Monocular Accommodative Amplitude Research Articles

스마트폰 사용에 의한 40대 중년층의 조절 및 폭주기능 변화

목적: 본 연구에서는 스마트폰을 이용한 과도한 근거리 작업이 40대 중년층의 자각증상과 조절 및 폭주 기능에 미치는 영향을 알아보고자 하였다. 방법: 단안과 양안의 시력이 각각 0.8 및 1.0 이상인 40대 중년층 40명(남자 10명, 여자 30명, 평균나이 <TEX>$43{\pm}7.2$</TEX>세)을 노안과 비노안으로 나누고 30분 동안 스마트폰으로 영상을 시청하도록 하였다. 스마트폰 사용 전과 후에 최대조절력, 조절용이성 및 상대조절을 측정, 비교하였다. 또한 스마트폰 사용에 따른 융합버전스와 근거리 사위도의 변화를 평가하였으며, 자각적 증상의 변화는 설문조사하였다. 결과: 40대 노안은 스마트폰 사용으로 안정피로, 흐림 현상 및 건조감의 순으로 불편감을 호소하였으며, 조절기능과 비사시성 양안시 기능이 전반적으로 감소하였다. 즉, 단안 조절용이성, 상대조절 등의 조절관련 기능은 통계적으로 유의하게 감소하였으며, 폭주 및 개산력 역시 저하되어 사위도의 변화가 나타났고, 음성융합버전스 값이 통계적으로 유의하게 감소하였다. 반면 40대 비노안의 경우는 안정피로, 건조감, 흐림 현상의 순으로 불편감을 호소하였고, 조절기능 중에서는 최대조절력 만이 통계적으로 유의하게 감소하였으며, 음성융합버전스 값의 유의한 감소를 나타내었다. 결론: 따라서 40대 중년층이 근거리 작업 후 자각적으로 느끼는 불편감의 원인은 노안여부에 따라 다르게 나타날 수 있으며, 단순히 조절기능의 감소에 의한 것이 아니라 사위, 융합력 등을 포함한 시기능의 전반적인 저하에 기인한 것임을 확인할 수 있었다. 따라서 40대 중년층이 근거리 작업으로 불편한 증상을 느낄 경우에는 연령증가로 인한 조절력 감소뿐만 아니라 사위, 융합력 검사 등 전반적인 시기능 검사를 통하여 그 원인을 정확히 판단해야 할 필요가 있음을 제안할 수 있다. Purpose: The present study was aimed to investigate the effect of excessive near work by using a smartphone on subjective symptoms and accommodative and convergent function in their 40s. Methods: A total of 40 subjects(male, 10; female, 30; age, <TEX>$43{\pm}7.2year$</TEX>) in their 40s who have monocular and binocular visual acuities of 0.8 and 1.0, respectively, were divided into presbyopia group and non-presbyopia group. The subjects were asked to watch a movie on the screen of smartphone for 30 minutes. Their accommodative amplitude and facility, and relative accommodation were measured and compared before and after the use of smartphone. Changes in fusional vergence and near heterophoria by using smartphone were also evaluated. Furthermore, the change of subjective symptoms was surveyed using a questionnaire. Results: The presbyopia in mid-40s reported discomfort in an order of asthenopia, blur and dryness after the use of smartphone. Accommodative function and non-strabismic binocular function were generally decreased. Accommodative functions such as monocular accommodative amplitude, and relative accommodation were significantly decreased after smartphone use, and the change of phoria was observed as a result of decreased convergence and divergence. Negative fusional vergence was also significantly reduced. On the other hand, non-presbyopia in mid-40s reported discomfort in an order of asthenopia, dryness and blur, and only accommodative amplitude among the accommodative functions was significantly reduced. Significant reduction of negative fusional vergence was also observed. Conclusion: From the results, it was confirmed that the subjective discomfort of mid-40s after smarphone use might be related to whether presbyopia or not. It was due to not only the reduction of accommodative function but also the overall deterioration of visual function including heterophoria and fusional vergence. Therefore, it suggests that the accurate determination of the cause based on the overall visual functional tests such as heterophoria, fusional vergence as well as the decrease of accommodation due to the aging may be necessary when the mid-40s feels discomfortable symptoms by near work.

