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At least 1,513 records · Page 84Linked to original sources
PubMed2000

Acquired color vision loss and a possible mechanism of ganglion cell death in glaucoma.

PURPOSE: First, to study the cellular mechanisms of acquired color vision loss in retinal detachment and diabetic retinopathy. Second, to learn why, in glaucoma, the type of color vision deficit that is observed is more characteristic of a retinal injury than it is of an optic neuropathy. Third, to test a hypothesis of photoreceptor-induced, ganglion cell death in glaucoma. METHODS: Various histologic techniques were employed to distinguish the L/M-cones (long/medium wavelength-sensitive cones, or red/green sensitive cones) from the S-cones (short wavelength-sensitive cones, or blue sensitive cones) in humans and monkeys with retinal detachment, humans with diabetic retinopathy, and both humans and monkeys with glaucoma. To test if the photoreceptors were contributing to ganglion cell death, laser photocoagulation was used in a experimental model of glaucoma to focally eliminate the photoreceptors. As a control, optic nerve transection was done following retinal laser photocoagulation in one animal. RESULTS: Selective and widespread loss of the S-cones was found in retinal detachment as well as diabetic retinopathy. By contrast, in human as well as experimental glaucoma, marked swelling of the L/M-cones was the predominant histopathologic feature. Retinal laser photocoagulation followed by experimental glaucoma resulted in selective protection of ganglion cells overlying the laser spots. This was not seen with retinal laser photocoagulation by optic nerve transection. CONCLUSIONS: In retinal detachment and diabetic retinopathy, acquired tritan-like color vision loss could be caused, or contributed to, by selective loss of the S-cones. Both L- and M-cones are affected in glaucoma, which is also consistent with a tritan-like deficit. Although not a therapeutic option, protection of ganglion cells by retinal laser in experimental glaucoma is consistent with an hypothesis of anterograde, photoreceptor-induced, ganglion cell death.

Adult↗
PubMedDate not supplied

[General criteria of working ability in subjects with color vision defects].

A correct evaluation of the colour vision is important to make decisions concerning the recruitment in numerous occupations that require colour discrimination. In order to identify valid pre-employment colour vision testing methods, tests actually used and in particular the Ishihara test are considered. After a careful examination we conclude that candidates who pass the Ishihara test have sufficient colour perception to meet ordinary needs and further trade test are not necessary. Nevertheless we do not consider sufficient to rely on the Ishihara test alone to reject a candidate. The diagnostic algorihm proposed is recommended in pre-employment medical examinations for distinguishing people with normal colour vision, slight or sever colour deficiency.

Algorithms↗
PubMed2001

Effects of lorazepam on vision and oculomotor balance.

BACKGROUND: Previous studies have shown an effect of the tranquilizer lorazepam on visual perception. We explored the effects of the drug on binocular vision, visual acuity and accommodation. SUBJECTS AND METHODS: Twenty-four paid healthy volunteers (13 women, 11 men) were recruited from the University of Strasbourg (mean age: 23.6 years, mean weight: 66.8 Kg). They were randomly assigned to one of two parallel groups of 12 subjects each (a placebo group and a lorazepam 0.038 mg/kg group). Visual acuity was measured for each eye separately (Snellen chart and Parinaud scale). Binocular vision was studied using the cover tests, measurement of the fusional amplitudes (with Berens prisms), and the Duane Scale Test (near point rule) measuring convergence and/or accommodation in centimeters or diopters as a function of age. RESULTS: Regarding vision, there was no lorazepam effect, at either 33 cm or 5 m. An esophoria was observed after the intake of lorazepam (0Delta before intake and 2.8Delta after intake, p=0.001). Both fusional convergence and fusional divergence amplitudes decreased by lorazepam, (p=0.008, and p=0.002). Lorazepam also impaired the near point of convergence but did not affect accommodation. CONCLUSION: A single dose of lorazepam induces an esophoric oculomotor imbalance and impaired fusional convergence and divergence amplitudes without impairing visual acuity or accommodation.

Accommodation, Ocular↗
PubMed2001

Modelling space perception in human early vision: a computational approach.

A computational approach in studying vision is important for understanding the biological mechanisms, as well as for integrating the known cortical architecture of primary visual area (V1) and the physiological functions (some of them experimentally proved, some only presumed). We present, in parallel, two models for early vision mechanisms: one for obtaining the disparity map in stereo vision, and the other for edges enhancement in contour integration, both of them seen from such a computational perspective. We implemented the two models and the results of the simulation were consistent with the biological data. They also account for the importance of interactions between parallel channels of visual information processing.

