Evaluation of preoperative dry eye in people undergoing corneal refractive surgery to correct myopia

AIM: To investigate the incidence of preoperative dry eye and related factors in patients undergoing corneal refractive surgery to correct myopia.METHODS: A total of 141 patients with myopia who underwent corneal refractive surgery were surveyed by questionnaires, tear film break-up time(BUT) test, Schimer I test(SIt), corneal fluorescein staining(FL) test and diagnosed according to the currently recognized domestic diagnostic criteria for dry eye. Correlation analysis of factors such as age, gender, regular wearing of contact lens(CL), diopter(spherical equivalent), corneal thickness, and corneal curvature that may affect the onset of dry eye was carried out to clarify the main influencing factors. RESULTS: There were 64 patients(45.39%) diagnosed with dry eye. The male patients(20.31%) was significantly less than that of non-dry eye subjects(41.56%;χ~2=7.260, P=0.007);the proportion of patients with dry eye wearing CL(81.25%) was significantly higher than that of non-dry eye subjects(51.95%;χ~2=13.234, P<0.001);the median diopter level of dry eye patients was-6.59(IQR:-8.87,-4.58) D, and the median diopter level of non-dry eye subjects was-5.69(IQR:-7.15,-4.03) D. The diopter level of dry eye patients was significantly higher(Z=-2.086, P=0.019). However, the age, best corrected visual acuity, and intraocular pressure of dry eye patients were not statistically different from those of non-dry eye subjects(t=-0.257,-0.383 and 0.778, P=0.798, 0.702, and 0.438);the corneal thickness and corneal curvature(K1 and K2) were also not statistically different either(Z=-1.487,-1.036 and-1.707, P=0.137, 0.300, and 0.088). The research further analyzes the three significant factors in the single factor analysis(gender, CL wear, and diopter) in a multi-factor way: CL wear and diopter were the influencing factors of dry eye disease. Among them, CL wear increased the risk of dry eye by 2.934 times compared with no CL wear;for every 1 D increase in diopter, the risk of dry eye increased by 0.761 times.CONCLUSION: Preoperative dry eye is relatively common in patients who undergo corneal refractive surgery to correct myopia, especially in patients who have a history of CL wear and a high diopter level before surgery. Therefore, it is necessary to carry out preoperative screening and timely treatment of dry eye to obtain the best treatment outcome and postoperative satisfaction.

One-year results for myopia control of orthokeratology with different back optic zone diameters: a randomized trial using a novel multispectral-based topographer

AIM:To present the 1-year results of a prospective cohort study investigating the efficacy,potential mechanism,and safety of orthokeratology(ortho-k)with different back optic zone diameters(BOZD)for myopia control in children.METHODS:This randomized clinical study was performed between Dec.2020 and Dec.2021.Participants were randomly assigned to three groups wearing ortho-k:5 mm BOZD(5-MM group),5.5 mm BOZD(5.5-MM group),and 6 mm BOZD(6-MM group).The 1-year data were recorded,including axial length,relative peripheral refraction(RPR,measured by multispectral refractive topography,MRT),and visual quality.The contrast sensitivity(CS)was evaluated by CSV-1000 instrument with spatial frequencies of 3,6,12,and 18 cycles/degree(c/d);the corneal higher-order aberrations(HOAs)were measured by iTrace aberration analyzer.The one-way ANOVA was performed to assess the differences between the three groups.The correlation between the change in AL and RPR was calculated by Pearson’s correlation coefficient.RESULTS:The 1-year results of 20,21,and 21 subjects in the 5-MM,5.5-MM,and 6-MM groups,respectively,were presented.There were no statistical differences in baseline age,sex,or ocular parameters between the three groups(all P>0.05).At the 1-year visit,the 5-MM group had lower axial elongation than the 6-MM group(0.07±0.09 vs 0.18±0.11 mm,P=0.001).The 5-MM group had more myopic total RPR(TRPR,P=0.014),with RPR in the 15°–30°(RPR 15–30,P=0.015),30°–45°(RPR 30–45,P=0.011),temporal(RPR-T,P=0.008),and nasal area(RPR-N,P<0.001)than the 6-MM group.RPR 15–30 in the 5.5-MM group was more myopic than that in the 6-MM group(P=0.002),and RPR-N in the 5-MM group was more myopic than that in the 5.5-MM group(P<0.001).There were positive correlations between the axial elongation and the change in TRPR(r=0.756,P<0.001),RPR 15–30(r=0.364,P=0.004),RPR 30–45(r=0.306,P=0.016),and RPR-N(r=0.253,P=0.047).The CS decreased at 3 c/d(P<0.001),and the corneal HOAs increased in the 5-MM group(P=0.030).CONCLUSION:Ortho-k with 5 mm BOZD can control myopia progression more effectively.The mechanism may be associated with greater myopic shifts in RPR.

