Comparison of form-deprived myopia and lens-induced myopia in guinea pigs

AIM: To study the efficacy difference between form-deprived myopia (FDM) and lens-induced myopia (LIM), the degree of myopia, axial length and pathological changes of the posterior sclera from guinea pigs were evaluated.METHODS: Four-week pigmented guinea pigs were randomly assigned into 3 groups, including normal control (n=6), FDM group with monocular cover (n=11) and LIM group with monocular -7D lens treatment (n=11). FDM group was form-deprived while LIM group was lens-induced for 14 d. Refractive error and axial length were measured prior to and post treatment, respectively. Morphological changes of sclera were examined using both light and electronic microscopes.RESULTS: After 14d treatment, refractive errors for FDM group and LIM group were -3.05±0.71D and -2.12±1.29D, respectively, which were significantly more myopic than that of normal controls and fellow control eyes (P<0.01). As for axial length, it was 7.93±0.03 mm for FDM group and 7.89±0.06 mm for LIM group, which were significantly longer than both normal and fellow controls (P<0.01). With respect to both refractory error and axial length, the differences between FDM group and LIM group were not significant (P>0.05). Under light microscope, both FDM group and LIM group showed thinned sclera, disarrangement of fibrosis and enlarged disassociation between fibers. Consistently, ultrastructural examination showed degenerated fibroblasts and thinned fibers in posterior sclera.CONCLUSION:Following two weeks of myopia induction in guinea pigs, with regard to the degree of myopia, axial length and pathological alterations, there was no significant difference between FDM and LIM models. Therefore, FDM and LIM are equally effective and useful as a model of experimental myopia and guinea pigs are ideal animals for induction of experimental myopia because their high sensitivity to both form-deprivation and lens-induction.     

近视、近视眼和近视眼病

近视是人类普遍存在的视觉现象,迄今仍停留在认识阶段。为求了解实质,有的放矢解决问题,本文试按临床流行病学要求及医学术语学的原则,并结合实践体会,特对复杂的近视现象,按视力、屈光与疾病的不同含义分别定名为“近视”、“近视眼”和“近视眼病”。讨论指出明确概念、规范检查、正确诊断及合理运用不同术语的重要性与实用性。本文无意更改沿用已久的习惯用词,只是建议在涉及基本概念时,有必要酌情作出准确选择。     

近视回归镜控制青少年近视发展的临床观察

目的:临床观察近视回归镜对青少年近视发展的防治作用。方法:随机选取52例在我院视光中心就诊的年龄在9~18岁近视患者配戴近视回归镜作为治疗组,观察裸眼视力变化,屈光度变化,眼轴长度及角膜曲率变化情况.并与52例年龄及屈光度相似的近视患者配戴框架眼镜作为对照组,观察时间12mo。结果:治疗组屈光度增加<0.50D者38例(76眼)有效率73.1%,对照组屈光度增加<0.50D者18例(36眼)有效率34.6%,两组间有显著差异(P<0.01);治疗组裸眼视力下降<2行者39例(78眼)有效率73.6%,对照组裸眼视力下降<2行者10例(20眼)有效率19.2%,两组间差异有显著性(P<0.05);眼轴长度及角膜曲率值变化治疗组与对照组之间无明显差别。结论:近视回归镜对青少年近视发展有延缓作用。     

中度曲率性近视与轴性近视的高阶像差比较研究

目的：针对不同类型中度近视眼高阶像差的分析,探讨中度近视眼中曲率性近视与轴性近视高阶像差的差异。方法：采用前瞻性研究,选取单纯性中度近视眼患者39例56眼,将其分为两组：A组为中度曲率性近视眼组（11例/16眼）,平均年龄22±2岁,平均眼轴长度23.89±0.13mm,平均角膜曲率45.56±0.95D,平均屈光度4.58±0.82D;B组为轴性近视眼组共28例40眼,平均年龄22±3岁,平均眼轴长度25.82±0.44mm,平均角膜曲率41.93±0.85D,平均屈光度4.50±0.78D。利用波前像差仪获取入选患眼瞳孔分别为4,5,6mm时高阶像差值,进行分组比较。结果：A,B两组平均年龄与平均屈光度比较,差异无显著性（P〉0.05）;两组平均角膜曲率与平均眼轴长比较,差异有显著性（P〈0.05）。A组与B组在瞳孔为6mm时RMS3,RMS4,RMS6,RMSh,C12值比较,A组/B组分别为：0.165±0.064/0.098±0.045,0.127±0.034/0.059±0.025,0.040±0.014/0.028±0.010,0.218±0.059/0.129±0.040,0.137±0.057/0.048±0.037,差异有显著性（P〈0.05）。其余不同直径瞳孔下的高阶像差各值比较,前者均高于后者,差异均有显著性（P〈0.05）。结论：在正常及中度散大瞳孔下,中度近视眼中曲率性近视的彗差、球差、次级球差及总高阶像差均较轴性近视眼为大。     

