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PubMed1995

Enhancement of text for the visually impaired.

Previous research has established the benefits of image enhancement by spatial filtering for face perception and motion video appreciation among elderly low-vision observers [Invest. Ophthalmol. Vis. Sci. 32, 2337 (1991); J. Opt. Soc. Am. A 11, 1929 (1994)]. It has also been reported that similar enhancement could increase reading speeds by a factor of 2-4 in the same population [cf. Ophthalmology 96, 115 (1989)]. In our experiments we sought to determine what benefit, if any, was derived from spatial filtering of text for low-vision readers. Results from this series of studies indicate that 66% of patients do increase their reading rate with enhancement, but this increase is small. Change in reading rate with spatial filtering ranged from a 100% decrement to a 125% improvement, with an average 13% improvement. Only 10 of 67 subjects increased their reading rates by 50% or more. The clinical information that we gathered does not allow us to predict accurately which patients will benefit from spatial filtering. On the basis of these findings we conclude that enhancement of text by spatial filtering does not substantially increase reading rates for most low-vision patients.

Adult↗
PubMed1998

The virtual retinal display: a new technology for virtual reality and augmented vision in medicine.

INTRODUCTION: The Virtual Retinal Display (VRD) is a new technology for creating visual images. It was developed at the Human Interface Technology Laboratory (HIT Lab) by Dr. Thomas A. Furness III. The VRD creates images by scanning low power laser light directly onto the retina. This special method results in images that are bright, high contrast and high resolution. In this paper, we describe how the VRD functions, the special consequences of its mechanism of action and potential medical applications of the VRD, including surgical displays and displays for people with low vision. A description of its safety analysis will also be included. In one set of tests we had a number of patients with partial loss of vision view images with the VRD. There were two groups of subjects: patients with macular degeneration, a degenerative disease of the retina and patients with keratoconus. Typical VRD images are on the order of 300 nanowatts. VRD images are also readily viewed superimposed on ambient room light. In our low vision test subjects, 5 out of 8 subjects with macular degeneration felt the VRD images were better and brighter than the CRT or paper images and they were able to reach the same or better level of resolution. All patients with Keratoconus were able to resolve lines of test several lines smaller with the VRD than with their own correction. Further, they all felt that the VRD images were sharper and easier to view. The VRD is a safe new display technology. The power levels recorded from the system are several orders below the power levels prescribed by the American National Standard. The VRD readily creates images that can be easily seen in ambient roomlight and it can create images that can be seen in ambient daylight. The combination of high brightness and contrast and high resolution make the VRD an ideal candidate for use in a surgical display. Further, tests show strong potential for the VRD to be a display technology for patients with low vision.

Equipment Design↗
PubMed2006

Effects of task lighting on visual function in age-related macular degeneration.

The purpose was to investigate the effects of the spectral power distribution (SPD) and illuminance of task lighting on visual function in age-related macular degeneration (ARMD) compared to normal healthy eyes. Twenty-eight subjects with ARMD and 18 age-matched normal subjects were studied. The effects on visual function were determined for four common task light sources: standard pearl coat incandescent (SP), daylight blue incandescent (DL), warm white fluorescent (WW) and cool white fluorescent (CW). Apart from a small, statistically significant improvement in contrast sensitivity with DL compared to SP lighting (0.5 dB, p = 0.01), there were no significant effects of SPD on other visual functions and no differences in the effects for subjects with ARMD and those with normal vision. Thus, for task lighting typically used in low vision rehabilitation, the SPD would seem to be of minimal clinical importance to visual function. However, increasing the task illuminance had a greater effect on visual function, in particular for subjects with ARMD (p < 0.01). For an increase in illuminance from 300 to 3000 lux, the mean increase in contrast sensitivity and near visual acuity was 1.5 dB and 0.13 log MAR, respectively. Although this effect is not large, we suggest that it is clinically relevant and supports the provision of additional task illuminance as an important part of low vision rehabilitation for patients with ARMD.