Long-term observation on safety and visual quality of implantable collamer lens V4c implantation for myopia correction:a 5-year follow-up

AIM:To elucidate the safety and visual quality of implantable collamer lens with central hole(ICL V4c)implantation for correcting moderate and high myopia for at least 5y.METHODS:This retrospective study was conducted on 58 patients(114 eyes)who were followed up for at least 5y after ICL V4c implantation.The observation was done before and on 1d,1mo,1 and 5y or more after the surgical procedure.The visual acuity,subjective refraction,intraocular pressure,vault,axial length,central hole position,pupil diameter,visual quality,and adverse events were analyzed.The visual quality includes aberration,the modulation transfer function cutoff frequency(MTF cutoff),objective scattering index(OSI),Stroller's ratio(SR),and visual quality questionnaire.RESULTS:The average follow-up period was 69.25±3.80mo(range 60–82mo)and the preoperative spherical equivalent(SE)was-8.66±1.97 D.At 5y after operation,the safety index was 1.01±0.02 and the efficacy index was 0.99±0.42 and SE was-0.65±0.63 D.The 59.6%of the eyes achieved an uncorrected distance visual acuity of 20/20,76.3%of the eyes had SE within±1.0 D at the last visit.The axial length increased by 0.29±0.71 mm 5y after the surgery(t=-3.843,P<0.001).The mean vault at the last follow-up was 510.59±245.61μm.The central hole was on the temporal side in 80 eyes(84.2%).The visual quality questionnaire showed that 98.2%patients were satisfied with the surgical procedure.Adverse events occurred in 4 eyes(3.5%),including the posttraumatic toric ICL rotation(2 eyes),iris incarceration(1 eye),and posttraumatic ICL displacement(1 eye)at the last follow-up.CONCLUSION:Long-term ICL V4c implantation is safe,effective,and stable for correcting moderate and to high myopia,and the visual quality with patients is excellent and satisfactory,but the progression of axial length still needs attention after surgery.

Refractive surgery: the most cost-saving technique in refractive errors correction

AIM： To compare the lifetime and annual economic burden of spectacles, contact lenses, and refractive surgery in correction of refractive errors.METHODS： This is a cross-sectional study with convenience sampling which 120 patients were interviewed in a tertiary referral hospital in the Iranian health care system. The bottom-up based cost of illness approach was estimated using a face-to-face interview to assess the direct and indirect cost of different refractive errors correction of any correction technologies. RESULTS： Correction with spectacle imposes a total direct cost of US dollar （US$） 342.5 （±8.41） per year and US$9373.5 （±230.1） per lifetime to each patient. These figures for the contact lenses were obtained US$198.3 （±0.12） and US$5203.1 （±256.3） and for refractive surgery were obtained US$19.1 （±1.2） and US$568.1 （±64.6）, respectively. Overall, based on age-adjusted prevalence rates, astigmatism had the highest share of refractive errors economic burden with a lifetime direct cost of slightly less than US$5.49 billion, while hyperopia and myopia imposed less than US$5.24 and 4.2 billion on patients, respectively. The annually imposed cost on each individual Iranian patient with refractive errors is US$308.5. CONCLUSION： Based on 18mo post refractive surgery course observation, which is generalized to whole life, refractive surgery significantly imposed much less cost compared with spectacles and contact lenses. Refractive errors among Iranians result in considerable economic burden. Using the refractive surgery instead of other two correction methods has the ability to reduce this economic loss in the future.

