近视性弱视儿童屈光状态变化的连续观察

目的 比较近视性弱视儿童与同龄矫正视力正常的儿童屈光状态变化的差别.方法 收集2006年1月～ 2015年12月诊为近视性屈光不正的儿童96例(174眼),按初诊时屈光状态分为低、中、高度近视.分别比较近视性弱视眼组与同期矫正视力正常的非弱视近视眼组年均屈光度改变情况.结果 非弱视组和弱视组近视屈光度每年加深(-0.67±0.74)D和(-1.09±1.38)D,差异有统计学意义(P＜0.05);初诊为低度、中度和高度近视的弱视眼近视屈光度年均加深(-0.97±0.88)D,(-1.48±1.29)D和(-1.89±1.06)D,低度、中度和高度近视的非弱视眼分别为(-0.57±0.61)D,(-0.68±0.49)D和(-0.78±0.29)D;低、中、高度近视性弱视儿童的近视屈光度年均加深幅度均显著高于非弱视眼(P＜0.05).结论 近视性弱视儿童与单纯近视儿童一样,近视屈光度随年龄增长逐年增加,近视程度愈高,增加的幅度愈大.且初诊为不同程度近视性弱视眼的近视屈光度逐年加深幅度均大于非弱视眼.     

远视性弱视儿童屈光状态演变的连续观察

目的比较不同程度远视性弱视儿童与同龄矫正视力正常的儿童屈光状态变化的差别。方法临床病例对照研究。收集2006～2014年在广州医学院附属广州市第一人民医院眼科初诊为远视性屈光不正的儿童184例340只眼,分为矫正视力正常的非弱视组和轻、中、重度弱视组。比较各组年均屈光度改变的情况。结果非弱视组和弱视组屈光度每年递减（0．66±0．57）D和（1．17±1．42）D,差异有统计学意义（P〈0．05）;男女两组和左右弱视眼的年均屈光度改变差异均无统计学意义（P〉0．05）;初诊为中度和高度远视的儿童,弱视眼远视屈光度年均下降（2．11±2．01）D和（2．82±1．32）D,非弱视眼分别为（0.67±0．43）D和（0．82±0131）D,差异有统计学意义（P〈0．05）;轻度弱视眼与非弱视眼的年均下降屈光度比较无统计学意义（P=0.266）,中、重度弱视眼的屈光度年均下降幅度显著高于非弱视眼差异有统计学意义（P〈0．05）。结论远视性弱视儿童与正常远视性屈光不正的儿童一样,远视屈光度随年龄增长逐年下降,且逐年减少幅度大于同龄的非弱视儿童。远视性弱视眼年均屈光度下降速度与性别和眼别无关,与初诊远视程度和弱视程度有关。     

Relationship between corneal topographical changes and subjective myopic reduction in overnight orthokeratology: a retrospective study

Background: To investigate the relationship between the change in the manifest refractive error (ΔM), the change in apical corneal power (ΔACP) and initial corneal asphericity (Q) in overnight orthokeratology (ortho‐K). Methods: One hundred and twenty‐eight clinical records of children undergoing ortho‐K from a university optometry clinic were reviewed. The refractive and topographical data at baseline and at two‐week visit of 58 patients who fulfilled the inclusion criteria were retrieved and analysed. Results: Significant differences (p < 0.001) between the change in manifest refractive error and changes in the apical corneal power or the maximum change in corneal power (ΔMCP) within the treatment zone were found. Linear regression analysis was used to describe the change in manifest refractive error and the change in apical corneal power, and the change in manifest refractive error and the maximum change in corneal power, with the equations: ΔM = 0.91ΔACP + 0.57 (r = 0.78, p < 0.001) and ΔM = 0.93ΔMCP + 0.01 (r = 0.79, p < 0.001) respectively. On average, the change in apical corneal power underestimated the change in manifest refractive error by 0.34 ± 0.57 D; whereas on average, the maximum change in corneal power overestimated the change in manifest refractive error by 0.23 ± 0.57 D (paired‐t‐tests, p < 0.001). A low but significant correlation between initial corneal asphericity and the change in manifest refractive error (Spearman r = ‐0.33, p = 0.01) was observed. Conclusions: The change in apical corneal power underestimates the change in manifest refractive error in ortho‐K, whereas the maximum change in corneal power overestimates this parameter. Compared with retinoscopy and autorefraction, the change in apical corneal power is still useful for estimation of the change in manifest refractive error. Although the maximum change in corneal power appears to give a closer estimation of the change in manifest refractive error than the change in apical corneal power, there is no advantage in the use of maximum corneal power (manually located) instead of apical corneal power (a default given by the topographer) to estimate the change in manifest refractive error, as there is no significant difference in the estimations by either parameter. Initial corneal asphericity measured by the Medmont E300 corneal topographer has limited usage in predicting the change in manifest refractive error in overnight ortho‐K.     