Computer Simulation↗
PubMed2002

The interface between ophthalmology and optometric vision therapy.

Considerable disparity lies between ophthalmologic impressions of optometric vision therapy, and the reality of optometric vision therapy as practiced in the United States. The viewpoint shared by ophthalmology in particular, and the medical field in general, is one that is filtered through organizational policy statements and the isolated experiences of influential individual practitioners. This has resulted in a skewed portrayal of optometric vision therapy. The purpose of this paper is to present a balanced perspective on this subject, and one that should be of assistance in creating an interface between ophthalmology and optometry that better serves the public.

Adult↗
PubMed2002

The impact of visual impairment and eye disease on vision-related quality of life in a Mexican-American population: proyecto VER.

PURPOSE: To describe the relationship of visual acuity impairment and eye disease on vision-related quality of life, as measured by the 25-item National Eye Institute Visual Function Questionnaire (NEI-VFQ-25), in a cross-sectional, population-based study of older Hispanic persons living in Arizona. METHODS: A random sample of block groups with Hispanic residents in Nogales and Tucson, Arizona, were selected for study. Participants were interviewed at home with a questionnaire that included the NEI-VFQ-25, an instrument measuring vision-related quality of life. Acuity was obtained with Early Treatment Diabetic Retinopathy Study (ETDRS) charts and standard protocol. Cataract was determined by clinical examination, diabetic retinopathy was diagnosed on stereo fundus photographs, and glaucoma was diagnosed on the basis of clinical examination and visual field results. Analyses were done to determine the degree of association between subscale scores and acuity in the better-seeing eye, monocular visual impairment, and specific eye diseases, with adjustment for acuity. RESULTS: Of the 4774 participants in the study, 99.7% had completed questionnaires that were not completed by proxy. Participants with visual impairment had associated decrements in scores on all subscales, with a decrease in presenting acuity associated with a worse score (P < 0.05), after adjustment for demographic variables. Monocular impairment was also associated with lower scores in several subscales. In those with cataract, low acuity explained most of the low scores, but those with glaucoma or diabetic retinopathy had low scores independent of acuity. CONCLUSIONS: In this study of Mexican-American persons aged 40 or more, monocular impairment and better-eye acuity was associated with a decrease in most domains representing quality of life. Subjects with uncorrected refractive error, cataract, diabetic retinopathy, and glaucoma had associated decrements in quality of life, many not explained by loss of acuity. Further work on the specific measures of vision associated with reported decreases in quality of life, such as visual field or contrast sensitivity, is warranted.

Adult↗
PubMed2002

The scientific basis for and efficacy of optometric vision therapy in nonstrabismic accommodative and vergence disorders.

BACKGROUND: For nearly 75 years, optometric vision therapy has been an important mode of therapy for both children and adults who manifested a range of nonstrabismic accommodative and vergence disorders. METHODS: In this article, the scientific basis for, and efficacy of, optometric vision therapy in such patients will be discussed. Using bio-engineering models of the oculomotor system as the conceptual framework, emphasis will be focused on studies that used objective recording techniques to directly assess therapeutically related changes in oculomotor responsivity. RESULTS AND CONCLUSIONS: The findings clearly support the validity of optometric vision therapy. Furthermore, the results are consistent with the tenets of general motor learning.

Accommodation, Ocular↗
PubMed1999

[The development of an intelligent vision testing instrument].

The paper introduces an intelligent vision testing instrument, which works on automatic method or manual method. The examinee inputs his or her judgement about the direction of the letter "E" with remote control. The system examines and judges the examinee's judgement, and then prints the testing report. The vision testing range is from logarithm vision 3.0 to 5.3. The distance between examinee and optometer can be measured automatically by the system with infrared and ultrasonic testing functions and a good accuracy.

Diagnosis, Computer-Assisted↗
PubMed2002

[The role of color vision disturbances in diagnostics of early diabetic retinopathy].