Night myopia

Although the phenomenon of night myopia has been recognized for two centuries, its causes are still not fully understood. Early studies implicated spherical aberration and accommodation, but the degree to which either contributed was not clearly established. More recently, "laser speckle" techniques to measure myopia have allowed the collection of data on large subject populations and it appears that night myopia represents a tendency for accommodation to approximate the dark focus as low luminance levels degrade the clarity of the retinal image. In this article, the authors review the past and present literature on night myopia and related anomalous myopias, and describe techniques for their evaluation and correction.     

Posterior segment conditions associated with myopia and high myopia

Myopia, and especially high myopia, is associated with a number of posterior segment changes that are considered to be mostly a consequence of the increased axial elongation. This can result in mechanical strain, attendant vascular changes, stretching and thinning of tissues, and atrophy/deformation of tissues in later or more advanced stages. Such myopia-related changes are observed as changes and/or abnormalities in the vitreous, choroid, retina and peripheral retina, sclera and/or optic disc. Although many of these changes are benign, at times they may be associated with significant vision impairment that either requires active intervention or may suggest future progression of the disease. This review systematically addresses the posterior segment conditions seen in myopic eyes, describes the features associated with the condition and details management pathways.     

Improving myopia awareness via school-based myopia prevention health education among Chinese students

AIM: To investigate the myopia awareness level, knowledge, attitude, and skills at baseline and to implement and evaluate the efficacy of myopia prevention health education among Chinese students. METHODS: A total of 1000 middle school students from 2 middle schools were invited to participate in the study, and myopia prevention health education was conducted. The students were assessed at baseline, followed by a survey. The efficacy of health education was evaluated using the self-comparison method pre- and post-health education. RESULTS: The study included 957 and 850 pre- and post-health education participants, respectively. The baseline knowledge of all respondents on myopic symptoms (87.5%), myopia is a risk of eyes (72.9%), myopia prevention (91.3%), myopia increases with age (86.7%), performing periodic eye examinations (92.8%), and one first, one foot, and one inch (84.8%) significantly increased after health education (P<0.001 for all). However, the percentage of students who still did not think it necessary to take breaks after 30-40min of continuous near work was 27.0%. The opinion that “myopia can be cured” was still present in 38.3%. CONCLUSION: Implementing school-based myopia prevention health education improves knowledge, attitudes, and skills regarding myopia among Chinese middle school students.     

早发性近视和迟发性近视张力性调节的比较

目的:通过一种测量张力性调节的方法,了解迟发性近视、早发性近视和正视眼的张力性调节表现。探讨张力性调节与近视的相互关系。方法:志愿参加本实验者54例,正视组18例,屈光度(-0.25～ 0.50)D之间,早发性近视组18例,平均为(-6.50±2.40)D,迟发性近视组18例,平均为(-3.00±1.75)D。在完全黑暗的环境下,用偏振光游标式调节检测仪对受试者进行张力性调节的测量,比较迟发性近视、早发性近视和正视眼的张力性调节的差异。结果:在缺乏任何视觉刺激的状态下,调节处于一定的静息状态,所有受试者张力性调节的平均值为(0.90±0.76)D。其中正视组的张力性调节平均为(0.80±0.64)D,早发性近视组的张力性调节为(1.32±0.80)D,迟发性近视组的张力性调节平均为(0.62±0.46)D。早发性近视的张力性调节高于正视组和迟发性近视组的张力性调节,差异有非常显著性(P<0.001);正视组和迟发性近视组的张力性调节,差异无显著性(P>0.05)。结论:早发性近视者有较强睫状肌的基础张力水平,易导致牵拉眼球而使近视进展。     

