Investigation of amplitude of accommodation among Ghanaian school children

Background: Deficient amplitude of accommodation is the most frequently used criteria in an optometric practice in diagnosing whether a patient has accommodative insufficiency. This deficiency is determined based on an age‐related expected finding calculated using Hofstetter's equation derived from Donder's and Duane's data. The aim of the present study was to investigate the amplitude of accommodation among Ghanaian school children and to compare the findings with age‐expected norms predicted by Hofstetter's equation. Methods: The amplitude of accommodation was measured using the push‐up method in a random sample of 435 school children from the Cape Coast Municipality. The mean amplitude of accommodation was compared with the age‐expected amplitude of accommodation as predicted by Hofstetter's equation for average amplitude of accommodation. Results: The mean amplitude of accommodation was 16.86 ± 3.07 D (95% CI = 16.57, 17.15). This is significantly higher than age‐expected norms calculated using Hofstetter's equation. The amplitude of accommodation showed the characteristic decline with age. Conclusion: From the results, we conclude that the age‐expected norms for amplitude of accommodation using Hofstetter's equation might not be accurate for Ghanaian children.     

青年人近视眼与各调节因素的关系

目的分析眼屈光不正与调节各因素的关系,探讨近视眼与眼调节之间的相关性。方法分别对45名大学生的90眼进行屈光不正、调节幅度、调节灵活度和正相对调节检查,然后将各项结果与屈光不正状况进行相关性统计分析。结果45名大学生受试者调节幅度的平均值为(8.49±1.61)D(6.25~13.70 D)。调节灵活度平均值为(9.64±2.30)周/min。正相对调节平均值为(-2.19±0.84)D。其中调节幅度与眼屈光度有显著相关性(r=-0.885,P≤0.05)。调节灵活度与眼屈光度无相关性。结论眼屈光不正与眼调节幅度有显著关系,眼的调节灵活度与屈光不正无相关关系。     

不同屈光状态在校大学生调节幅度和立体视的测定

目的:分析在校大学生不同屈光状态与调节幅度、立体视的关系。方法:对入选的150名在校大学生行客观验光、综合验光及相关双眼视功能的检查,包括立体视、调节幅度等的测量。按是否有近视分为:(1)正视组(11名),+0.75D≤SE(等效球镜度数)<-0.50D;(2)近视组(139名),SE≥-0.5D。近视组中按近视的度数分为:低度近视组(51名),中度近视组(69名),高度近视组(19名)。按是否有屈光参差分为:非屈光参差组(123名),屈光参差组(27名)。分析研究不同屈光状态学生的调节幅度、立体视的状况以及屈光参差对立体视的影响。结果:近视组的调节幅度较正视组的调节幅度大,差异有统计学意义(t=1.16,P<0.05),近视组间调节幅度值有差异(F=1.474,P<0.05),其中高度近视组与低度近视组、中度近视组之间差异有统计学意义(P<0.05),近视度数越大,测得的调节幅度值越大(r=0.2698,P<0.05);正视组与近视组之间立体视无显著差异(χ2=0.325,P>0.05),低、中、高度近视组之间立体视无显著差异(χ2=0.16,P>0.05);屈光参差组的立体视功能比非屈光参差组差,差异有统计学意义(Fisher,P<0.05)。结论:近视组较正视组的调节幅度大,近视组中,调节幅度与近视的度数呈正相关性。屈光参差组较非屈光参差组的立体视功能差。     

近视患者LASIK术后早期单眼调节幅度的变化观察

目的:观察近视患者准分子激光原位角膜磨镶术(laser in situ keratomileusis,LASIK)术后早期单眼调节幅度(amplitude of accommodation,AMP)的变化。方法:用LASIK治疗近视患者53例,根据等效球镜度数分为轻度、中度和高度近视组,所有被测者均进行规范的主觉验光,采用移近法在术前、术后1wk;1mo和3mo测量左眼调节幅度,所得结果输入SPSS11.0统计软件包。结果:LASIK术后1wk和1mo调节幅度明显低于术前AMP(P<0.05),术后3mo不同近视程度患者调节幅度与术前比较无统计学差异(P>0.05)。结论:不同近视程度近患者LASIK术后早期单眼调节幅度变化趋势基本相同,即均表现为先下降,后上升,至术后3mo时AMP基本恢复到术前戴镜水平;LASIK手术对近视患者单眼调节幅度无明显不良影响。     

The amplitude of accommodation in 6–10-year-old children – not as good as expected!

