Monocular deprivation in an identical twin.

PURPOSE: The scientific literature contains minimal human studies of the effect of monocular deprivation on a single eye of twins. This report examines the effects of early visual deprivation on axial length measurements by comparing the refractive findings and axial length measurements of identical twins' 4 eyes, 1 visually deprived and 3 nondeprived. METHODS: A retrospective record review was performed on the medical records of identical 6-year-old Hispanic female twins. Both patients had received eye care at the University Optometric Center, State University of New York, for a period of at least 5 years. Subsequently, an Internal Review Board-approved prospective study was undertaken. Each twin received a comprehensive eye examination and an A-scan. RESULTS: The findings of the 3 nondeprived eyes were compared with those of the 1 deprived eye. The 3 nondeprived eyes had at least 20/20 visual acuity, low hyperopia or astigmatism, low with the rule keratometric findings, 12-mm corneal diameters, and A-scan results ranging from 21.0 to 21.55 mm. The remaining eye, which was visually deprived secondary to congenital cataract from birth to 6 months of age, had an aphakic refractive condition, decreased visual acuity, glaucoma, esotropia, and borderline microcornea. Keratometric findings were comparable with those of the other 3 eyes, whereas the A-scan finding was 25.16 mm. CONCLUSION: This case presented a unique opportunity to directly examine the effect of visual deprivation on axial elongation. Although other factors, such as glaucoma and borderline microcornea, may influence axial elongation, the findings in this patient indicate that a substantial portion, if not all, of the axial elongation can be attributed to early monocular deprivation.     

The regulation of eye growth and refractive state: an experimental study of emmetropization

During growth the vertebrate eye achieves a close match between the power of its optics and its axial length with the result that images are focused on the retina without accommodative effort (emmetropia). The possibility that vision is required for the regulation of eye growth was studied experimentally in chicks made myopic or hyperopic by different visual manipulations. After discontinuing these visual manipulations, the eyes returned quickly to emmetropia mainly by adjusting the growth of their vitreous chambers; growth stopped in eyes recovering from myopia and continued in eyes recovering from hyperopia. Because both hyperopic and myopic eyes were already larger than normal controls, the difference in growth indicates that refractive error, rather than eye size per se, guides the eye toward emmetropia. Evidence is also presented for nonvisual shape-related control of eye growth, but this is slow-acting and cannot explain the emmetropization from induced refractive errors. Both the visually guided and shape-related mechanisms work even in eyes with the optic nerve cut, indicating that the two mechanisms are local to the eye. Although the optic-nerve-sectioned eye can sense the sign of a refractive error and initially adjust growth accordingly, it eventually overshoots emmetropia and reverses the sign of the initial refractive error. Whether this is due to loss of feedback from the central nervous system or retinal ganglion cells is unclear.     

双生子弱视儿童多导视觉诱发电位分析

对７对双生子（ＭＺ４对，ＤＺ３对）的弱视儿童进行了视力及多导视觉诱发电位分析，经配对ｔ－检验结果表明：ＭＺ之间尽管临床检查视力有差异，但ＶＥＰ潜伏期（ＬＰ１）无差异（Ｐ〉０．０５），４对ＭＺ中均仅有一人为双眼弱视，似乎表明环境因素对弱视的发病起着重要作用。     

双生子屈光状态与遗传的关系

目的：探讨双生子视力、眼位、屈光性质、弱视分类的遗传规律。方法：对７对同卵双生子和８对异卵双生子的远近视力、眼位、眼度、屈光进行和统计学分析,并计算一致率及遗传指数。结果：同卵双子视力、眼位、屈光性质、弱视分类的一致率分别为８５．７１％、８５．７１％、８５．５８％、７７．７８％;异卵双生子的一致率分别为３１．２５％、５０．０％、６２．５％、４０．０％;遗传度分别为７１．２１％、７１．４２％、６１．     

The refractive development of untreated eyes of rhesus monkeys varies according to the treatment received by their fellow eyes.