The development of myopia in Hong Kong children between the ages of 7 and 12 years: a five-year longitudinal study

The purpose of this work was to characterize the development of refractive error in Hong Kong children between the ages of 7 and 12 years. A non self-selected sample of 7-year old children was recruited and followed for 5 years, non-cycloplegic refractions being carried out annually. A life-table was used to determine myopia incidence and prevalence. The mean annual change in the spherical equivalent refraction (SER) was -0.32 D; 75 out of 83 subjects followed for 5 years became less hyperopic or more myopic, the maximum progression occurring between 9 and 11 years of age. The mean change in SER over the 5 years in children who were myopic at age 12 years was significantly greater than that in children who remained non-myopic. The incidence of myopia at age 7-8 years was 9% and at age 11-12 years was 18-20%. At age 7 years the prevalence of progressive myopia was 1.6% and 2.5% of subjects had anisometropia. Any treatment to prevent myopia should start by the age of 6 years and treatment to retard development should commence before age 9 years.     

A pilot study on the corneal biomechanical changes in short-term orthokeratology

Purpose:  To investigate the biomechanical changes in the cornea, in terms of corneal hysteresis (CH) and corneal resistance factor (CRF), with short-term orthokeratology (ortho-k) treatment, using the Ocular Response Analyser (ORA; Reichert Ophthalmic Instruments, Buffalo, NY, USA).
Methods:  Twenty young myopes wore ortho-k lenses in four different sessions: 15, 30, 60 min and overnight respectively. Except for the overnight session which was always the final trial, those sessions were randomly assigned with a 1-week washout period in between. CH and CRF were measured using the ORA and results were compared between the baseline and after each wearing session.
Results:  The mean baseline CH and CRF were 11.1 ± 1.0 mmHg and 10.7 ± 1.3 mmHg, respectively. There was no significant change in CH throughout the study, while a decreasing trend of CRF was shown. Paired t -test with Bonferroni correction found a significantly reduced CRF of 10.1 mmHg after overnight wear.
Conclusions:  Short-term ortho-k treatment was shown to alter some corneal biomechanical properties. CRF was shown to decrease with increasing duration of lens wear. Further study is warranted to investigate the long term effect on corneal biomechanics from ortho-k treatment.     

屈光不正儿童眼屈光状态变化规律探讨

目的 :了解屈光不正儿童屈光发育变化的规律。方法 :眼科初诊病例 ,经常规检查 ,无眼部器质性病变或显斜者 ,用 1%阿托品眼膏进行睫状肌麻痹视网膜检影验光后 ,选择 3～ 10岁屈光不正儿童进行 3年追踪观察。每年验光一次。结果 :3年来的主要表现为远视等效球镜值增加 ,球镜度减少 ,远视散光明显增多P <0 0 1。结论 :屈光不正的儿童 ,其屈光度及屈光状态不是一成不变的 ,为了确保儿童斜视弱视的治疗 ,在对屈光不正儿童处方配镜时 ,要重视追踪管理 ,散光和屈光参差的不稳定性必须给以考虑 ,不能像成人那样多年使用一付眼镜     