A comparison in university students of the amplitude of accommodation determined subjectively

Background: Historically, the push-up and the minus lens methods have been used for the measurements of the amplitude of accommodation, and the differences between the results of these methods are well known.Aim: The purpose of this study was to compare three methods for determining the monocular amplitude of accommodation and consider whether agreement exists between such methods.Setting: The study was conducted at the Optometry Clinic, University of Limpopo.Method: Thirty-four (N = 34) African optometry students participated in this study. There were 20 female and 14 male students. The age range of the participants was 20–34 years. Amplitude of accommodation was measured via the subjective push-up, push-down and minus lens methods only on the right eyes of the sample.Results: The highest average amplitude of accommodation was obtained with the push-up method (10.20 D ± 0.96 D), while the minus lens method produced the smallest mean amplitude of accommodation (9.66 D ± 0.75 D). A higher correlation was found between the push-up and push-down methods (r = 0.80, p = 0.06). The smallest correlation was observed between the push-up and the minus lens methods (r = 0.60, p = 0.062). There were no statistically significant differences between the amplitude of accommodation in male and female students for all three methods (p &gt; 0.005).Conclusion: It seems easier to recognise the point where one can identify a target in pushdown amplitude than the point of first sustained blur in the push-up method. The push-up method tends to overestimate the actual amplitude of accommodation because of the effects of depth of focus. The less evaluated method in the literature is the push-away method; however, further research is necessary to answer the question of which (if any) method is more accurate.

Effect of Vision Therapy on Accommodation in Myopic Chinese Children

Introduction. We evaluated the effectiveness of office-based accommodative/vergence therapy (OBAVT) with home reinforcement to improve accommodative function in myopic children with poor accommodative response. Methods. This was a prospective unmasked pilot study. 14 Chinese myopic children aged 8 to 12 years with at least 1 D of lag of accommodation were enrolled. All subjects received 12 weeks of 60-minute office-based accommodative/vergence therapy (OBAVT) with home reinforcement. Primary outcome measure was the change in monocular lag of accommodation from baseline visit to 12-week visit measured by Shinnipon open-field autorefractor. Secondary outcome measures were the changes in accommodative amplitude and monocular accommodative facility. Results. All participants completed the study. The lag of accommodation at baseline visit was 1.29 ± 0.21 D and it was reduced to 0.84 ± 0.19 D at 12-week visit. This difference (−0.46 ± 0.22 D; 95% confidence interval: −0.33 to −0.58 D) is statistically significant (p < 0.0001). OBAVT also increased the amplitude and facility by 3.66 ± 3.36 D (p = 0.0013; 95% confidence interval: 1.72 to 5.60 D) and 10.9 ± 4.8 cpm (p < 0.0001; 95% confidence interval: 8.1 to 13.6 cpm), respectively. Conclusion. Standardized 12 weeks of OBAVT with home reinforcement is able to significantly reduce monocular lag of accommodation and increase monocular accommodative amplitude and facility. A randomized clinical trial designed to investigate the effect of vision therapy on myopia progression is warranted.

Independent development of refraction, accommodation and convergence over two years in primary school children