The aim of this study was to measure the amplitude of accommodation for junior level school children and to compare it with age‐expected values. A junior level school in Göteborg, Sweden, was randomly chosen and the amplitude of accommodation among 76 children aged 6–10 years was examined using Donders’ push‐up method. The results showed lower amplitude than expected in a large group of children. Results also showed lower amplitude than previously reported for this age group, especially under monocular conditions, which revealed an average dioptric difference from the expected value of ?3.60 dioptres (D) right eye (mean 12.40 D, median 12.00 D, S.D. 3.7 D) and ?3.50 D left eye (mean 12.50 D, median 12.70 D, S.D. 3.8 D) (p < 0.001 for both eyes). Consequently, we conclude that it cannot be assumed that the amplitude of accommodation is in the expected amplitude range for all children of these ages.     

Lens fluorescence and accommodative amplitude in pre-presbyopic and presbyopic subjects

Accommodative amplitude (AA; the difference, measured in diopters, between the near and far points of vision) declines steadily with age such that, by midlife, most individuals are unable to focus clearly on near objects and, thus, are said to be presbyopic. Conversely, intrinsic lens fluorescence (LF) increases steadily with age. Previous studies have suggested that AA and LF are negatively correlated, independent of age. Were this to be the case, it might suggest that the biochemical modifications underlying increased tissue fluorescence (for example, glycation of lens proteins) contribute to presbyopia. We used quantitative techniques to re-evaluate the relationship between AA and LF in 161 healthy volunteers aged between 25 and 70. Our data confirmed that AA decreases with age, becoming essentially zero by age 55, and LF increases with age. However, in marked contrast to previous reports, statistical analysis failed to detect any correlation between LF and AA independent of age. Thus, the biochemical processes responsible for increased LF observed in the aged lens are unlikely to contribute directly to presbyopia.     

配戴角膜塑形镜后调节幅度的改变及其控制近视进展的临床观察

目的:观察和分析配戴角膜塑形镜后调节幅度、眼轴的改变,探讨配戴角膜塑形镜延缓近视进展的机制。方法:前瞻性研究。收集2018-05/2019-08至我院治疗的7～14岁中低度青少年近视患者215例。行全面眼科检查后,根据检查结果、患者及家长依从性等综合评估,其中113例患者配戴角膜塑形镜,102例患者配戴框架眼镜。配戴期间规律复诊,测量角膜塑形镜组戴镜前,戴镜后1、3、6mo, 1a时的调节幅度及1a后两组眼轴的改变。结果:随访1a后,角膜塑形镜组共100例100眼完成随访,13例13眼失访。框架眼镜组共77例77眼完成随访,25例25眼失访。配戴角膜塑形镜前,患者调节幅度为13.57±2.47D,戴镜后1、3、6mo, 1a后调节幅度均较戴镜前显著提高(均P<0.005),调节幅度在戴镜6mo时达到峰值,戴镜1a(15.44±2.35D)较戴镜6mo(15.74±2.32D)略有下降。配戴角膜塑形镜1a后眼轴增长明显小于框架眼镜组(0.13±0.15 vs 0.50±0.28mm,P<0.001)。结论:中低度青少年近视患者在配戴角膜塑形镜后伴有调节幅度的提高。配戴角膜塑形...     

老视前期近视患者LASIK术后单眼调节幅度的变化

目的探讨老视前期近视患者准分子激光原位角膜磨镶术（laser in situ keratomileusis,LASIK）后单眼调节幅度的变化。方法随机选择接受LASIK手术治疗的老视前期近视患者29例（58眼）,按平时戴镜情况分为两组：角膜接触镜组（13例26眼）和框架眼镜组（16例32眼）,比较术前,术后第10天、第1个月和第3个月的单眼调节幅度（负镜片法）,并将第10天的调节幅度下降程度与术前屈光度数作相关分析。结果角膜接触镜组术前,术后第10天、第1个月和第3个月的调节幅度分别为（7．15±1．02）D、（6．14±1．32）D、（6．69±1．43）D和（7．17±1．15）D;框架眼镜组术前、术后第10天、第1个月和第3个月的调节幅度分别为（6．32±1．07）D、（5．49±1．06）D、（5．90±1．33）D和（6.31±1．19）D。术后第10天、第1个月的调节幅度与术前相比,两组均有显著性下降,差异有统计学意义（P〈0．05）;到术后第3个月时已恢复到术前水平,差异无统计学意义（P〉0．05）。术前角膜接触镜组的调节幅度明显高于框架眼镜组（P=0．004）．但是术后第10天调节幅度的下降值两组间差异无统计学意义（P=0．464）。术后第10天调节幅度的下降程度与术前屈光度数呈正相关（r=0．52,P〈0．01）。结论老视前期近视患者LASIK术后早期单眼调节幅度的降低是暂时性的。不会引起患者老视的提早出现。     

