Low Vision Devices Research Articles

Instruments/techniques

We developed a system of coaxial video cameras that records monocular eye position and scene, and superimposes these images using a digital video mixer. We mounted miniature video cameras above and below a cube beam-splitting prism in the spectacle plane. An infrared emitting diode was imaged in the cornea to locate eye position. The technique was accurate to about 0.5 degrees within 15 degrees of primary gaze; however, we see its main advantages as being its low cost and simple design that, for some applications, does not require complex computer analysis and data manipulation. With improved camera optics, it has the potential for helmet mounting and use remote from a recording console. We used the instrument to monitor a reader's eye position when using low vision devices, and see applications of the technique in the field of visual ergonomics and sports vision.

Vision assessment and rehabilitation in low vision.

This subjective review of the year's literature on low vision, with particular emphasis on rehabilitation, attempts to search out and discuss what is new and innovative rather than to cover the year's publications with equal weight. The review covers areas of testing and assessment of children and the multiply impaired with low vision, vision stimulation, low vision aids and devices, approaches in congenital and acquired nystagmus, potential advances in high-technology applied to low vision, and psychological and educational aspects including lighting requirements for the elderly.

Considerations on Dispensing Low Vision Devices

Considerations on Dispensing Low Vision Devices

The Relative Effectiveness of Reading in Large Print and with Low Vision Devices for Students with Low Vision

This study explored the value of an objective procedure to evaluate the relative effectiveness of reading large print and reading regular print with low vision devices for six students with low vision. Data on observable reading behaviors—oral and silent reading rates, working distance, and oral reading miscues—were collected and analyzed using a case-study approach. The procedure provided useful information for consideration by multidisciplinary teams.

Reading Speed through Different Equivalent Power Low Vision Devices with Identical Field of View

Adequate reading speed is one of the criteria low vision patients may use to assist them when they are comparing and selecting equivalent power low vision devices. Inherently, various optical devices of equivalent power will produce different fields of view. We compared the reading speed of 32 trained, normal observers with 4 commonly prescribed types of low vision devices of +12 D equivalent power (spectacles, hand magnifier, stand magnifier, and telemicroscope) which were modified to provide nearly identical fields of view. Our results show that only the reading speed obtained with the telemicroscope was significantly different from those of the other systems (p less than 0.01). Implications are that the field of view provided by a low vision device is the primary parameter limiting reading speed of equivalent power devices.

Comparison of Reading Speed in Normal Observers through Different Forms of Equivalent Power Low Vision Devices

Compensation at near for vision loss can be achieved using a variety of equivalent forms of low vision magnifiers. Each has inherent advantages and disadvantages in terms of field, working distance, etc. We compared the reading speed of 60 trained, normal observers with 4 commonly prescribed types of low vision devices of +12 D equivalent power (spectacles, hand magnifier, stand magnifier, and telemicroscope) to their normal reading speed. Although there was individual variance in performance, reading speed with all the devices was generally within 20% of normal reading speed. Implications are that in terms of differences in reading speed for normals, the form of the low vision device is not as significant as acquiring proficiency in the use of the selected device.

Techniques for Teaching Young Children to Use Low Vision Devices

The traditional techniques for helping low vision children deal with print materials in school are time consuming and contribute to social isolation. Therefore, even preschool-age children should be trained to use low vision devices. Since low vision devices have typically been used with adults, there are few materials and techniques suitable for the young learners. This article presents a practical guide to help professionals develop techniques and materials that motivate children to learn to use low vision devices.

Reducing Late-Life Dependence Resulting from Declining Visual Acuity

This article reports on a project in 39 counties of rural Missouri to screen and provide low vision devices and rehabilitation services to elderly persons with declining visual acuity. A concomitant goal was to establish low vision resource centers in nursing homes and congregate sites for elderly persons. Two significant results of the project were the high level of interest in and use of the low vision resource centers and the dissemination of information on visual loss to potential clients, the public, and local professionals.

A survey of low vision patients in Hong Kong

This report provides some statistical information based on clinical data gathered on low vision patients who attended the low vision clinic of the Hong Kong Society for the Blind in the first three years of its operation. In this period, low vision devices were prescribed for 393 patients (46.5 per cent of the sample). The most commonly prescribed aids were simple magnifiers and distance telescopes. Cataract was the major cause of low vision.

