Management of anxiety in the refractive surgery patient

Refractive surgery has rapidly evolved to become a preferred alternative for the correction of refractive errors. As the quest to obtain faster visual recovery, fewer complications, and early stability continues, there is little in the literature that addresses the anxiety experienced by most refractive surgical patients. Although vision-correction surgery uses highly technical and precise procedures, the need to develop therapeutic caring and communicative techniques for these patients has not been adequately addressed. There has been insufficient research in the literature focusing on the patient's fear. Respecting the patient's fear and concerns and supporting them by developing a humanistic approach to patient care may prove to be beneficial to the patient and the refractive team.     

准分子激光近视矫正术治疗患者10年随诊结果分析

目的分析准分子激光近视矫正术的远期疗效。方法选择2002年10月至2004年3月于荆州市中心医院行准分子激光近视矫正术治疗,且随诊10年、资料完整的近视患者136例(241眼)。将241眼分为中度近视组(近视度-3.00~-6.00D,48眼)、高度近视组(近视度-6.00~-10.00D,134眼)和超高度近视组(近视度-10.00~-16.00D,59眼)。术后随诊10年,观察并记录视力、屈光度、角膜前表面曲率和眼压。结果中度近视组术后10年裸眼视力大于0.5和1.0比例分别为100.00%、84.00%,高度近视组分别为100.00%、83.95%,超高度近视组分别为91.45%、33.33%。各研究组术后10年最佳矫正视力达到或超过术前最佳矫正视力的比例分别是98.21%、98.43%、92.34%。术后第1年屈光度回退明显,超高度近视组回退量最大,中度近视组回退量最小;术后第2~10年,超高度近视组屈光度回退最大,中度和高度近视组回退不明显。术后第1年角膜前表面曲率变化较之后更明显,超高度近视组角膜前表面曲率改变最多,中度近视组改变最少。术后10年随诊时,患者眼压均在正常范围内。结论准分子激光近视矫正术远期效果稳定,是治疗近视有效且安全的方法,但近视程度越大,手术效果的预测性及术后视力稳定性越小。     

Finite element simulation of Goldmann tonometry after refractive surgery

BackgroundThe problem of accuracy of intraocular pressure (IOP) measurement using Goldmann Applanation Tonometry (GAT) after a refractive surgery is still unresolved.In this study a numerical simulation of refractive surgery and GAT is proposed as a method to evaluate accuracy of the correction formula for GAT reading after changes in corneal curvature and thickness.MethodsIn the finite element analysis the effect of the corneal shell buckling was taken into account. This effect is responsible for the nonlinear relation of Goldmann applanation tonometer measurement and intraocular pressure. Goldmann applanation tonometry was simulated for different ablation depths and values of intraocular pressure levels.FindingsThe results of the simulation indicate a strong relation between the Goldmann applanation reading and the intraocular pressure level for values greater than nominal (about 16 mmHg). The estimation error of the intraocular pressure after changes in corneal geometry, is lower than 1 mmHg for IOP = 32 mmHg and lower than 3 mmHg for IOP = 48 mmHg.InterpretationThe proposed correction formula of Goldmann applanation tonometry occurred to be useful in the cases after the corneal refractive surgery regardless of the intraocular pressure values and ablation depth.     

角膜屈光术后人工晶状体度数计算的研究进展

随着角膜屈光手术的不断完善及盛行,越来越多的屈光不正患者接受了该项手术,然而,用常规方法计算的人工晶体度数常常不准确,术后往往出现严重屈光偏差。国内外研究认为,这主要与测量误差、人工晶状体计算公式误差有关。至今学者们已提出了多种矫正方法。     

Kappa角对近视屈光手术偏心量的影响

目的:研究近视国人Kappa角的分布特征.探讨国人Kappa角大小对近视屈光手术切削偏心量的影响.方法:选择门诊行近视激光手术术前检查的连续病例200名,根据近视屈光度分为低、中、高度3组.用OrbscanⅡ测量其角膜地形图得到Kappa角及其在角膜的水平和垂直偏移量,进行分组统计.取这些受试者中行近视屈光手术患者135例,测量其术后1个月随访时的角膜地形图,分析激光切削偏心量和Kappa角之间的关系.结果:低、中、高度近视患者的Kappa角水平偏移量差异具有显著性(P值均为0.000),其中,低度近视组的水平偏移量最大,而高度近视组的水平偏移量最小.Kappa角的水平和垂直偏移量与术后激光切削偏心的水平和垂直偏移量高度相关(水平P=0.000;垂直P=0.000),Kappa角的角膜偏移量在术前术后并无明显变化(水平P=0.964,垂直P=0.861).结论:总体而言,Kappa角在国人中随近视屈光度数增加而减小.近视屈光手术的效果受Kappa角影响,尤其是低度近视患者的大Kappa角会造成较大的切削偏心.     