To determine the extent to which the visual experience of one eye may influence the refractive development of its fellow eye, we analyzed the data of untreated (UT) eyes of monkeys that received different types of unilateral pattern deprivation. Subjects were 15 juvenile rhesus monkeys, with five monkeys in each of three treatment groups: aphakic eyes with optical correction (AC), aphakic eyes with no correction (ANC), and eyes that were occluded with an opaque contact lens (OC). Under general anaesthesia, refractive error (D) was determined by cycloplegic retinoscopy and axial length (mm) was determined with A-scan ultrasonography. For measurements of refractive error of the UT eyes, there was a significant main effect of groups according to the treatment of the fellow eyes, F(2, 12) = 6.6. While UT eyes paired with AC fellow eyes (mean = +4.2 D) were significantly more hyperopic than the eyes of age-matched normal monkeys (mean = +2.4 D), t(25), = 2.5, UT eyes paired with OC fellow eyes (mean = -0.5 D) were significantly more myopic than the eyes of normal monkeys, t(25) = -9. UT eyes paired with ANC fellow eyes (mean = +1.9 D) were not significantly different from normal eyes. For measurements of axial length there was also a significant main effect of groups, F(2, 12) = 6.9. While UT eyes paired with AC fellow eyes (mean = 16.9 mm) were significantly shorter than the eyes of age-matched normal monkeys (mean = 17.5 mm), t(25) = 2.3, UT eyes paired with OC fellow eyes (mean = 18.1 mm) were significantly longer than the eyes of normal monkeys, t(25) = 2.3. UT eyes paired with ANC fellow eyes (mean = 17.5 mm) were not significantly different from the eyes of normal monkeys. The measurements of axial length and of refractive error of the UT eyes were also significantly correlated with one another, probably indicating that the differences in refractive error were due to differences in axial length, r = -0.8. The present data reveal that despite normal visual experience, UT eyes can have their refractive development altered, systematically, simply as a function of the type of pattern deprivation received by their fellow eyes. These data add to the growing evidence that there is an interocular mechanism that is active during emmetropization. As a consequence, future models of eye growth will need to consider both: (1) the direct influence of visual input on the growing eye; as well as (2) the indirect influence coming from the fellow eye.     

WHAT YOU ALWAYS WANTED TO KNOW ABOUT MYOPIA-BUT NEVER DARED TO ASK*

For the past 25 years it has been possible to measure ail of the major elements that contribute to the total refractive state of the eye. Measurements of the elements of refraction on large numbers of people have contributed to our understanding of myopia. The refractive state of the eye is not normally distributed, the frequency distribution being leptokurtic, negatively skewed, and demonstrating an irregularity (hump) in the myopic tail of the curve. Analysis of the distribution curves show that there is some correlation between some pairs of elements, and that the distribution curve for axial length Is ieptokurtic and skewed. The best explanation for the observed deviations from normality of the curves is that there are two populations — one of subjects whose eyes grow relatively slowly and whose axial growth is compensated by growth of other elements; the other population consisting of subjects whose eyes grew at a more rapid rate during childhood. Although the cause of this rapid growth is not known, current research is tending to suggest that febrile disease or collagen disease may be involved — for some subjects at least. The next breaklhrough in our understanding of myopia will likely come from clinical research in which the elements of refraction are measured and considered In the light of the subject's visual and general health history.     

Refractive and structural measures of lid-suture myopia in tree shrew

In order to study more thoroughly the refractive and structural changes associated with lid-suture myopia, five tree shrews were raised for approximately 16 weeks with monocular visual experience produced by lid closure. Four animals raised with normal laboratory visual experience served as a control group. Compared to the paired open eye, lid-sutured eyes were myopic (-12.1 +/- 6.3 diopters by retinoscopy), corneas were flatter (0.26 +/- 0.18 mm radius increase by photokeratometry) and axial lengths were greater (0.32 +/- 0.17 mm longer by A-scan ultrasonography). The axial length increase was due to elongation of the vitreous chamber (0.38 +/- 0.19 mm longer by A-scan ultrasonography). The open eyes of experimental animals were not significantly different than the normal eyes of control animals. Two of these treatment effects, namely, refractive state changes and axial length increases, were demonstrated with independent techniques: streak retinoscopy was compared to coincidence optometry, and A-scan ultrasound was compared to axial measurements of photographs of frozen, sectioned eyes. The three main ocular effects of eyelid closure were stable over three measurement sessions completed within a 4 week period. Additional refractive and A-scan measurements taken 7.5 months later showed no significant changes. Optical modelling showed that the observed myopia of the lid-sutured eye is consistent with the observed elongation of the vitreous chamber coupled with the flattened cornea although other changes could not be ruled out. We conclude that an axial myopia is produced reliably in tree shrews by raising them with eyelid closure and that the measurement techniques used in this study have sufficient resolution to study the development of myopia in this species.     