Aged↗
PubMed2000

[Follow-up of patients suffering from age-related macular degeneration, supplied with visual aids].

BACKGROUND: Age-related macular degeneration (AMD) is at present the major cause of legal blindness in industrialized countries. The results of various treatments are often not satisfactory and follow-up by Low-Vision services is then the only solution for this population. Few studies have been published on this subject. The purpose of this study is to present the use of magnifying systems and the degree of satisfaction obtained for this series of patients 6 months after prescription. PATIENTS AND METHODS: Forty-four patients were examined, 42 of whom were eligible for the study. Lenses, magnifying glasses, visual systems for intermediate distance, and electronic systems were proposed. A low-vision training was given to every patient. RESULTS: The highest degree of use and satisfaction was achieved with the electronic systems. In some cases, however, the other systems were well accepted by the patients. CONCLUSION: The follow-up of patients with age-related macular degeneration is of great social importance. The independence of elderly people can be safeguarded thanks to the help of Low-Vision services with a good equipment and a well-trained team. Sometimes, unsophisticated systems such as magnifying glasses can be proposed, but the best results are mostly obtained through electronic systems (TV).

Aged↗
PubMed1995

New ergonomic stand magnifiers.

BACKGROUND: Stand magnifiers are not satisfactory for reading and other near visual requirements for many low vision patients. METHODS: Four new stand magnifiers have been developed with ergonomic advantages such as a comfortable viewing angle, the capacity for both reading and writing, better illumination, a wider field of view, variable power and magnification, and a longer working distance. The four new stand magnifiers are a spherical mirror magnifier, a cylindrical mirror magnifier, a reflecting prism magnifier, and a zoom magnifier. These magnifiers were tested on 39 subjects from five low vision clinics and compared to a commercial stand magnifier. The study determined reading speed and subject preference for these magnifiers. RESULTS: The reading speed of subjects with the new magnifiers increased over time and there was a significant change in preference over time. Results showed that 29 out of the 39 subjects on the final day of testing picked one of the new magnifiers as their device of choice. Reading speeds were comparable overall on all devices except for the cylindrical magnifier which was somewhat less. CONCLUSIONS: These four new ergonomically designed magnifiers were preferred by low vision patients compared to a commercial stand magnifier.

Equipment Design↗
PubMed1989

The programmable remapper: clinical applications for patients with field defects.

NASA, Johnson Space Center is developing an electronic image remapper which will warp an image from one coordinate system onto another with great flexibility and speed. The Programmable Remapper will transform images at conventional video frame rate. The Remapper was designed to be used in conjunction with an optical correlator to enhance object recognition through "real time" Fourier analysis. We are investigating an additional potential application for the Remapper as a low-vision aid. In diseases which result in obvious field defects such as age-related maculopathy (ARM) or retinitis pigmentosa (RP), the Remapper can be used to redistribute onto the still-functioning retina the image information that would otherwise be lost due to the associated field defect. Compared with eccentric viewing, this process makes use of the acuity of a larger area of the retina. We envision the future aid to consist of a portable spectacle-mounted display with miniaturized camera input and the Remapper. The patient will view the remapped world on this display. Patients may require training with feedback as to eye and scotoma position in order to use the Remapper most effectively. The Remapper might be reduced in cost, weight, and size to the point of being a feasible low-vision prosthesis as a result of development required by military, space, and industrial utilization. In order to demonstrate how such an aid may work, we have generated static images on an image processor which have undergone radial-only remapping; i.e., image points are slid along radii, with their azimuths unchanged. The remapping process and the application to low vision along with static images are presented in this paper.

Audiovisual Aids↗
PubMed2006

A proposed rapid methodology to assess the prevalence and causes of blindness and visual impairment.