Corneal neuromediator profiles following laser refractive surgery

Laser refractive surgery is one of the most commonly performed procedures worldwide.In laser refractive surgery,Femtosecond Laser in Situ Keratomileusis and Refractive Lenticule Extraction have emerged as promising alternatives to microkeratome Laser in Situ Keratomileusis and Photorefractive Keratectomy.Following laser refractive surgery,the corneal nerves,epithelial and stromal cells release neuromediators,including neurotrophins,neuropeptides and neurotransmitters.Notably,nerve growth factor,substance P,calcitonin gene-related peptide and various cytokines are important mediators of neurogenic inflammation and corneal nerve regeneration.Alterations in neuromediator profiles and ocular surface parameters following laser refractive surgery are attributed to the surgical techniques and the severity of tissue insult induced.In this review,we will discuss the(1)Functions of neuromediators and their physiological and clinical significance;(2)Changes in the neuromediators following various laser refractive surgeries;(3)Correlation between neuromediators,ocular surface health and corneal nerve status;and(4)Future directions,including the use of neuromediators as potential biomarkers for ocular surface health following laser refractive surgery,and as adjuncts to aid in corneal regeneration after laser refractive surgery.

Femtosecond laser corneal refractive surgery for the correction of high myopic anisometropic amblyopia in juveniles

AIM： To evaluate the effects of femtosecond laser-assisted in situ keratomileusis（FS-LASIK） and small-incision lenticule extraction（SMILE） to correct high myopic anisometropic amblyopia in juvenile patients. METHODS： From November 2013 to January 2015, 33 amblyopic patients with high myopic anisometropic amblyopia were studied. FS-LASIK（30 eyes） or SMILE（3 eyes） was performed in the amblyopic eyes. Visual acuity, refraction, contrast sensitivity, stereoacuity and complications were evaluated. Patients completed followup examinations at 3 d, 1 mo, 3 mo and the last follow-up time（mean 8.17±3.23 mo） after surgery. RESULTS： The mean age at surgery was 9.04±3.04 y（range 6-16 y）. The mean spherical equivalent in the amblyopic eyes was significantly decreased from-10.00±2.39 D preoperatively to-0.06±1.06 D at 1 mo,-0.19±1.33 D at 3 mo and-0.60±1.43 D at approximately 8 mo postoperatively（P〈0.05 for all）. The mean myopic anisometropia was significantly decreased from-9.45±2.33 D preoperatively to ＋0.37±1.48 D at 1 mo,-0.46±1.47 D at 3 mo and-0.09±1.83 D at approximately 8 mo（P〈0.05 for all）. The logarithm of the minimum angle of resolution（log MAR） for uncorrected and corrected distance visual acuity（UDVA and CDVA, respectively） of the amblyopic eye improved from 1.74±0.35 and 0.98±0.63 preoperatively to 0.45±0.31 and 0.41±0.33 at approximately 8 mo after surgery, respectively. The logM AR CDVA at 3 d, 1, 3 and 8 mo postoperatively improved by means of 1.42, 2.22, 2.96, and 4.39 lines, and a gain of more than two lines accounted for 45%, 50%, 74% and 86% of all patients, respectively. The contrast sensitivity of both amblyopic eyes and dominant eyes at 0.5, 2, 8 cycles perdegree was significantly improved postoperatively（P〈0.05 for all）. Of the 33 pediatric patients, no patients had near stereopsis preoperatively and seven patients（21.2%） recovered near stereopsis（400″ to 60″） at approximately 8 mo after surgery. No intraoperative or postoperative complications occurred in any patient.CONCLUSION： FS-LASIK or SMILE can be promising alternative methods to correct high myopic anisometropic amblyopia in juvenile patients who have failed with traditional approaches.

Progress of corneal collagen cross-linking combined with refractive surgery

As a photochemical reaction that can stiffen the cornea,corneal collagen cross-linking(CXL) is the only promising method of preventing the progress of keratectasia,such as keratoconus and secondary ectasia following refractive surgery. The aim of CXL is to stabilize the underlying condition,with a small chance of visual improvement. Combining CXL with refractive surgery targeting both stabilization and reshaping of the corneal tissue for visual function improvement is a good treatment option. This review aims to provide a comprehensive and unbiased summary of the published research regarding combined CXL and refractive surgery,including measures and results,to help elucidate the future direction of CXL.