准分子激光角膜切削术性光学离焦对幼猴正视化影响的研究

目的了解视觉反馈对幼猴正视化过程的调控作用。方法年龄2～3个月的健康恒河猴8只,每只猴一只眼接受准分子激光角膜屈光手术(PRK),使术后产生3．0O D相对近视或远视性离焦(各4只);另一只眼作为对照。术后不同时间用角膜地形图、散瞳验光、A超和裂隙灯显微镜动态观察猴眼的变化。结果术眼角膜上皮均在术后3d之内完全愈合,在观察期内角膜保持透明。实验眼均表现为代偿生长的过程,玻璃体腔增长速率随术后屈光状态不同而变化。术后远视性离焦,玻璃体腔增长速率较对照眼快(t=3．656,P=0．0354);术后近视性离焦,玻璃体腔增长速率较对照眼慢(t=3．576,P=0．0374)。结论PRK造成光学离焦,可以调控幼猴的玻璃体腔生长和正视化过程,表明幼猴的正视化过程受视觉反馈的调节,提示临床上婴幼儿屈光不正的光学矫正应慎重。PRK造成猴眼光学离焦动物模型可用于视觉科学的研究。     

角膜塑形镜联合视觉训练控制青少年近视进展效果分析

目的：研究角膜塑形镜联合视觉训练控制青少年近视进展的效果。方法：前瞻性非随机对照研究。 选取2018年1─10月在唐山市眼科医院视光诊疗中心符合角膜塑形镜配戴标准的患者120例,均以右眼为研究对象。将所有受试者分成3组：视觉训练（VT）组40例,角膜塑形镜（Ortho-k）组40例, 角膜塑形镜联合视觉训练（OCVT）组40例。观察1年后3组患者近视屈光度及眼轴长度（AL）增长情 况。3组患者近视屈光度及AL干预前后数据比较采用单因素方差分析及多重比较。结果：干预1年后3组患者近视屈光度（F=5.597,P=0.006）及AL（F=6.354,P=0.003）差异均有统计学意义。进一步多重比较后发现,VT组与OCVT组的近视屈光度（P=0.001）及AL（P=0.001）比较差异均有统计学意义,Ortho-k组与OCVT组的近视屈光度（P=0.036）及AL（P=0.011）比较差异均有统计学意义,而VT 组与Ortho-k组之间差异无统计学意义。结论：角膜塑形镜联合视觉训练控制青少年近视疗效优于单纯使用角膜塑形镜或单纯视觉训练。     

Effects of apomorphine, a dopamine receptor agonist, on ocular refraction and axial elongation in a primate model of myopia

The authors examined the effect of local administration of a dopamine receptor agonist on visual deprivation-induced excessive ocular growth and myopia. Eight rhesus monkeys were monocularly deprived of vision from birth with opaque contact lenses. Four of the monkeys received drops of 1% apomorphine HCl 2-3 times/day in the occluded eye; the four control monkeys received vehicle only. Axial lengths were determined by A-scan ultrasonography at birth and at 5-7 months of age. The authors assessed the axial elongation by comparing the postnatal growth in the axial dimension of the occluded eyes with the postnatal growth in nonoccluded eyes. In three of the four control monkeys, occlusion increased axial growth by an average of 1.3 mm. In contrast, they found that growth of the occluded and nonoccluded eyes of the apomorphine-treated monkeys was equivalent, except in one monkey whose nonoccluded eye did not develop normally and was anomalously small. At 6.5-9.5 months of age, three of four controls had myopic refractive errors (-3 to -7 diopters) in the occluded eyes; three of four of the apomorphine-treated monkeys had hyperopic refractive errors (+1-(+)3 diopters) in their occluded eyes. The occluded eye of the fourth monkey was only -0.5 diopters myopic. The findings suggest that apomorphine administration retards excessive axial elongation and the concomitant development of myopia associated with visual deprivation in primates.     

