老视的角膜矫正手术

老视是随着年龄增长、调节能力丧失出现视近物困难的一种生理现象,发病机制尚不明确。人口老龄化使老视人口及老视矫正的需求逐渐增多,老视的手术矫正方法正成为眼科医师关注的热点。随着技术和材料的不断发展,出现了多样化的老视矫正手术,包括经角膜老视矫正手术、晶状体老视矫正手术和巩膜老视矫正手术。尽管还没有一种完美的老视矫正手术能真正恢复眼的调节功能,现有的手术已取得一些临床效果。现对老视的角膜手术矫正方法做一综述。     

A new method of cornea modulation with excimer laser for simultaneous correction of presbyopia and ametropia

Purpose

To investigate the outcomes of simultaneous correction of presbyopia and ametropia by a bi-aspheric cornea modulation technique, based on the creation of a central area hyperpositive for near vision and leaving the pericentral cornea for far vision in hyperopic, emmetropic, and myopic presbyopic patients.

Setting

Sixty eyes of 30 patients were treated with the PresbyMAX technique by one surgeon (D.U.) at the Eye Hospital Bellevue, Kiel, Germany.

Methods

Twenty eyes with hyperopic presbyopia, 20 eyes with emmetropic presbyopia, and 20 eyes with myopic presbyopia underwent Femto-Lasik, and were assessed up to 6?months postoperatively. All eyes underwent cornea treatment using the PresbyMAX? software, delivering a bi-aspheric multifocal ablation profile developed by SCHWIND eye-tech-solutions (Kleinostheim, Germany). All flaps were created by Ziemer LDV Femtolaser (Port, Switzerland).

Results

The mean binocular distance of uncorrected visual acuity (DUCVA) improved in the hyperopic group from 0.28?±?0.29 logMAR to ?0.04?±?0.07 logMAR, in the emmetropic group from ?0.05?±?0.07 logMAR to 0.02?±?0.11 logMAR, and in the myopic group from 0.78?±?0.27 logMAR to 0.09?±?0.08 logMAR. The mean binocular near uncorrected visual acuity (NUCVA) increased in the hyperopic group from 0.86?±?0.62 logRAD to 0.24?±?0.23 logRAD, and in the emmetropic group from 0.48?±?0.14 logRAD to 0.18?±?0.11 logRAD. The myopic presbyopes showed a decrease of the mean binocular NUCVA from 0.04?±?0.19 logRAD to 0.12?±?0.18 logRAD. The mean postoperative spherical equivalent for distance refraction was ?0.13?±?0.61 D for the hyperopic presbyopia, ?0.43?±?0.35 D for the emmetropic presbyopia, and ?0.68?±?0.42 D for the myopic presbyopia group, whereas the software took aim at ?0.50 D in all groups.

Conclusions

In presbyopic patients without symptomatic cataracts, but refractive errors, PresbyMAX? will decrease the presbyopic symptoms and correct far distance refraction in the same treatment, offering spectacle-free vision in daily life in most of the treated patients. Further investigation is necessary to evaluate the overall benefit of this procedure.     

Presbyopia: perspective on the reality of pseudoaccommodation with LASIK

The authors present their detailed technique for the correction of presbyopia with pseudoaccommodative cornea laser in situ keratomileusis. A detailed commentary of the procedure is presented along with the authors' views about the present state and future of multifocal corneal surgery. Sample cases with suggested nomogram calculations are presented.     

老视手术治疗进展

随着人们对视觉质量要求的提高,不损伤远视力的前提下恢复近视力是目前老视矫正手术所追求的目标.为了达到此目的,出现了多种手术方法.本文就近年来国内外报道的有关角膜、晶状体及巩膜等的老视矫正术作一综述.     

老视矫治的研究进展

老视是一种与年龄相关、因调节能力下降而引起的渐进性视近困难,目前发生机制尚不明确,但矫正方法很多,包括配镜、角膜手术、巩膜手术、晶状体手术和药物治疗,也是屈光手术矫正近视、远视、散光取得良好效果后需要突破的重点;但各种方法均以增加屈光力为目的,并不能真正逆转老视的发生。就老视治疗的方法和集中关注的问题进行综述。     

PresbyLASIK

Presbyopia represents the most common refractive error. There is currently no surgical treatment for presbyopia, which is effective, reliable, and safe.Excimer laser surgery has become a routine procedure for the correction of myopia, hyperopia, and astigmatism for years. Various treatment strategies for presbyopia have been brought forward using the excimer lasers. Besides monovision, creation of a multifocal cornea represents an attractive option. This procedure is also called "PresbyLASIK." Different ablation profiles to form a multifocal cornea are reviewed here and first clinical results are summarized."PresbyLASIK" is a new, interesting treatment strategy, with a huge potential for the future. At the present it should be used in controlled studies only because of some unsolved questions.     

