Orthokeratology has been widely accepted in clinic as an available option for myopia reducing temporarily. Many studies on orthokeratology have been conducted and their outcomes about the safety and effectiveness have being implemented in fitting guidance. The results of slowing down myopia progression raise more interesting among eye doctors and patients. Since the adolescents myopia progression and its clinical interventions is a big concern. This article will analyze the update information in this field， declared controversial viewpoints and the current research limitation. The importance on clinical study design and analysis are interrelated.

Objective To quantitatively evaluate the centration and fitting characteristics of the overnight orthokeratology lens using ultra-long scan depth spectral domain optical coherence tomography （UL-OCT）. Methods This was a prospective cohort study. Thirty-three subjects （33 eyes， 23 women and 10 men； mean age： 26.0±3.2 years， range： 22-37 years） were enrolled in the study to wear the reverse-geometry orthokeratology lenses in both eyes for one night. Images with the lens on the eye were acquired by a custom-built UL-OCT before and after one night of orthokeratology lens wear. Custom software was used to quantify lens decentration. At the same time， lens fitting under fluorescein staining patterns was evaluated by a slit-lamp microscope imaging system. A Kappa test was used. Results The mean decentration was 0.62±0.31 mm based on the UL-OCT evaluation method. Results showed that 42%（14/33） had optimal fitting， 42%（14/33） had moderate decentration which was clinically acceptable， and 15%（5/33） had severe decentration. The fluorescein patterns showed 58%（19/33） had optimal fitting， 33%（11/33） had moderate decentration， and 9%（3/33） had severe decentration. A Kappa test result for the consistency of the two methods was 0.647. The interactions between the orthokeratology lens and ocular surface were observed through the OCT images. Abnormal deformation of the corneal epithelium occurred when the fitting was not optimal. Conclusion OCT could quantify the orthokeratology lens under the condition lens on eye. The result of OCT evaluation matched with the traditional fluorescein staining by moderate consistency.

Objective To compare axial length growth and myopia progression among myopic Chinese children wearing single-vision spectacle lenses （SVs）， orthokeratology lenses， rigid gas-permeable contact lenses （RGPCLs） or progressive-addition spectacle lenses （PALs） and to evaluate their efficacy in the control of myopia. Methods This was a prospective， non-randomized and case-controlled clinical study. One hundred and four myopic children aged 9 to 15 years were enrolled in this study. Subjects′ refractive conditions ranged from -0.50 to -4.50 DS with astigmatism less than 2.00 DC. Each subject was allocated to one of four correction groups （SV， orthokeratology lens， RGPCL， or PAL）， and followed for 24 months. Twenty-one children were fitted with SVs， 24 with orthokeratology lenses， 30 with RGPCLs， and 29 with PALs. Cycloplegic refraction， axial length and topography measurements were performed. Data were analyzed using ANOVA， repeated measured ANOVA and a chi-square test. Results At baseline， the four groups were comparable in terms of age， k-reading， and axial length， exception for spherical equivalent refractive error （F=6.920， P<0.01）. The RGPCL group （-3.04±0.79 D） was more myopic than the SV （-2.35±0.80 D）， orthokeratology lens （-2.33±1.02 D） and PAL （-2.15±0.60 D） groups at baseline. Axial length increased significantly over 2 years （F=315.912， P<0.01） for the SV group （0.57±0.23 mm）， orthokeratology lens group （0.31±0.20 mm）， RGPCL group （0.51±0.30 mm） and PAL group （0.61±0.27 mm）， with a significant interaction between time and groups （F=4.175， P<0.01） and significant differences among the four correction methods （F=6.599， P<0.01）. Axial elongation was slower in the orthokeratology lens group compared to the others， but there were no differences among the SV， RGPCL and PAL groups. Myopia progressed significantly over 2 years （F=121.840， P<0.01） for the SV group （-1.23±0.64 D）， RGPCL group （-0.82±0.69 D） and PAL group （-1.12±0.53 D）， with insignificant interaction between time and group （F=1.300， P>0.05） and no significant differences among those three correction methods （F=2.987， P>0.05）. Conclusion For the efficacy of myopia control， the orthokeratology lens is most remarkable. Rigid gas permeable contact lenses and progressive-addition lenses are not more effective for myopia control than single-vision spectacle lenses.

