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At least 1,459 records · Page 81Linked to original sources
PubMed2005

The development of the Indian vision function questionnaire: field testing and psychometric evaluation.

OBJECTIVE: To develop and evaluate the acceptability, reliability, validity, and responsiveness of the Indian vision function questionnaire (IND-VFQ). METHODS: Problem statements from previous qualitative studies were reduced to a 45 item interviewer administered questionnaire representing three a priori domains (general functioning, psychosocial impact, and visual symptoms) which was evaluated in patients with cataract (n = 420), glaucoma (n = 120), diabetic retinopathy, or age related macular degeneration (n = 120) and normal controls (n = 120). Standard methods were used for item reduction and to evaluate psychometric properties. RESULTS: Psychometric item reduction produced a 33 item questionnaire. Psychometric evaluation showed that two of the three scales (psychosocial impact and visual symptoms) had good acceptability, and that all three scales showed high internal consistency (alpha >0.80; item-total correlations 0.54-0.86) and test-retest reliability (>0.89). All three scales showed moderate evidence of convergent and discriminant validity. Responsiveness, assessed in cataract patients (n = 120) before and after surgery, was good for all three scales (effect sizes >1). CONCLUSIONS: The IND-VFQ33 is a psychometrically sound measure of vision function addressing a gap in patient defined measures of vision function developed in populations living in low income countries.

Activities of Daily Living↗
PubMed1989

Spontaneous recovery of vision following an orbital haemorrhage.

A 73-year-old man presented to casualty with a penetrating orbital injury and total loss of vision in the affected eye. He subsequently spontaneously recovered full vision. We stress the need for frequent assessment of vision before considering potentially hazardous surgical intervention.

Aged↗
PubMed1993

Ocular and vision defects in preschool children.

Ocular and/or vision defects are one of the commonest reasons for the referral of young children to hospital. In a survey of a birth cohort in one health district, 7.1% of children were diagnosed as having such defects by their fifth birthday; 2.1% were detected before the age of 2 years, and 5.1% between 2 and 5 years. Up to the age of 2 years, low birthweight children and those who require postnatal special care had a higher risk of having an ocular or vision defect diagnosed and were more likely to have serious visual impairment than other children. In contrast, between the ages of 2 and 5 years of age these high risk children showed no continuing increased risk of having a defect diagnosed, nor did they show any differences in the severity or type of vision defects compared with other children. Averaged over the years studied, the incidence of defects presenting to specialist eye clinics among all 2-5 year olds was 1.7%, higher than the 1.1% found for 0-2 year olds. This increase consisted primarily of children with refractive errors only.

Child, Preschool↗
PubMed1994

Prevalence of blindness and low vision of people over 30 years in the Wenchi district, Ghana, in relation to eye care programmes.

A population based survey on the prevalence of major blinding disorders was conducted in the Wenchi district in central Ghana between March and May 1991. In 10 villages, 1425 people of 30 years and older were screened, using the WHO eye examination record. The prevalence of bilateral blindness above 30 years proved to be 1.7% (best acuity < 3/60): the prevalence of low vision above 30 years was 2.0% (best visual acuity 6/18 to 3/60). The causes of blindness were determined as cataract (62.5%), onchocerciasis (12.5%), corneal opacity (non-trachomatous) (8.2%), refraction anomalies (4.2%), phthisis bulbi (4.2%), optic atrophy (4.2%), and vascular retinopathy (4.2%). In the Wenchi district, 1.0% of the population over the age of 30 years was found to need a cataract extraction because of blindness of both eyes. Another potential 1.0% needs a cataract extraction because of low vision. A minor second study (n = 149) was undertaken in the same district, but in a village in an area near the Black Volta river in which onchocerciasis is endemic. The prevalence of blindness (8.1%) and low vision (3.4%) caused by onchocerciasis and cataract both proved to be higher. The survey provided the basis for a preventive and curative eye care programme.

Adult↗
PubMed1995

How effective is an integrated approach to low vision rehabilitation? Two year follow up results from south Devon.

AIMS: A survey was undertaken to assess the effectiveness of an integrated approach to the provision of low visual aids (LVAs) in south Devon over a 2 year follow up period. This integrated approach includes the assessment of patient needs by low vision therapists, followed by the provision of suitable LVAs, with particular emphasis on training in their use. METHODS: A total of 125 patients were selected at random from the 445 patients seen in the low vision clinic at Torbay Hospital in the year 1991. These patients were sent questionnaires relating to the service over a 2 year period. Questionnaires from 111 patients were analysed at 1 year and 75 questionnaires together with 46 clinical reassessments, after 2 years. RESULTS: Using a similar questionnaire to one used in a previous study in the UK from a unit where LVA training was not provided, not only was a higher rate of satisfaction found with the services provided, but also the LVAs dispensed were used more frequently. The majority of the LVAs provided were of the simple, inexpensive variety and wastage was very low. CONCLUSIONS: It was concluded that this integrated approach to low vision rehabilitation with emphasis on training in the use of less complex LVAs exceeds the performance of other types of service that rely on the dispensing of more complex LVAs.

