Refractive surgery.

Refractive surgery has evolved beyond laser refractive techniques over the past decade. Laser refractive surgery procedures (such as laser in-situ keratomileusis), surface ablation techniques (such as laser epithelial keratomileusis), and photorefractive keratectomy have now been established as fairly safe procedures that produce excellent visual outcomes for patients with low-to-moderate amounts of ametropia. Additionally, a broader selection of options are now available to treat a wider range of refractive errors. Small incision lenticule extraction uses a femtosecond laser to shape a refractive lenticule, which is removed through a small wound. The potential advantages of this procedure include greater tectonic strength and less dry eye. In the future, intracorneal implants could be used to treat hyperopia or presbyopia. Phakic intraocular implants and refractive lens exchange might be useful options in carefully selected patients for correcting high degrees of ametropia. Thus, physicians are now able to provide patients with the appropriate refractive corrective option based on the individual's risk-benefit profile.

[The rapid development and changes of corneal refractive surgery in China].

Corneal refractive surgery in China, represented by laser corneal surgery, has undergone great changes in recent 30 years. Almost one million corneal refractive surgeries are performed each year. With the rapid technological innovation, the corrective effect is constantly higher, and complications are continuously controlled and reduced. The team of practitioners keeps expanding, and the academic strength is approaching the international level. With the application and promotion of various new technologies, the formulation of relevant norms and the increase of academic researches, corneal refractive surgery in China has stepped into the stage of diversification, intelligence and standardization. However, we should recognize the shortcomings while facing the great achievements. More efforts are still needed to provide the best visual quality and natural vision correction effect for patients. We would like to send congratulations on the 70th anniversary of Chinese Journal of Ophthalmology with this article. (Chin J Ophthalmol, 2020, 56: 81-85).

[Advance of femtosecond small incision lenticule extraction (SMILE) in clinic application].

Femtosecond small incision lenticule extraction (SMILE) had been performed in clinic more than 5 years in China. With the gradual development of the technology, SMILE has caused more and more attention because of the remarkable clinical effect, micro incision, minimally invasive and refractive stability. The reuse of the refractive lenticule (RL) from SMILE has recently become extensive focus, which brings potential method to corneal refractive surgery from subtraction to addition. This review has clarified the technology of SMILE on the aspects of corneal refractive correct, the clinical effect of reuse the materials (RL), the basis of related research and the possible improvement in the future.

[Keratoconus: modern approaches to pathogenetic studies, diagnosis, optical correction, and treatment].

OBJECTIVE: To evaluate modern approaches to pathogenetic studies, diagnosis, optical correction, and treatment of keratoconus (KC). MATERIAL AND METHODS: Research results over the recent years obtained with up-to-date methods of pathogenetic studying, diagnosis, correction, and treatment of KC are presented. RESULTS: Modern approaches to KC consist in analysis of corneal composition and trace elements migration as well as influencing factors. Topographic keratometry and pachymetry proved effective in early detection of KC. Results of intrastromal corneal segments implantation and corneal collagen cross-linking for optical correction and prevention of progression of KC are presented. The use of contact lenses and penetrative keratoplasty for optical correction in KC is comparatively analyzed. A new technique of complete corneal stromoplasty with viscoablation, which does not require anterior corneal stroma pre-separation and removal over the whole area of transplantation and ensures good visual control of Descemet's membrane separation, is suggested. Combined eximer laser photorefractive and phototherapeutic keratectomy for early keratoconus is theoretically substantiated. CONCLUSION: In most patients the discussed methods ensure prevention of progression of keratoconus, optical correction, and treatment. Prospects of further improvement of early diagnosis and treatment are associated with profound studying of the disease pathogenesis.

Trends in refractive surgery at an academic center: 2007-2009.