PURPOSE: To determine whether a sample of the 50-year-old and above population would provide comparable information to a total population-based survey. METHODS: In 1996, a national eye survey of the total population in The Gambia was undertaken and the results concerning the prevalence and distribution of blindness and low vision have been reported. The same data set was used to analyse the prevalence and causes of blindness and low vision in people aged 50 years and above, and to compare the findings with the total population. RESULTS: Of 55 bilaterally blind people in the total population, 83.6% were 50 years of age or older. The distribution by cause of blindness was similar for the total population and for those aged 50 years and above. Cataract and uncorrected aphakia accounted for 46% and 13%, respectively, in the total population and 48% and 15% in the 50 year and above age group. Trachoma accounted for 5% and 4%, and other corneal opacities for 16% and 13%, respectively. Phthisis bulbi, which may follow perforated corneal ulcers, ocular trauma/surgery or occasionally severe uveitis, accounted for 4% in both age groups, and glaucoma accounted for 9% in the total population and 11% in the 50 year plus group. CONCLUSION: Assessment of the 50 year and above age group proved to be a good indicator for the causes of blindness and visual impairment in the total population and for determining those causes of blindness that are avoidable. Such an assessment requires a much smaller sample size, less than 20% of the sample size for the total population, and is likely to be less expensive.

Adolescent↗
PubMed1985

[Magnifying vision aids and their use by vision-handicapped patients].

Patients with visual acuities of below 0.4 at both long and short range cannot be sure of seeing well enough to read or watch TV. Low-vision aids improve vision to a such a degree that these activities can be performed once again. However, aside from this positive effect, low-vision aids have some disadvantages which sometimes prevent patients from actually using them. An investigation conducted among 150 patients revealed that 84% of them used their low-vision aids for about an hour or so a day.

Adolescent↗
PubMedDate not supplied

Psychosocial issues in older adults' adjustment to vision loss: findings from qualitative interviews and focus groups.

Although more therapists are responding to the increasing need for visual rehabilitation services for older adults, little is reported in the literature about the emotional experience of vision loss, especially in the words of persons with low vision themselves. This paper reports findings from a qualitative inquiry involving focus groups and in-depth interviews with 15 older adults using or considering using low vision assistive devices (Copolillo & Teitelman, 2005). Although the study's original intent was to focus primarily on decisions about LVAD use, psychological and social implications of vision loss emerged spontaneously as a dominant area of concern for participants. From an analysis of 154 codes derived from transcripted data, three themes related to psychosocial experience were generated: (a) Emotional Challenges, (b) Negative Emotional Outcomes, and (c) Indicators of Emotional Adaptation. In this article, individual components of the themes are described using illustrative quotes, and potential practice implications for therapists are presented.

Adaptation, Psychological↗
PubMedDate not supplied

Factors affecting the visual outcome after cataract surgery.

Postoperative visual outcome and factors related to poor visual acuity three months after cataract surgery were evaluated in 243 cataract patients operated on at the Oulu University Hospital in 1990. The surgical technique used was a planned extracapsular cataract extraction with implantation of an intraocular lens (IOL) in 240 cases: a posterior chamber IOL in 231 cases and an anterior chamber IOL in 9 cases. The postoperative visual acuity was 0.5 or better in 74.5% of the eyes, 11.9% (29 eyes) had low vision and 2.4% (6 eyes) were blind. The visual outcome was significantly related to age. The most common causes for low vision or blindness were age related macular degeneration and glaucoma. There was one case of postoperative endophthalmitis but other surgical complications did not result in visual loss. Visually significant posterior capsular opacification was observed in 2.5%, and significant postoperative astigmatism (> or = 3.5 D) was present in 11.1%.

Adult↗
PubMed2003

Support for patients loosing sight.

This overview on support of patients loosing sight is based on a literature survey regarding reading disabilities and orientation and on results of experience trials performed at the University Eye Clinic Tübingen. In reading disorders, the main goal of rehabilitation is to regain or maintain the ability to read newspaper print. The fundament of rehabilitation is the use of optical and electronical devices and the application of specially designed training programs. The ability of a person with low vision to achieve successful orientation and mobility rehabilitation depends on residual vision, posture and balance, body image, auditory and tactile abilities, intelligence and personality. Rehabilitation efforts focus on the enhancement of residual vision applying magnifying contrast-enhancing and photomultiplying devices. The main pillar of orientation and mobility rehabilitation is a training especially designed for the patient's needs. Rehabilitation efforts must be tailored to the type of vision loss and to specific functional implications--the success rate is high. An optimal fitting of the required spectrum of low vision aids should be provided to the patient and importantly, professional teaching and training is recommended. Activities of daily living, orientation and mobility, and psychological concerns must be addressed. Close cooperation with other branches of rehabilitation is essential.