Measurement of posterior corneal asphericity on Hong Kong Chinese: A pilot study

The posterior comeal p-value and apical radius of 60 Hong Kong Chinese were assessed. The values were derived based on the information of the anterior corneal topography and the corneal thickness in different regions. The mean posterior corneal apical radius along the horizontal meridian was 6.51 mm (SD ± 0.40 mm) and the p-value was 0.34 (SD ± 0.38). The apical radius is greater while the p-value is smaller than a previous study using a similar principle. This may indicate a flatter posterior cornea and greater peripheral flattening in Hong Kong Chinese. No significant difference between the nasal and temporal corneal thickness, nasal and temporal posterior p-value and apical radius was demonstrated The right and left eyes were also similar in different ocular parameters apart from a smaller anterior corneal p-value on the fight eye (R eye: 0.70 ± 0.13: L eye: 0.67 ± 0.12), but the difference may not be significant clinically. The method used here is simple and the generation of posterior corneal topography is informative.     

The Hong Kong progressive lens myopia control study: study design and main findings

PURPOSE: To determine whether the use of progressive addition spectacle lenses reduced the progression of myopia, over a 2-year period, in Hong Kong children between the ages of 7 and 10.5 years. METHODS: A clinical trial was carried out to compare the progression in myopia in a treatment group of 138 (121 retained) subjects wearing progressive lenses (PAL; add +1.50 D) and in a control group of 160 (133 retained) subjects wearing single vision lenses (SV). The research design was masked with random allocation to groups. Primary measurements outcomes were spherical equivalent refractive error and axial length (both measured using a cycloplegic agent). RESULTS: There were no statistically significant differences between the PAL and the SV groups for of any of the baseline outcome measures. After 2 years there had been statistically significant increases in myopia and axial length in both groups; however, there was no difference in the increases that occurred between the two groups. CONCLUSIONS: The research design used resulted in matched treatment and control groups. There was no evidence that progression of myopia was retarded by wearing progressive addition lenses, either in terms of refractive error or axial length.     

Accommodation and binocular vision changes after wearing orthokeratology lens in 8- to 14-year-old myopic children

Graefe's Archive for Clinical and Experimental Ophthalmology - The study aimed to observe and analyze the dynamic accommodation and binocular vision changes in myopic children after they...     

A 2-year longitudinal study of myopia progression and optical component changes among Hong Kong schoolchildren.

This study investigated refractive error and optical component changes in a group of 142 Hong Kong schoolchildren from age 6 to 17 years over a 2-year period between 1991 and 1993. Subjects were refracted subjectively and corneal curvatures and ocular dimensions were measured. At the end of the 2-year study, the mean spherical equivalent refraction (SER) was -1.86 D (SD 1.99 D) and 62% of the schoolchildren were myopic. The annual incidence of myopia was 11.8%. Children aged 10 years and under had a greater change in SER toward myopia than older children. The annual rate of myopia progression for the myopic children was -0.46 D (SD 0.40 D) and the rate of progression was greatest between age 6 and 10 years old. Vitreous depth/axial length elongation was the main component contributing to the progression of myopia. Hong Kong schoolchildren develop myopia as early as 6 years old and myopia progresses at a greater rate compared with children of European extraction.     

