Monovision slows juvenile myopia progression unilaterally

AIM: To evaluate the acceptability, effectivity, and side effects of a monovision spectacle correction designed to reduce accommodation and myopia progression in schoolchildren. METHODS: Dominant eyes of 11 year old children with myopia (-1.00 to -3.00 D mean spherical equivalent) were corrected for distance; fellow eyes were uncorrected or corrected to keep the refractive imbalance 相似文献   

Animal models in myopia research

Our current understanding of the development of refractive errors, in particular myopia, would be substantially limited had Wiesel and Raviola not discovered by accident that monkeys develop axial myopia as a result of deprivation of form vision. Similarly, if Josh Wallman and colleagues had not found that simple plastic goggles attached to the chicken eye generate large amounts of myopia, the chicken model would perhaps not have become such an important animal model. Contrary to previous assumptions about the mechanisms of myopia, these animal models suggested that eye growth is visually controlled locally by the retina, that an afferent connection to the brain is not essential and that emmetropisation uses more sophisticated cues than just the magnitude of retinal blur. While animal models have shown that the retina can determine the sign of defocus, the underlying mechanism is still not entirely clear. Animal models have also provided knowledge about the biochemical nature of the signal cascade converting the output of retinal image processing to changes in choroidal thickness and scleral growth; however, a critical question was, and still is, can the results from animal models be applied to myopia in children? While the basic findings from chickens appear applicable to monkeys, some fundamental questions remain. If eye growth is guided by visual feedback, why is myopic development not self‐limiting? Why does undercorrection not arrest myopic progression even though positive lenses induce myopic defocus, which leads to the development of hyperopia in emmetropic animals? Why do some spectacle or contact lens designs reduce myopic progression and others not? It appears that some major differences exist between animals reared with imposed defocus and children treated with various optical corrections, although without the basic knowledge obtained from animal models, we would be lost in an abundance of untestable hypotheses concerning human myopia.     

周边屈光对近视的影响

周边屈光,即周边视网膜的屈光状态,指与视轴成一定的夹角,距注视点30°以外周边视野内的屈光状态。动物及人类研究表明,周边屈光与近视存在密切关系。周边相对远视的屈光度数能影响中央近视度数,不同年龄阶段人群周边相对远视的屈光状态均呈现为近视发生的危险因素,并可能为近视眼屈光度进展的危险因素之一。周边近视离焦可能阻止眼轴增长,从而控制近视进展、促进视力恢复。我们归纳近年来周边屈光对近视的发生、发展及控制的影响,及其与眼球形态、调节、遗传的关系进行综述。     

周边离焦设计框架眼镜在近视防控中的进展

近视在世界各地越来越普遍,发病人群也逐渐扩大。多种治疗方法已经被用于近视防控,包括光学、药物、环境或行为等,但结果各不相同,而且缺乏标准化。周边离焦技术目前已有多项试验证明其对近视控制有一定的作用。基于这一技术,在中国的医疗和视光机构常见到多区正向光学离焦技术(DIMS)、高非球面微透镜技术(HAL)和同心圆带微柱镜技术(CARE)三种周边离焦设计的框架眼镜镜片。这些镜片在提供了中央区清晰视觉的同时,在周边提供了一定量的近视性离焦来控制近视的进展。文章目的是关注以上三种周边离焦设计镜片的设计原理和近视防控效果,并评价其在临床实践中的有效性。     

Effect of nearwork-induced transient myopia on distance retinal defocus patterns

The purpose of the current study was to assess the effect of nearwork-induced transient myopia (NITM) on retinal defocus patterns during distance viewing. An empirically derived, conceptual model of human blur perception and related retinal defocus patterns has been extended to determine the effect of NITM on the relative contributions of myopic and hyperopic retinal defocus during distance viewing. Under the normal hyperfocal refractive condition during distance viewing with isolated stimulus conditions, there is very small myopic defocus (～0.25 diopters), and no hyperopic defocus, present. After sustained nearwork generating NITM, a moderate increase in this myopic defocus contribution takes place. In the normal isolated distance viewing situation with only very small myopic defocus present, as would occur with many far outdoor activities, the paucity of overall retinal defocus may provide a “protected” condition against myopia development. In contrast, with the addition of NITM producing increased myopic retinal defocus only, there is an imbalance of retinal defocus that may be myopigenic, especially in the context of foveal and peripheral retinal interactions.     