BACKGROUND: The United States officially entered a recession in December 2007, and it officially exited the recession in December 2009, according to the National Bureau of Economic Research. Since the economy may affect not only the volume of excimer laser refractive surgery, but also the clinical characteristics of patients undergoing surgery, our goal was to compare the characteristics of patients completing excimer laser refractive surgery and the types of procedures performed in the summer quarter in 2007 and the same quarter in 2009 at an academic center. A secondary goal was to determine whether the volume of astigmatism- or presbyopia-correcting intraocular lenses (IOLs) has concurrently changed because like laser refractive surgery, these "premium" IOLs involve out-of-pocket costs for patients. METHODS: Retrospective case series. Medical records were reviewed for all patients completing surgery at the Wilmer Laser Vision Center in the summer quarter of 2007 and the summer quarter of 2009. Outcome measures were the proportions of treated refractive errors, the proportion of photorefractive keratectomy (PRK) vs. laser-assisted in-situ keratomileusis (LASIK), and the mean age of patients in each quarter. Chi-square test was used to compare the proportions of treated refractive errors and the proportions of procedures; two-tailed t-test to compare the mean age of patients; and two-tailed z-test to compare proportions of grouped refractive errors in 2007 vs. 2009; alpha = 0.05 for all tests. Refractive errors were grouped by the spherical equivalent of the manifest refraction and were considered "low myopia" for 6 diopters (D) of myopia or less, "high myopia" for more than 6 D, and "hyperopia" for any hyperopia. Billing data were reviewed to obtain the volume of premium IOLs. RESULTS: Volume of laser refractive procedures decreased by at least 30%. The distribution of proportions of treated refractive errors did not change (p = 0.10). The proportion of high myopes, however, decreased (p = 0.05). The proportions of types of procedure changed, with an increase in the proportion of PRK between 2007 and 2009 (p = 0.02). The mean age of patients did not change [42.4 ± 14.4 (standard deviation) years in 2007 vs. 39.6 ± 14.5 years in 2009; p = 0.4]. Astigmatism-correcting IOL and presbyopia-correcting IOL volumes increased 15-fold and three-fold, respectively, between 2007 and 2009. CONCLUSIONS: Volume of excimer laser refractive surgery decreased by at least 30% between 2007 and 2009. No significant change in mean age or in the distribution of refractive error was seen, although the proportion of high myopes decreased between summer quarters of 2007 and 2009. PRK gained as a proportion of total cases. Premium IOL volume increased, but still comprised a very small proportion of total IOL volume.

Recent trends of refractive surgery rate and detailed analysis of subjects with refractive surgery: The 2008-2015 Korean National Health and Nutrition Examination Survey.

The present study was conducted to investigate recent trends of refractive surgery rates and analyze subjects undergoing refractive surgery using large-scale population studies over the past 8 years. We used the dataset of the Korean National Health and Nutrition Examination Surveys, a nationwide population-based cross-sectional study which were performed from 2008 to 2015. Of the 21,415 participants aged 20 to 49 years, 1,621 had refractive surgeries. Seventy three percent of them were females and 81% of them were aged under 40 years old. Over the past 8 years, cumulative prevalence of refractive surgery rate increased more than 10%. Although young (< 40 years, odds ratio (OR) 0.31, P<0.001) women (OR 1.86, P<0.001) living in urban areas (OR 0.51, P<0.001) with high educational attainment (OR 2.67, P<0.001) and income levels (OR 3.16, P<0.001) accounted for a high proportion in refractive surgery group through all survey years, subgroup analyses revealed that gaps between genders (ORs 3.8 in 2008-2009, 2.1 in 2010-2012, and 1.5 in 2013-2015), educational level (ORs 3.0, 2.5, and 2.1, respectively), and highest/lowest quartiles of household income (ORs 5.2, 2.6, and 2.4, respectively) were decreasing over time. Overall, our study suggests that refractive surgery has reached an age where the majority accepts it, and indeed more and diverse people are undergoing refractive surgeries.

Refractive surgery trends and practice style changes in Germany over a 3-year period.

PURPOSE: To study the current practice styles and preferences of refractive surgeons in Germany. METHODS: In February 2008, a seven-item questionnaire regarding the practice of refractive surgery was mailed to 282 members of the German Society of Intra-ocular Lens Implantation, Interventional, and Refractive Surgery (DGII) and the Commission of Refractive Surgery (KRC). Most questions were identical to our 2005 German refractive surgery survey. All data were analyzed in a masked fashion. RESULTS: The response rate was 42.2%. The majority (68%) of respondents reported that they perform refractive surgery in laser centers (exclusively or partially) followed by general hospitals (19.4%) and universities (12.6%). Although LASIK was the predominant type of refractive surgery performed (80.6%), other refractive procedures included refractive lens exchange (60.2%), photorefractive keratectomy (47.6%), phakic intraocular lens implants (45.6%), laser-assisted subepithelial keratectomy (36.9%), epithelial laser in situ keratomileusis (15.5%), intracorneal rings (5.8%), and limbal relaxing incisions (2.9%). The volume of refractive surgery procedures and the preferred type of excimer laser systems, microkeratomes, and diagnostic devices varied at different institutions. Most respondents performed either wavefront-guided custom ablation or wavefront-optimized ablation (63.1%) compared with conventional excimer laser correction (36.9%). CONCLUSIONS: Refractive surgery practice styles and preferences in Germany are comparable to trends in other European countries. Although LASIK is the most commonly performed refractive procedure, the numbers of various surface ablation techniques and refractive intraocular lens procedures are increasing.

Lasers in refractive surgery: history, present, and future.