Prevalence of presbyopia in a semi-urban population of southwest,Nigeria: a community-based survey

Uncorrected presbyopia is a major cause of poor near vision in the developing countries. To determine the prevalence and demographic characteristics of presbyopia among adult populations (40 years and above) in a sub-urban population, southwest Nigeria, a population-based cross-sectional study was carried out from April to May 2014. A multi-stage sampling method was used to select eligible respondents. All participants had distance visual acuity assessment done and participants with visual acuity of less than 6/6 were refracted. Near vision was then assessed at 40 cm with distance correction in place if required. Information on near vision was obtained from the participants using interviewer administered questionnaires. Data collected were analysed using SPSS version 22. A total of 440 subjects aged 40 years and above were studied. Prevalence of presbyopia was 75 % and was significantly associated with increasing age. There was higher prevalence of presbyopia among females than males (76.3 % vs. 73.5 %), though not statistically significant. Also prevalence of presbyopia was not significantly associated with educational and occupational status in the study. This study demonstrated a high prevalence of presbyopia. There is need for improved awareness on presbyopia screening and available correction in the local government.     

Characterization, passive and active treatment in strabismic amblyopia: a narrative review

AIM: To assess objective visual quality after presbyopia correction using the PresbyMAX monocular mode. METHODS: This prospective, nonrandomized study included 28 eyes from 18 patients (mean age 50.4±5.6y) who underwent presbyopia correction with the PresbyMAX monocular mode. Monocular and binocular visual acuities were evaluated preoperatively at 1d, 1wk, 1, 3mo, and 1y after surgery. Optical quality was analyzed by Hartmann-Shack wavefront aberration supported cornea ablation, and modulation transfer function (MTF) cutoff frequency, Strehl ratio, and objective scattering index (OSI) were analyzed using an optical quality analysis system. RESULTS: One year after surgery, 100% and 94.4% of patients achieved binocular uncorrected distance and near visual acuity of 20/25, respectively. Spherical aberration and total higher aberration were higher than the corresponding preoperative levels (P<0.001) at the last visit; however, no significant difference was found in MTF, OSI, or Strehl ratio. Transient decreases in OSI and MTF mainly occurred in the nondominant eyes. There was no significant difference in optical quality between the dominant and nondominant eyes, except for spherical aberration and horizontal coma (P<0.05). CONCLUSION: The PresbyMAX monocular mode is safe and effective for presbyopia correction. It has little effect on optical quality, though short-term degraded optical quality occurred mainly in the bi-aspheric ablated eyes.     

Cylinder axis sensitivity with different chevron angles

The sensitivity of the chevron test for cylinder axis was investigated on 16 subjects for 4 chevron angles, 30°, 45°, 60° and 90°. The 60° chevron gave most sensitive results, and the 90° chevron gave the least sensitive results. Cylinder values from the chevron tests often differed markedly from cross cylinder results. This may be due to interference from monocular diplopia when the eye is made myopic for the chevron test.     

不同手术切口设计的SMILE术后角膜知觉的变化

目的：探讨不同手术切口设计的SMILE术后角膜知觉的变化。

方法：选取2016-05-12/2018-01-18于我院行SMILE手术的近视及近视伴散光患者30例60眼,所有患者右眼手术切口设计在颞上方135°位置,左眼手术切口设计在正上方90°位置。分别于术前和术后1、7d,1、3mo采用角膜知觉计检测距角膜中央3mm位置3：00、6：00、9：00、12：00位及角膜中央的角膜知觉,并采用眼表疾病指数量表(OSDI)进行干眼症状评分。

结果：手术前后,本组患者左右眼之间5个位置的角膜知觉无明显差异(P>0.05)。术后1d,双眼5个位置的角膜知觉均较术前和术后1、3mo显著降低(P<0.05),但术后1、3mo双眼5个位置的角膜知觉均与术前无明显差异(P>0.05)。术前和术后1、7d,1、3mo本组患者OSDI分值分别为10.739±7.576、15.003±11.296、16.357±14.467、14.020±10.128、11.968±7.586分,无明显差异(F=1.583,P=0.204)。

结论：不同手术切口设计的SMILE术后角膜知觉无明显差异,均在术后1d明显下降,至术后1mo基本恢复至术前水平。     

Akkommodation und Presbyopie

There are two basic approaches for the surgical correction of presbyopia: increasing depth of focus (e.g. by means of multifocal laser abrasion of the cornea), Or restoring accommodation in the sense of a dynamic change in ocular refraction (accommodative intraocular lenses, scleral expansion). Pseudoaccommodative procedures are able to achieve satisfactory near vision, albeit at the price of lower performance in the intermediate range and decreased image quality. The restoration of accommodation remains problematic, partly because the mechanism of accommodation and the development of presbyopia are still not fully understood. Some surgical procedures are based on concepts, the validity of which is not confirmed or which even contradict experimental evidence. Thus, it is necessary to assess the results and presumed mechanisms critically and objectively.     