Laser safety aspects for refractive eye surgery with femtosecond laser pulses

We report on laser safety aspects for near infrared femtosecond laser refractive surgery. In particular, the transmittance of microjoule laser pulses at 1040 nm through the cornea during flap procedures based on femtosecond laser induced multiphoton ionization and photodisruption has been determined. When using focusing optics with a numerical aperture of 0.3, more than 20% of the incident NIR photons are propagating towards the retina. In addition, self-focusing, white light and second harmonic generation, and destructive photodisruptive side effects have to be considered when using such high energy laser pulses of amplified laser systems. Microjoule femtosecond laser pulses in combination with low NA objectives have the potential to induce destructive intraocular side effects. Further studies are required to evaluate the damage potential of the transmitted photons absorbed by the retinal pigment epithelium and other intraocular compartments. Because of the fact that flaps can be also generated with low nanojoule energy femtosecond laser pulses of non-amplified MHz lasers in combination with high NA objectives, a compromise between procedure time, pulse energy and numerical apertures has to be found for safe ocular femtosecond laser surgery.     

Contact lenses and refractive surgery. Addressing patient problems and concerns

Contact lenses, used by millions of people throughout the United States, are a safe, effective way to correct refractive errors and to improve the vision of patients with diseased corneas. Proper care and cleaning of contact lenses is very important; at the first sign of eye irritation, the lenses should be removed and a physician should be consulted. New advances include improved gas-permeable materials, new hypoallergenic solutions, and planned replacement systems. Excimer laser treatment and radial keratotomy are more invasive methods of correcting refractive problems and must be approached with great care and caution.     

Interfaces detection after corneal refractive surgery by low coherence optical interferometry

The detection of refractive corneal surgery by LASIK, during the storage of corneas in Eye Banks will become a challenge when the numerous operated patients will arrive at the age of cornea donation. The subtle changes of corneal structure and refraction are highly suspected to negatively influence clinical results in recipients of such corneas. In order to detect LASIK cornea interfaces we developed a low coherence interferometry technique using a broadband continuum source. Real time signal recording, without moving any optical elements and without need of a Fourier Transform operation, combined with good measurement resolution is the main asset of this interferometer. The associated numerical processing is based on a method initially used in astronomy and offers an optimal correlation signal without the necessity to image the whole cornea that is time consuming. The detection of corneal interfaces - both outer and inner surface and the buried interface corresponding to the surgical wound - is then achieved directly by the innovative combination of interferometry and this original numerical process.     

193nm氟化氩激光应用于屈光性角膜切削的精确性及预测性

1975年有学者发现了准分子激光并将它应用于角膜屈光性手术,使屈光手术有了重大突破,成为现代眼科学中发展最快的领域之一.波长为193nm的氟化氩激光可以使角膜组织分子气化,故准确度非常高,而且对于被照射部位旁边的组织不产生热效应,对角膜的构造不会产生不良的效应.目前准分子激光已成功应用丁角膜放射状切开术、准分子激光屈光角膜切削术、准分子激光原位角膜磨镶术、准分子激光角膜上皮瓣下磨镶术及机械法准分子上皮下角膜磨镶术等.随着对准分了激光认识的不断深入,以及临床经验的不断积累,新的、精确度高的、预测性好的准分子激光屈光性角膜手术方式将不断涌现.     

未行准分子激光角膜屈光手术（LASIK／LASEK）原因分析

目的探讨近视患者接受术前检查而未行准分子激光角膜屈光手术（LASIK／LASEK）的原因。方法对1476例近视患者中156例检查后未行手术的原因进行分析。结果未行手术156例,其中因心理因素及社会因素放弃者62例（占39．74％）;存在禁忌证94例（占60．26％）,其中角膜方面原因共52例（占33．33％）,包括角膜厚度不足、角膜屈光率偏高、角膜疾病;眼底病变者20例（占12．82％）,包括视网膜变性、眼底干孔、孔源性视网膜脱离;术前矫正视力不佳者10例（占6．41％）;眼压高者7例（占4．49％）;其他：瞳孔过大、干眼症、严重瘢痕体质共5例（占3．21％）。结论LASIK／LASEK术前检查应详细认真,严格掌握手术的适应证及禁忌证,确保手术安全。     

Malignant glaucoma presenting with uncontrolled intraocular pressure and myopic refractive surprise after cataract surgery

We present a seemingly typical case of bilateral angle closure with elevated intraocular pressures. After cataract surgery, there was axial shallowing, escalating intraocular pressure, anterior displacement of the IOL, and myopic shift in the left eye. Irido‐zonulo‐hyaloido‐vitrectomy resolved the angle closure, normalized intraocular pressure, and corrected the myopic shift.     