Dr.Father Waclaw Szuniewicz,a forgotten pioneer in refractive surgery and his work in China

Father Waclaw Szuniewicz(1891-1963) was a skilled ophthalmic surgeon, missionary, and teacher. For several years he worked in China, afterwards in the United States and in Brazil. The aim of the paper is to present the unanalyzed issues of Szuniewicz’s research regarding corneal refractive surgery. Szuniewicz performed experiments on changing the corneal curvature with anterior, posterior and full-thickness incisions. The results of modifying the anterior and posterior corneal curvature were satisfactory, however, diminished significantly within months after surgery. Corneal band resections were superior in terms of efficacy, however, such an intervention commonly led to complications in animal studies. Szuniewicz’s work was not published during his life. Nevertheless, as a result of strong impact of his personality and ideas, he is frequently considered as a pioneer of corneal refractive surgery.

Corneal re-innervation following refractive surgery treatments

Laser refractive surgery is one of the most performed surgical procedures in the world. Although regarded safe and efficient, it has side effects. All of the laser based refractive surgical procedures invoke corneal nerve injury to some degree. The impact of this denervation can range from mild discomfort to neurotrophic corneas. Currently, three techniques are widely used for laser vision correction: small incision lenticule extraction, laser-assisted keratomileusis in situ and photorefractive keratotomy. Each of these techniques affects corneal innervation differently and has a different pattern of nerve regeneration. The purpose of this review is to summarize the different underlying mechanisms for corneal nerve injury and compare the different patterns of corneal reinnervation.

Iris recognition:a biometric method after refractive surgery

Iris recognition,as a biometric method,outperforms others because of its high accuracy. Iris is the visible internal organ of human,so it is stable and very difficult to be altered. But if an eye surgery must be made to some individuals,it may be rejected by iris recognition system as imposters after the surgery,because the iris pattern was altered or damaged somewhat during surgery and cannot match the iris template stored before the surgery. In this paper,we originally discuss whether refractive surgery for vision correction(LASIK surgery) would influence the performance of iris recognition. And experiments are designed and tested on iris images captured especially for this research from patients before and after refractive surgery. Experiments showed that refractive surgery has little influence on iris recognition.

Suicide after Excimer Laser Refractive Surgery: On the Importance of Matching Expectations

Background: Refractive surgery may change the individual life to the better largely eliminating the need for spectacles. However, expectations may vary and postoperative reality may come as a surprise. Aim: To emphasize the need for thorough alignment of expectations and options between surgeon and patient. Methods: A case is presented in which a successful refractive laser operation is a part of a trigger mechanism for a depressive episode leading to suicide. It emphasizes the crucial importance of constructive alignment of expectations between patient and treating physician prior to surgery. Results: The case presented outlines that ophthalmic surgery at the edge of high-tec with all its tempting features is also very attractive to individuals with very well defined and less flexible expectations. The possible irreversibility of some of the refractive surgery may force the patient postoperatively into a psychological corner, immobilizing him/her and restricting his/her options. Conclusions: High-tec operations dealing with one of the most elementary senses we have, vision, demand a thorough estimation of the patients profile prior to any surgery. Only matching expectations between the possible and desired outcome and reconfirmation of the match may reduce the risk of postoperative crisis which may carry a risk the patient’s life.

Application of Complementary Error Function to the Transition Zone of Myopic Ablation Shapes in Refractive Surgery

In refractive surgery, the cubic spline fit for the transition zone breaks down for myopia and myopic meridians in mixed astigmatism as in many cases the cubic spline function runs into negative values. In this paper, the complementary error function is proposed instead of the cubic spline function as the transition zone function, due to the availability of analytical expression of its derivatives and the nonnegativity fact. It is shown that with the use of the complementary error function, transition zones for all refractive types work correctly.

Assessing the Effect of Colored Filters on Glare Sensitivity of Post Refractive Surgery Patients

Purpose:The use of colored filters is one recommended way for patients to reduce glare..This study assessed the effect of colored filters for reducing glare symptoms in post refractive surgery patients.Method:.Log MAR visual acuity was determined in 70 participants.(140 eyes).who had undergone PRK refractive surgery using three colored filters(Yellow,Green,and Red)in different light conditions.Results:.Measured visual acuity was significantly reduced with red and green filters in glare and nonglare conditions when compared to its measurement without a filter.An asymmetrical light condition also revealed a significant difference in the visual acuity of the right and left eye when compared to each other.However,no significant differences were observed for the yellow filter in either the measured visual acuity of each eye in both light conditions or of the right and left eyes compared to each other.Conclusion:Red and green filters are poor choices for reducing glare in post refractive surgery patients but a yellow filter could be used to decrease glare and improve acuity.