Anti-retinal autoantibodies in myopic macular degeneration: a pilot study

AimThe aim of this study is to evaluate the frequency and types of anti-retinal autoantibodies (ARAs) in highly myopic patients and to explore any association between ARAs and the severity of myopic macular degeneration (MMD).MethodsThis was a clinic-based study of 16 patients with high myopia (spherical equivalent worse than −6 dioptres or axial length (AL) ≥ 26.5 mm) recruited from the High Myopia clinic of the Singapore National Eye Centre. MMD was graded from fundus photographs according to the Meta-analysis for Pathologic Myopia (META-PM) classification. Severe MMD was defined as META-PM category 3 or 4. AL and logarithm of the minimal angle of resolution (logMAR) best corrected visual acuity (BCVA) were measured. Sera were obtained from subjects and analysed for the presence of ARAs with the western blot technique.ResultsThe mean AL was significantly longer in patients with severe MMD (n = 8) than those without severe MMD (n = 8) (31.50 vs. 28.51, p = 0.005). There was at least one ARA identified in all patients. The most common ARA was anti-carbonic anhydrase II (anti-CAII), present in nine patients (56.3%). Anti-CAII was detected in more patients with severe MMD than those without (75 vs. 37.5%, p = 0.32). LogMar BCVA was also worse in subjects with anti-CAII (0.5 ± 0.38 vs. 0.22 ± 0.08, p = 0.06). The number of ARAs significantly correlated with increasing AL (r = 0.61, p = 0.012).ConclusionsARAs are prevalent in patients with high myopia, and this increases with increasing AL. In particular, anti-CAII antibodies were highly prevalent in patients with severe MMD, suggesting that ARAs may be associated with MMD. Further studies are necessary to confirm these observations in larger cohorts.Subject terms: Education, Autoimmunity     

The incidence of refractive errors among school children in Hong Kong and its relationship with the optical components

This study aims to provide information about the prevalence of refractive errors among Chinese school children in Hong Kong, and its relationship with the optical components of the eye. Subjective refraction, corneal curvatures and ocular biometry were performed on 383 school children from age six to 17 years. The prevalence of myopia increases from 30 per cent at age six to seven to 50 per cent (girls) and 70 per cent (boys) at age 16–17. The mean spherical equivalent refraction gradually changes from plano at age six to seven to -2.00 D of myopia at age 1617. Our results are different from Caucasian data but comparable with those of other studies of Chinese in Asia. The increase in myopia correlates well with the axial length of the eye. Further studies are needed to investigate the cause for the development of myopia.     

角膜塑形镜与框架眼镜对近视儿童眼调节参数的影响

目的：评估配戴夜戴型角膜塑形镜对近视儿童眼调节参数的影响。

方法：连续性分析2015-09/2018-03在我院配戴角膜塑形镜的8～15岁患者临床资料。配戴角膜塑形镜Ortho-k组为研究组,并以年龄、性别、等效球镜及眼轴长度为匹配因素进行1：1的频数匹配同时期配戴单焦点眼镜(SVL)的近视患儿做为对照组。通过测量配镜前及配镜后1、3、6、12mo的调节幅度(AA),调节灵敏度(AS),调节滞后(LAG),负相对调节(NRA)和正相对调节量(PRA)并运用重复测量方差分析来评估两组患儿配镜前与配镜后调节参数的变化情况。

结果：近视儿童54例完成随访：研究组27例,对照组27例。各调节参数组间均无差异(P>0.05); 矫正时间对两组的各调节参数均有显著影响(F_AA=4.7,F_AS=5.6,F_LAG=10.2,F_NRA=7.06,F_PRA=8.8,均P<0.05); 矫正时间和矫正方式之间的交互作用对两组的调节参数均有显著影响(F_AA=5.3,F_AS=4.6,F_LAG=11.4,F_NRA=3.4,F_PRA=11.1,均P<0.05)。

结论：配戴角膜塑形镜可以改善近视儿童的调节功能,这可能是塑形镜控制近视的机制之一。     

AC/A ratios in myopic and emmetropic Hong Kong children and the effect of timolol§

