Chinese Journal of Optometry Ophthalmology and Visual science

Objective To evaluate the safety,efficacy,and stability of the INTRACOR femtosecond laser-based intrastromalprocedure to treat presbyopia.Methods In a retrospective case-series study,the nondominant eye (28 eyes in 28 presbyopic cases) was treated with femtosecond laser based on the INTRACORE technique and comparisons were made before and after the operation for near and distance visual acuity,refractive error,intraocular pressure,endothelial cell density,corneal topography,contrast sensitivity,glare sensitivity and patient satisfaction.All patients were followed up for 6 months.Data were analyzed using paired t test or paired Wilcoxon rank sum test.Results All cases were uneventful.Mean distance visual acuity (VA) at 6 months postoperatively was 0.0 logMAR (range,0.2 to-0.1) compared to a preoperative VA of 0.0 logMAR (rauge,0.2 to-0.1).The difference was not significant.Mean near visual acuity at 6 months postoperatively was 0.25 logMAR (range,0.4 to 0.0) compared to 0.5 logMAR (range,1.0 to 0.3) preoperatively.The elevated postoperative value (6.25±1.74 lines) was significantly different than the preoperative value (t=18.66,P＜0.01).The mean values for spherical power,cylinder equivalent and spherical equivalent at 6 months postoperatively were-0.25 D (range,-0.75 to 0.25 D),0.0 D (range,-0.75 to 0.25 D) and-0.37 D (range,-0.75 to 0.25 D),respectively,compared to preoperative values of 0.5 D (range,-0.25 to 1.0 D),0.0 D (range,-0.5 to 0.0 D) and +0.25 D (range,-0.12 to 0.75 D),respectively.The differences before and after the operation were significant for both spherical power and spherical equivalent values (Z=-4.50,-4.57,both P＜0.01).However,there was no significant difference in the cylinder equivalent value before and after the operation.The INTRACORE treatment induced a slight myopic shift of-0.54 D and there were no significant differences for intraocular pressure,endothelial cell density,contrast sensitivity and glare sensitivity before and after the operation.The average score was 89±14 for the quality of life questionnaire at 6 months postoperatively.Conclusion Femtosecond laser-based treatment using the INTRACORE technique appears to improve near visual acuity in presbyopic patients but there was no apparent effect on distance visual acuity.Femtosecond laser-based treatment with the INTRACORE technique is safe and has good visual outcomes.

Objective To compare changes in wavefront aberrations on the anterior and posterior corneal surfaces after laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) for myopia,especially for spherical aberrations,coma,trefoil and total higher order aberrations.Methods A prospective study was designed for 68 eyes of 34 patients who had undergone LASIK and LASEK.The patients were divided into 2 groups according to the procedure used.An oculyzer analytical system was used to measure corneal aberrations before and after surgery.Data were analyzed using ANOVA,independent samples t test and pearson correlation.Results One and 3 months after surgery,spherical aberrations and total higher-order aberrations of the anterior corneal surface in the LASIK group increased (P＜0.01),but the differences at 1 month and 3 months were not significant (P＞0.05).The same results occurred in the LASEK group for spherical aberrations,coma and total higher-order aberrations of the anterior corneal surface.Spherical aberrations and total higher-order aberrations of the anterior corneal surface were higher in the LASIK group than in the LASEK group 1 month after surgery (P＜0.01),and the same tendency was found 3 months after surgery.However,coma aberrations on the anterior corneal surface in the LASIK group were less than those in the LASEK group at any time after surgery (P＜0.05).No differences were found in trefoil aberrations on the anterior corneal surface during both procedures (P＞0.05).Furthermore,the amount of correction achieved was positively correlated to these changes.Wavefront aberrations on the posterior corneal surface remained constant with both procedures and there were no differences when the procedures were compared (P＞0.05).Conclusion Spherical aberrations,coma and total higher-order aberrations on the anterior corneal surface increased after both procedures,and did not recover until the 3 month after surgery.The changes in spherical aberrations and total higher-order aberrations on the anterior corneal surface were higher in the LASIK group than in the LASEK group,and depended on correction achieved in both procedures.The two procedures had no effect on wavefront aberrations on the posterior corneal surface.