The role of clinical diagnosis criteria on the frequency of accommodative insufficiency

AIM: To estimate and compare the frequency of accommodative insufficiency (AI) within the same clinical population sample depending on the type of clinical criteria used for diagnosis. Comparing the frequency within the same population would help to minimize bias due to sampling or methodological variability. METHODS: Retrospective study of 205 medical records of symptomatic subjects free of any organic cause and symptoms persisting despite optical compensation evaluated. Based on the most commonly clinical diagnostics criteria found in the literature, four diagnostics criteria were established for AI (I, II, III and IV) based on subjective accommodative tests: monocular accommodative amplitude two or more diopters below Hofstetter’s minimum value [15-(0.25×age)] (I, II, III, IV); failing monocular accommodative facility with minus lens, establishing the cut-off in 0 cycles per minute (cpm) (I) and in 6 cpm (II, III); failing binocular accommodative facility with minus lens, establishing the cut-off in 0 cpm (I) and in 3 cpm (II). RESULTS: The proportion of AI (95%CI) for criteria I, II, III and IV were 1.95% (0.04%-3.86%), 2.93% (0.31%-4.57%), 6.34% (1.90%-7.85%) and 41.95% (35.14%-48.76%) respectively, with a statistically significant difference shown between these values (χ2=226.7, P<0.001). A pairwise multiple comparison revealed that the proportion of AI detected for criterion IV was significantly greater than the proportion for the rest of the criteria (P-adjusted<0.05 in all cases). CONCLUSION: The prevalence of cases of AI within the same clinical population varies with the clinical diagnostic criteria selected. The variation is statistically significant when considering the monocular accommodative amplitude as the only clinical diagnostic sign.     

Effect of whiplash injury on accommodation

Background: Accommodative disturbance has been cited as one of the causes of visual disturbance following whiplash injury but to date, with one exception, none of the studies have incorporated a group of control subjects; none of the results have been statistically analysed. The aim of the present study was to examine the amplitude of accommodation in a group of whiplash subjects, the majority of whom had specifically complained of visual/ocular symptoms. Methods: The whiplash group consisted of 19 subjects and the control group consisted of 43 subjects. The amplitude of accommodation of the right and left eyes of the whiplash and control group subjects was measured and the results of the two groups compared. Results: There was reduced amplitude of accommodation of the right (P = 0.02) and left (P = 0.02) eyes in the whiplash group subjects compared to the control group subjects. Conclusion: These results indicate that whiplash was associated with defective accommodation in the present select group of whiplash subjects.     

Accommodation and the relationship to subjective symptoms with near work for young school children

The aim of this work was to study the relation between subjective symptoms at near and ocular accommodation in terms of the amplitude of accommodation and the relative accommodation. A secondary aim was to discuss the diagnosis of accommodative insufficiency. The chosen cohort was examined on two occasions with 1.8 years in between. The first examination included 72 children, 43 boys (mean age 8.1 years, ranging from 5.8 to 9.8) and 29 girls (mean age 8.3 years, ranging from 6.2 to 10.0). The second examination included 59 of these children, 34 boys (mean age 9.9 years, ranging from 7.8 to 11.7) and 25 girls (mean age 10.1 ranging from 8.0 to 11.8). Subjective symptoms at near work (headache, asthenopia, floating text, facility problems) were recorded and the amplitude and the relative accommodation, both positive and negative, were measured. The result from the questionnaire showed that at the first examination more than one‐third of the children (34.7%) reported at least one subjective symptom when doing near work and 42.4% at the second examination. No symptoms were found among children younger than 7.5 years, but for children between 7.5 and 10 years old at the first examination, the prevalence of at least one symptom was 47.2%. At the second examination, symptoms were reported also for the youngest children, i.e. from the age of 8 years. The discrimination ability for the amplitude of accommodation, both monocular and binocular, was significant. In the first examination the difference between the mean for the two groups (i.e. with and without at least one symptom) was around 2.00 D monocular and 3.00 D binocular. Corresponding figures from the second examination was a difference between the mean for the two groups of around 3.50 D monocular and nearly 4.00 D binocular. We suggest that accommodation measurements should be performed more routinely and regularly, maybe as screening, especially in children over 8 years of age.     