Use of refractive direct ophthalmoscopy for estimation of refractive error

The purpose of this study was to find if direct ophthalmoscopy, a simple technique, could be used to give an approximate value of the refractive correction for a patient. This would shorten the time and lessen the effort to be expended during the following retinoscopic examination done for finding the patient's refractive correction. The use of direct ophthalmoscopy for this specific purpose is especially desirable where retinoscopic examination is quite tedious, e.g. uncooperative patients like children, bed-ridden patients and mentally retarded subjects, in patients with a large central corneal opacity and in patients having a large refractive error. The study was divided into two phases. In phase I, refractive direct ophthalmoscopy followed by classical retinoscopy was done for 92 subjects (184 eyes) in the age group of 11-35 years. The method of regression analysis was used to find a regression equation relating the readings to refractive error determined by the two above techniques. In phase II of study, the refractive correction needed for 50 other subjects in the similar age group was estimated using this regression equation by inserting their respective direct ophthalmoscopy readings. Then, these estimated values and classical retinoscopic examination values were compared. The refractive error determined after retinoscopy and that derived from regression equation (incorporating direct ophthalmoscopy readings) was statistically comparable (t = 0.52, p = 0.60). The correlation coefficient (r value) between the two methods was 0.37. Direct ophthalmoscopic lens reading can be used to give a fairly accurate estimate of refractive error in a patient's eye by using a linear regression equation, which relates these two examination techniques. The magnitude of astigmatic error, however, cannot be obtained.     

Possible retina damage potential of the femtosecond laser in situ keratomileusis (fs-LASIK) refractive surgery

Since the early 1990s, the laser in situ keratomileusis (LASIK) procedure has been successfully implemented in refractive eye surgery to correct ametropia. Rapid development in new laser technology enables the application of ultrashort laser pulses in the femtosecond (fs) regime that marks advancement in conventional standard procedures of refractive surgery by eliminating the use of mechanical knives. With the fs-LASIK procedure, ultrashort laser pulses focus in the near-infrared spectral range and create a laser-induced breakdown (LIB) that disrupts the corneal tissue. During the cutting process not all of the pulse energy is deposited in the cornea. Approximately half the remaining energy is propagated through the eye and reaches the retina, as well as the strongly absorbing layers behind.In the current standard refractive surgery procedures, such as photorefractive keratomileusis (PRK) and LASIK, retina damage is reduced because of the complete absorption of ultraviolet irradiation by corneal tissue during ablation.The aim of this project was to investigate possible retina damage under fs-LASIK conditions and to optimize external parameters during surgery, such as pulse energy and numerical aperture, to reduce risk potential. The process was simulated with a conventional fs-laser system integrated into an experimental set-up. To investigate the retina damage thresholds, in vivo investigations were carried out systematically on enucleated porcine eyes. Damage thresholds were determined in terms of macroscopic and histopathological observations. The results of these studies indicate possible retina damage.     

民航飞行学员角膜屈光术后高阶像差变化及角膜后表面稳定性的研究

目的分析已接受角膜屈光激光手术（CRS）的飞行学员高阶像差的变化及角膜后表面稳定性,探讨民航招收飞行学员对于放开CRS标准后的安全性和稳定性。 方法选取2017年9月至2018年3月在民航总医院和中国民航飞行学院体检鉴定中心参加招飞体检以及年度体检的飞行学员进行调查。随机选取未行CRS且裸眼视力≥1.0的飞行学员50例（100眼）作为正常对照组;选取已行CRS的飞行学员67例（131眼）作为实验组,其中行飞秒激光制瓣的准分子激光原位角膜磨镶术（FS-LASIK）者29例（56眼）,行准分子激光上皮瓣下角膜磨镶术（LASEK）者22例（43眼）,行飞秒激光小切口角膜基质透镜取出术（SMILE）者16例（32眼）。分别对其进行裸眼远视力、屈光度、对比敏感度、泪膜破裂时间（BUT）以及角膜地形图等检查,同时比较手术前后中央前房深度、眼轴长度、晶状体厚度等变化情况,分析各组间高阶像差及角膜后表面稳定性。 结果正常对照组和实验组对比敏感度、BUT等差异无统计学意义（P>0.05）。实验组术后6个月总高阶像差、球差、彗差、三叶草像差等较术前均增高,差异有统计学意义（P<0.05）。实验组各组间术后总高阶像差、球差、彗差比较差异均有统计学意义（P均<0.05）;三叶草像差比较差异无统计学意义（P>0.05）。FS-LASIK组与LASEK组高阶像差、球差术后比较,差异均有统计学意义（P均<0.05）,彗差、三叶草像差等术后比较,差异均无统计学意义（P均>0.05）;与SMILE组高阶像差、球差、彗差、三叶草像差术后比较,差异均有统计学意义（P<0.05）。各组间角膜后表面高度及眼球轴长之间差异均无统计学意义（P均>0.05）,而晶状体厚度较术前显著增加,差异有统计学意义（P<0.05）,中央前房深度较术前显著下降,差异有统计学意义（P<0.05）。 结论民航飞行学员行CRS安全有效,FS-LASIK可明显提升飞行学员术后的高阶像差。     

Optical side-effects of fs-laser treatment in refractive surgery investigated by means of a model eye

Optical side-effects of fs-laser treatment in refractive surgery are investigated by means of a model eye. We show that rainbow glare is the predominant perturbation, which can be avoided by randomly distributing laser spots within the lens. For corneal applications such as fs-LASIK, even a regular grid with spot-to-spot distances of ~3 µm is sufficient to minimize rainbow glare perception. Contrast sensitivity is affected, when the lens is treated with large 3D-patterns.OCIS codes: (320.2250) Femtosecond phenomena, (330.7335) Visual optics, refractive surgery, (330.1720) Color vision, (330.4460) Ophthalmic optics and devices