0.05% atropine on control of myopia progression in Chinese school children: a randomized 3-year clinical trial

·AIM:To evaluate the effect of 0.05%atropine on the control of myopia for 2y(phase I)and on spherical equivalent refraction(SER)progression for 1y(phase II)after its withdrawal in Chinese myopic children.·METHODS:Totally 142 children with myopia were randomly assigned to the 0.05%atropine group or to the placebo group.In phase I,children received 1 treatment for each eye daily.In phase II,the patients received no treatment.Axial length(AL),SER,intraocular pressure(IOP)and atropine-related side effects were assessed at 6 months’intervals.·RESULTS:During phase I,the mean change of SER was-0.46±0.30 D in the atropine group,compared to-1.72±1.12 D in the placebo group(P<0.001).The mean change of AL in the atropine group(0.26±0.30 mm)was significantly shorter than that in the placebo group(0.76±0.62 mm,P=0.002).In addition,in phase II(12mo after the withdrawal of atropine),there was no significant difference in AL change from the atropine group,when compared with that from the placebo group(0.31±0.25 mm vs 0.28±0.26 mm,P>0.05).Furthermore,the change in SER from the atropine group was 0.50±0.41 D,which was significantly lower than 0.72±0.60 D from placebo group,(P<0.05).Finally,there were no statistically significant differences in IOP between the treatment and control groups at any stages(all P>0.05).·CONCLUSION:The use of 0.05%atropine for two consecutive years may effectively control elongation of AL and thus progression of myopia,without significant SER progression 1y after atropine withdrawal.Therefore,treatment with 0.05%atropine daily for 2y is effective and safe.

Quality of life and depression among patients with high myopia in Nigeria:a cross sectional study

AIM:To evaluate the quality of life(QOL)and level of depression among participants with high myopia in Nigeria and the demographic factors associated with these outcomes.METHODS:This cross-sectional study was conducted on 100 adult participants with high myopia(defined as refractive error≤-5.00 D or worse,and uncorrected visual acuity worse than 6/18 in the better seeing eye)attending ophthalmology centres in Nigeria from 2 October 2021 to 30 August 2022.The means and standard deviations were calculated for each of the four domains of World Health Organization Quality of life scale(WHOQOL-BREF)using the transformed scores.The Beck Depression Inventory(BDI)scale was used to assess the level of depression.RESULTS:The highest and the lowest mean scores of WHOQOL-BREF domains were found for the psychological and physical health domains(mean percentage scores were 67.0[95% confidence intervals(CI)64.1-68.9]and 55.3(95%CI 51.8-58.8,P<0.001),respectively.One-way analysis of variance(ANOVA)revealed significant differences in physical health with educational status(higher among those with tertiary education:mean difference 0.9,95%CI-0.2-2.1;P=0.049),differences in psychological health with working status(higher among those who were working 1.2,95%CI 0.3-2.1;P=0.012).Also,the result showed a statistically significant association between environmental health and marital status(higher among non-married:1.7,95%CI-0.9-2.3;P=0.012)while overall health was associated with place of residence(higher in urban areas:2.3,95%CI 1.2-3.5;P=0.024).For depression,one in every nine participants reported major depressive symptom,mostly younger people(aged 16-29 vs 30-49y:17.0%vs 0,P=0.019),and slightly more women than men(14.3%vs 0,P=0.064).There were significant negative correlations between the depression scores and psychological health(r=-0.48,P<0.001),physical health(r=-0.29,P=0.002),social and relationship(r=-0.49,P<0.001),environmental(r=-0.48,P<0.001)and overall health(r=-0.49,P<0.001)CONCLUSION:People with high myopia have a relatively moderate QOL,but poor physical health,particularly the younger age group,and women who are more likely to experience clinically relevant depression.Eye care professionals should consider possible referrals for counselling for people with high myopia.