Humans↗
PubMed1997

Age-related eye disease in the elderly members of rural African community.

The results of eye examination of the elderly persons (above age sixty years) in a rural population in south-western Nigeria are presented. The group comprised only 8.4% of the total population of the village studied, but its members constituted 37% of the persons with blindness and low vision and 27.9% of the persons with ocular abnormalities. Cataract was the commonest cause of blindness and low vision. Age-related macular degeneration (ARMD) and glaucoma were also important causes. Seven of the 208 members of the community aged above sixty years had demonstrable ARMD. This incidence is much higher than found in hospital studies performed earlier. The study demonstrates clearly the fact that blindness prevalence increases with age and highlights the causes of blindness and low vision in this population. An early, well-structured approach to age-related eye diseases is suggested, to prevent it from being a serious problem.

Adolescent↗
PubMed2002

Gaining insight into age-related macular degeneration.

PURPOSE/OBJECTIVE: To enhance nurse practitioner (NP) recognition of clients with age-related macular degeneration (AMD) based on history and physical examination findings, to encourage prompt initial referral of these clients to an ophthalmologist for a treatment evaluation, and to acquaint NPs with low vision rehabilitation services. DATA SOURCES: Government documents, professional association practice guidelines, original research articles, journal articles, and Internet resources. CONCLUSIONS: Age-related macular degeneration is a common, chronic vision-threatening condition necessitating prompt recognition and professional evaluation. If not recognized early, AMD can lead to low vision and a diminished quality of life for the elderly client. IMPLICATIONS FOR PRACTICE: Even though NPs have a limited role in the treatment of AMD, they are in an instrumental position as a primary care providers to screen for this disease chiefly by: (a) adherence to eye examinations intervals, (b) recognition of risk factors, (c) use of the Amsler grid, (d) awareness of psychosocial dimensions, (e) making appropriate referrals, and (f) advocating low vision rehabilitation services.

Age Factors↗
PubMed1997

[Visual rehabilitation: magnifying vision aids].

Many retinal diseases can be treated either with laser treatment or with vitreo-retinal surgery. However, in some of these cases a severe visual loss cannot be avoided and visual rehabilitation has to be initiated. Visual rehabilitation is initially performed by fitting low vision aids. With low vision aids the patients ability to read can be restored as well as many other needs of every days life e.g. reading bus numbers, street names, bank notes or letters. In analogy with the higher life expectancy in the middle european countries the incidence of age related maculopathy will increase in the next years. Thus, the need for visual rehabilitation will increase as well.

Adult↗
PubMed1995

Causes of visual impairment in central Ethiopia.

A survey conducted on a stable, mainly rural population of 60,820 in Central Ethiopia revealed an overall blindness prevalence of 1.1%. A follow up study was carried out to accurately determine the etiologies and causes of visual loss and impairment. A detailed ophthalmic evaluation was done on 523 out of 872 individuals identified as being visually impaired. The results showed that 194 (37%) were blind (Categories 3, 4, and 5 = maximum visual acuity less than 3/60 in the better eye). One hundred and seven (21%) (Categories 1 & 2 = maximum visual acuity better than 3/60 to less than 6/18 in the better eye using the WHO categories of visual impairment). The rest 222 (43%) were blind in one eye only. The commonest anatomical cause of blindness is corneal (32%). Cataract (25%), atrophied globe(s) (20%) and glaucoma (17%) follow as the other leading causes. Trachoma (35%), degenerative conditions (35%) and other infections (9%) were the major etiologies of blindness. Similar pattern of anatomical causation was observed in those classified under categories of visual impairment 1 and 2, referred to as "low vision". The most important etiologies of low vision were trachoma (30%), degenerative (24%), trauma (13%) and other infections (8%). Trauma was the most important etiology of monocular blindness (39%). Blindness was either preventable or curable in 74% of the cases.

