at 1 day， 7 days， 1 month and 3 months postoperatively were also insignificant for the three groups （F=1.88， 1.03， 2.18， P>0.05）. Conclusion  Clinical outcomes of SE and UCVA were stable for different target refractions with the SMILE procedure for myopia and myopic astigmatism. This study suggests that the nomogram needs to be adjusted for different ages to account for potential refractive changes. Nomogram adjustment is safe and feasible for controlling overcorrections within 0.50 D.

Objective  To investigate the clinical efficacy， safety， predictability and stability of femtosecond laser small incision lenticule extraction （SMILE） for the treatment of myopia. Methods  In this prospective observational study， 94 patients （170 eyes） with myopia underwent SMILE surgeries. The average age of the patients was 26.8±4.7 years （range 18 to 44 years）. The mean preoperative spherical equivalent （SE） was -6.20±1.37 diopters （D）， from -3.25 to -9.13 D. The median myopic astigmatism was -0.75（0.75） D， up to -3.25 D. The mean corneal thickness was 554.7±27.5 μm （range 484 to 600 μm）. Routine ophthalmic examinations were performed. The patients were followed from 6 months to 2 years with uncorrected visual acuity （UCVA）， best corrected visual acuity （BCVA）， manifest refraction， intraocular pressure， corneal topography， and slit lamp examinations. The results were analyzed with a paired t test and linear regression analysis. Results  All procedures were completed successfully. At the long-term follow-up examination， 97% of eyes had a UCVA of 1.0 or better and 100% of eyes had a UCVA of 0.8 or better. BCVA was equal to or better than the preoperative BCVA in 100% of eyes. 35% gained one line and 10% gained two lines of BCVA. The mean postoperative SE was -0.01±0.45 D and 87% and 100% were within ±0.50 and ±1.00 D of the attempted correction. The root mean square （RMS） values of total higher order aberrations （HOA）， spherical aberrations and coma increased by a significant amount after surgery： 0.15±0.12 μm， 0.04±0.11 μm， 0.14±0.14 μm （t=-6.861， -2.078， -5.672， P<0.05）. Conclusion  The SMILE procedure is safe， effective， predictable and the results were stable for treating myopia. HOA， spherical and coma aberrations increased postoperatively but the change in spherical aberrations was small.

Objective  To compare the corneal topography of patients with myopia and astigmatism 3 months after femtosecond lenticule extraction （Flex） and femtosecond laser in situ keratomileusis （FS-LASIK）. Methods  In this prospective study， 323 myopic eyes of 165 patients with astigmatism who underwent Flex or FS-LASIK from January to September in 2013 in Beijing Tongren Hospital were examined. An independent samples t test was used to compare visual acuity， refraction and corneal topography measurements 3 months after surgery. Results  Three months after surgery， uncorrected visual acuities （UCVA） of logMAR in Flex and FS-LASIK were -0.10±0.08 and -0.11±0.10 and best corrected visual acuities （BCVA） were -0.11±0.07 and -0.12±0.07. These measurements were better than the BCVAs before surgery， which were -0.07±0.03 and -0.07±0.04 （t=4.083， 5.594 and 3.458， 6.440， P<0.01）. No significant difference in postoperative UCVA was seen between Flex and FS-LASIK （t=-0.811， -1.864， P＞0.05）. The cutting decentration with Flex （0.29±0.17 mm） was smaller than with FS-LASIK （0.40±0.17 mm）， respectively （t=5.662， P＜0.01）. There was no correlation with spherical equivalent （SE） in Flex （r=0.122， P＞0.05）， but there was a positive correlation with SE in FS-LASIK （r=0.210， P<0.01）. The postoperative surface regularity index （SRI） of Flex was higher than that of FS-LASIK， 0.34±0.25 and 0.22±0.21， respectively （t=-4.627， P＜0.01）. Conclusion  The cutting decentration of Flex is smaller than that of FS-LASIK， however the regularity of the corneal surface after FS-LASIK is better than that of Flex. Both techniques result in satisfactory visual acuity.