Role of parental myopia in the progression of myopia and its interaction with treatment in COMET children

PURPOSE: The present study investigated the relationship between parental refractive error and myopia progression in their offspring and the interaction between parental ametropia and the effects of wearing progressive-addition (PALs) or single-vision (SVLs) lenses on the progression of myopia in children enrolled in the Correction of Myopia Evaluation Trial (COMET). METHODS: The progression of myopia in a subset of COMET children (N= 232; 49% of initial group) was defined as the difference in mean spherical equivalent refraction of both eyes obtained by cycloplegic autorefraction between the baseline and 5-year visit. Parental refractions were obtained by noncycloplegic autorefraction (81%) or from recent eye examination records (19%). RESULTS: The number of myopic parents (mean spherical equivalent refraction 相似文献   

Oculomotor functions and late-onset myopia

In order to elucidate the role of optical defocus in the development of late-onset myopia (LOM), we employed both theoretical and experimental approaches. In the theoretical study, which has been reported previously, we suggested a model in which an accommodative sensory operator was added to simulate the sensory part of the accommodation system. Results derived from the model showed that the sensory part might increase the system's threshold to the accommodative error (or defocus) signal. In this study, we measured the perceptual depth-of-focus and the system's threshold to the defocus signal for three refractive error groups: emmetropic (Emm), stable myopic (S.M.), and progressing myopic (P.M.). Results show that there are no significant differences in the perceptual depth-of-focus among the three groups. However, the defocus threshold values of the P.M. group are significantly higher than the values of the other two groups. This result in combination with our previous findings, leads us to suggest that individuals susceptible of developing myopia from sustained near-work have a specific oculomotor risk profile. Although we are still trying to determine the specific sequence of changes among dark-focus, AC/A ratio, the accommodative system's defocus threshold, and refractive error, we are convinced that the changes of oculomotor parameters underlie the type of myopia associated with near-work.     

Myopia and contrast sensitivity function

PURPOSE: to measure the contrast sensitivity function of varying degrees of myopia with two types of optical correction (spectacle lens and contact lens). METHODS: One hundred and five myopic eyes and twenty-eight emmetropic eyes were collected. The myopic group included 105 eyes corrected with spectacle lenses and 71 eyes of them corrected with contact lenses, too; all had corrected vision acuity of 20/20 or better. The myopic eyes were divided into four groups: group 1 (-1D to -3D), low myopia; group 2 (-3.25D to -6D), medium myopia; group 3 (-6.25D to -12D), high myopia; and group 4 (> -12D), severe myopia. Spatial contrast sensitivity was measured using the OPTEC 2000 Contrast Sensitivity System. RESULTS: In groups 1 and 2, no statistically significant difference was found between myopes and emmetropes. In group 3, statistically significant loss of contrast sensitivity at higher spatial frequencies was found for myopic subjects corrected with spectacle lens, but not for myopes corrected with contact lens. In group 4, myopic subjects corrected with spectacle lenses showed significantly reduced contrast sensitivity function at all spatial frequencies; subjects corrected with contact lenses showed statistical sensitivity losses at 6, 12, 18 cycle/degree spatial frequencies. CONCLUSIONS: 1. We may suppose that low and medium myopes (groups 1 and 2), who showed normal contrast sensitivity functions, had no retinal dysfunction. 2. For high myopes, contact lens correction could reduce optical defocus and improve contrast sensitivity function in high spatial frequencies. 3. As retinal function disturbances occurred in severe myopes, the diminished contrast sensitivity was not fully compensated by contact lens correction. 4. Loss of contrast sensitivity might be interpreted as evidence for early retinal function disruption before retinal pathological events occur in severe myopes.     