Objective To describe the regression of refraction and corneal curvature shortly after discontinuing orthokeratology lens wear. Methods This was a self-controlled study. Thirty-six patients （69 eyes） were assessed after wearing orthokeratology lenses for 3 months. Refractive error， uncorrected visual acuity （UCVA） and corneal topography were measured within zero hour after waking and at 10 and 24 hours. Comparison of regression was analyzed for the three levels of myopia achieved （>-4.50 D， -3.12~-4.50 D， -0.12~-3.00 D）. Descriptive statistics were used in this study. Results In general， all the parameters returned toward the baseline after discontinuation of lens wear. At 10 and 24 hours， UCVA （logMAR） returned to 0.09±0.20 （regression rate 11%） and 0.30±0.24 （regression rate 36%）， respectively. Spherical equivalent refraction returned to 0.25±0.74 D （regression rate 8%） and 1.15±1.05 D （regression rate 36%）， respectively. Corneal curvature （simK） returned to 0.00±0.85 D （recovery rate 0%） and 0.62±0.68 D （recovery rate 46%）. The greater the magnitude of refractive error， the more quickly it returned to baseline. Conclusion Refractive error and corneal curvature were relatively stable for 10 hours after discontinuation of orthokeratology lens wear， but all parameters returned and trended to baseline 24 hours after discontinuation. The greater the refractive error， the more quickly it returned to baseline.

Objective A laser confocal microscope was used to investigate changes in the cornea from wearing orthokeratology lenses during the night. Methods In a retrospective case study， 60 people were chosen from patients at the Ophthalmology Department of the General Hospital of Nanjing Military Command during January 2009 to December 2012. Among them， 30 patients （total 60 eyes）， the experimental group， had worn orthokeratology night lenses for 2 years and the other 30 patients （total 60 eyes）， the control group， had never worn any form of orthokeratology. All patients underwent laser confocal microscopy examinations at the centre of the cornea， 2-3 hours after the experimental group had removed the orthokeratology lenses. An independent t test was used. Results Corneal surface shape may change significantly. Wrinkles could be observed from the epithelium to the anterior stroma. The subepithelial plexus was distorted and uneven in density but the stromal nerve and endothelial cell morphology were normal. The epithelial cell count was 4818±148， former stromal cells count was 1345±154， the rear stromal cell count was 799±76， and the endothelial cell count was 3025±193. All these counts were not statistically different from the control group. Conclusion Long-term orthokeratology lens wear during the night can induce changes in the corneal subepithelial plexus but there were no significant changes in stromal or endothelial cells.

Objective To evaluate the impact of pupil diameter on controlling the development of myopia in orthokeratology. Methods Forty-nine children aged 7 to 14 years were enrolled in this prospective clinical study. Orthokeratology was performed to correct the refractive errors of these children after measurements of refraction， pupil diameter and axial length. Axial length （AL） and pupil diameter were measured 24 months after lens wearing. The average pupil diameter was calculated and was used as the criterion for dividing the children into ″pupil size above average″ vs ″pupil size below average″. Data were analyzed by a paired t-test， an independent t-test， repeated measured ANOVAs and Pearson correlation analysis. Results AL increased significantly throughout the 24-month observation period （F=67.182， P＜0.01）. The axial growth of subjects with below average pupil sizes and those with above average pupil sizes was 0.43±0.28 mm and 0.24±0.27 mm， indicating a statistically significant difference （t=2.379， P＜0.05）. AL change in subjects with above average pupil diameters was 55.81% of that for subjects with below average pupil diameters. Baseline pupil diameter was negatively correlated with axial growth at the 24-month visit （r=-0.361， P＜0.05）. Linear regression analysis was used between baseline pupil diameter and 2-year axial growth： Axial growth=-0.161× baseline pupil diameter +0.987 （F=7.048， P＜0.05）. The average pupil diameter for subjects with above average pupil sizes and those with below average pupil sizes after 2 years was 3.72±0.53 mm and 3.51±0.37 mm， indicating no statistically significant difference （t=2.543， P＞0.05）. Conclusion The effect of orthokeratology to control myopia would be more beneficial for children with larger pupil diameters than for children with smaller pupil diameters. This may be due to the enhancement of the myopic shift in the peripheral retina.

Objective To conduct preliminary analysis and investigate the demands and psychology of adolescents wearing orthokeratology lens. Methods Investigation study. Conducted questionnaires for 100 adolescent patients in the Eye Hospital， who wore orthokeratology lens for the correction of myopia. Separate questionnaires were given before wearing the lens， after wearing the lens for 1 week， 1 month， and 3 months. Investigation mainly included： awareness and demand of orthokeratology lens and psychological impact of wearing orthokeratology lens. Altogether 84 complete questionnaires were collected for statistical analysis， and the Chi-square tests were used with the data. Results Among the adolescents wearing orthokeratology lens， 78% of them were willing to wear orthokeratology lens； 83% of adolescent wearers believed that it did not influence sleep when wearing the lens at night； 60% expected to control the myopia. About 50% adolescents believed there were some advantages in aspects such as appearance， self-confidence， and convenience when wearing orthokeratology lens. After wearing the lens for 1 month， these psychological advantages were more apparent to the patients. The self-confidence between 1 month and 1 week were stastically different （χ²=7.871， P<0.05）. Conclusion Wearing orthokeratology lens had various degrees of impact on adolescents′ daily life， sight， and psychology. This subject needs further study and to more fully understand of healthy and safety because it is a longitudinal social issues.