Objective To assess the clinical effectiveness of photorefractive keratectomy (PRK)versus laser subepithelial keratectomy (LASEK) for the correction of myopia.Methods A meta-analysis of the literature was conducted that included a review of randomly controlled trials in Pubmed,EMbase,National Knowledge Infrastructure and CQVIP.Data were selected by two independent reviewers using an extraction method.The results included efficacy outcomes (UCVA≥0.8,UCVA≥ 1.0postoperatively),accuracy outcomes (proportion of eyes within ±0.50 diopters of the target refraction postoperatively),safety outcomes (loss of ≥2 lines of BSCVA postoperatively),mean pain scores on day 1 postoperatively,timeline for complete healing of epithelial defects and mean corneal haze scores postoperatively.The Cochrane Collaboration's RevMan 5.0 software was used for statistical analysis.Results Nine RCTs involving 884 eyes with myopia were included.Meta-analysis showed that the efficacy (OR=1.08,95％CI:0.62-1.89),accuracy (OR=0.81,95％CI:0.53-1.24) and safety outcomes between PRK and LASEK were comparable.Compared to PRK,LASEK was better in reducing postoperative corneal haze intensity (WMD=0.23,95％CI:0.13-0.33).Conclusion PRK and LASEK have the same effectiveness,accuracy and safety for myopia,but LASEK results in less corneal haze intensity than PRK postoperatively.

Objective To study the normal strehl ratio (SR) values of total aberrations and the SR values of total higher order aberrations on the anterior corneal surface of myopic eyes with different pupil diameters; to study the relationship between SR values and the modulation transfer function (MTF).Methods It was a cross-sectional study.The SR values of total aberrations and total higher order aberrations of the anterior corneal surfaces of 200 people (400 eyes) were examined with a SIRIUS 3D topography system.One-way ANOVA aualysis was used to compare the SR values of total aberrations and total higher order aberrations of the anterior corneal surface for different pupil diameters (3.0,5.0,6.0,7.0 mm).A Pearson correlation analysis was used to study the relationship between the two types of SR values and the corresponding root mean square (RMS) values; and the relationship between SR values of the total aberrations and corresponding MTF values.Results The results for different pupil diameters (3.0,5.0,6.0,7.0 mm) of the anterior corneal surface were as follows:the SR value of total aberrations 100' (0.46±0.13)-(0.14±0.03); the SR value of total higher order aberrations 100' (0.69±0.15)-(0.17±0.04); the SR value of total aberrations 200' (0.45±0.13)-(0.16±0.04); and the SR value of total higher-order aberrations 200' (0.70±0.15)-(0.20±0.05).The SR values of each group decreased with an increase in pupil diameter.The SR values of total aberrations and total higher-order aberrations on the anterior corneal surface were negatively correlated with the corresponding RMS values.When the pupil diameter was small,the SR value of total aberrations was more closely related to the higher frequency region of the MTF.When the pupil diameter was large,the SR value of total aberrations was more closely related to the lower frequency region of the MTF.Conclusion The SR values of total aberrations and total higher-order aberrations on the anterior corneal surface in myopic eyes are negatively correlated with pupil diameter.There is a certain correlation between SR values and the corresponding RMS and MTF values.