Accommodation and presbyopia : part 2: surgical procedures for the correction of presbyopia

There are two basic approaches for the surgical correction of presbyopia: increasing depth of focus (e.g. by means of multifocal laser abrasion of the cornea), Or restoring accommodation in the sense of a dynamic change in ocular refraction (accommodative intraocular lenses, scleral expansion). Pseudoaccommodative procedures are able to achieve satisfactory near vision, albeit at the price of lower performance in the intermediate range and decreased image quality. The restoration of accommodation remains problematic, partly because the mechanism of accommodation and the development of presbyopia are still not fully understood. Some surgical procedures are based on concepts, the validity of which is not confirmed or which even contradict experimental evidence. Thus, it is necessary to assess the results and presumed mechanisms critically and objectively.     

Conductive keratoplasty

PURPOSE OF REVIEW: Conductive keratoplasty is a noninvasive, in-office procedure for the correction of hyperopia, hyperopic astigmatism, and management of presbyopia. It serves as an alternative to laser-based refractive surgery with essentially no intraoperative or postoperative complications. RECENT FINDINGS: In the past decade, photorefractive keratectomy and laser in-situ keratomileusis have been the most popular refractive surgical procedures to correct myopia, hyperopia and astigmatism. Although relatively safe, flap-related complications often result in undesirable visual acuity. Since US Food and Drugs Administration approval in 2002, conductive keratoplasty has become a promising technique to correct low to moderate hyperopia and astigmatism. The procedure was first used by Mendez and colleagues in 1993. It is a nonlaser, no cutting procedure that delivers radio-frequency energy to corneal stroma in a circular fashion to steepen the cornea. Multiple studies have shown that conductive keratoplasty offers equal or superior efficacy, predictability, stability and safety than currently used refractive procedures to correct hyperopia or hyperopic astigmatism. In addition, monovision conductive keratoplasty has been shown to be successful for the management of presbyopia. SUMMARY: Conductive keratoplasty, an alternative to the laser-based procedure, is effective, predictable, and safe to correct low to moderate hyperopia, astigmatism, and manage presbyopia.     

Oxygen and glucose distribution after intracorneal lens implantation.

PURPOSE: Insertion of an implant in the cornea to achieve corneal multifocality has been suggested as a solution for presbyopia. However, unresolved issues related to nutrient transport need to be resolved. Our aim was to find the best lens position and influence lens transport properties in order to optimize nutrient supply to corneal cells. METHOD: An axisymmetric corneal model was built to simulate the nutrient transport in the cornea. Oxygen and glucose concentrations were calculated for normal cornea and intracorneal lens wearing conditions. The simulation considers the different tissue layers (epithelium, stroma, and endothelium) as well as layer and solute concentration dependent consumption. RESULTS: The minimum oxygen tension in the cornea was found to be higher when the lens was placed at 3/4 of the corneal thickness. Moreover, in this position, the influence of the inlay diffusivity was smaller than at more anterior or posterior placements. The diffusivity of the inlay affects the way nutrients will be transported through the cornea. The threshold where glucose may diffuse through or around the implant was found to be 1/100th of the stromal diffusivity. CONCLUSIONS: Computational methods are especially attractive to study nutrient transport in the cornea due to the difficulties associated with in vivo or in vitro measurements. The exact parameters that dictate the corneal metabolism are not known. However, the combined analysis of oxygen and glucose distribution is valuable in order to predict the complex physiological changes that arise under intracorneal lens implantation.     

人工晶状体眼老视验光配镜分析

目的:探讨人工晶状体眼老视的科学检测方法。方法:随机抽取年龄在40～75岁之间"白内障超声乳化+人工晶状体植入"术后老视患者80例(118眼)从术后1wk开始随访6mo以上,检测角膜散光度数变化,并根据患者的阅读需要和距离进行客观和主观验光。结果:白内障术后角膜散光1wk～1mo的平均度数与术前比较差异有显著性(P<0.01),3mo的角膜散光与术前比较差异无显著性,白内障人工晶状体眼的老视近附加3个年龄组间比较差异无统计学意义。结论:白内障术后人工晶状体眼的近附加验配不随年龄的增加而增加,应待角膜散光稳定后根据被测的调节参数进行精确的验配,而不能简单地按照经验公式开出处方。     

Color vision in the peripheral retina under photopic conditions

Chromaticities of spectral colors were measured during the cone-plateau period at 17°, 25°, 40° and 60° in the nasal field of view and at 40° and 70° in the temporal field. The results obtained in the nasal field show a progressive contraction of the color gamut with distance from the fovea with maximum shrinkage in the middle-wave region. Color discrimination in the temporal field of view was found to be much better developed than in the nasal field. Thus, all the primary hues were clearly observable at 70° temporally. The exceptionally good color discrimination obtained in the present study is explained on the assumption that only cones are effectively excited upon stimulation during the cone-plateau period.     