角膜塑形镜离焦技术在近视防控中的研究进展

近视发病率在全球范围内呈逐渐上升趋势,严重影响青少年儿童的眼部健康,引起了巨大的经济和社会效益损失。因此,近视防控工作至关重要且刻不容缓。近年来,角膜塑形镜逐渐在近视防控领域体现出其优越性。目前,角膜塑形镜控制近视发展的原理主要以视网膜远视性光学离焦学说为主,促使近视患者的远视性离焦向近视性离焦漂移从而延缓眼轴增长。其控制近视发展的效果与多种因素相关,包括离焦总量、瞳孔直径、光学区设计及镜片偏心等。角膜塑形镜的广泛使用将有效降低青少年儿童的近视发病率,本文就角膜塑形镜利用离焦技术控制近视发展的原理、离焦量和离焦环位置与近视防控效果的关系等方面进行综述,旨在阐明角膜塑形镜离焦技术在近视防控中的研究进展。     

周边视网膜相对屈光度与近视进展的关系

在正视眼或者低度远视眼中,周边视网膜呈相对远视屈光状态者比周边视网膜呈相对近视屈光状态者更容易发展为近视眼.正视眼周边视网膜呈轻度相对近视屈光状态,未矫正的远视眼周边视网膜呈稍大程度的相对近视屈光状态,未矫正的近视眼周边视网膜呈轻度相对远视屈光状态或比正视眼程度轻的相对近视状态.这两种观点已经被学者广泛接受.动物实验也证明异常视觉信号不仅能引起中央视网膜屈光不正,也能改变眼球后极部眼球形态和周边视网膜相对屈光不正的类型,并且黄斑切除并不影响正视化过程.相反,周边视网膜能单独调控眼球正视化过程并能对异常视觉信号起作用进而发展为各种屈光不正.临床研究表明,矫正视网膜周边远视性离焦的框架镜片对近视眼进展能起到一定的控制作用.虽然,周边视网膜远视性离焦是否促进近视进展的确切原因还不能肯定,但目前的研究倾向于认为两者之间可能有某种关系.     

A comparison of clinical acuity and contrast sensitivity charts: effect of uncorrected myopia

We have examined the effect of corrected and uncorrected myopia on visual acuity and contrast sensitivity using a standard acuity chart and two commercially available printed contrast sensitivity charts (Vistech and Pelli-Robson). We tested 140 eyes of 70 young adults. Most subjects were myopic and were tested with and without their optimum spectacle or contact lens correction. We found no effect of myopia, if well corrected, on acuity or contrast sensitivity. All three test scores were sensitive to uncorrected myopia. The Pelli-Robson contrast sensitivity chart, which was designed to be insensitive to defocus, required more than three diopters of refractive error to elicit a two line change in performance, and it was generally very insensitive to uncorrected myopia. Although the Vistech chart was sensitive to uncorrected myopia, the large step sizes used in the chart, and the higher inter- and intra-subject variability in scores reduces its potential value for refraction. The Snellen letter chart gave the most sensitive and reliable changes in performance with uncorrected myopia.     

New perspectives on the prevention of myopia

 Abstract: The high prevalence of myopia and its public health and clinical consequences make prevention of myopia a top priority. Traditional approaches to prevention have been based on reducing accommodative load, and have generally been unsuccessful. Only treatment with atropine eye-drops has produced clinically significant effects, which are however of limited duration and suffer from potential side-effects. In addition, based on animal experimentation, it is now clear that atropine blocks eye growth by mechanisms which do not involve accommodation. More generally, experimentation on animal models of myopia has shown that accommodation is not important for the control of eye growth, whereas exposure to hyperopic (growth-promoting) and myopic (growth-inhibiting) defocus is more important. Recent epidemiological evidence has also questioned the importance of near work, although education is clearly important. This suggests a preventive approach based on deliberately increasing the amount of myopic defocus a child is exposed to may be successful. There is also convincing evidence that children who spend more time outside are less likely to become myopic, which also suggests a quite non–invasive approach to prevention. These new directions need to be pursued.     

