Effect of light-emitting diode colour temperature on magnifier reading performance of the visually impaired

Background: As light‐emitting diodes become more common as the light source for low vision aids, the effect of illumination colour temperature on magnifier reading performance was investigated. Methods: Reading ability (maximum reading speed, critical print size, threshold near visual acuity) using Radner charts and subjective preference was assessed for 107 participants with visual impairment using three stand magnifiers with light emitting diode illumination colour temperatures of 2,700 K, 4,500 K and 6,000 K. The results were compared with distance visual acuity, prescribed magnification, age and the primary cause of visual impairment. Results: Reading speed, critical print size and near visual acuity were unaffected by illumination colour temperature (p > 0.05). Reading metrics decreased with worsening acuity and higher levels of prescribed magnification but acuity was unaffected by age. Each colour temperature was preferred and disliked by a similar number of patients and was unrelated to distance visual acuity, prescribed magnification and age (p > 0.05). Patients had better near acuity (p = 0.002), critical print size (p = 0.034) and maximum reading speed (p < 0.001), and the improvement in near from distance acuity was greater (p = 0.004) with their preferred rather than least‐liked colour temperature illumination. Conclusion: A range of colour temperature illuminations should be offered to all visually impaired individuals prescribed with an optical magnifier for near tasks to optimise subjective and objective benefits.     

Low vision aids for reading in scar stage of age-related macular degeneration

PURPOSE: To evaluate the inter-relationship among near visual acuity, eccentricity of preferred retinal locus(PRL), and choice of low vision aids for reading in patients with bilateral age-related macular degeneration(AMD). SUBJECTS AND METHODS: The preferred eye of 44 patients having bilateral disciform stage AMD was examined. The PRL was detected and its eccentricity from the fovea was measured by scanning laser ophthalmoscopic microperimetry. Magnification of a low vision aid for reading newsprint was determined by the critical print size which was calculated using the MNREAD-J. The type of preferred aid was chosen from high-plus lens glasses, magnifiers, and closed-circuit televisions. The inter-relationship among near visual acuity, eccentricity of the PRL, and magnification and type of low vision aid for reading were evaluated. RESULTS: The magnification of the aid was correlated with the eccentricity of PRL in eyes with near visual acuity of 0.2 or less although no correlation was found in eyes with near visual acuity better than 0.3. High plus lens glasses were selected by patients with near visual acuity better than 0.2 and eccentricity of 2 degrees or less. Magnifiers were selected by patients with near visual acuity better than 0.1 and eccentricity of 5 degrees or less. Closed-circuit televisions were selected by patients with near visual acuity of 0.1 or less and eccentricity of 5 degrees or more. CONCLUSION: The eccentricity of PRL should be taken into account in determining low vision aids for reading, especially in patients with near visual acuity of 0.2 or less. Choice of the type of low vision aid depends on not only near visual acuity but also on eccentricity of PRL.     

Reading performance in children with low vision

Purpose: While educators and optometrists are concerned with reading efficiency in children with low vision, in most low vision assessments, children's reading performance is assessed only by a brief evaluation of reading fluency. We examined the relationships between clinical vision measures and reading performance in children with low vision. Methods: Subjects were 71 students with low vision, aged seven to 18 years. The vision and reading performance measures were: high contrast distance visual acuity, contrast sensitivity using both the Pelli‐Robson and LH symbol charts, near text visual acuity and reading rates on a range of print sizes. Results: Most children achieved maximum reading rate at print sizes between 2.5 and seven times larger than threshold print size. Maximum reading rate increased significantly with age and near visual acuity. There was no significant relationship between reading rate and contrast sensitivity. Conclusions: The majority of children with low vision can achieve near normal reading rates with magnification. Age is the strongest predictor of reading rate in children with low vision. They need print sizes well above threshold to achieve maximum reading rate. Routine contrast sensitivity testing of visually impaired students is not indicated for reading assessment.     