Objective To discuss the imaging ability of different anterior optical coherence tomography (OCT) systems.Methods It was a cross-sectional study.Six normal volunteers (12 eyes,24 directions) were involved in this cross-sectional study.Three different OCT systems were used to acquire images of their eyes.The important structures:scleral spur,Schlemm's canal,anterior segment angle recess and Schwalbe line were defined.The trabecular-iris angle (TIA500),angle opening distance at 500 μm (AOD500),the area of the trabeculo-iris space at 500 μm (TISA500),the widest diameter of Schlemm's canal,and the area and circumference of Schlemm's canal were measured if possible.Results Using real-time Fourier-domain anterior segment OCT,the scleral spur,Schlemm's canal,anterior segment angle recess and the Schwalbe line were defined in 8 eyes (67％) 13 positions (54％),12 eyes (100％) 22 positions (92％),12 eyes (100％) 24 positions (100％),and 6 eyes (50％) 9 positions (38％),respectively.Using RTV-ue 100 OCT,Schlemm's canal and the Schwalbe line could be defined in 8 eyes (67％) 8 positions (33％) and 10 eyes (83％) 19 positions (79％),respectively.The scleral spur and anterior segment angle recess could not be seen.The scleral spur and anterior segment angle recess were defined in 12 eyes (100％) 21 positions (88％) and 12 eyes (100％) 24positions (100％),respectively using Visante OCT,but Schwalbe's line and Schlemm's canal could not be defined.There was a significant difference in their ability to define important structures (scleral spur,P＜0.01; Schlemm's canal,P＜0.01; anterior segment angle recess,P＜0.01; and Schwalbe line,P＜0.01).The TIA500,AOD500 and TISA500 measured by Real-time Fourier-domain anterior segment OCT and Visante OCT were similar,and the area and widest diameter of Schlemm's canal measured by Real-time Fourier-domain anterior segment OCT and RTV-ue 100 OCT were also similar.The differences were not significant.Conclusion All three OCTs can acquire clear images of the anterior segment angle.Real-time Fourier-domain anterior segment OCT and RTV-ue 100 OCT can acquire high-resolution images and are good at imaging subtle structures.Real-time Fourier-domain anterior segment OCT and Visante OCT are good at imaging deep structures.

Objective To evaluate the topographic profile and influential factors of peripapillary retinal nerve fiber layer (RNFL) thickness in young myopia.Methods It was a cross-sectional study.One hundred and sixty-two eyes of 162 consecutive refractive surgery candidates were included in this study.The mean age of the subjects was 27.0±4.6 years old,the average spherical equivalent (SE) was-4.98±2.64 D with a range of-0.75 D to-11.00 D,of 54 eyes were low myopia with the mean SE was-2.27±0.64 D,55 eyes were moderate myopia with the average SE was-4.54±0.79 D,53 eyes were high myopia with the mean SE was-8.19±1.51 D.All subjects underwent ophthalmic examination and the imaging with the Stratus optical coherence tomography (Stratus OCT).Data were analyzed using a partial correlation.Results The global RNFL thickness was 103.6±9.5 μm,the RNFL thickness of the superior quadrant was 128.7±16.8 μm,the RNFL thickness of the nasal quadrant was 67.8±16.5 μm,the RNFL thickness of the inferior quadrant was 125.9±17.2 μm,the RNFL thickness of the temporal quadrant was 91.9±16.9 μm.No statistically significant associations between the parameters of RNFL thickness and age,gender,corneal curvature,central corneal thickness (CCT),negative correlation between the axial length and RNFL thickness of the global,superior quadrant,the nasal quadrant,the inferior quadrant (r=-0.379,-0.297,-0.180,-0.291,All P value ＜0.05),while no statistically significant associations between the RNFL thickness of temporal and the axial length.The partial correlation coefficient between the RNFL thickness of the superior quadrant,the nasal quadrant,the inferior quadrant,the temporal quadrant and SE was r=0.003 (P=0.968),r=-0.233 (P=0.003),r=-0.163 (P=0.039),r=0.159 (P=0.045),respectively.Conclusion The topographic profile of peripapillary RNFL thickness is the superior quadrant ＞the inferior quadrant ＞the temporal quadrant ＞the nasal quadrant in these young myopia.The global RNFL thickness and the RNFL thickness of the nasal quadrant decreased with the axial length,also in the superior quadrant and the inferior quadrant.The RNFL thickness of the nasal and the superior quadrant are decrease with the SE,while the RNFL thickness of the temporal quadrant is increased.