Axial length and refractive error in X-linked retinoschisis

PURPOSE: To examine the relationship between axial length and refractive error in patients with X-linked retinoschisis. DESIGN: To determine whether the hypermetropia frequently found in patients with X-linked retinoschisis is axial hypermetropia. METHODS: The axial length and refractive error were measured in 29 right eyes of 29 patients. The patients were divided into two groups: a juvenile group with ages <13 years (12 eyes) and an adult group with ages > or =13 years (17 eyes). The axial length of the right eye of 30 adult men without eye diseases whose refractive error ranged from +/- 1.0 diopter served as controls. RESULTS: In the adult patient group, the refractive error was significantly more hypermetropic and the axial length was significantly shorter than was the normal adult group (P <.001). CONCLUSION: These results strongly suggest that the hypermetropia in patients with X-linked retinoschisis is axial hypermetropia.     

形觉剥夺性眼病与轴性近视关系的探讨

目的　研究形觉剥夺对眼球发育及屈光状态的影响 ,探讨近视眼发病机理及近视发生的危险因素。方法　对一组单眼患早期形觉剥夺性眼病患者的眼球各屈光因子 ,进行生物学测量比较 ,确定其屈光状态 ,并用t检验及多元相关分析的方法找出形觉剥夺性近视的危害因子。结果　患眼与健眼相比 ,患眼有较明显的近视倾向 ,平均屈光力相差 1 2 0 1D。两组比较角膜屈光力、晶状体厚度差异无显著性意义 ;前房深度、玻璃体腔长度、眼轴长度、眼的屈光状态差异均具有显著性意义。玻璃体腔长度为近视眼发生的主要危险因素。结论　早期形觉剥夺可发生近视眼 ,其主要危险因子是眼轴长度 ,主要危害部位在眼后段。尽早去除形觉剥夺 ,保持或恢复视觉发育敏感期的正常视觉环境 ,有利于预防近视眼的发生。     

A morphological analysis of experimental myopia in young chickens

Devices that degrade vision were applied to the left eyes of 3-day old chicks. The dome device affected the entire visual field, and the arch device, only the lateral field. Control chicks wearing a circumorbital ring and untreated chicks were also examined. The dome device produced -15D and the arch device -4D of mean refractive error, while the ring and untreated chicks were emmetropic. Morphological measurements were made from macrophotographs of the intact and hemisected eyes fixed as for electron microscopy. The effects of the devices were analysed from the mean differences between the left (treated) and right (control) eyes. Nearly linear growth of the normal eye was found during the period in which measurements were taken (age 20-55 days). The ring device did not affect eye growth. The arch device significantly increased the dorsoventral equatorial diameter of the eye. The dome device had the greatest effect, and resulted in increases in both axial length and equatorial diameter during the treatment period. Dome eyes had a bulging cornea, increased anterior chamber depth, more open angle, and greater corneal diameter than controls. The axial length and equatorial diameter of the posterior segment also were increased. Two inflammatory responses of the eye were found, particularly in dome eyes; about 50% of treated eyes exhibited choroidal swelling, and vitreal clouding was found less frequently. The association between inflammation and excessive accommodation in producing the observed changes is discussed.     

高度近视白内障超声乳化人工晶状体植入术27例

目的:探讨高度近视眼合并白内障行超声乳化白内障吸除人工晶状体植入术治疗的临床疗效。方法:27例(37眼)因白内障合并高度近视行超声乳化白内障吸除+人工晶状体植入术。记录术前眼轴长度和术后视力,屈光度数,观察手术并发症术后眼部情况。术后随访时间为6～24mo。结果:术前平均眼轴长度为28.3mm。术后最佳矫正视力≥0.2共35眼(95%),≥0.5者共33眼(89%)。术中无后囊膜破裂;术后角膜水肿2眼,术后一过性高眼压1眼,后发性白内障2眼;术后发现黄斑变性和眼底出血共4例,无视网膜和脉络膜脱离者。结论:超声乳化白内障吸除低度数折叠式人工晶状体植入术是治疗白内障合并高度近视眼安全、有效的方法。     

Reprint of “The role of the lens in refractive development of the eye: Animal models of ametropia” [Experimental Eye Research 87 (2008) 3-8]