近视眼患者血清多巴胺含量测定

目的　通过对近视眼患者的血清多巴胺含量测定 ,从临床角度探讨近视眼的发病机制。方法　采用高压液相色谱 /电化学检测法测定中学生近视眼组和正常对照组血清中多巴胺 (DA)的含量 ,并进行分析和比较。结果　近视眼组血清中多巴胺含量明显低于正常对照组 (P <0 0 1) ,近视眼组血清中多巴胺含量与性别和近视程度无明显相关(P >0 0 5 )。结论　青少年学生体内多巴胺的平衡失调 ,可能与青少年学生近视眼形成密切相关。     

论近视眼的分类

近视眼分类是否合理,对于正确了解近视眼性质、深入探讨病因机制及有效选用防治方法至关重要。本文对各种近视眼诊断名称及分类方法进行分析比较,认为近视眼按性质分类比较合理,即近视眼以原发性为主,其中包括单纯性近视眼(生理性近视眼)与病理性近视眼(变性近视眼)两类。(眼科,2007,16:294-297)     

近视眼流行病学调查现状

近视眼是目前最普遍的视觉问题,严重影响个人生活质量.高度近视眼可造成白内障、青光眼、视网膜脱离、脉络膜新生血管形成及近视性黄斑病变等并发症.以人群为基础的流行病学调查显示,尽管不同种族和地域的近视眼患病率存在较大差异,但其流行程度近年来普遍加重,尤其是较富裕地区以及东亚的工业化地区.近视眼的环境危险因素与社会经济地位以及生活方式相关这一观点已得到证实.过去十年,对近视眼的分子生物学机制有了进一步了解,进一步证实了遗传因素和环境因素相互作用导致近视眼的发生.     

儿童原发性近视眼

目的　分析儿童原发性近视眼的特点。方法　①对象流行病学调查发现的50例(3～7岁)及临床就诊的39例(1～12岁),静态屈光均为近视眼。②观察指标远视力、近视力、屈光(用1%阿托品)、眼底、角膜曲率、眼轴。结果　儿童近视眼多数为原发性(82例),继发于其它疾病的有7例,无明显性别差异。儿童原发性近视眼为先天性,眼轴多明显延长,长度与屈光度成正相关,角膜屈折力无明显病理意义。屈光度进行性发展,随年龄增加而加深,是日后成年期变性近视眼的主要组成。结论　儿童近视眼可分为原发性和继发性。其中主要为原发性变性近视眼。     

Time trends in myopia and high myopia prevalence in young university adults in China

AIM: To investigate time trends in myopia and high myopia prevalence over 6y among young university adults in China. METHODS: This is a 6-year series cross-sectional study from 2016 to 2021. Totally 4910 freshmen were enrolled and completed a questionnaire concerning age, gender, and disease history. Students with eye diseases were excluded after a detailed eye examination. The refractive status was measured by non-cycloplegic objective refraction and ocular parameters were measured by Lenstar 900. The examination followed the same protocol each year. Trends over time in myopia and high myopia prevalence, as well as ocular biometry parameters, were analyzed. RESULTS: From 2016 to 2021, the axial length (AL) and corneal radius (CR) increased significantly (P=0.002 for AL; P=0.04 for CR). However, the spherical equivalent (SE) and the ratio of axial length to the corneal radius (AL/CR) did not change significantly (P=0.59 for SE; P=0.24 for AL/CR). The frequency of AL ≥26.0 mm increased from 26.6% in 2016 to 29.3% in 2021 (P=0.05 for trend). The prevalence of myopia and high myopia did not change significantly in our study (P≥0.18). Compared to a similar cross-sectional study conducted 10 years ago, the prevalence of myopia decreased significantly (94.9% vs 91.8%, P<0.001). Whereas the prevalence of high myopia increased largely (18.12% vs 27.6%, P<0.001). CONCLUSION: The prevalence of high myopia increases in young university adults during 10y period. Myopia control should begin earlier in childhood. However, these interventions are still needed for high myopia even in young adulthood.     