可调节型人工晶状体眼调节幅度的计算及其影响因素分析

目的①推导出计算可调节型人工晶状体(accom-modative intraocular lens,AIOL)植入术后眼的调节幅度(ac-commodative amplitude,AA)的数学公式。②探讨影响人工晶状体眼AA的相关因素,为研究AIOL植入手术的治疗效果提供理论依据。方法根据高斯近轴光线光学理论推导得出计算AIOL植入眼AA的理论计算公式,以人工晶状体(in-traocular lens,IOL)焦点的移动量(effective intraocular lensposition,ΔELP)、眼轴长(axial length,AL)、角膜屈光力(corneal power,K)、IOL的有效位置(effective lens position,ELP)、植入IOL的屈光力(power of the implanted IOL,IOLImp)计算AA,分别建立AA与ΔELP、AL、K、ELP、IOLImp的函数关系,分析以上各参数对AA的影响。结果①人工晶状体眼AA受ΔELP、AL、K、ELP、IOLImp的影响(AL=23.65mm、K=43.8D、ELP=5.8mm),屈光状态为正视、ΔELP...     

眼调节幅度与近视眼的关系研究

目的　评价不同屈光状态下的眼调节幅度特点 ,分析调节幅度在近视眼的发生发展中的作用 ,进一步明确眼调节幅度与近视眼的因果关系。方法　被测者共 3 5人 ,其中男 17人(4 8 6% ) ,女 18人 (5 1 4% ) ,年龄 19～ 3 5岁 ,平均 2 6 49± 3 3 3岁。所有被测者均进行规范的主觉验光 ,每眼矫正视力均≥ 1 0。移近法测得左眼调节幅度 ,采用SPSS9 0应用软件包对不同分组进行比较分析。结果　①近视组AMP明显高于正视组 ;②正视组、轻度近视和中度近视组三组之间AMP存在显著差异 ,其中正视组最低 ,其次是轻度近视和中度近视 ;③正视组、迟发性近视组和早发性近视组三组之间AMP存在显著差异 ,其中正视组最低 ,其次是迟发性近视和早发性近视。④对调节幅度和近视屈光度做相关分析后 ,可见AMP随着近视屈光度的不断加深呈现上升趋势 ,直线回归方程为AMP =9 95 2 -0 764 屈光度。⑤将AMP和近视发生与否做Logistic回归分析 ,结果认为AMP可能是近视发生的原因之一。结论　高调节幅度可能是引发近视的原因之一 ,而弱的交感神经和强的副交感神经可能是引发高调节幅度 ,继而引发近视的解剖学因素。     

两种矫正方式对近视患者AC/A的对比研究

目的:研究青少年近视患者在配戴角膜塑形镜与配戴框架眼镜后各自AC/A的变化情况,并进行对比分析,进一步明确角膜塑形镜与框架眼镜对近视患者视功能的影响,及对青少年近视的控制作用。方法:随机选取60例来我院成功验配角膜塑形镜的青少年近视患者作为试验组,随机选取60例门诊就诊并给予框架眼镜的青少年近视患者作为对照组,观察两组患者屈光矫正前后AC/A及等效球镜度的变化并进行对比研究。随访时间依次为戴镜1,3,6mo;1a。结果:试验组戴镜前和后1,3,6mo;1a的AC/A值分别为4.05±2.03,3.05±1.85,3.31±1.02,3.14±1.64,3.20±1.55,戴镜后1,3,6mo;1a与戴镜前比较,差异均有统计学意义(P<0.05)。对照组戴镜前和后1,3,6mo;1a分别为4.12±1.86,4.09±1.38,3.58±1.45,3.84±1.41,4.23±2.01,戴镜后1,6mo;1a与戴镜前比较,差异无统计学意义(P>0.05),戴镜后3mo与戴镜前比较,有显著差异(P<0.05)。两组戴镜前无显著差异(P>0.05);戴镜后1,6mo;1a,两组有显著差异(P<0.05);戴镜后3mo两组差异无统计学意义(P>0.05)。近视度数增长的观察时间为1a。试验组等效球镜度增加了0.38±0.35DS,对照组增加了0.84±0.56DS,两组差异有统计学意义(P<0.05)。结论:两种矫正方式都能降低高AC/A值,试验组较对照组能更快更好地改善调节与集合的关系,近视度数增长后AC/A值会偏高。角膜塑形镜对中低度近视的矫正有效,它较框架眼镜能更有效地控制青少年近视的增长速度,是目前控制近视的一种有效方法。它对近视患者视功能的改善机制还有待进一步的研究。     

Effect of timolol on the amplitude and dynamics of accommodation

There is still debate about whether the ciliary muscle is innervated by the sympathetic nervous system. We investigated the amplitude and the dynamics of accommodation under influence of the non-selective beta-blocker timolol. For this purpose the variations in thickness of the human lens during step-like changes in accommodation were measured with high-resolution A-scan echography. Results showed that the dynamics of accommodation, expressed in the time constants of the response, were affected as well as the amplitude.