Three-year results of small incision lenticule extraction and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis for correction of high myopia and myopic astigmatism

AIM： To compare and calculate the 3-year refractive results, higher-order aberrations （HOAs）, contrast sensitivity （CS） and dry eye parameters after small incision lenticule extraction （SMILE） and wavefront-guided femtosecond laser-assisted laser in situ keratomileusis （FS-LASIK） for correction of high myopia and myopic astigmatism. METHODS： In this prospective, non-randomized comparative study, 78 eyes with spherical equivalent （SE） of -8.11±1.09 diopters （D） received a SMILE surgery, and 65 eyes with SE of -8.05±1.12 D received a wavefront-guided FS-LASIK surgery with the VisuMax femtosecond laser （Carl Zeiss Meditec, Jena, Germany） for flap cutting. Visual acuity, manifest refraction, CS, HOAs, ocular surface disease index （OSDI） and tear break-up time （TBUT） were evaluated during a 3-year follow-up. RESULTS： The difference of uncorrected distance visual acuity （UDVA） postoperatively was achieved at lmo and at 3mo, whereas the difference of the mean UDVA between two groups at 3y were not statistically significant （t=-1.59, P=-0.13）. The postoperative change of SE was 0.89 D in the FS-LASIK group （t=5.76, P=0.00）, and 0.14 D in the SMILE group （t=-0.54, P=0.59） from lmo to 3y after surgery. At 3-year postoperatively, both HOAs and spherical aberrations in the SMILE group were obviously less than those in the FS-LASIK group （P=0.00）, but the coma root mean square （RMS） was higher in the SMILE group （0.59±0.26） than in the FS-LASIK group （0.29±0.14, P=0.00）. The mesopic CS values between two groups were not statistically significant at 3y postoperatively. Compared with the FS-LASIK group, lower OSDI scores and longer TBUT values were found in the SMILE group at Imo and 3mo postoperatively. With regard to safety, no eye lost any line of CDVA in both groups at 3y after surgery. CONCLUSION： Both SMILE and wavefront-guided FS- LASIK procedures provide good visual outcomes. Both procedures are effective and safe, but SMILE surgery achieve more stable long-term refractive outcome and better control of early postoperative dry eye as compared to FS-LASIK.

Comparative analysis of the clinical outcomes between wavefront-guided and conventional femtosecond LASIK in myopia and myopia astigmatism

AIM:To compare the clinical outcomes of wavefront guided femtosecond LASIK(WFG LASIK)and conventional femtosecond LASIK(NWFG LASIK)in eyes with myopia and myopia astigmatism.METHODS:This was a retrospective,nonrandomized,comparative investigation enrolling 236 eyes of 122 patients(18-50 y)with low&moderate and high myopia.The WFG group including 97 eyes(50 patients)undergone WFG LASIK and the NWFG group including 139 eyes(72 patients)undergone conventional LASIK.Mean efficacy index,high order aberrations(HOAs),pupil size and the quality of visual questionnaire were evaluated 6 mo postoperatively.RESULTS:There is no difference between WFG group(-0.054±0.049 in logMAR)and NWFG group(-0.040±0.056)in uncorrected distance visual acuity(UDVA)postoperatively.The myopia astigmatism is higher in WFG group than that in NWFG group(P<0.05).However,the mean efficacy index(MEI)in the WFG group(1.09±0.106)is better than that in the NWFG group(1.036±0.124;P<0.001).Increased HOAs were observed in NWFG group(0.30±0.196)than that in WFG group(0.146±0.188;P<0.001).The pupil size is larger in WFG group(5.15±0.76 mm)than that in NWFG group(4.32±0.52 mm).The patients are satisfied with the clinical surgery,yet WFG group showed better visual quality using the questionnaire survey.Meanwhile,high myopia would result in worse MEI,HOAs and visual quality than low&moderate myopia.CONCLUSION:WFG and NWFG FS-LASIK are both effective and safe procedures to correct low&moderate and high myopia,but WFG FS-LASIK gives a better postoperative MEI,aberrometric control and predictable outcome.Meanwhile,WFG FS-LASIK is better than NWFG FS-LASIK in correction of myopia astigmatism.Low&moderate myopia allow better clinical outcomes than high myopia using any surgical method.