Adolescent↗
PubMedDate not supplied

Tracking retinal motion with a scanning laser ophthalmoscope.

The vast majority of people with low vision retain some functional vision to perform everyday tasks. To study the effectiveness and efficiency of the visual tasks performed by people with low vision, knowing the movement patterns of their preferred retinal locus (PRL) used for fixation, saccade, and pursuit is critical. The scanning laser ophthalmoscope (SLO) has been used to acquire retinal images while a subject is performing a visual tracking exercise. SLO data has traditionally been analyzed with the use of manual techniques that are both time-consuming and prone to errors due to operator fatigue. To improve the speed and accuracy of the analysis of retinal motion from SLO image sequences, we developed an automated image processing technique and tested it using MATLAB(TM) (The MathWorks, Natick, MA) software. The new software technique was experimentally tested on both normal- and low-vision subjects and compared with the results obtained using manual techniques. The findings indicate that the new technique works very well for most subjects, fairing poorly only in subjects where the quality of the SLO images was substandard.

Adult↗
PubMed2003

Driving habits and health-related quality of life in patients with age-related maculopathy.

PURPOSE: To characterize the driving habits of persons with age-related maculopathy who present to a low-vision rehabilitation clinic and to examine how driving status relates to vision-specific health-related quality of life. METHODS: The Driving Habits Questionnaire, the National Eye Institute Vision Function Questionnaire-25, and the Life Space Questionnaire were administered via telephone interview to 126 patients with age-related maculopathy who presented to a low-vision clinic during the previous year and were either past or current drivers. RESULTS: Twenty-four percent of the sample reported being a current driver. Compared with those who stopped driving, current drivers were more likely to be male, younger, have better visual acuity and higher National Eye Institute Vision Function Questionnaire-25 scores. Drivers reported driving an average of 4 days and 10 miles per week. Over 50% of drivers reported that because of their vision, they had difficulty with or did not drive at all in rain, at night, on freeways or interstate highways, in heavy traffic areas, or during rush hour. Drivers and nondrivers did not differ in their life space, the spatial extent of their excursions into their environment. CONCLUSION: Some individuals who present to a low-vision clinic with age-related maculopathy do drive, although their driving exposure is low and they report avoiding challenging on-road situations. Driving status in age-related maculopathy appears to be related to better eye visual acuity and vision-specific health-related quality of life.

Activities of Daily Living↗
PubMed2005

Changes to the subscales of two vision-related quality of life questionnaires are proposed.

BACKGROUND AND OBJECTIVE: Psychometrically sound questionnaires for the assessment of vision-related quality of life (QOL) are scarce. Therefore, the objective was to further validate two vision-related QOL questionnaires in a Dutch population of visually impaired elderly. METHODS: A total of 329 visually impaired older persons referred to low vision services completed the low vision QOL (LVQOL) and Vision-Related Quality of Life Core Measure (VCM1) questionnaires at baseline, after 1-4 weeks (retest), and after 5 months. Confirmatory factor analyses were performed on baseline data. The smallest detectable change (SDC) was assessed, based on the standard error of measurement (SEM). Change scores between the baseline and 5 months follow-up data were related to a general transition question to assess the minimal important change (MIC). Furthermore, the MIC was related to the SDC, to examine whether the MICs were detectable beyond measurement error. RESULTS: The original factor structures could not be confirmed. After omitting items and remodeling, adequate fits were obtained. SDCs comprised at least one quarter of the scale for all scales and subscales on the individual level and exceeded the MICs on every occasion. CONCLUSION: We propose MICs of 5-10 points for the scales and subscales of the LVQOL and VCM1. The questionnaires are not useful in the follow-up of individual patients.

Aged↗