Age-related macula degeneration and diabetic retinopathy -- differences in optic rehabilitation

BACKGROUND: Age-related macular degeneration (AMD) and diabetes mellitus are the major contributing causes of visual impairment in the industrial nations. This study shows how far visual acuity (VA) and magnification demand (MD) influence the selection of suitable low vision aids. Based on this information, differences regarding the spectrum of prescribed magnifying devices between both patient groups will be presented. MATERIALS AND METHODS: Between January 2003 and October 2004, a total of 2500 patients was seen in our Low Vision Department. Among them were 1198 patients with AMD (48 %) and 296 visually impaired patients because of diabetic ocular involvement (12 %). In every patient, best corrected distance and near VA as well as the required MD were measured. Finally, matching of magnifying aids and discussing aspects of professional and social rehabilitation were the main parts of our interdisciplinary Low Vision Service. RESULTS: In AMD patients, the average of best corrected distance VA at the better eye was 0.24, the best corrected near VA was 0.19. In diabetes patients, the average of best corrected distance VA at the better eye was 0.28, the best corrected near VA was 0.22. The required mean MD was 4.0 x (related to the reading of newspaper text) compared to 7.6 x in patients with AMD. In 94 % of the visually impaired diabetes patients, optical magnifiers could be prescribed (e. g. magnifying eyeglasses, telescopes, monoculars, Galelean and Keplerian systems), whereas electronic devices were necessary in only 6 %. In comparison, 14.8 % of the patients with AMD had to be provided with electronic systems. CONCLUSIONS: In 94 % of the visually impaired patients caused by diabetes, reading ability could be restored using optical low vision aids. In AMD patients, this could be achieved in only 85.2 %. This fact can mainly be explained with the negative effect of absolute central scotomas on reading speed in AMD patients which leads, compared to diabetes patients, to elevated magnification factors. Therefore, the choice of certain magnifying devices depends not only on VA, but has mainly to be evaluated based on the individual MD.     

不同程度视力残疾患者应用助视器的康复效果

目的探讨不同程度视力残疾患者在应用光学和电子助视器后远、近视力的康复效果。方法对天津医科大学眼科中心低视力康复中心283例(9～79岁)视力残疾患者按视力残疾程度分为盲(110例)和低视力(173例)两组。分别比较两组应用Keplerian及Galilean望远镜前后远视力及脱残率的差异,以及应用带光源手持放大镜、近用眼镜式助视器及电子助视器后阅读成功率的差异。应用助视器前后的远视力差异采用配对t检验,脱残率及阅读成功率的差异采用χ2检验。结果两组应用两种远用助视器后远视力均有所提高,差异均有统计学意义(均为P<0.01);盲目组应用Keplerian及Galilean望远镜后脱残率分别为10.9%和9.1%,低视力组分别为76.3%和77.5%,差异均无统计学意义(P=0.823、P=0.899)。两组应用电子助视器阅读成功率(26.4%、86.1%)均高于带光源手持放大镜(13.6%、71.1%)及近用眼镜式助视器(15.5%、68.2%),差异均有统计学意义(P=0.031、P<0.01)。结论助视器能帮助视力残疾患者有效利用其残余视力,改善视功能及提高生活质量,是视力残疾患者康复的有效手段,应加强宣传及推广普及。     

Assessment of age‐related maculopathy using subjective vision tests

This paper reviews non‐standard, clinical vision tests that may be used to detect the earliest visual loss in age‐related maculopathy (ARM), before fundus changes are detected. We recommend a clinical test battery for all patients aged 60 years and older, comprising low luminance/low contrast (SKILL) VA or low contrast VA, desaturated D‐15 colour vision assessment, flicker perimetry, glare recovery and dark adaptation if possible, together with conventional assessments of case history, ophthalmoscopy and high contrast visual acuity (VA) for the detection and diagnosis of ARM. Reading rate is also discussed as a potential indicator of early visual loss. For monitoring the progressive visual loss in age‐related macular degeneration (AMD) and determining the requirements for optometric vision rehabilitation, we recommend more conventional clinical vision tests of distance and near visual acuity, reading rate, the effects of varying illumination and a functional central visual field assessment.     

The reading speed of adolescent with low vision used electronic visual aids

PURPOSE:To evaluate the reading speed of adolescents with different causes of low vision using electronic visual aids. METHODS:The screening of 10 young students from Quanzhou Blind School could read Chinese N5 print by different optical aids. After their refractive correction and ophthalmic examination, the reading speeds with Chinese N5 print were measured using various optical and electronic visual aids. RESULTS:The reading speed of (34.36±5.06) word / min by electronic visual aids performed faster than that of (18.50±6.54) word / min by optical visual aids in 10 young students with low vision (P<0.05). The reading speed of young people with low vision due to different causes had no direct linear correlation with their near visual acuity（P>0.05）. CONCLUSION:The electronic visual aids more significantly improve the reading speed of young people with low vision than the optical visual aids did. The reading speed of young people with low vision is not relevant to their near visual acuity induced by different causes.     