Adult↗
PubMed1999

A vision specific functional index for use in patients with age related macular degeneration.

AIM: To develop and evaluate a new vision specific functional index for use in individuals with age related macular degeneration (AMD). METHODS: Following consultation with patients with AMD and healthcare professionals, a questionnaire entitled the Daily Living Tasks Dependent on Vision (DLTV) was constructed. It was administered by interview to three separate groups of individuals aged 50 years or older: people with AMD, people with cataract, and people with no visual disability. The relations between DLTV, distance visual acuity, and disorder were examined using Pearson's product moment correlation coefficients, stepwise regression, and principal component analysis. RESULTS: There was a positive correlation between DLTV items and distance visual acuity in the better eye. Principal component analysis showed that the DLTV has a major single dimension within it. This first principal component accounted for 59% of the variation and correlated well with distance visual acuity in the better eye. Other components were found, one of which correlated with the difference in vision in the two eyes and one which featured in the differentiation of AMD subjects from individuals with cataracts. CONCLUSIONS: The DLTV provided information on visual impairment in patients over and above that obtained from a measure of visual acuity. It also showed that patients with AMD experience greater difficulty with daily living tasks for any given level of acuity than do patients with cataract.

Activities of Daily Living↗
PubMed2000

Use of vision tests in clinical decision making about cataract surgery: results of a national survey.

AIM: To provide information on the use of vision tests in clinical decision making about cataract surgery in the UK. METHOD: A questionnaire survey was mailed to 703 consultant ophthalmologists. RESULTS: A response rate of 70% was obtained. Monocular distance visual acuity was the only visual function that was tested routinely by all surgeons. Supplementary use of contrast sensitivity and glare testing was low. Many surgeons (35%) were willing to consider surgery at acuity levels better than 6/9 and a small but substantial number (12%) indicated that they did not use an acuity criterion. Being prepared to consider surgery at relatively good levels of acuity was not associated with more common use of other tests of vision. CONCLUSION: Many UK surgeons are prepared to consider cataract extraction at relatively good levels of visual acuity and use other vision tests infrequently.

Aged↗
PubMed2001

The use of a newspaper insertion to promote DIY testing of vision in India.

BACKGROUND: The mass media have the potential to motivate people to participate in self appraisal of their own health status. An innovative communication package was designed to help people to examine vision at home. The impact of publishing the "do it yourself" (DIY) kit in Indian newspapers was evaluated. METHODS: A pretested bilingual vision testing kit was published in three newspapers. The kit comprised four tumbling Es corresponding to 6/12 line of Snellen's optotypes. Directions on using the kit were enclosed. 3 -7 days after publication of the kit, a telephone survey of newspaper readers was undertaken to evaluate the impact and cost effectiveness. RESULTS: 603 people were contacted over the telephone. 125 (20.73%) subscribed to the newspaper carrying the DIY insertion. 43.2% (54) noticed the insertion of which 88.89% (48) read the enclosed instructions carefully. 58.33% respondents felt sufficiently motivated to contact an ophthalmologist. Graduates had a 3.83 times higher probability of reading the communication insertion compared with others. Differences in relation to other demographic variables were not statistically significant. CONCLUSIONS: Newspapers are an excellent medium for communicating self appraisal kits for vision testing. The medium is cost effective and has significant reach in the urban agglomerates of India.

Adolescent↗
PubMed1989

Review of children referred from the school vision screening programme in Kettering during 1976-8.

The progress of 108 children who were identified by the vision screening programme in school as having defective vision (excluding those with puberty onset myopia) was reviewed. Treatment of these children resulted in improvement in visual acuity of the worst eye (two lines or better) for 16 children. Eighteen children had severe amblyopia (6/24 or worse). Among these the vision of only five was improved by treatment. Two thirds of the children had refractive errors in the better eye which required correction. It seems sensible to identify and treat children with bilateral refractive errors, but the need to treat children with lesser degrees of amblyopia is questioned.

Amblyopia↗
PubMed1991

Vision screening in preschool children: comparison of orthoptists and clinical medical officers as primary screeners.