Abstract Purpose: To examine whether age-related changes in refraction covary with changes in parameters describing accommodation and convergence over time in a group of Danish school children. Methods: Two-hundred and seventy-eight unselected Danish school children (7.1-13.9 years) without manifest strabismus were studied at baseline and after two years. Each examination included measurement of distance visual acuity, unilateral cover test, non-cycloplegic autorefraction, monocular amplitude of accommodation, monocular accommodation facility, near phoria, near point of convergence, and positive and negative fusional vergence. The changes in the measured parameters were studied over time, followed by the testing for dependencies in the development of these parameters. Results: After two years there was a significant increase in distance visual acuity (p=0.04), monocular accommodation facility (p&lt;0.001), near point exophoria (p=0.04), near point of convergence (p=0.01), and fusional range (p&lt;0.001), a significant reduction in hyperopia (p=0.01) and monocular amplitude of accommodation (p&lt;0.001), while the midpoint of the fusional range changed significantly towards convergence (p&lt;0.001). The increase in near point of convergence correlated significantly with the decrease in monocular amplitude of accommodation (p&lt;0.001) and the convergent shift in the midpoint of the fusional range was significantly correlated with a larger fusional range (p&lt;0.001). The changes in all other parameters were independent. Conclusions: The development of refraction, accommodation, and convergence parameters in school children over two years are independent. This may be due to separate processes regulating development, and suggests that therapeutic intervention may be performed on each of the parameters individually without a derived effect on the other parameters.

Accommodative changes produced in response to overnight orthokeratology.

To evaluate short-term (3 months) and long-term (3 years) accommodative changes produced by overnight orthokeratology (OK). A prospective, longitudinal study on young adult subjects with low to moderate myopia was carried out. A total of 93 patients took part in the study. Out of these, 72 were enrolled into the short-term follow-up: 21 were on a control group, 26 on a Paragon CRT contact lenses group, and 25 on a Seefree contact lenses group. The other 21 patients were old CRT wearers on long-term follow-up. Accommodative function was assessed by means of negative and positive relative accommodation (NRA / PRA), monocular accommodative amplitude (MAA), accommodative lag, and monocular accommodative facility (MAF). These values were compared among the three short-term groups at the follow-up visit. The long- and short-term follow-up data was compared among the CRT groups. Subjective accommodative results did not suffer any statistically significant changes in any of the accommodative tests for any of the short-term groups when compared to baseline. There were no statistically significant differences between the three short-term groups at the follow-up visit. When comparing the short- and long-term groups, only the NRA showed a significant difference (p = 0.0006) among all the accommodation tests. OK does not induce changes in the ocular accommodative function for either short-term or long-term periods.

스마트폰 사용에 따른 20대 성인의 조절기능 변화

목적: 본 연구에서는스마트폰을 이용한 근거리 작업 시 조절 기능의 변화가 유도되는가를 알아보고자 하였다. 방법: 20대의 총 63명 (남성 26명, 여성 37명)을 대상으로 조절 기능과 교정 전 등가구면도수를 측정하여 대조군 값으로 하였다. 실내조명 아래에서 연구대상자들에게 30분 동안 책을 읽게 한 후 30분간의 휴식 시간을 가지게 하고 순차적으로 동일한 시간 동안 스마트폰으로 영화를 보게 하거나 작업순서에 따른 오차를 배제하기 위하여 반대의 순서로 영화보기와 책읽기를 하게 하였다. 연구대상자들의 조절기능은 1) 최대조절력, 2) 조절 용이성, 3) 양성 및 음성상대조절, 4) 조절 래그 및 교정하지 않은 등가구면도수를 각 작업 후에 다시 검사하고 대조군 값과 비교하였다. 결과: 단안 최대조절력은 독서 후와 비교하여 스마트폰 시청 후 유의하게 감소하였다. 단안 및 양안 조절용이성은 독서나 스마트폰 사용 후 모두 감소하는 경향을 보였으나 통계적으로 유의한 차이는 아니었으며, 양성상대조절값은 독서나 스마트폰 사용 후 모두 유의한 변화가 없었다. 스마트폰 사용 후 음성상대조절 값은 독서 후와는 달리 거의 변화가 없었다. 스마트폰 사용 후 조절래그 값은 독서 후의 경우보다 유의하게 높았다. 결론: 30분 동안의 스마트폰을 사용한 근거리 작업은 일부 조절기능의 변화를 유발하였으며, 그 변화는 동일한 작업 환경에서의 독서 시 보다 유의하게 컸다. Purpose: The present study was conducted to investigate whether near work with smartphone could induce the change of accommodative function. Methods: Total 63 subjects(26 male and 37 female) in their 20s were firstly examined their visual functions related to accommodation and uncorrected spherical equivalent power as the control. After that, the subjects were asked to read a book for 30 min and sequentially watch a movie on smartphone for the same time after 30 min-break under the indoor light or as it was in the reverse order to avoid time-ordered effect. Their accommodative functions, 1) accommodative amplitude, 2) accommodative facility, 3) relative positive/negative accommodation, and 4) accommodative lag and their uncorrected spherical equivalent power were examined again following each task and compared with the control values. Results: The monocular accommodative amplitude was significantly decreased after smartphone watching compared with it after reading. The monocular and binocular accommodative facilities were tended to reduce after smartphone watching and book reading but were not significantly different. Neither significant change in positive relative accommodation was determined after smartphone watching nor book reading. Negative relative accommodation after smartphone watching was almost unchanged unlike reading a book. The accommodative lag after smartphone work was significantly higher than after book reading. Conclusions: The near work with a smartphone for 30 min induced the change of some accommodative functions, which was significantly greater than when reading under the same working environment.