Objective To evaluate the efficacy,safety,and biocompatibility of a posterior chamber phakic intraocular lens (PCPIOL) to correct high myopia within 1 year.Methods In a retrospective case series study,an implantable intraocular lens was implanted in 290 eyes of 149 patients with a mean age of 29.0±6.5 years (range 20 to 49 years).There were 107 eyes from males and 183 eyes from females.Mean preoperative myopia was-13.2±5.6 D (range-6.0 to-32.0 D).The follow-up included tests for visual acuity,intraocular pressure,manifest refraction,and adverse reactions.Results Postoperatively,all eyes had a significant increase in uncorrected visual acuity (UCVA).Best corrected visual acuity (BCVA) had improved by 1 or more lines in 199 eyes (68.6％)at 1 year.No eye lost BCVA.Thirty-two eyes developed intraocular pressure (IOP) more than 35 mmHg within 3 hours after the implatation.Pupillary blockage caused an increase in IOP in 13 eyes and insufficient removal of viscoelastic material caused an increase in 19 eyes.IOP returned to normal in the following days after quick treatment.Three eyes had intraocular pressure between 21-25 mmHg.Two eyes had macular hemorrhage 3 months after the implantation,and the hemorrhage regressed 3 month later.Throe IOLs were removed from 2 patients because of an intolerant halo.The IOLs were exchanged in 12 eyes in 1 year because of high or low vault.Conclusion After 1 year of follow-up,IOL implantation had good visual and refractive results with excellent biocompatibility and fewer adverse reactions.

Objective To assess the clinical outcomes and rotational stabilility of toric intraocular lenses (IOL) for the correction of preexisting corneal astigmatism in cataract patients with myopia.Methods Forty-seven eyes of 32 patients were enrolled in this prospective study.Preoperative corneal astigmatism was more than 1.0 diopter (D) for all eyes.All patients underwent similar phaeoemulsification combined with toric IOL implantation.Uncorrected visual acuity (UCVA),best corrected visual acuity (BCVA),preoperative corneal astigmatism,anticipated residual astigmatism,postoperative residual astigmatism and toric lens axis were measured.The postoperative IOL position was assessed at 1 day,1 week,1 month and 3 months using digital pictures under a slit lamp.Data were analyzed using chi-square test and paired t test.Results At 3 months following surgery,91％ of the eyes had 0.5 or better UCVA,much higher than preoperative BCVA (x2=80.67,P＜0.05).Mean preoperative corneal astigmatism was 2.11±0.83 D and postoperative refractive cylinder was 0.47±0.35 D,indicating a significant decrease in refractive cylinder after surgery (t=12.48,P＜0.05).The mean rotation of the toric IOLs was 3.75°±1.39° after 3 months postoperatively.Only 3 eyes had more than 5° of rotation after the operation and none eye had more than 10° of rotation.Conclusion Toric IOLs provide cataract patients with better UCVA,good rotational stability and predictability in the correction of corneal astigmatism.The combined procedure of phacoemulsification and posterior chamber toric IOL implantation is an effective option for the correction of preexisting corneal astigmatism in cataract patients with myopia.

Objective To investigate the effectiveness of posterior scleral reinforcement (PSR)combined with strabismus surgery for treating pathological myopia and strabismus.Methods In this case-series study,33 patients with pathological myopia and strabismus were treated between March 2005 and August 2009 in Eye Hospital of Wenzhou Medical College.Patients ranged in age from 5 to 65 years old.In all cases,the angle of strabismus was greater than 15°; 31 patients were exotropic and 2 were esotropic.Pathological myopia ranged from-8.00 to-30.00 D.All corrected visual acuity was less than 4.9.The patients were divided into 3 groups by age.The modified Snyder-Thompson PSR and strabismus surgery were performed on the 33 patients.Data were analyzed with a paired t test.Results After 1 to 5.3 years of follow-up,only the children's group showed a statistically significant change in the eyes length (t=-2.56,P=0.025).When eyes were rechecked with optical coherence tomography,the macular hemorrhage in 2 eyes had faded,the retina foveoschisis in 3 eyes had disappeared and 2 eyes had became shorter.The residual strabismus of 4 patients was 10°; the residual strabismus in the other patients was less than 5°.All patients were satisfied with the improvement in the eyes' appearance.Conclusion PSR combined with strabismus surgery can prevent or delay the progress of myopia,improve the eyes' appearance,and reduce the pain that would result if each operation were done separately.The combined surgery also reduces adherence restrictions and the difficulty of the operation for doctors.PSR combined with strabismus surgery is feasible and safe.