The history of laser refractive surgery is reviewed, followed by an overview of the current state of the field as well as a look at promising future developments.

Comparison of the Trend of Excimer laser refractive surgery in Provinces of Iran between 2010 and 2014.

Purpose. The aim of the present study was to compare the trend of excimer laser refractive surgery in different provinces of Iran. Methods. This cross-sectional study was performed in 12 provinces of Iran in 2015 using the data of 2010 to 2014. A total of 28 surgical centers were selected. For each center, one week per season was randomly selected, giving a total of 20 weeks for all seasons of the study years. Then, to estimate the surgical rate in the selected provinces, since 4 weeks were selected each year, the number of operations on the 4 weeks was multiplied by 12.5 to generalize the results to 50 weeks (= 1 year). After applying the weight of each center, the number of refractive operations on each year was divided by the population of the province on that year, and reported per million population. Results. On average, Kermanshah (35.8%, P<0.001) and Tehran (3.1%, P<0.001) had the highest and lowest annual increase and Qom (11.8%, P<0.001) had the highest annual decrease in the rate of excimer laser refractive surgery, respectively. The highest rate was seen in Tehran in 2012 (8885 operations per million population) and the lowest rate was seen in Gilan in 2010 (142 operations per million population). Moreover, the concentration index was 0.25 in 2012, indicating a socioeconomic inequality in the rate of excimer laser refractive surgery. Conclusion. The results of the present study showed an increasing trend in the rate of the excimer laser refractive surgery in 9 Iranian provinces for the first time. Moreover, concerning the inequalities and the higher surgical rate in provinces with a better economic status, it is necessary to expand an insurance coverage and equip more public centers with the instruments and devices required for laser refractive surgery.

Research Progress of the Application of Hypothermia in the Eye.

Hypothermia is widely used in the medical field to protect organs or tissues from damage. Different research fields have different explanations of the protection mechanism of hypothermia. Hypothermia is also widely used in the field of ophthalmology, for example, in the eye bank, the preservation of corneal tissue and the preservation of the eyeball. Low temperature can also be applied to some ophthalmic diseases, such as allergic conjunctivitis, retinal ischemia, and retinal hypoxia. It is used to relieve eye symptoms or reduce tissue damage. Hypothermic techniques have important applications in ophthalmic surgery, such as corneal refractive surgery, vitrectomy surgery, and ciliary body cryotherapy for end-stage glaucoma. Hypothermia can reduce the inflammation of the cornea and protect the retinal tissue. The eyeball is a complex organ, including collagen tissue of the eyeball wall and retinal nerve tissue and retinal blood vessels. The mechanism of low temperature protecting eye tissue is complicated. It is important to understand the mechanism of hypothermia and its applications in ophthalmology. This review introduces the mechanism of hypothermia and its application in the eye banks, eye diseases (allergic conjunctivitis, retinal ischemia, and hypoxia), and eye surgeries (corneal transplant surgery, corneal refractive surgery, and vitrectomy).

Refractive surgery in the United States Air Force.

PURPOSE OF REVIEW: Laser refractive surgery in the United States Air Force has developed into a robust program since its inception in 2001. The goal of this study is to summarize recent developments in the program. Presentations at national meetings, recently published articles, and unpublished data from ongoing studies in the area of photorefractive keratectomy and laser-assisted in-situ keratomileusis are discussed. RECENT FINDINGS: Photorefractive keratectomy continues to be the most commonly performed corneal refractive surgery procedure in the United States Air Force. However, as the overall superiority of femtosecond laser-assisted in-situ keratomileusis flaps compared with microkeratome-assisted flaps continues to be established, there is an increasing trend towards this procedure. With a recent change in Air Force policy, photorefractive keratectomy and laser-assisted in-situ keratomileusis are now both approved for nonaviators and aviators, with the aviators undergoing contrast sensitivity and other additional testing to ensure readiness. SUMMARY: As members of the United States Air Force have stringent visual demands in carrying out their duties, the quality and safety of any refractive procedure are of the utmost importance. Thorough evaluation of ongoing advances in refractive surgery will help ensure that our airmen continue to meet the visual demands placed on them.

Emerging trends for procedure selection in contemporary refractive surgery: consecutive review of 200 cases from a single center.