Objective  To observe the safety and efficacy of liquid infiltration method to separate lenticule in small incision lenticule extraction （SMILE）. Methods  In this prospective study， 72 patients were included. Randomly selected one eye was performed conventional method； the contralateral eye was performed liquid infiltration method. The corneal epithelium injury around the incision in surgery and the smoothness of the lenticule edge was observed under optical microscope. The differences of visual acuity， refraction， contrast sensitivity postoperatively between the two groups using independent samples t test. Results  The corneal epithelium injuries were observed in 2 eyes in liquid infiltration method and 14 eyes in conventional method during surgery， the difference was statistically significant （χ2=6.41， P<0.01）， the lenticule edges of liquid infiltration method were smoother than conventional method. The visual acuity， spherical equivalent （SE） and residual astigmatism of liquid infiltration method and conventional method 1 day postoperative were： 4.98±0.06 and 4.89±0.53， +0.20±0.42 D and +0.30±0.37 D， 0.14±0.40 D and 0.41±0.57 D respectively. The difference of residual astigmatism was statistically significant（t=-3.29， P<0.05）. The visual acuity， spherical equivalent and residual astigmatism of liquid infiltration method and conventional method 1 month postoperative were： 4.99±0.06 and 4.97±0.06， +0.11±0.40 D and +0.13±0.41 D， 0.05±0.46 D and +0.36±0.66 D， respectively. The difference of residual astigmatism was statistically significant （t=-3.41， P<0.05）. The difference of contrast sensitivity was without statistically significant. Conclusion  The liquid infiltration method makes the edge of lenticule smoother and effectively reduces the corneal epithelial injury and residual astigmatism. It is a safe and feasible skill in SMILE.

Objective  To evaluate the characteristics of anterior corneal asphericity and higher order aberrations after SMILE surgery， and to analyze the correlation between them. Methods  In this prospective study， 41 subjects who underwent SMILE surgery were enrolled with right eyes selected for the study. The asphericity coefficient Q-value at diameters of 6， 7， 8 and 9 mm and total higher order aberrations （HOA）， spherical aberrations （Z40）， secondary spherical aberrations （Z60）， vertical coma （Z3-1）， horizontal coma （Z31）， y-trefoil （Z3-3） and x-trefoil （Z33） of the cornea were measured before surgery and 3 months following the surgery. A paired-samples t test and Pearson correlation were used for analysis. Results  All Q-values increased from negative to positive after SMILE surgery and the differences were statistically significant （t=-23.558， -26.661， -28.366， -28.788， P<0.01）. Corneal HOA， Z40， Z60， Z3-1 and Z31 increased and the differences were statistically significant as well（t=-11.815， -11.813， -16.209， 6.470， 4.835， P<0.01）. However， the change in Z3-3 or Z33 was not significant （t=0.278， -1.064， P>0.05）. Among corneal higher order aberrations， a linear correlation was found between the Q-value and corneal HOA， Z40 and Z3-1 before surgery （P<0.05）. The change in corneal HOA and Z40 had a positive linear correlation with the Q-value at each diameter （HOA： r=0.554， 0.480， 0.416， 0.352， P<0.05； Z40： r=0.671， 0.577， 0.495， 0.395， P<0.05）. The difference in Z3-1 had a positive linear correlation with the Q-values at diameters 6 and 7 mm （r=0.377， 0.342， P<0.05）. The difference in Z31 had a positive linear correlation with the Q-values at diameters 6， 7 and 8 mm （r=0.436， 0.385， 0.316， P<0.05）. No linear correlation was found between the changes in the Q-values at each diameter and those of Z3-3， Z33 or Z60 （P>0.05）. There was not a linear correlation between the change in the Q-values and lens diameter （P>0.05）. Lens diameter had a negative linear correlation with the changes in HOA and Z40 （r=-0.315， -0.393， P<0.05）. No linear correlation was found between the changes in Z60， Z3-1， Z31， Z3-3， Z33（P>0.05）. Conclusion  The anterior corneal asphericity changed from negative to positive and corneal higher order aberrations increased after surgery. The smaller the lens diameter， the larger the changes in HOA and Z40. There were positive linear correlations between the changes in anterior corneal asphericity and those of corneal HOA， Z40， Z3-1 and Z31 with the change in spherical aberrations having the closest correlation with the Q-value.