Effectiveness of peripheral defocus spectacle lenses in myopia control: a Meta-analysis and systematic review

AIM: To evaluate the effectiveness of peripheral defocus spectacle lenses (PDLs) in myopia control. METHODS: Literature retrieval on PubMed, Cochrane Library, Embase, and Web of Science databases, and the search time limit was from the establishment of each database to December 29, 2021 were conducted. Change of spherical equivalent refraction (SER) and axial change (AL) were extracted from the literatures that met the inclusion criteria, and RevMan5.3 software was used for Meta-analysis. RESULTS: A total of 4 randomized controlled trials (RCTs) were included in this Meta-analysis, involving 770 myopic children. The results showed that PDLs could delay the progression of myopia in children with myopia compared with single vision spectacle lenses (SVLs; WMD=0.21 D, 95%CI: 0.01, 0.41, P=0.04). However, there was no significant difference in controlling the growth of axial length (AL) in myopic children (WMD=-0.10 mm, 95%CI: -0.21, 0.01, P=0.07). The results of the effectiveness of myopia control between the two spectacle lenses showed that PDLs were more effective in controlling the progression of myopia (OR=5.73, 95%CI: 2.58, 12.70, P<0.001) and delaying the growth of AL (OR=44.25, 95%CI: 8.84, 221.58, P<0.001) than SVLs, and the differences were statistically significant. CONCLUSION: PDLs can control the progression of myopia compared with SVLs, but cannot delay the growth of AL, and the effectiveness of PDLs in myopia control better than SVLs.     

视网膜周边离焦与近视防控的研究进展

近视患病率在全球范围逐年增高,随之导致诸多眼健康问题和社会学影响。近年来,视网膜周边离焦被证实与近视的发生发展密切相关,改变视网膜的周边离焦状态能够显著影响近视发展和正视化进程,但其具体作用机制仍不明确。目前临床中尚无能够完全控制近视的方法,现有的主要方法包括硬性角膜塑形镜、周边离焦镜、多焦软镜等均被证实与视网膜周边离焦紧密相关,本文将总结归纳周边离焦相关的控制手段的发展、控制效果。并对国内外视网膜周边离焦与近视防控的相关机制研究进行回顾,提出周边离焦防控近视的潜在机制,以期为进一步提高各种防控手段的效果或研发新的防控措施以及降低近视的发病率和发展速度提供思路。     

An examination of the baropathic nature of axial myopia

An examination of how intraocular pressure distending forces on the posterior sclera are an important mechanism in the development and progression of axial myopia has been made. Papers were selected from the results of PubMed (143) and Science Direct (1,398) searches using the key word combinations of ‘axial myopia’ and ‘intraocular pressure’. The main points include that the sclera is exposed to distending forces at all levels of physiological and pathological intraocular pressure. Reversible axial elongation is a common physiological response to elevated intraocular pressure in healthy eyes but more so in myopic eyes. Key variables, which appear to determine pathological (non‐reversible) axial elongation include the thickness, rigidity and viscoelasticity of the posterior sclera and the associated increased susceptibility of it to distending forces. Intraocular pressure appears likely to have a greater role when it is above normal. Intraocular pressure elevations, which are not detected by clinical or experimental tonometry, may be significant contributors to axial elongation. Axial elongation can be pathological in myopic or myopically predisposed eyes, when elongation is not reversible. Axial elongation has also been associated with retinal defocus in both animals and humans, when thinning due to loss of scleral collagen and/or ground substance, which is driven by the retina, appears likely to be associated with increased scleral susceptibility to intraocular pressure. As myopia progresses, signs of retinal and choroidal stretching are an increasingly apparent consequence of the balloon‐like expansion of the posterior sclera in response to intraocular pressure. Avoidance or moderation of activities which are known to elevate intraocular pressure may improve the prognosis for patients with genetic and/or environmental predisposition to myopic progression and may be an important consideration, even when other myopic control measures are being used.     