OBJECTIVE: To see if there were differences in referral rates and abnormalities detected from two areas that were operating different preschool vision screening programmes. DESIGN: Cohort study using case notes of referrals. SETTING: Community based secondary referral centres in the county of Avon. PATIENTS: 263 referrals from a child population of 7105 in Southmead district, an area that used orthoptists as primary vision screeners; 111 referrals from a child population of 2977 in Weston-super-Mare, an area that used clinical medical officers for screening. MAIN OUTCOME MEASURES: Amblyopia and squint detection rates, together with false positive referral rates. RESULTS: The amblyopia detection rate in Southmead district was significantly higher than in Weston-super-Mare (11/1000 children v 5/1000), as was the detection rate of squint (11/1000 v 3/1000). However, the false positive referral rate from Southmead was significantly lower than that from Weston-super-Mare (9/1000 v 23/1000). CONCLUSION: Preschool vision screening using orthoptists as primary screeners offers a more effective method of detecting visual abnormalities than using clinical medical officers.

Amblyopia↗
PubMed1982

Suprathreshold vision in acute optic neuritis.

The perception of contrast was measured in patients with acute unilateral optic neuritis by a technique of subjective suprathreshold contrast matching, and was compared with contrast sensitivity as defined by threshold measurements. The suprathreshold apparent contrast and threshold contrast sensitivity was repeatedly assessed during the recovery phase. Generally, an attenuation of suprathreshold apparent contrast was found for high and intermediate spatial frequencies in the eye with optic neuritis. At a low spatial frequency, however, the suprathreshold contrast vision was spared. The threshold contrast sensitivity was not however, spared at low spatial frequencies. During recovery this frequency-specific loss in suprathreshold apparent contrast diminished and finally a "normal" suprathreshold contrast vision was observed in all affected eyes reaching a visual acuity of 1.0 or better. In these cases also subjectively normal vision was reported in site of a persisting abnormality in threshold contrast sensitivity.

Acute Disease↗
PubMed1996

An assessment of a proposed method for adjusting and focusing ANVIS night vision goggles.

Night vision goggles are becoming an increasingly important tool in military aviation. They provide superior visual capability over unaided night vision, but any reduction in goggle performance can have a serious effect on flight safety and operational effectiveness. This study shows that the use of a standard adjustment procedure in a night vision goggle (NVG) test lane, with a resolution chart, provides an effective method for aircrew to obtain better visual capability than is currently obtained by focusing on distant features of the landscape. Visual acuity (VA) was measured for 20 aircrew representing all crew positions, after using both the current adjustment method and the proposed method for adjusting ANVIS NVGs. The average visual acuity showed an improvement from 6/19 (s.d. = 3.9) with the current method to 6/13 (s.d. = 2.8) with the proposed method. However, NVG test lanes cannot be used with goggles which have fixed infinity objective lenses eg Nite.

Aerospace Medicine↗
PubMed1999

Effects of experimental exposure to triethylamine on vision and the eye.

OBJECTIVES: To determine the effect of triethylamine (TEA) on the cornea and to evaluate the cause of blurred vision. To find the lowest observed effect concentration of exposure to TEA. METHODS: Four people were exposed to TEA for 4 hours at concentrations of 40.6, 6.5, and 3.0 mg/m3. Before and after every exposure, symptoms and ocular microscopy findings were recorded. Binocular visual acuity and contrast sensitivity at 2.5% contrast were also measured. Also, before and after the 40.6 mg/m3 exposure, corneal thickness was measured and ocular dimensions were recorded by ultrasonography, endothelial cells of the cornea were analysed, and serum and lacrimal specimens were collected for the analysis of TEA. RESULTS: After exposure to 40.6 mg/m3 TEA there was a marked oedema in the corneal epithelium and subepithelial microcysts. However, corneal thickness increased only minimally because of the epithelial oedema. The lacrimal concentrations of TEA were, on average (range) 41 (18-83) times higher than the serum TEA concentrations. The vision was blurred in all subjects and visual acuity and contrast sensitivity had decreased in three of the four subjects. After exposure to TEA at 6.5 mg/m3 two subjects experienced symptoms, and contrast sensitivity had decreased in three of the four subjects. There were no symptoms or decreases in contrast sensitivity after exposure to a TEA concentration of 3.0 mg/m3. CONCLUSIONS: TEA caused a marked oedema and microcysts in corneal epithelium but only minor increases in corneal thickness. The effects may be mediated by the lacrimal fluid owing to its high TEA concentration. Four hour exposure to a TEA concentration of 3.0 mg/m3 seemed to cause no effects, whereas exposure to 6.5 mg/m3 for the same period caused blurred vision and a decrease in contrast sensitivity.

Adult↗
PubMed2006

Surgical treatment of low vision.