The future of clinical trials of myopia control

In the field of myopia control, effective optical or pharmaceutical therapies are now available to patients in many markets. This creates challenges for the conduct of placebo-controlled, randomised clinical trials, including ethics, recruitment, retention, selective loss of faster progressors and non-protocol treatments:

1. Ethics: It is valid to question whether withholding treatment in control subjects is ethical.
2. Recruitment: Availability of treatments is making recruitment into clinical trials more difficult.
3. Retention: If masking is not possible, parents may immediately withdraw their child if randomised to no treatment.
4. Selective loss: Withdrawal of fast progressors in the control group leading to a control group biased towards low progression.
5. Non-protocol treatment: Parents may access other myopia treatments in addition to those within the trial.

We propose that future trials may adopt one of the following designs:

1. Non-inferiority trials using an approved drug or device as the control. The choice will depend on whether a regulatory agency has approved the drug or device.
2. Short conventional efficacy trials where data are subsequently entered into a model created from previous clinical trials, which allows robust prediction of long-term treatment efficacy from the initial efficacy.
3. Virtual control group trials based on data relating to axial elongation, myopia progression or both, accounting for subject's age and race.
4. Short-term control data from a cohort, for example, 1 year or less, and applying an appropriate, proportional annual reduction in axial elongation to that population and extrapolating to subsequent years.
5. Time-to-treatment-failure trials using survival analysis; once a treated or control subject progresses or elongates by a given amount, they exit the study and can be offered treatment.

In summary, the future development of new treatments in myopia control will be hampered if significant changes are not made to the design of clinical trials in this area.     

多巴胺在形觉剥夺性近视眼中的作用

形觉剥夺性近视眼 (formdeprivedmyopia,FDM)是眼球在失去视觉信号的刺激后 ,前后径异常生长而致的近视眼。大量阅读的人群由于在阅读过程中未充分利用非黄斑区的视网膜 ,可引起FDM ,故人们制作了各种动物模型来研究此类近视眼眼球的形态、电生理、神经递质的分泌等的变化。视网膜中的多巴胺与FDM的关系密切 ,但它在FDM中的确切机制仍不很清楚 ,本文综述了FDM中多巴胺的作用     

高度近視眼合并白内障超聲乳化摘除術

目的觀察高度近視合并白内障超聲乳化摘除及人工晶狀體植入術的療效.方法對72例(79眼)高度近視白内障患者術前檢查眼軸長,計算人工晶狀體屈光度,經鞏膜隧道切口行超聲乳化摘除及人工晶狀體植入術,對術后視力及并發症進行觀察.結果 79眼術后視力不同程度提高,術后1月視力≥0.5者48眼,＜0.3者13眼,高度近視合并眼底病變是白内障術后視力不佳的原因.結論白内障超聲乳化摘除聯合人工晶狀體植入術是高度近視合并白内障較理想的手術方式,及早抓住手術時機,可以减少手術并發症的發生,獲得良好的手術效果.     

Myopia control in Mendelian forms of myopia

Purpose

To study the effectiveness of high-dose atropine for reducing eye growth in Mendelian myopia in children and mice.

Methods

We studied the effect of high-dose atropine in children with progressive myopia with and without a monogenetic cause. Children were matched for age and axial length (AL) in their first year of treatment. We considered annual AL progression rate as the outcome and compared rates with percentile charts of an untreated general population. We treated C57BL/6J mice featuring the myopic phenotype of Donnai–Barrow syndrome by selective inactivation of Lrp2 knock out (KO) and control mice (CTRL) daily with 1% atropine in the left eye and saline in the right eye, from postnatal days 30–56. Ocular biometry was measured using spectral-domain optical coherence tomography. Retinal dopamine (DA) and 3,4-dihydroxyphenylacetic acid (DOPAC) were measured using high-performance liquid chromatography.

Results

Children with a Mendelian form of myopia had average baseline spherical equivalent (SE) –7.6 ± 2.5D and AL 25.8 ± 0.3 mm; children with non-Mendelian myopia had average SE −7.3 ± 2.9 D and AL 25.6 ± 0.9 mm. During atropine treatment, the annual AL progression rate was 0.37 ± 0.08 and 0.39 ± 0.05 mm in the Mendelian myopes and non-Mendelian myopes, respectively. Compared with progression rates of untreated general population (0.47 mm/year), atropine reduced AL progression with 27% in Mendelian myopes and 23% in non-Mendelian myopes. Atropine significantly reduced AL growth in both KO and CTRL mice (male, KO: −40 ± 15; CTRL: −42 ± 10; female, KO: −53 ± 15; CTRL: −62 ± 3 μm). The DA and DOPAC levels 2 and 24 h after atropine treatment were slightly, albeit non-significantly, elevated.