Competencies and a Bibliography Addressing Students’ Use of Low Vision Devices

The increasing demand for the use of low vision devices by school-aged students has left special educators with a need to develop competency-based teaching approaches. In addition, these educators may lack a thorough background of knowledge about visual development, visual skills, and a theoretical framework of low vision. What follows are competencies for students and a bibliography for special educators.

Assessing the Environment of Low Vision Persons: A Validation of Procedure

The work environment is a concern to individuals having low vision. Eye care professionals have traditionally prescribed low vision aids for use on the job knowing only the visual requirements as described by the low vision person. The Work Environment Visual Demands Protocol (WEVD) was developed to be used as a tool in analyzing the visual demands of a job held or desired by a visually impaired person. An evaluation of the usefulness of the WEVD indicates that it may contribute to greater use of low vision devices, greater patient comfort while using theirs, and fewer follow-up visits.

Teaching Ophthalmology Residents about Rehabilitation

Ophthalmolody is a medical specialty which deals with large numbers of patients who have irreversible impairments. A survey of all ophthalmology residency programs in the United States found, that most programs require that residents receive training in low vision aids and devices, but they do not require training in seven other topics concerning the rehabilitation of visually impaired and blind patients. Those programs that do offer training in rehabilitation rely heavily on clinical training. Since practicing ophthalmologists themselves have an incomplete knowledge of the rehabilitation system, it is unlikely that the clinical model will provide residents with sufficient information about rehabilitation. Ophthalmologists need formal training about the rehabilitation process in order to ensure that their patients receive adequate referrals.

Coping with Impaired Vision and Aging

Visual function in older persons may decline gradually or in some cases acutely. Most degenerative eye diseases are age-related and adversely affect performance of all visual tasks. Diseases of the optical media reduce contrast, macular disorders reduce central acuity, while glaucoma and neurologic diseases reduce peripheral visual field. A low vision evaluation will determine the types of optical or non-optical low vision aids, devices, or services indicated for an individual with low vision.

Assessing the Needs of a Blind Client Population

A needs assessment was conducted to measure perceived unmet needs of the blind population of Massachusetts. Some 1,050 client interviews were conducted, using a sample stratified by age and region. The results indicated that the highest needs were for instruments specifically designed for the blind, such as low vision devices and the Optacon; transportation services, especially public transit and volunteer drivers; recreation services; training in daily living procedures; and medical health care. Very little need was expressed for personal or family counseling services, and there was relatively little need for housing services.

Low vision devices

A person with low vision has some useful sight. However, low vision usually interferes with the performance of daily activities such as reading or driving. Because low vision cannot be improved by mere traditional methods (i.e., the use of eyeglasses, contact lenses, etc), persons with low vision often rely on the use of a number of different instruments, called low vision devices, and tailored equipment for improved vision. Low vision devices are described in this article.

A profile of low vision among the blind school students in Lumbini Zone of Nepal

There is an increasing awareness about the needs of students with low vision, particularly in developing countries where programs of integrated education are being developed. However, the appropriate low vision services are usually neither available, nor affordable. To study the profile of students with low vision in Lumbini Zone of Nepal. A cross-sectional study included students with low vision from 8 integrated schools. The reading performance was measured using their own text-books with optical low vision devices prescribed for near reading. The reading rates were measured on a range of print sizes. The Standard Clinical Low Vision Assessment Form and the National Low Vision Program protocol were used. SPSS software was used in data analysis. Of 46 students enrolled, 23 had a mild visual impairment, 18 had severe visual impairment and 5 were blind. Spectacles were needed for 29 (63 %) students. Of the 11 students who had been wearing glasses, the visual acuity improved in 4 with a change in prescription. 91 % of the students had near vision better or equal to 1.5 M with optical low vision services for near reading. The reading rate was 24 WPM at the age of 5 years, whereas at the age of 21 years, it was 55 WPM. The majority of the students with low vision need optical low vision services. Accurate refraction is important in these students. The reading rate increases significantly with improved near visual acuity.