Effects of wearing yellow spectacles on visual skills, reading speed, and visual symptoms in children with reading difficulties

Possible beneficial effects of yellow-tinted spectacle lenses on binocular vision, accommodation, oculomotor scanning, reading speed and visual symptoms were assessed in children with reading difficulties. A longitudinal prospective study was performed in 82 non-dyslexic children with reading difficulties in grades 3-6 (aged 9-11 years) from 11 elementary schools in Madrid (Spain). The children were randomly assigned to two groups: a treatment (n = 46) and a without-treatment group (n = 36). Children in the treatment group wore yellow spectacle lenses with best correction if necessary over 3 months (in school and at home). The tests were first undertaken without the yellow filter. With best spectacle correction in each subject, measurements were made of: distance and near horizontal heterophoria, distance and near horizontal fusional vergence ranges, the accommodative convergence/accommodation (AC/A) ratio, near point of convergence (NPC), stereoacuity, negative relative accommodation (NRA) and positive relative accommodation (PRA), monocular accommodative amplitude (MAA), binocular accommodative facility (BAF), oculomotor scanning, and reading speed (words per minute). The Convergence Insufficiency Symptom Survey (CISS) questionnaire was completed by all children. After the 3-month period, measurements were repeated with the yellow lenses (treatment group) or without the yellow lenses (without-treatment group) but with refractive correction if needed. Over the 3 months, the two groups showed similar mean changes in the variables used to assess binocular vision, accommodation, oculomotor scanning, and reading speed. However, mean relative changes in convergence insufficiency symptoms differed significantly between the groups (p = 0.01). No effects of wearing yellow spectacles emerged on binocular vision, accommodation, oculomotor scanning, and reading speed in children with reading difficulties. The yellow filter had no effect even in children with low MAA and BAF. The reduction in visual symptoms observed in children with reading difficulties using the yellow filters was clinically insignificant.

Objective Amplitude of Accommodation Computed from Optical Quality Metrics Applied to Wavefront Outcomes

Purpose We studied the accuracy and precision of 32 objective wavefront methods for finding the amplitude of accommodation obtained in 180 eyes. Methods Ocular accommodation was stimulated with 0.5 D steps in target vergence spanning the full range of accommodation for each subject. Subjective monocular amplitude of accommodation was measured using two clinical methods, using negative lenses and with a custom Badal optometer. Results Both subjective methods gave similar results. Results obtained from the Badal optometer where used to test the accuracy of the objective methods. All objective methods showed lower amplitude of accommodation that the subjective ones by an amount that varied from 0.2 to 1.1 D depending on the method. The precision in this prediction also varied between subjects, with an average standard error of the mean of 0.1 D that decreased with age. Conclusions Depth of field increases subjective of amplitude of accommodation overestimating the objective amplitude obtained with all the metrics used. The change in the negative direction of spherical aberration during accommodation increases the amplitude of accommodation by an amount that varies with age.