Predicting prescribed magnification.

AIM: To determine the best method of estimating the optimum magnification needed by visually impaired patients. METHODS: The magnification of low vision aids prescribed to 187 presbyopic visually impaired patients for reading newspapers or books was compared with logMAR distance and near acuity (at 25 cm) and magnification predicted by +4 D step near additions. RESULTS: Distance letter (r = 0.58) and near word visual acuity (r = 0.67) were strongly correlated to the prescribed magnification as were predictive formulae based on these measures. Prediction using the effect of proximal magnification resulted in a similar correlation (r = 0.67) and prediction was poorer in those who did not benefit from proximal magnification. The difference between prescribed and predicted magnification was found to be unrelated to the condition causing visual impairment (F = 2.57, p = 0.08), the central visual field status (F = 0.57, p = 0.57) and patient psychology (F = 0.44, p = 0.51), but was higher in those prescribed stand magnifiers than high near additions (F = 5.99, p < 0.01). CONCLUSIONS: The magnification necessary to perform normal visual tasks can be predicted in the majority of cases using visual acuity measures, although measuring the effect of proximal magnification demonstrates the effect of stronger glasses and identifies those in whom prescribed magnification is more difficult to predict.     

Reading ability and need for reading aids, inadequate management of a nursing home population

INTRODUCTION: In our society people are getting older and often become handicapped and immobile. Reading then is one of their main passtime and very important for their social integration and independence. PATIENTS AND METHODS: Seventy-seven (6 males, 71 females) randomly chosen elderly people (age ranged from 77 to 94 years, mean: 85.5 years) staying in nursing homes were examined concerning their reading ability of newspaper print with their own reading equipment. Exclusion criteria were extensive organic diseases and impaired mental ability, such as dementia. Relevant anamnestic data, including ophthalmologic, family and social history were ascertained by questionnaire. Special attention was given to visual acuity for near distance, reading ability, motivation and personal reading aids. Further questions dealt with general diseases, medication, social contacts inside and outside the nursing homes and the former occupation of the patient. If reading of newspaper print with individual glasses was impossible, the effect of magnification was evaluated and the magnification factor was determined (Zeiss reading charts). RESULTS: Thirty-eight people (45%) were unable to read with their own reading glasses. 91% of them regained reading ability by magnification, they had inadequate visual aids. 77% of this group had a magnification requirement of 1 to 3 times, 14% needed 10 to 25 times of magnification and 9% more than 25 times. Only one person had an electronic magnifying reading system (CCTV). CONCLUSION: Reading aids of elderly people very frequently are insufficient. Magnification can be helpful in most cases and various magnification systems are available. With this support elderly people could regain their quality of life, their independence and socialization. Nursing costs could also be reduced.     

老年黄斑变性低视力患者的视觉康复

应用光学助视器,对14例(25眼)老年黄斑变性低视力患者作了视觉康复.经用远用助视器,25眼中的24眼(95%)远视力有改善,其中12眼(48%)远视力≥0.4;经用近用助视器,全部眼(100%)的近视力有改善,13眼(52%)近视力达≥0.5,10例患者可阅读5号中文印刷体,阅读成功率达71.4%.结果表明助视器的应用对改善老年黄斑变性低视力患者的远、近视力是一种有效方法.     

Reading with a head-mounted video magnifier.

PURPOSE: This study compared the effectiveness of a head-mounted video magnifier, low-vision enhancement system (LVES), with closed-circuit TV (CCTV) and large print as a device or means of improving reading performance in people with low vision. METHODS: The reading performance of ten low-vision participants was assessed in two ways: (1) By measuring reading speed as a function of print size with LVES and without LVES, and (2) by comparing reading speed and comprehension of news articles using the LVES vs. a popular non-head-mounted video magnifier, the CCTV. RESULTS: Maximum reading speeds with LVES matched the maximum reading speeds with unaided vision attained by enlarging print. The critical print size (the smallest print size that could be read at maximum reading speed) improved significantly for all participants using LVES compared with unaided vision. When comparing reading performance using LVES and CCTV, we found that reading speed and comprehension for the two conditions were equivalent. The two low-vision participants with lowest acuities (20/640 and 20/960) could not read the 10-point newspaper articles with LVES, even with an 8 D auxiliary reading lens that permitted a very close reading distance. CONCLUSIONS: Head-mounted video magnifiers, such as LVES, can support good low-vision reading performance, but the restricted range of magnification may limit the usefulness of the device as a reading magnifier for people with very low acuity.     