Objective  To investigate the influence of FS-SBK， SBK， and SMILE refractive surgeries on visual quality by analyzing variations in the glare index and the visual quality parameters of distinct refractive errors. Methods  In this prosective cases control study， 122 patients， who underwent SBK， FS-SBK or SMILE surgery， were enrolled from August to October 2013 and divided into high， moderate and low myopia groups. The glare index （opposite sector index， OSI） and modulation transfer function cut-off （MTF cut-off） were measured with a OQAS visual quality analyzing system preoperatively and one day， one week and one month postoperatively. Additional measurements were made to evaluate the differences among the three surgical methods. Results  The effects on postoperative visual quality due to the different surgical procedures were as follows： ①Vision： visual acuity improved after all surgeries and there were no significant differences among the results. ②OSI： there was no statistically significant difference between SBK and FS-SBK. When compared with pre-operative OSI， there was a statistically significant difference between moderate and high myopia groups one week after SMILE surgery. ③MTF cut-off： there were no statistically significant differences before and after surgery in the FS-SBK group， but there was a statistically significant difference from both SBK and SMILE surgeries in the moderate myopia group 1 week postoperatively compared with the preoperative period and 1 month postoperatively. However， there were no significant differences for the remaining time points. No significant differences were found between the different myopia groups. Conclusion  Postoperative visual quality improves after the three surgical procedures discussed above. Due to a raised OSI after SMILE surgery， LASIK is the better option for high and moderate degrees of myopia. While the MTF cut-off did not vary significantly between pre- and postoperative FS-SBK， it decreased one week later after SBK and SMILE surgeries but recovered after one month in the moderate myopia group， even reverting to pre-operative levels.

Objective  To compare the outcomes of small incision lenticule extraction surgery （SMILE） and wavefront supported corneal ablation （WASCA） LASIK surgery in treating myopia. Methods  In this cases control study， 34 eyes of 17 patients who underwent SMILE and 39 eyes of 20 patients who underwent WASCA LASIK were included. Before surgery there were no significant differences between the two groups in spherical equivalent， age， gender and scotopic pupil diameter. All patients were followed up for more than 3 months. UCVA， BCVA， spherical equivalent and higher order aberrations before surgery and 1 month and 3 months after surgery were compared between the two groups. Results  There were no statistically significant differences in uncorrected or best corrected visual acuity and spherical equivalence after the two surgical procedures （P>0.05）. Three months after surgery， the SMILE group had a significantly higher percentage of eyes whose SE range was -0.50 D to +0.50 D compared with the WASCA group （P<0.05）. There were no statistically significant differences in higher-order aberrations induced by SMILE and WASCA 1 month and 3 months after surgery （P>0.05）. However， SMILE induced far fewer spherical aberrations than WASCA LASIK （P<0.01）. Conclusion  Both SMILE and WASCA LASIK have good efficacy， safety， stability and predictability in treating myopia. However， SMILE induces far fewer spherical aberrations and results in better visual quality.

Objective  To evaluate and compare corneal sensitivity after Femtosecond LASIK （FS-LASIK） and small incision lenticule extraction （SMILE） from a systematic review of literature. Methods  This was a meta-analysis study. A systematic literature retrieval was conducted in Medline， the Cochrane Library， CBM disc， and CNKI. Central corneal sensitivity after FS-LASIK and SMILE was compared by meta-analysis， including pre-operation， 1 week， 1 month， 3 months and 6 months post-operation. A statistical analysis was performed using RevMan 5.0 software. Weighted mean difference （WMD） （95%CI） was used to analyze continuous variables. The quality of the included literature was scored according to the Jadad scale. Results  A total of 4 studies with a total of 198 patients （316 eyes） in the literature met the inclusion criteria Meta analysis results showed that there was no difference in central corneal sensitivity between FS-LASIK and SMILE before surgery （WMD=0.28， 95％CI： -0.73~1.29， P>0.05）； however， 1 week， 1 month， 3 months and 6 months after surgery， corneal sensitivity after SMILE was significantly higher than after FS-LASIK （WMD=-14.56， 95％CI： -23.79~-5.34， P<0.01； WMD=-15.29， 95％CI： -22.46~-8.11， P<0.01； WMD=-13.12， 95％CI： -18.77~-7.46， P<0.01； WMD=-3.45， 95％CI： -5.72~-1.18， P<0.01）. Conclusion  Compared with FS-LASIK， central corneal sensitivity after SMILE has a smaller decrease and faster recovery. Corneal sensitivity after SMILE is still higher than FS-LASIK during the 6-month period after surgery.