Accommodative function in school ‐age children with poor reading skills

Abstract Purpose Prior findings suggest correlation between reading problems and accommodative function, but few studies have assessed accommodation in children with poor reading skills. Our aim was to characterize monocular accommodative amplitude, relative accommodation and binocular accommodative facility in a population of healthy, non‐dyslexic primary school children with reading difficulties. Methods We conducted a cross‐sectional study on 87 poor readers and 32 control children (all 8‐13 years of age) in grades three to six recruited from eleven elementary schools in Madrid, Spain. In each subject with best spectacle correction, negative relative accommodation and positive relative accommodation were measured using a phoropter, monocular accommodative amplitude was determined using the minus lenses method, and binocular accommodative facility was measured using the Bernell Acuity Suppression Slide (VO/9) and a ± 2.00 D accommodative demand during 1 minute. Results Monocular accommodative amplitude was significantly lower (p &lt; 0.001) in the group of poor readers (right eye 9.1 D ± 2.3, left eye 9.0 D ± 2.3) than in the control group (right eye 10.5 D ± 1.7, left eye 10.5 D ± 1.7). Binocular accommodative facility values were significantly lower (p&lt;0.05) in the poor readers (4.9 cpm ± 3.1) than controls (6.3 cpm ± 2.9). Negative and positive relative accommodation values were similar in both groups of children. Conclusion This study provides data on the accommodative capacity of a population of children with reading difficulties. Our findings suggest a reduced monocular accommodative amplitude and binocular accommodative facility such that this function should be assessed by an optometric clinician in children whose reading level is below average.

Accommodative function in school children with reading difficulties

Prior findings suggest correlation between reading problems and accommodative function, but few studies have assessed accommodation in children with poor reading skills. Our aim was to characterize monocular accommodative amplitude, relative accommodation and binocular accommodative facility in a population of healthy, non-dyslexic primary school children with reading difficulties. We conducted a cross-sectional study on 87 poor readers and 32 control children (all between 8 and 13 years of age) in grades three to six recruited from 11 elementary schools in Madrid, Spain. In each subject with best spectacle correction, negative relative accommodation (NRA) and positive relative accommodation (PRA) were measured using a phoropter, monocular accommodative amplitude (MAA) was determined using the minus lenses method, and binocular accommodative facility (BAF) was measured using the Bernell Acuity Suppression Slide (VO/9) and a +/- 2.00 D accommodative demand for a period of 1 minute. Monocular accommodative amplitude was significantly lower (p < 0.001) in the group of poor readers (right eye 9.1 D +/- 2.3, left eye 9.0 D +/- 2.3) than in the control group (right eye 10.5 D +/- 1.7, left eye 10.5 D +/- 1.7). Binocular accommodative facility values were significantly lower (p < 0.05) in the poor readers (4.9 cpm +/- 3.1) than controls (6.3 cpm +/- 2.9). Negative and positive relative accommodation values were similar in both groups of children. This study provides data on the accommodative capacity of a population of children with reading difficulties. Our findings suggest a reduced monocular accommodative amplitude and binocular accommodative facility, such that this function should be assessed by an optometric clinician in children whose reading level is below average.

Enhanced near stereopsis after phacoemulsification and implantation of posterior chamber intraocular lens by prescribing addition properly

To improve near stereopsis in pseudophakic eyes after phacoemulsification and implantation of posterior chamber intraocular lens (IOL). This prospective case-series study comprised 92 eyes of 46 patients aged 50 to 70 years [mean age (61.33 +/- 5.54) years] who had phacoemulsification and implantation of posterior chamber IOL, including 24 unilateral pseudophakia (Group A) and 22 bilateral pseudophakia (Group B). The accommodative amplitude, relative accommodation, reading addition, near stereoacuity, etc. were measured. All data were analyzed with the SPSS11.0 for Windows. (1) The mean value of monocular accommodative amplitude in the group A and group B was (2.05 +/- 1.12) and (2.35 +/- 1.30) D, respectively. (2) In the group A and group B, the binocular add was (2.08 +/- 0.37) and (2.13 +/- 0.46) D, respectively, and the monocular add was (2.20 +/- 0.42) and (2.01 +/- 0.39) D, respectively. There was a significant difference between the binocular add and the monocular add (t = 2.33, 2.20, P<0.05) , and between left monocular add and right one (t =3.70, 5.02, P<0.01) in each group. (3) The near stereopsis with monocular add was better than that with binocular add in each group, the difference was significant (X2 = 6.46, 7.02, P = 0.04, 0.03). Monocular add is beneficial to a pseudophakia with posterior chamber IOL implantation to improve near stereopsis.