VISUAL REHABILITATION IN LOW VISION PATIENTS WITH AGE-RELATED MACULAR DEGENERATION

Using optical visual aids, visual rehabilitation was performed in 14 low vision patients(25 eyes) with age-related macular degeneration. With distance aids, visual acuity improvement appeared in 24 eyes(95%) out of the 25 eyes. Twelve eyes(48%) obtained a visual acuity equal to or better than 0.4. With near visual aids, near acuity of all eyes(100%) was improved. Thirteen eyes(52%) got the near vision equal to or better than 0.5. Ten patients could read No.5 Chinese Reading Card. The reading success rat...     

Benefits of electronic vision enhancement systems (EVES) for the visually impaired

PURPOSE: To examine whether objective performance of near tasks is improved with various electronic vision enhancement systems (EVES) compared with the subject's own optical magnifier. DESIGN: Experimental study, randomized, within-patient design. METHODS: This was a prospective study, conducted in a hospital ophthalmology low-vision clinic. The patient population comprised 70 sequential visually impaired subjects. The magnifying devices examined were: patient's optimum optical magnifier; magnification and field-of-view matched mouse EVES with monitor or head-mounted display (HMD) viewing; and stand EVES with monitor viewing. The tasks performed were: reading speed and acuity; time taken to track from one column of print to the next; follow a route map, and locate a specific feature; and identification of specific information from a medicine label. RESULTS: Mouse EVES with HMD viewing caused lower reading speeds than stand EVES with monitor viewing (F = 38.7, P <.001). Reading with the optical magnifier was slower than with the mouse or stand EVES with monitor viewing at smaller print sizes (P <.05). The column location task was faster with the optical magnifier than with any of the EVES (F = 10.3, P <.001). The map tracking and medicine label identification task was slower with the mouse EVES with HMD viewing than with the other magnifiers (P <.01). Previous EVES experience had no effect on task performance (P >.05), but subjects with previous optical magnifier experience were significantly slower at performing the medicine label identification task with all of the EVES (P <.05). CONCLUSIONS: Although EVES provide objective benefits to the visually impaired in reading speed and acuity, together with some specific near tasks, some can be performed just as fast using optical magnification.     

Improvement of reading speed after providing of low vision aids in patients with age‐related macular degeneration

Purpose: Age‐related macular degeneration (AMD) is the most common cause of severe visual impairment, including loss of reading ability, among elderly persons in developed countries. The aim of the present study was to evaluate reading ability before and after providing of appropriate low vision aids. Methods: Five hundred and thirty patients with different stages of AMD (age 82 ± 8 years) were included in this retrospective study. All patients underwent a standardized ophthalmological examination including evaluation of magnification requirement and careful providing of low vision aids. Before and after the provision of low vision aids, reading speed [words per minute (wpm)] was evaluated using standardized reading texts. Results: For the whole group, the average best‐corrected distance visual acuity of the better eye was 0.18 ± 0.15, with 69% of patients having visual acuity of 0.1 (20/200) or better. The mean magnification requirement was 7.4 ± 6.3‐fold (range 2–25). Visual rehabilitation was achieved with optical visual aids in 58% of patients, whereas 42% of patients needed electronically closed‐circuit TV systems. Mean reading speed was 20 ± 33 wpm before and increased significantly to 72 ± 35 (p < 0.0001) after the provision of low vision aids for the whole group. Between patients with visual acuity < 0.1 and patients with visual acuity of 0.1 or better, there are highly significant differences in reading speed before (0.4 ± 3.8 versus 20 ± 28 wpm, p ≤ 0.0001) and after providing of visual aids (40 ± 13 versus 84 ± 30 wpm, p ≤ 0.0001). Patients with severe visual impairment (visual acuity ≤ 0.1) showed significantly lower improvement of reading speed compared to patients with visual acuity of 0.1 or better following rehabilitation (p ≤ 0.0001). Before providing of low vision aids, only 16% of patients were able to read; in contrast, reading ability was achieved in 94% of patients after the provision of low vision aids for the whole group. Conclusion: Our results indicate the great value of low vision rehabilitation through adequate providing of vision aids for the improvement of reading ability, with a highly significant increase of reading speed without training of eccentric viewing in patients with retained central fixation. The prompt implementation of low vision aids in patients with macular degeneration will help them to maintain and regain their reading ability, which can lead to an increase in independence, communication, mental agility and quality of life.     