Cornea and lens oxygen consumption in rabbit and trout: a comparative study

The oxygen consumption and Q₁₀ values of rabbit and trout cornea and lens were measured with an oxygen electrode and the Yellow Springs Biological Oxygen Monitor. These in vitro studies have shown that rabbits weighing 3·6 kg have an average corneal thickness of 0·46 mm and their corneal oxygen consumption at 37°C is significantly lower than corneas from rabbits weighing 1 and 2·2 kg, which have thinner corneas averaging 0·36 and 0·41 mm respectively, and with an increased proportion of epithelial and stroma cells. Corneal oxygen consumption measured for trout cornea at 14·5°C was similar to rabbit corneal oxygen consumption at 37°C. Calculated corneal Q₁₀ values were 1·96 and 1·45 for rabbit and trout respectively.The trout lens oxygen consumption at 14·5°C was three-fold higher than the rabbit lens at 37°C with the calculated Q₁₀ value for lenses of 1·26 and 1·56 respectively for rabbit and trout.     

��bereinstimmung subjektiver und objektiver Refraktionsmessungen nach INTRACOR-Femtosekundenlaser-Behandlung

Background

The goal of this study was to determine the accuracy of autorefraction measurements in patients after INTRACOR intrastromal femtosecond laser treatment of presbyopia by comparing the agreement between the subjective and objective refraction.

Patients and methods

In this study the data of 19 patients with a mean age of 56.5±6.0 years following INTRACOR treatment were analyzed pre-operatively and 12 months postoperatively. Measurements of the subjective refraction and the results of the autorefractor Nidek-660A in miosis were compared. INTRACOR is a refractive intrastromal femtosecond laser treatment to correct presbyopia. During the procedure a series of five concentric rings in the central stroma are cut which cause a change in the curvature of the cornea.

Results

The differences in sphere and spherical equivalent between subjective refraction and autorefraction were not significant (t-test p>0.05 and Wilcoxon test p>0.05). Comparing the cylinder of the two measurements a significant difference (t-test p<0.05) was found. Focusing on the difference of the postoperative measurements of the subjective refraction and autorefraction a correlation (within ±0.5?D) of 89% in the sphere, 100% in cylinder and 68% in the spherical equivalent was detected. With one exception the differences in sphere, cylinder and the spherical equivalent were within ±1.25?D. In several patients the performance of the autorefraction with the Nidek-660A was somewhat complicated and the measures had to be repeated frequently.

Conclusion

The agreement between subjective refraction and objective measurements of the Nidek-660A of patients following INTRACOR-treatment was good. However there was a significant difference in the cylinder values. Therefore thorough comparison of measurements obtained with the autorefractor and the subjective refraction is recommended.     

角膜缘潜在性功能的开发应用

角膜缘界于透明的角膜、结膜和不透明的巩膜之间,是调控眼球生理功能和病理进程的重要枢纽。它在临床上的重要性包括：供给周边部角膜的营养;包含房水排出通道;调节眼前节的免疫状态;是角膜上皮再生器官干细胞的坐落场所;是白内障、青光眼、眼表移植和屈光成形等眼科手术切回的必经之路。从以下５个领域,对角膜缘潜在性功能开发应用进行简明扼要的阐述：１．角膜缘于细胞移植;２．眼表重建术的策略和展望;３．血管化角膜增视性移植;４．前睫状巩膜切开矫治老视和远视;５．角膜缘弧形松弛切开治疗角膜散光。内容包括基本原理、手术时机、基本术式、关键手术技巧和临床效益。     

Bezold-Brücke phenomenon of the far peripheral retina

The Bezold-Brücke phenomenon was measured during the cone-plateau period of the longterm dark-adaptation curve at 25°, 40° and 60° in the nasal field of view, and at 40° and 70° in the temporal field. In striking contrast to previous measurements of the B-B phenomenon the present results generally show that an increase of the luminance level in the middle- and long-wave regions of the spectrum produces, respectively, a trend toward green and red instead of toward yellow. The present results are explained on neural rather than on photochemical mechanisms.