Clinical effect of rigid gas permeable contact lenses on myopia progression in adolescents

Objective To evaluate the effect of Menicon-Z gas permeable contact lenses (RGPCLs)in controlling the progression of myopia in adolescents.Methods It was a prospective self-control study.Seventy-six myopia patients under the age of 18 (148 eyes) were recruited for this study.Divided into 4 groups according to the degree of refractive error (-0.50--3.00 D,-3.25--6.00 D,-6.25--9.00 D,-9.25--20.00 D).Clinical data included corrected visual acuity,refractive power,corneal curvature,axial length,annual progression rate of myopia and follow-up records for (15.2±5.2)months were analyzed.Data analysis included a paired samples t test and ANOVA on the effect of clinical RGPCLs to control juvenile myopia progression.Results There were significant differences in corneal curvature after wearing RGPCLs (FK t=4.80,P＜0.01 ;SK t=7.76,P＜0.01).There were no obvious differences in refractive power,astigmatism or axial length.However,there was a significant difference in the range of myopia progression (from-1.10±0.53 D to-0.00±0.47 D)that showed a decrease after wearing RGPCLs for about 1 year (t=-13.95,P＜0.01).There were statistically significant differences between different refractive power groups (F=4.84,P=0.004):for higher refractive powers,myopia progression was least.Conclusion Long-term wear of Menicon-Z RGPCLs is safe for adolescents.And it effectively decreases the progression of myopia,corneal curvature and axial length,especially in more severe myopia cases.

Objective To analyze the safety and efficacy of excimer laser epithelial keratomileusis (LASEK) in the treatment of myopia.Methods It was a retrospective case series study.For the period of 2001-2009 in Beijing Intech Eye Hospital,4628 eyes of 2314 cases with myopia were treated with LASEK.Patients with varying degrees of myopia were grouped for analysis:group Ⅰ,-1.25～-6.00 D,1456 eyes; group Ⅱ,-6.25～-10.00 D,2164 eyes; group Ⅲ,-10.25～-16.75 D,1008 eyes.Postoperative follow-up assessments were performed at 3,6 and 12 months.Postoperative measurements included slit-lamp microscopy for corneal healing,manifest refraction,uncorrected visual acuity (UCVA),refraction (spherical equivalent),intraocular pressure,haze,etc.The results were analyzed with a x2 test and ANOVA by SPSS 13.0 software.Results The postoperative UCVA at 1 year was equal to or greater than 1.0:group Ⅰ (1430 eyes) 98.21％; group Ⅱ (1898 eyes) 87.71％; group Ⅲ (781 eyes) 77.48％.The occurrence of haze at 3-6 months:group Ⅰ (4 eyes) 0.27％; group Ⅱ (50 eyes) 2.31％; these were statistically significant differences in group Ⅲ (90 eyes) 8.93％ (x2=159.4,P＜0.01).The incidences of high intraocular pressure induced by the topical use of corticosteroid eye drops were:group Ⅰ (79 eyes) 5.42％; group Ⅱ (443 eyes) 20.47％; group Ⅲ (266 eyes) 26.39％.The results for the 3 groups showed significant differences (x2=219.4,P＜0.01).Analysis of variance was used to compare the changes in the spherical equivalence of each of the 3 groups at 3 months to 1 year and the differences between any 2 groups.These were statistically significant differences (F=16.813,P＜0.05).Conclusion LASEK is a safe and effective surgical procedure to correct myopia,for a thin cornea,high myopia and ultra high myopia.Intraocular pressure should be monitored during the follow-up periods so the occurrence of steroid-induced glaucoma can be prevented.

Laser in situ keratomileusis (LASIK) is an established corneal refractive surgery.Keratectasia after LASIK is a dormant and serious complication that is still one of the most perplexing and widely discussed clinical issues facing refractive surgeons.An understanding of keratectasia after LASIK,including etiology,pathology,risk factors,preventions and treatments,is of great practical significance.This article reviews the current status of these aspects.