Research with young mammals and chicks has shown that the visual environment can affect the refractive development of the eye by enhancing or slowing axial eye growth, but the effect on the refractive components of the eye, the lens and cornea, are less clear. A review of the literature indicates that the lens is minimally affected, if at all, and results vary depending on whether the lens is studied in an isolated state or with the accommodative apparatus intact. Research has shown that the development of myopia or hyperopia in young chicks alters lens focal length and magnitude of the accommodative response. However, the result may be indirect or passive due to the effect of the change in size and shape of the globe on the articulation between the ciliary body and lens. Recent research has also investigated the role of the lens in induced refractive error development in a fish, tilapia (Oreochromis niloticus). Translucent goggles were sutured over one eye for 4 weeks to induce form deprivation myopia while the untreated eye served as an untreated contralateral control. In addition to measuring refractive state and intraocular dimensions, a scanning laser system was used to determine the optical quality of excised lenses. All the deprived fish eyes developed significant amounts of myopia and the vitreous and anterior chambers of the treated eye were significantly longer axially than those of the untreated contralateral eyes. No significant change in optical quality was found between lenses of the myopic and non-myopic eyes and the fish recovered completely from the myopia five days after the goggle was removed. The results show that although fish, unlike higher vertebrates, are capable of lifelong growth, the visual environment is an important factor controlling ocular development in this group as well, and eye development is not strictly genetically determined. This review indicates that lens growth and optical development is independent from the refractive development of the whole eye.     

手法小切口联合负度数人工晶状体植入术治疗白内障合并超高度近视

目的:探讨手法小切口联合负度数人工晶状体植入术治疗白内障合并超高度近视眼的临床疗效。方法:对因白内障合并超高度近视眼行小切口联合负度数人工晶状体植入术的75例98眼患者进行回顾性研究,记录术前眼轴长度和术后视力、屈光度数及其与预期屈光度数的偏差值(屈光度数偏差值),观察手术并发症和术后眼部情况。术后随访6～12mo。结果:术前平均眼轴长度为32.05±1.78mm。术后最佳矫正视力≥0.2者66眼(67.3%);≥0.5者43眼(43.9%),术后屈光度数偏差值<±1.00D者48眼(49.0%);<±2.00D者78眼(79.6%)。术中后囊膜破裂3眼。术中出现后弹力层部分脱离1例。术后角膜不同程度水肿21眼。术后6mo有13眼出现后囊混浊,经Nd:YAG激光切开后视力恢复。未见发现视网膜脱离、继发性青光眼、黄斑囊样水肿、人工晶状体移位等并发症。术后2眼出现双眼干扰症状,经过3mo后行另一眼人工晶状体植入术,术后症状消除。结论:手法小切口白内障摘除负度数人工晶状体植入术是治疗白内障合并超高度近视眼安全、有效的方法。     

A biometric investigation of ocular components in amblyopia

The aim of this study was to investigate the ocular parameters and their contribution to total axial length, and any inter-ocular differences when compared to the fellow non-amblyopic eye, in a population of paediatric amblyopes. Inter-ocular differences in visual acuity, refractive error, corneal curvature, anterior chamber depth and their contribution to total axial length were analysed in four populations: adult controls (n=26), paediatric controls (n=24), paediatric strabismic amblyopes (n=18) and paediatric anisometropic amblyopes (n=27). In the two control groups, there were small inter-ocular differences between the components, none of which were statistically or clinically significant. Anisometropic amblyopic eyes were found to have statistically and clinically significant differences in refractive error, crystalline lens power, vitreous chamber depth and total axial length when compared to the fellow eye. Anterior and vitreous chamber depths, when expressed as a percentage of the anterior and vitreous chambers in the non-amblyopic fellow eye, were approximately 95% of the size. When parameters were normalised by expressing as a percentage of total axial length, the contribution of the anterior chamber, crystalline lens and vitreous chamber to total axial length in both eyes were comparable, suggesting that all components of the anisometropic amblyopic eye are proportionately reduced in size. The strabismic amblyopic eyes were in the main isometropic. There were however statistically significant differences in anterior chamber depth, crystalline lens power, vitreous chamber depth and total axial length, but not in crystalline lens thickness. When the components were expressed as a percentage of the component in the non-amblyopic fellow eye, the anterior and vitreous chambers were approximately 90% of the size of the fellow non-amblyopic eye and made a significantly smaller contribution to total axial length when normalised. Crystalline lens thickness contributed significantly more to the total axial length in a strabismic eye. This suggests that, unlike control eyes or anisometropic amblyopic eyes, the strabismic eye is physically, though not proportionately, reduced in size.     