Purpose: Caucasian children with myopia have elevated response accommodative vergence to accommodation (AC/A) ratios. The purpose of this study was twofold: to determine if response AC/A ratios vary with refractive error and with myopic progression rate in Hong Kong Chinese children, and to determine the effect of beta‐adrenergic antagonism with topical timolol application on AC/A ratios. Methods: Thirty children aged eight to 12 years participated in the study. All refractive errors were corrected with spectacle lenses. Accommodative responses were measured using a Shin‐Nippon autorefractor and concurrent changes in vergence were assessed using a vertical prism and a Howell‐Dwyer card at three metres and 0.33 metre. Accommodative demand was altered using plus or minus two dioptre lenses and lens‐ and distance‐induced response AC/A ratios were calculated. Measurements were repeated 30 minutes after the instillation of topical timolol maleate (0.5 per cent). Results: AC/A ratios appeared higher in progressing myopic children but the difference was not statistically significant. Timolol application reduced accommodative convergence (AC) in the stable myopes (reduction = ‐3 ± 1.14^A) but not in the emmetropes (0.69 ± 0.9^P) or progressing myopes (0.16 ± 0.43^A) and this difference between refractive groups was statistically s ignificant (F^2,27= 3.766; P= 0.036). However, timolol did not produce a significant change in the accommodative response to positive or negative lenses or response AC/A ratios. Conclusions: We did not find that AC/A ratios in myopic Chinese children were elevated and therefore, it is unlikely that elevated AC/A ratios are responsible for the high levels of myopia that occur in Hong Kong. The finding that timolol reduced AC in the stable myopes suggests that the autonomic control of accommodative convergence in these children may be different from that in emmetropic children and those with progressing myopia.     

Comparison of myopia control between toric and spherical periphery design orthokeratology in myopic children with moderate-to-high corneal astigmatism

AIM: To compare clinical results between toric and spherical periphery design orthokeratology (ortho-k) in myopic children with moderate-to-high corneal astigmatism. METHODS: This retrospective study enrolled 62 eyes of 62 subjects using toric ortho-k lenses. These subjects were assigned to the toric group. Based on the one-to-one match principle (same age, proximate spherical equivalence and corneal astigmatism), 62 eyes of 62 subjects were enrolled and included in the spherical group. At one-year follow-up visit, visual acuity, corneal astigmatism, treatment zone decentration, axial elongation and adverse reaction were compared between these two groups. RESULTS: At the one-year visit, corneal astigmatism was significantly lower in the toric group (1.22±0.76 D) than in the spherical group (2.05±0.85 D) (P=0.012). The mean magnitude of the treatment zone decentration was 0.62±0.42 mm in the toric group and 1.07±0.40 mm in the spherical group (P=0.004). Axial elongation was significantly slower in the toric group (0.04±0.13 mm) than in the spherical group (0.09±0.13 mm) (P=0.001). The one-year axial elongation was significantly correlated with initial age (r=-0.487, P<0.001) and periphery design of ortho-k lens (r=0.315, P<0.001). The incidence of corneal staining was lower in the toric group (8.1%) than in the spherical group (19.4%) (P<0.001). CONCLUSION: Toric periphery design ortho-k lenses may provide lower corneal astigmatism, better centration, slower axial elongation and lower incidence of corneal staining in myopic children with moderate-to-high corneal astigmatism.     

The effect of a beta-adrenoceptor antagonist on accommodative adaptation in Hong Kong children

PURPOSE: Increased susceptibility to nearwork-induced accommodative adaptation has been suggested as a risk factor for myopia development. We investigated whether accommodative adaptation may explain in part the high prevalence of myopia in Hong Kong children and examined the effect of beta-antagonism with topical timolol maleate on accommodative adaptation.Methods: Thirty children (10 emmetropes and 20 myopes) aged between 8 and 12 years were recruited. Tonic accommodation was measured before and after 5 min of video game-playing using an open-field Shin-Nippon autorefractor. Measurements were repeated 30 min after timolol instillation. RESULTS: Children with progressing myopia demonstrated accommodative adaptation following the near task, whereas stable myopes showed counter-adaptive, hyperopic accommodative changes. Timolol increased the magnitude of accommodative adaptation in the stable myopes but had little effect on responses of the progressing myopes or emmetropes. CONCLUSIONS: Neuropharmacological modulation of the accommodative system may have a possible etiological role in the progression of myopia.