Conclusions

High-dose atropine had the same effect on AL in high myopic children with and without a known monogenetic cause. In mice featuring a severe form of Mendelian myopia, atropine reduced AL progression. This suggests that atropine can reduce myopia progression even in the presence of a strong monogenic driver.     

高度近视眼巩膜生物力学特性初步研究

目的　观察高度近视眼巩膜与对照眼巩膜的生物力学特征。方法　高度近视合并裂孔源性视网膜脱离的患者 ,行纬线位巩膜层间加压、电凝并联合放液术 ,术中将加压后富余的板层浅层巩膜取成 6mm× 2mm的试件 ,对照组摘除的眼球去除眼内容物后放入保存液中置于液氮内保存。在生物力学实验前 ,取出复温后 ,在赤道部按不同方向剪成10mm× 3mm的试件。试验在Instron 5 5 44力学实验机上进行 ,实验参数由计算机自动记录并分析。结果　高度近视眼巩膜的力学特征与对照组比均有明显的差异 ,其中弹性模量 (3 0 8± 1 3 7)Mpa及单位宽度所受的力 (1 5 6± 0 81)N/mm小于对照眼巩膜 (12 0 8± 10 0 1)Mpa、(12 89± 12 5 3 )N /mm ,高度近视眼的最大载荷 (0 83± 0 5 1)N、最大应力(0 96± 0 47)Mpa均低于对照组 (15 3 3± 8 44 )N、(3 77± 1 92 )Mpa ,而最大应变 (5 7 2 6± 49 82 ) %则明显高于对照组(2 4 2 2± 12 17) %。结论　高度近视眼与正常眼相比更容易发生变形 ,具有较低的承载能力。     

准分子激光上皮瓣下角膜磨镶术治疗异常眼的近视眼

目的探讨准分子激光上皮瓣下角膜磨镶术治疗异常眼的近视群体的方法。方法用准分子激光上皮瓣下角膜磨镶术治疗异常眼的近视群体（眼球较小、眼窝较深、角膜较薄等）。观察术后视力恢复情况。结果25例50眼中，术后3月视力在1．0以上47眼（94％）。0．6～0．8的2眼（4％）。0．5以下的1眼（2％）。结论准分子激光上皮瓣下角膜磨镶术拓展了准分子激光的治疗范围。     

Contralateral effect in progression and recovery of lens-induced myopia in mice

Purpose

Apart from genetic factors, recent animal studies on myopia have focused on localised mechanisms. In this study, we aimed to examine the contralateral effects of monocular experimental myopia and recovery, which cannot be explained by a mere local mechanism.

Methods

One eye of 3-week-old C57BL/6 male mice was fitted with a −30 dioptre (D) lens. The mice were distributed into two groups based on different conditions in the contralateral eye: either no lens (NLC) (n = 10) or a Plano lens on the contralateral eye (PLC) group (n = 6). Mice receiving no treatment on either eye were set as a control group (n = 6). Lenses were removed after 3 weeks of myopia induction. All mice were allowed to recover for 1 week in the same environment. Refractive status, axial length (AL) and choroidal thickness were measured before myopia induction, after 1 and 3 weeks of lens wear and after 1 week of recovery.

Results

One week after removing the lenses, complete recovery was observed in the eyes that wore the −30 D lenses. In both the PLC and NLC groups, the refractive status showed a myopic shift after lens removal. Additionally, the choroid was significantly thinned in these eyes. The −30 D wearing eye showed a significant increase in AL after 3 weeks of lens wear. While the AL of the −30 D wearing eye ceased to grow after the lens was removed, the AL in the PLC and NLC contralateral eyes increased, and the binocular ALs gradually converged.

Conclusions

Recovery of lens-induced myopia was observed in mouse models. In the fellow eyes, the effects, including thinning of the choroid and changes in refractive status, were triggered by contralateral visual cues.