视觉训练对低视力儿童阅读速度的影响

目的评价视觉训练对已有助视器的低视力儿童阅读速度的影响。方法共有9位有助视器使用经验的低视力儿童,先测量其阅读速度,再进行一系列的视觉训练和阅读训练,2个月后,当他们完成训练时,再次测量对相同文章的阅读速度,并比较训练前后患儿阅读速度的变化。结果在训练前后患儿阅读四号字的速度差异有显著性(P=0.003);在训练前后患儿阅读小五号字的速度差异有显著性(P=0.002)。结论视觉训练和阅读训练对提高低视力儿童的阅读速度是有效的,在临床低视力康复工作中,我们不应仅仅只把助视器提供给低视力儿童,同时还应进行适当的视觉训练和阅读训练来提高患儿的阅读速度,这对于正在学习阶段的儿童尤为重要。     

手持放大镜对阅读速度的影响

目的探讨手持放大镜对视力正常者和低视力患者阅读速度的影响。设计前瞻性对照研究。研究对象初次使用手持放大镜的低视力患者13例和37例视力正常者。方法分别测试视力正常者不用手持放大镜阅读小五号字及初次使用＋10D、＋20D两种不同度数的手持放大镜、采用10cm、35cm两种不同距离阅读小五号字时的速度;并测量低视力患者首次使用手持放大镜阅读小五号字和不用放大镜阅读相同放大率的大字印刷体的阅读速度。主要指标阅读速度（字数／分钟）。结果视力正常者不用手持放大镜的阅读速度（194．6±45．2字／分）比用＋10D手持放大镜在眼睛到放大镜10cm（159．7±44．7字／分）、35em（162．5±46．7字／分）的阅读速度快,也比用＋20D手持放大镜在眼睛到放大镜10em（150．3±43．3字份）、35cm（150．0±43．4字,分）的阅读速度快,差异有统计学意义（P=0．001、0．002、0．000、0．000）;在相同放大倍率下,眼睛到放大镜的距离分别为10cm和35cm时,阅读速度的差异没有统计学意义（＋10D,P=0．783;＋20D,P=-0．981）。低视力患者首次使用手持放大镜阅读小五号字的速度（54．2±8．2字／分）比不用放大镜阅读相同放大率的大字印刷体的速度（64．0±9．4字／分）要慢,两者相比差别有统计学意义（P=0．000）。结论初次使用手持放大镜阅读者,无论是正常人还是低视力患者阅读速度均慢。因此低视力患者使用放大镜时要有熟练过程。（眼科,2010,19：139—141）     

Near Vision Aids In Geriatric Patients With Reduced Visual Acuity

ABSTRACT The usefulness of near vision aids was studied in one hundred and forty-one patients in a geriatric hospital. The patients were over 65 years of age and had reduced vision. Where lens power exceeded +10DS spectacle lenses seldom worked well. Aspheric stand magnifiers were the most useful device in cases where greater magnification was needed. Elderly patients had difficulty in adapting to optical aids over 5X. Impaired cerebral function was the main reason for failure of the low vision aids of lower magnification.     

Low vision correction for high myopia.

High myopia is favorable for low vision corrections because the vision has usually been poor since childhood and the person has been able to read at close range, producing magnification. For near vision, in addition to bringing objects close, magnification is produced by high-add bifocals, trifocals, strong near vision spectacles and nonspectacle magnifiers. Hand magnifiers held at a distance from the eye are used with the spectacle correction. This paper describes the Visolett, used without correction or near vision correction, as the preferred non-spectacle magnifier because the reading area is self-illuminated, it doubles the approach magnification, rests on the paper, is simple to use, produces binocular vision, and attracts the least attention. Combination method of magnification consists in the use of the Visolett in addition to a spectacle magnifier, which doubles the magnification.