PURPOSE: To quantify emerging refractive surgery trends in a single refractive surgery practice. METHODS: A retrospective chart review was performed of 200 consecutive candidates (377 eyes) for refractive surgery from July 20, 2007 to October 31, 2007. Patient age, manifest refraction spherical equivalent, pachymetry at the thinnest location (CCT), topographic symmetry patterns, and comeal apex location were analyzed. Patients were recommended sub-Bowman's keratomileusis (SBK), photorefractive keratectomy (PRK), conductive keratoplasty (CK), phakic intraocular lens implants (PIOL) or refractive lens exchange (RLE). Corneal excimer procedures were either wavefront-optimized or wavefront-guided ablations. RESULTS: Mean patient age for refractive surgery was 44+/-12 years (range: 18 to 68 years). The mean MRSE was -2.78+/-3.37 diopters (D) (range: -12.75 to +6.25 D). Of the 200 patients, 75% (n=151, 288 eyes) were recommended corneal excimer procedures. Of these, the mean CCT was 548+/-36 microm (range: 466 to 628 microm). Symmetric topographic patterns were observed in 54% (n=155) of eyes, whereas 32% (n=92) were borderline and 14% (n=41) were asymmetric. The corneal apex was centered in 79% (n=226) of eyes, whereas 18% (n=51) were borderline and 3% (n=10) were decentered (>2.5 mm from the center). Overall, 69% (n=139) of patients were recommended SBK, 16% (n=32) RLE, 6% (n=12) PRK, 5% (n=9) CK, and 4% (n=8) PIOL. Of the corneal excimer group, 88% (n=132) were scheduled for wavefront-optimized ablations and 12% (n=18) for wavefront-guided ablations. CONCLUSIONS: Sub-Bowman's keratomileusis was the predominant refractive surgical procedure offered in this practice, followed by RLE, PRK, CK, and finally PIOL. Of the corneal excimer procedures recommended, the majority of patients were scheduled for a wavefront-optimized ablation.

Investigation of the Changes in Refractive Surgery Trends in Korea.

PURPOSE: To evaluate changes in clinical practice in the field of refractive surgery in Korea over the past 10 years. METHODS: A survey consisting of 59 multiple-choice questions regarding the preferred types of refractive surgery, excimer laser machine, and presbyopia surgery was mailed to 742 members of the Korean Society of Cataract and Refractive Surgery in January 2016, and 50 members responded to the survey. These data were compared with the 2005 or 2007 survey results. RESULTS: The majority of respondents were in their 40s (54%), and the average number of refractive surgeries performed in one month was 53. The most commonly used excimer laser machine was the VISX S4 in both 2005 (32%) and 2015 (25%); however, a greater variety of machines (EX500 [18%], Allegretto wave Eye-Q [13%], AMARIS 750 [10%]) were used in 2015. The preferred corneal refractive surgery in 2015 was surface ablation (40%), representing a significant increase in its popularity compared to 2005 (15%) (p < 0.001). The popularity of laser in situ keratomileusis (LASIK) surgery decreased to 20% in 2015 compared to 48% in 2005 (p < 0.001). Eighty percent of LASIK procedures in 2015 were performed using femtosecond laser. In 2015, surface ablation and phakic intraocular lens implantation were preferred for the treatment of myopia less than -8 diopters and more than -8 diopters, respectively. The proportion of respondents performing presbyopia surgery in 2015 (76%) was significantly increased from 2007 (30%) (p < 0.001). CONCLUSIONS: Over the past decade, the most commonly performed corneal refractive surgery has changed from LASIK to surface ablation, and there has been a significant increase in the popularity of presbyopia surgery.

[SMILE (Small Incision Lenticule Extraction) among the corneal refractive surgeries in 2018 (French translation of the article)]. / Quelle place pour le SMILE (Small Incision Lenticule Extraction) dans la chirurgie réfractive cornéenne en 2018.

Refractive surgery is a field in constant evolution. In recent years, a new procedure has appeared under the name SMILE (Small Incision Lenticule Extraction). This technique, carried out solely with a femtosecond laser, should make it possible to better preserve corneal innervation and biomechanics. After a detailed review of the technique itself, we then focus on the scientific evidence for the safety and efficacy of SMILE and its current indications. Advantages of SMILE will be discussed in comparison to disadvantages of the conventional techniques, particularly concerning dry eye and the risk of corneal ectasia with LASIK. Lastly, the current limitations of SMILE (indications, retreatment) are discussed, and future applications are considered regarding improvements in the technique.

Advances in Refractive Surgery: June 2014 to July 2015.

PURPOSE: The objective of this study was to review the advances in the field of refractive surgery as reported in the peer-reviewed literature during the previous year. DESIGN: A literature review. METHODS: In this review, we highlight the most pertinent articles in the field from June 2014 to the end of July 2015. RESULTS: This past year has seen a growing body of research on small-incision lenticule extraction, presbyopic inlays, and phakic intraocular lenses, as more clinicians are adopting these techniques into their armamentarium. CONCLUSIONS: Laser-assisted in situ keratomileusis and photorefractive keratectomy continue to dominate the keratorefractive literature, as they remain the most frequently performed refractive surgeries.