Effects of different concentrations of atropine on controlling myopia in myopic children.

Although 1% atropine effectively slows myopia progression, it is associated with adverse effects, including photophobia, blurred near vision, and poor compliance. We investigated whether lower doses of atropine would control myopia progression. One hundred and eighty-six children, from 6 to 13 years of age, were treated each night with different concentrations of atropine eye drops or a control treatment for up to 2 years. The mean myopic progression in each of the groups was 0.04 +/-0.63 diopter per year (D/Y) in the 0.5% atropine group, 0.45+/-0.55 D/Y in the 0.25% atropine group, and 0.47+/-0.91 D/Y in the 0.1% atropine group. All atropine groups showed significantly less myopic progression than the control group (1.06+/-0.61 D/Y) (p<0.01). Our study also showed that 61% of students in the 0.5% atropine group, 49% in the 0.25% atropine group and 42% in the 0.1% atropine group had no myopic progression. However, 4% of children in the 0.5% atropine group, 17% in the 0.25% atropine group, and 33% in the 0.1% atropine group still had fast myopic progression (>-1.0 D/Y). In contrast, only 8% of the control group showed no myopic progression and 44% had fast myopic progression. These results suggest that all three concentrations of atropine had significant effects on controlling myopia; however, treatment with 0.5% atropine was the most effective.     

Juvenile myopia progression,risk factors and interventions

The development and progression of early onset myopia is actively being investigated. While myopia is often considered a benign condition it should be considered a public health problem for its visual, quality of life, and economic consequences. Nearly half of the visually impaired population in the world has uncorrected refractive errors, with myopia a high percent of that group. Uncorrected visual acuity should be screened for and treated in order to improve academic performance, career opportunities and socio-economic status.Genetic and environmental factors contribute to the onset and progression of myopia. Twin studies have supported genetic factors and research continues to identify myopia genetic loci. While multiple myopia genetic loci have been identified establishing myopia as a common complex disorder, there is not yet a genetic model explaining myopia progression in populations.Environmental factors include near work, education levels, urban compared to rural location, and time spent outdoors. In this field of study where there continues to be etiology controversies, there is recent agreement that children who spend more time outdoors are less likely to become myopic.Worldwide population studies, some completed and some in progress, with a common protocol are gathering both genetic and environmental cohort data of great value. There have been rapid population changes in prevalence rates supporting an environmental influence.Interventions to prevent juvenile myopia progression include pharmacologic agents, glasses and contact lenses. Pharmacological interventions over 1–2 year trials have shown benefits. Peripheral vision defocus has been found to affect the emmetropization process and may be affected by wearing glasses or contacts. Accommodation accuracy also has been implicated in myopia progression.Further research will aim to assess both the role and interaction of environmental influences and genetic factors.     

光学离焦技术控制近视的研究进展

近视是一种常见的眼病,近年来,近视的发生率在全球范围内呈逐年上升趋势,高度近视会增加视力丧失的风险,近视的并发症可引起巨大的经济和社会效益损失。因此,实施控制近视的有效措施至关重要且迫在眉睫。人们对近视的发病机制研究表明,周围远视离焦引起眼球轴向伸长不受控制可能是近视发展的机制之一,由此引申的各种光学策略尤其是光学离焦技术控制近视日益成为近视管理主流临床实践的一部分。本文从光学离焦控制近视的原理、离焦性近视动物实验研究、不同光学离焦技术控制近视的最新临床应用等方面进行综述,总结了使用渐进多焦眼镜、周边离焦框架眼镜、多点近视离焦框架眼镜、角膜塑形镜及多焦点软性角膜接触镜控制近视的临床研究结果,拟为延缓近视进展的治疗方案设计提供新的选择。