Objective To assess the clinical efficacy of orthokeratology in the treatment of adolescents with moderate myopia； to assess the changes in refraction， corneal thickness and axial length after 1 year of wear. Methods This was a prospective study. Thirty-seven young myopia patients （9-15 years old） were fitted with orthokeratology lenses and refraction， visual acuity， and corneal curvature were measured. Patients wore the ortokeratology lenses for one year and then were required to discontinue wearing the lenses. Fifty patients （9-15 years old） were fitted with spectacles for the same time period. The changes in refraction and axial length were measured one month after the discontinuation of lens wear. Data were analyzed using repeated measured ANOVA and independent t test. Results After 1 year， the spherical equivalent refractions were -4.69±0.57 D in the orthokeratology lens group and -4.72±0.80 D in the spectacle group. Increases in spherical equivalent refraction were 0.31±0.21 D and 0.77±0.46 D， respectively， in the two groups， indicating a statistically significant difference （t=30.109， P＜0.01）. The axial length increases were 0.11±0.26 mm and 0.26±0.60 mm， respectively， in the two groups， indicating a statistically significant difference （t=18.565， P＜0.01）. The corneal thickness in orthokeratology group before and 1 year after lens wear was insignificantly different. Conclusion Orthokeratology treatment for moderate myopia in adolescents can significantly improve visual acuity. The progression of myopia can be controlled to a certain extent. And the increase in axial length can be effectively controlled.

Objective To investigate the effect of the rigid gas permeable contact lens （RGPCL） on keratoconus in clinical practice. Methods In this retrospective study， 496 eyes of 260 patients with keratoconus were fitted with RGPCLs at the optometry center of Shenyang Aier Eye Hospital between 2005 and 2009. The patients included 212 males and 48 females. Evaluations were performed on all patients. The follow-up period lasted at least 4 years to assess visual acuity， pattern matching， changes in keratometry， the apex K value， the apex thickness of the cornea and complications. Data were analyzed using a paired t test. Results All patients wearing RGPCLs obtained acceptable vision. There was a statistically significant improvement in corrected visual acuity with RGPCLs compared to spectacles （t=-30.02， P<0.05） before and after 4 years. There was also an apex K value improvement with RGPCLs （t=3.02， P<0.05） before and after 4 years， but not in the apex thickness of the cornea （t=1.46， P＞0.05）. Four hundred thirty-two eyes （87.1%） had a three-point-touch relationship and 46 eyes （9.3%） had an apical clearance relationship. Eighteen eyes （3.6%） had an apical contact relationship. Keratometry steepness increased in only 3 eyes （0.6%） and 64 eyes （12.90%） had a flat keratometry value that was steeper than before. All patients could wear RGPCLs all day with the exception of 33 patients （6.6％） whose corneas were stained. There were no severe complications like corneal neovascularization， corneal abrasion， or keratohelcosis. Conclusion The successful fit rate of RGPCLs for keratoconus is higher. The RGPCL is safe and effective for keratoconus.

Objective To evaluate the clinical efficacy of rigid gas-permeable contact lenses （RGPCLs） in the treatment of keratoconus and irregular astigmatism after corneal surgery. Methods This was a prospective study. Twenty-nine patients （38 eyes） were fitted with RGPCLs. The patients included 12 with secondary keratoconus after LASIK （14 eyes） and 1 after LASEK （1 eye）， 8 with irregular astigmatism after corneal transplants （13 eyes）， 2 after ridial keratotomy surgery （4 eyes） and 6 after LASIK surgery （6 eyes）. A paired t-test was used to compare best corrected visual acuity （BCVA） with spectacles and RGPCLs. Patients filled out a subjective assessment questionnaire for evaluating RGPCLs for comfort and ease of cleaning. Results BCVA was ≤4.2 （5 eyes， 13%）， 4.3~4.4 （5 eyes， 13%）， 4.5~4.6 （8 eyes， 21%）， 4.7~4.8 （10 eyes， 26%）， 4.9~5.0 （10 eyes， 26%） and 0 eye （0%） was >5.0 with spectacles. BCVA with RGPCLs was 0 eye （0%）， 0 eye （0%）， 0 eye （0%）， 3 eyes （8%）， 15 eyes （39%） and 20 eyes （53%）. The average BCVA was better with RGPCLs than with spectacles （t=-4.416， P＜0.01）. No serious complications occurred during the follow-up period. Patients reported wearing the lenses feeling comfortable （48%）， easy to wear and pick out lenses （69%） and easy to clean （59%）. Conclusion The RGPCL was significantly more effective than spectacles for secondary kerotoconus and irregular astigmatism after corneal surgery. And RGPCLs were safe to wear.