Objective  To investigate if the chronic ocular hypertension （COHT） in a monkey model presents indistinguishable from humans in its retinal nerve fiber layer （RNFL） and optic nerve head （ONH） damage. Methods  This was an experimental study. Models of COHT were induced in 12 eyes of rhesus monkeys were induced by using VISULAS Trion to disturb the aqueous humor outflow and cause the elevation of intraocular pressure. Some measurements have been taken such as intraocular pressure （IOP）， fundus photography， the ONH parameters， and the RNFL thickness were taken every week before and after laser treatment. Results  The main results were as follows： the IOP of the twelve eyes of the monkeys was 16.08±2.02 mmHg， the central corneal thickness was 489.17±17.82 μm and the ocular axials length was 20.32±0.84 mm. Eleven eyes， underwent 3 to 4 laser photocoagulation treatments， were induced to the COHT model. The average IOP in 27 weeks was 30.32±14.59 mmHg， and the variation was 8.19±7.45 mmHg. Optical coherence tomography displayed revealed the a lost rim area that changed from 1.67±0.44 mm2 to 0.43±0.34 mm2 in the monkey COHT model. The RNFL was changed from 97.92±6.79 μm to 64.46±17.44 μm. Conclusion  The monkey COHT model mimicks the natural ocular hypertension/open angle glaucoma procedure and shares similar glaucomatous damage patterns， such as the reactivity of ONH to ocular hypertension， and the presence of the optic cup and the damage phenomenon of RNFL. The monkey model is an ideal animal model for studying damage of the optic nerve head and RNFL.

Objective  To compare the ocular biometry and build up the normative database in cataract patients older than 50 years from Tibet， Xinjiang and Guangdong. To provide reference data for cataract patient in different areas. Methods  This study nonrandomly selected one thousand nine hundred ninty four eyes from 1 994 subjects aged ＞50 years. Subjects from Tibet， Xinjiang and Guangdong were 249， 615 and 1 080 respectively. All subjects received cataract surgeries on Lifeline Express from 2007 to 2008. A-scan ultrasound and auto keratometer were used to measure axial length （AL）， anterior chamber depth （ACD）， lens thickness （LT）， vitreous cavity depth （VH）， vertical and horizontal keratometry， vertical and horizontal radius of corneal curvature. Normative data of all measured ocular biometry were determined and compared for the three areas. ANOVA and Hotelling T2 test was used for data analysis. Results  For female subjects form Tibet， Xinjiang and Guangdong， the mean AL were 22.52±0.79 mm， 22.63±0.68 mm and 22.80±0.84 mm， the mean ACD were 2.63±0.43 mm， 2.81±0.42 mm and 2.74±0.41 mm， the mean LT were 3.95±0.45 mm， 4.16±0.54 mm and 4.11±0.52 mm respectively. For male subjects， the mean AL were 22.97±0.80 mm， 23.19±0.70 mm and 23.23±0.77 mm， the mean ACD were 2.81±0.49 mm， 2.95±0.43 mm and 2.78±0.44 mm， the mean LT were 3.98±0.48 mm， 4.19±0.54 mm and 4.22±0.55 mm respectively. Significant difference was found for AL （male F=4.781， P<0.01， female F=7.324， P<0.01）， LT （male F=8.835， P<0.01， female F=8.446， P<0.01） and ACD （male F=8.914， P<0.01， female F=5.903， P<0.01） among three areas. For male patients， AL and LT of Guangdong and Xinjiang were larger than Tibet （all P<0.05）. ACD of Tibet and Guangdong was larger than Xinjiang （all P<0.05）. For female patients， AL of Tibet and Xinjiang was smaller than Guangdong （all P<0.05）. ACD and LT of Guangdong and Xinjiang were larger than Tibet （all P<0.05）. Keratometry was largest in Guangdong and smallest in Xinjiang （all P<0.05）. Conclusion  This study built up the normative database of ocular biometry in three areas and found biometry was different with sex and areas. Ocular biometry is different among areas with different races and environmental factors. Cautions should be exercise in clinical practice in these areas.

Sympathetic ophthalmia is a rare bilateral granulomatous inflammation that follows accidental or surgical insult to the uvea of one eye. Onset of sympathetic ophthalmia can be insidious or acute， with variable clinical manifestations. Sympathetic ophthalmia can deteriorate repeatedly and induce blindness. Clinical presentation shows mutton-fat keratic precipitates， choroidal infiltrations， and Dalen-Fuchs nodules. Histopathology reveals diffuse or nodular granulomatous inflammation of the uvea. Prevention and treatment strategies for sympathetic ophthalmia include medicine and surgery. The mechanism of the disease is still unclear but is largely thought to be autoimmune in nature.