Properties of the feedback loops controlling eye growth and refractive state in the chicken.

Recent experiments in chickens provide evidence that axial eye growth and refractive state are guided by mechanisms sensitive to refractive error. To determine whether or not the sign of refractive error is derived from longitudinal chromatic aberration we raised chicks with spectacle lenses in monochromatic light. The eyes showed an appropriate growth response to correct for the defocus imposed by the lenses no different than in previous experiments in white light. Thus, in normally accommodating chicks chromatic cues are not necessary for emmetropization to occur. We examined the linearity of feedback loops controlling axial eye growth: positive spectacle lenses were found to inhibit axial growth very efficiently making the eyes shorter than normal whereas negative lenses had little effect on axial elongation: feedback loops for regulation of axial growth are highly nonlinear and act most efficiently on the myopic side. We found that, subsequent to a period of binocular deprivation of form vision, the refractive errors acquired are highly correlated in both eyes. Since both eyes grew without visual feedback we conclude that the gains in the feedback loops that control axial growth must be similar in both eyes. We suggest that the gains are genetically determined and are typical for each individual. Chicks made near-sighted in both eyes by "deprivation of form vision" were corrected by appropriate negative lenses. Three out of five chicks recovered from myopia despite the correction. Also two chicks that were made near-sighted in one eye recovered with no regard to the correcting lens. Three chicks remained more myopic than the correcting lens required and finally started to recover while the lens was still in place. Two out of three chicks that were made far-sighted showed recovery despite appropriate correction by positive lenses. We conclude that there must be a nonvisual mechanism highly sensitive to abnormal eye shape. During expt (4) we found unexpectedly that the development of form deprivation myopia is inhibited if no part of the retina in an animal is exposed to normal visual experience. The result indicates that some communication between both eyes exists, although form deprivation myopia itself has been shown to develop independently in both eyes.     

儿童青少年近视患者屈光度与黄斑血流的相关性

目的：探讨儿童青少年近视患者近视屈光度与黄斑区血流密度、黄斑区中心凹无灌注区（FAZ）大小 的关系。方法：系列病例研究。收集2019年7月至2020年1月就诊于宁德市医院视光门诊儿童青少 年近视患者50例（100眼）。所有患者行身高、裸眼视力、屈光度、矫正视力检查后,行眼轴测量和 OCTA检查。按照等效球镜度（SE）大小分为正视及轻度近视组（-3.0 D相似文献   

Postnatal axial eye elongation in normal and visually deprived rhesus monkeys

The influence of anomalous visual experience on the postnatal regulation of axial eye elongation was explored by raising newborn rhesus monkeys under different types of monocular and binocular deprivation and comparing their eye growth pattern with that of age-matched normal monkeys. Monocular manipulations included eyelid suture to eliminate pattern vision; continuous occlusion with an opaque lens to prevent visual experience; surgical removal of the natural lens to induce continuous blur; and correction of surgically induced aphakia with extended-wear contact lenses (EWCLs) to provide a focused image of near objects. Binocular manipulations involved correction of aphakia with an EWCL in one eye and continuous or partial occlusion of the phakic fellow eye. After monocular eyelid suture or occlusion, the deprived eyes were longer than the unmanipulated fellow eyes. Aphakic eyes, however, were shorter than their unmanipulated fellow eyes. The unmanipulated eyes followed the eye elongation pattern of age-matched normal monkeys. Binocular manipulations also resulted in differences in axial length between the two eyes. Aphakic eyes were shorter, and continuously occluded eyes were longer, than eyes of age-matched controls. After partial occlusion, however, the axial length of occluded eyes was similar to that of normal eyes. The finding that lid-sutured and occluded eyes become longer while aphakic eyes remain shorter than normal eyes suggests that additional factors besides retinal image quality control postnatal eye growth.