Evaluation of the Clinical Efficacy of Full Femtosecond Laser Surgery in the Treatment of Myopia

Objective:To evaluate the clinical effect of full femtosecond laser surgery in the treatment of myopia patients.Methods:120 myopia patients admitted to our hospital from January 2022 to June 2023 were selected.According to the random number table method,60 patients in the observation group underwent full femtosecond laser surgery,and 60 patients in the control group underwent femtosecond laser-assisted in situ keratomileusis(FS-LASIK)surgery.The clinical effects of the two groups were compared.Results:10 days postoperatively and 6 months after operation,the visual acuity level of the observation group was higher than that of the control group,the postoperative corneal asphericity coefficient and corneal full-thickness were lower than those of the control group,and the total effective rate 6 months after operation was higher than that of the control group(P<0.05).Conclusion:Full femtosecond laser surgical treatment can improve the postoperative visual acuity of patients with myopia,enhance the corneal asphericity coefficient(Q)and corneal full-thickness,and exert significant clinical effects.

Relationship between higher-order aberrations and myopia progression in schoolchildren: a retrospective study

AIM: To investigate the relationship between higher- order aberration (HOA) and myopic progression in schoolchildren. ·METHODS: Between April 23 2011 and August 29, 2011 in the children’s myopia outpatient clinic of the West China Hospital of Sichuan University, 148 eyes of 74 schoolchildren were reviewed. HOAs for a 6 -mm pupil were measured with an aberrometer. Myopic progression rate was defined according to the change in spherical equivalent refraction (SER) divided by the time span (years). Subjects with myopic progression rate of ≥0.50 diopters (D) were classified as the ’fast’group and the subjects with myopic progression rate of 【0.50D were classified as the’slow’group. A retrospective study was conducted to compare HOA between the two groups, using root mean square (RMS) values and Zernike coefficients. ·RESULTS: The RMS values of HOA (t =2.316, P =0.02), HOA without Z 4 0 (t =2.224, P =0.03),third-order aberrations (t’ =2.62, P =0.01), and coma (t’ =2.49, P =0.01) were significantly higher in the fast group than those in the slow group. The individual Zernike coefficients of Z 3 -1 (t = -2.072, P =0.04) and Z 5 1 (Z =-2.627, P =0.01) displayed statistically significant differences between the two groups. Significant correlations were found between the RMS values of HOA (r =0.193, P =0.019), RMS values of HOA without Z 4 0 (r =0.23, P =0.005), RMS values of coma(r =0.235,P =0.004),RMS values of third-order aberrations (r =0.243, P =0.003), and the progression rate. · CONCLUSION: Our results provide evidence of a relationship between HOA and myopic progression. In a future prospective longitudinal study, we aim to verify whether HOA is a risk factor for myopic progression.

Relative peripheral refraction and its role in myopia onset in teenage students

AIM:To characterize peripheral refraction and its relationship with myopia development in a selected group of male teenage Chinese students.METHODS:This 2-year prospective cohort study randomly enrolled 85 non-myopic boys(age,14-16 y)from the Experimental Class of Air Force in China.Cycloplegic peripheral refraction was examined at 0°,±10°,and±20°along the horizontal visual field in the right eye at the baseline and 2-year follow-up.RESULTS:The incidence of myopia at the 2-year followup was 15.29%(13/85).The baseline central refraction(CR)and peripheral refraction at±10°were significantly lower in students who developed myopia than in those who did not(P<0.05).Relative peripheral refraction(RPR)did not differ between students with and without myopia(P>0.05).At the 2-year follow-up,the RPR at±10°and 20°nasal was significantly more hyperopic in the myopic group than in the non-myopic group.Multiple linear regression analysis indicated that the change in CR was significantly correlated with the changes in RPR at 20°nasal,10°nasal,and 20°temporal.Multivariate Logistic regression analysis indicated that the baseline CR[odds ratio(OR):0.092,95%confidence interval(CI):0.012-0.688,P=0.020]and the baseline RPR at 10°nasal(OR:0.182,95%CI:0.042-0.799,P=0.024)were significantly correlated with incident myopia(Omnibus test,χ=10.20,P=0.006).CONCLUSION:CR change is significantly correlated with changes in RPR,and students who develop myopia have more relative peripheral hyperopia.More baseline CR and relative peripheral hyperopia at 10°nasal are protective of myopia onset.