C677T Methylene-H4-Folate-Reductase Variant Decreases Binocular Accommodation

The C677T polymorphism of methylene tetrahydrofolate reductase (MTHFR) lowers the activity of this enzyme, producing moderate elevation of blood levels of homocysteine (Hcy) and lowering the levels of 5-methyl-tetrahydro-folic acid (5-MeTHFA), methionine (Meth), and S-adenosylmethionine (SAM). In this study we examined 100 apparently normal subjects of both sexes (average age 25.6 +/- 4.25) for the genotypic presence of the T allele and its association with accommodative amplitude (AA). The amplitude of accommodation was measured by the subjective "push-up" technique. DNA from buccal cells was genotyped for the C677T polymorphism of MTHFR by a PCR-restriction fragment length polymorphism genotyping assay. Descriptive statistics were obtained by frequency distribution and univariate analysis. Comparisons between monocular and binocular AA were obtained by t-test statistics or ANOVA. Associations between genotype and phenotype were analyzed using regression models. The C677T polymorphism was associated with decreased binocular AA (p = 0.0087). Monocular AA was not associated with the MTHFR genotype. Our results suggest a role for the C677T polymorphism in damaging the neural aspects of binocular vergence accommodation. The postulated neural damage could be due to the decreased formation of 5-MeTHFA and the defective synthesis of Meth, SAM and neurotransmitters or other methyl acceptors in nervous tissue of bearers of the C677T polymorphism. The differential effect upon monocular and binocular accommodation is hypothetically explained by a greater involvement of methylation reactions in vergence accommodation. A similar mechanism is proposed to explain the prevalent insufficient accommodation of Down's syndrome in which the blood levels of Meth and SAM are reduced.

Amplitude, facility and accuracy of accommodation in a primary school population

Vision screening at an early age in children is important as it can identify aspects in the visual system that may need to be managed to enable a child to function optimally at school. The National School Vision Screening Programme was discontinued in many provinces of South Africa, often due to a lack of financial resources or adequately trained personnel. This action has resulted in the majority of children not having a visual examination during their school career. In a few instances where vision screenings are performed, these are usually limited to visual acuity (VA) evaluation alone; an endeavour that may miss many significant visual problems. The purpose of this article is to highlight the need for vision screening to be conducted in schools and for the screening protocols to include the various accommodative tests. A retrospective analysis of the amplitudes of accommodation, accommodative facility and accuracy of accommodation findingsfrom a primary school vision screening of 264 children between 6 and 13 years was undertaken in this study. Data was captured and analysed with Microsoft Excel. The ages of the children ranged from 6 to 13 years with a mean of 9.38 years (SD = 1.85). One hundred and thirty eight (52.3%) were males and 126 (47.7%) females. A significant number of the children failed the monocular accommodative amplitude tests (24%), binocular accommodative amplitude test (26%), the accommodative facility (30%) and the MEM test (27%). These results highlight the need for a more comprehensive vision screening exercise rather than VA alone as this approach would have missed more than a quarter of the children who had other visual problems that could impact on their ability to perform optimally at school.

Effect of Relative Distance Magnification on the Monocular Amplitude of Accommodation

Many factors influence the measurement of the amplitude of accommodation. One factor that is frequently stated to have a major effect, the increase in the retinal image size as the target approaches the eye, has not previously been separated statistically from the other influences. In this experiment, the effect of relative distance magnification on the amplitude is assessed by comparing Donder's push-up technique with a Badal optometer technique. The push-up method indicates 0.6 D more amplitude of accommodation than the Badal method for subjects between ages 32 and 40.