Objective To observe the morphological characteristics of corneal topography in patients with keratoconus using the ALLEGRO Oculyzer for measurements； to provide data for early diagnosis and screening of keratoconus and an analysis of the pathogenesis of keratoconus. Methods This was a retrospective case control study. Sixty-two clinical keratoconus patients （66 eyes）， 57 subclinical keratoconus patients （57 eyes） and 35 healthy people （70 eyes） were enrolled in this research. All of them were examined using the Oculyzer for measurements. Posterior surface topography classifications for elevation were divided into 6 types： island， incomplete island， increasing bridge， decreasing bridge，incomplete bridge and irregular type. The morphological features of the elevation pattern maps and the position of the cornea at the thinnest point were studied by observing the pachometer apex and the pupil center. The collected data were analyzed with one-way ANOVA and a nonparametric test. Results The types of topography of the posterior surface in the normal eyes （group 1） were mainly an incomplete bridge （61%） and decreasing bridge （26%）， the topography of the subclinical keratoconus eyes （group 2） were mainly an increasing bridge （40%） and an incomplete island （25%）， and the clinical keratoconus eyes （group 3） were mainly an incomplete island （33%） and island （56%）. The thinnest points were located in the inferior temporal region in 81%， 86%， and 76%， respectively. The distance between the thinnest point and corneal apex in groups 1， 2， and 3 were 0.59±0.20 mm， 0.77±0.27 mm， 0.66±0.32 mm， respectively， and the differences were statistically significant （F=6.903， P<0.01）. The angles in the inferior temporal region in groups 1， 2， and 3 were （41.96±17.30）°， （49.14±18.83）°， （49.40±16.77）°， respectively， and the differences were statistically significant （F=3.112， P<0.05）. Conclusion The posterior surface of the cornea in patients at risk for keratoconus ranged from the development of an incomplete bridge type to an incremental type. Moreover， the increases in distance between the thinnest corneal position and the corneal apex are related to the development of keratoconus. More attention should be paid to this condition.

Objective To discuss the relationship between changes in the posterior corneal surface and refractive surgery using Sirius 3D topography； to further analyze and evaluate factors that affect the posterior corneal surface. Methods This was a prospective clinical study. Myopic patients who underwent excimer laser refractive surgery from May 2012 to July 2013 in Ningbo First Hospital were chosen （74 eyes of 37 LASIK patients and 52 eyes of 26 LASEK patients）. Sirius 3D topography was used to reveal the corneal topography of the posterior corneal surfaces preoperatively. Ablation depth （AD）， ablation ratio （ablation depth/corneal thickness， AD/CT） and residual bed thickness （RBT） were recorded for every patient during surgery and again at 1 week， 1 month and 3 months postoperatively. Data were compared by repeated measured ANOVA， multiple linear regression was used to reveal the relationship between the related factors and the changes in the posterior corneal surface. Results The posterior corneal surface had a slightly forward shift after refractive surgery. There were significant differences in posterior surface elevation before and after LASIK and LASEK at 1 week， 1 month and 3 months （F=43.58， 7.51， P<0.01）. RBT was correlated with the posterior corneal surface variations at 1 week， 1 month， and 3 months after LASIK （t=-3.421， -3.376， -3.116； P<0.01） and 1 month and 3 months after LASEK （t=-3.077， -2.872； P<0.01）. Conclusion Sirius 3D topography measurements show that the corneal posterior surface has a slightly forward shift in both LASIK and LASEK. RBT has a strong influence on corneal posterior surface variation.

Lacrimal outflow obstruction is a common disease， which can be divided into congenital and acquired lacrimal obstruction according to the etiology. The site of obstruction can be divided into superior lacrimal passage obstruction （lacrimal punctum， canalicular and common canalicular） and lower lacrimal passage obstruction （lacrimal sac and nasal lacrimal duct）. In recent years， with the continuous development and improvement of the laser， endoscope， and a variety of biological materials， treatment of lacrimal duct obstruction tends to be diverse. The traditional methods are usually done by conservative treatments like probing and external dacryocystorhinostomy. Recently， new lacrimal stents and lacrimal endoscopes are used more and more in lacrimal duct obstruction. In summary， various methods have their advantages and disadvantages， which require surgeons to evaluate the condition and choose the best method.