Recent advances in technology are driving a renewed search to find surgical solutions for low vision rehabilitation. The scope of surgery is now being pushed beyond the initial goal of repairing existing anatomical structures. Today, the goal for vision rehabilitation is no less than replacing damaged ocular tissues with artificial ones. Surgical management of low vision may be subdivided into two categories, those procedures aimed at restoring ultrastructural visual function and those aimed at enhancing visual acuity of the residual retina with various levels of magnification. This paper briefly reviews advances in ultrastructural restoration by repair and considers in more detail enhanced acuity through magnification or replacement.

Humans↗
PubMed2000

A programmable VLSI filter architecture for application in real-time vision processing systems.

An architecture is proposed for the realization of real-time edge-extraction filtering operation in an Address-Event-Representation (AER) vision system. Furthermore, the approach is valid for any 2D filtering operation as long as the convolutional kernel F(p,q) is decomposable into an x-axis and a y-axis component, i.e. F(p,q)=H(p)V(q), for some rotated coordinate system [p,q]. If it is possible to find a coordinate system [p,q], rotated with respect to the absolute coordinate system a certain angle, for which the above decomposition is possible, then the proposed architecture is able to perform the filtering operation for any angle we would like the kernel to be rotated. This is achieved by taking advantage of the AER and manipulating the addresses in real time. The proposed architecture, however, requires one approximation: the product operation between the horizontal component H(p) and vertical component V(q) should be able to be approximated by a signed minimum operation without significant performance degradation. It is shown that for edge-extraction applications this filter does not produce performance degradation. The proposed architecture is intended to be used in a complete vision system known as the Boundary-Contour-System and Feature-Contour-System Vision Model, proposed by Grossberg and collaborators. The present paper proposes the architecture, provides a circuit implementation using MOS transistors operated in weak inversion, and shows behavioral simulation results at the system level operation and electrical simulation and experimental results at the circuit level operation of some critical subcircuits.

Computer Simulation↗
PubMed1980

Results of colour vision tests in alcoholic and in mentally disordered subjects.

The responses at the Ishihara test, the Nagel anomaloscope, the standard Panel D--15 and the 100 hue test (with correction of the age effect) were recorded in 38 alcoholics in deprivation period (successively subdivided according to age, to abstinence duration and to liver condition) and in 32 subjects suffering from mental diseases (successively subdivided according to ethylic past, to age, to duration of the stay in the hospital and to activity). It is shown that alcoholism causes a diminution of the performance at the used colour vision tests and especially at the 100 hue test. The defect can be ascribed to psychical factors (chiefly in the cases of mental disease and in the younger people), but also to an acquired blue-yellow defectiveness of colour vision with a shift of the Rayleigh match to red (such a defectiveness can also be due to a liver damage and to some intoxications) and even to a Type II acquired red-green defectiveness of colour vision (possibly by tobacco or disulfiram intoxication). The defect due to alcohol itself soon disappears during desintoxication. The authors draw some practical conclusions.

Adult↗
PubMed1981

Color vision and other parameters of macular function after retinal reattachment.

Patients with a preoperatively detached macula and operated upon between October 1976 and July 1978 were analyzed for three parameters of macular function after surgical repair. Reattachment was achieved by cryopexy, an external sponge plombage and nondrainage. The observation period was a minimum of 1 year. Visual acuity increased in all patients with a maximum improvement in the first 3 months after macular reattachment. Color vision was postoperatively defective in every second patient. In the majority of cases it was a trito disturbance. The disturbance in color vision was most prominent in patients over 60 years old. During the period of 1 year, normalization of color vision occurred for the most part only in patients under 60 years of age. Metamorphopsia proved to be the most sensitive indicator of an episode of previous macular detachment. It occurred in every patient independently of age and was still present at the end of 1 year. It could be considered as a 'scar in the Amsler grid.' The occurrence of metamorphopsia was independent of whether subretinal fluid was drained or allowed to absorb spontaneously.

Adult↗
PubMed2000

The architecture of visual cortex and inferential processes in vision.

This paper is organised approximately into two halves. In the first half, I review evidence about the structure of the visual system, and I use that evidence to frame what I think are widely held but often implicit ideas about how it works, namely that vision is principally analysis of retinal input. These ideas have been strongly influenced by engineering approaches; form a default view of the visual system that suffuses all the language used to describe it (at least in visual neuroscience); and are to some extent supported by the structural evidence. In the second half, I explore some inconvenient facts from neuroanatomy and neurophysiology which are quite uncomfortable for the traditional view. I then set out a contrary view of how structure and function are linked in the visual system, which is a neurobiological variety of the quite developed view in psychophysics that vision is better understood as knowledge-rich inference. Finally, I explore some of the ramifications of this view for neurophysiological understanding of how the visual system might operate during normal vision.

Animals↗