PURPOSE: The evaluations of color vision sensitivity in children with type I diabetes mellitus without retinopathy. MATERIAL AND METHOD: We examined 96 young patients. They was divided into three groups: I: 35 children from 7 to 16 years old with insulin-dependent diabetes mellitus duration of 1-8 years, II: 30 children with type I diabetes lasting more then 8 years, III--31 non-diabetic subjects as a control-matched for age and sex, without visual or systemic symptoms. The examinations of colour vision sensitivity were done with the IF-2AII-color Anomaloscope. In all cases were tested the dynamic blue-green equation of Moreland and two variables were determined: setting (matching) range (SR), calculated mid point (matching mid point) (CMP). RESULTS: In the blue-green equation setting range (SR) was significantly (p < 0.01) enlarged in the II group (diabetes mellitus duration > 8 years) and calculated mid point (CMP) was shifted but no significant. The results indicate a diminution of the colour discriminating sensitivity in the short wavelength half of the visible spectrum and diminution of the blue cone sensitivity in early diabetic retinopathy. CONCLUSIONS: Blue-green colour vision testing with the anomaloscope may serve as an additional test in the diagnosis of early diabetic retinopathy in children without vascular changes at the eye fundus.

Adolescent↗
PubMed1992

The contrast sensitivity function in low vision.

The contrast sensitivity of 51 low vision patients (95 eyes) showed a substantial decrease in all spatial frequencies. The peak contrast sensitivity was shifted to 1 C/D from the normal 3-4 C/D. The high-frequency cut off is correlated to the visual acuity positively. Of the 33 patients, the preferred eye was the eye with better peak sensitivity in 28 patients (84%), while the preferred eye was the eye with better visual acuity in 22 patients (66%). It seems that the peak sensitivity is more important than visual acuity in determining eye preference. It provides a useful information for the clinician to determine which eye to train with low vision aids. Forty patients among 46 patients (87%) with RFN (Recognized Frequency Number) > or = 3 are able to read No.5 reading card, while 5 patients among 5 patients with RFN < 3 are not able to read No.5 reading card. The contributions of CSF to the low vision are evaluated.

Adolescent↗
PubMed1992

[An epidemiological survey of blindness and low vision in Shandong Province].

An epidemiological survey of blindness and low vision was carried out in a sample population of 115 167 in Shandong Province to find that the prevalence of binocular blindness was 0.34%, that of unilateral blindness 0.65%, that of binocular low vision 0.46%, and that of unilateral low vision 0.64%. The prevalence rates increased with age and the leading causes of blindness, in order of importance, were cataract, corneal diseases and glaucoma in urban areas, and cataract, corneal diseases and retinal diseases in rural areas.

Adolescent↗
PubMedDate not supplied

[Blue color vision as a sign of digitalis poisoning].

The paper deals with the course of the illness in a 66 years old male, who had taken an amount of 0.2 mg of medigoxin for an unknown period of time, because of chronic heart failure due to atherosclerotic heart disease and chronic atrial fibrillation. He have had a cholelithiasis also and reduced renal reserve. He was admitted by an emergency admittance because of nausea, vomiting, color vision disturbances: blue colored vision, and with other signs of digitalis toxicity: diffuse abdominal pain, an absolute arrhythmia with a slow ventricular rate, and with a short corrected Q-T interval in an electrocardiogram of 0.315 seconds and with high serum digoxin level reacted 3.8 nmol/L. After stopping of a digitalis treatment, in a period of time of four days, all signs of digitalis toxicity including blue color vision disturbances disappeared. In the paper that rare sign of digitalis toxicity is discussed.

Aged↗
PubMed1992

[An epidemiological survey of blindness and low vision in Hebei Province].

Following the national unified criteria and methods, an epidemiological survey of blindness and low vision was carried out in Hebei Province from April to June, 1987. In 77,948 persons examined, there were 291 cases of bilateral blindness, representing a prevalence of 0.37% (male 0.29%, female 0.45%, urban areas 0.19%, plain areas 0.42%, and mountainous areas 0.36%). The prevalences of monocular blindness, bilateral and monocular low vision were 0.72%, 0.57% and 0.30% respectively. Subjects over 60 years of age had significantly higher prevalences of bilateral blindness and low vision. The chief blinding diseases were cataract, trachoma complications, corneal disease and glaucoma, in order of importance.

Age Factors↗
PubMed1992

[A telescopic system for distance consisting of contact lens and spectacle lens for low vision patients].

A telescopic system for distance consisting of a negative contact lens (-10.0 - -20.0 D) as the eye piece and a positive spectacle lens (+8.0 - +16.0 D) as the objective, a modification of the Galilean telescope was examined. First the system was tried in 15 normal subjects, whose visual acuity was reduced to 20/200 or less by providing several occlusion membranes, and results were compared with customary full correction for distance. The best improvement of their vision by this system was achieved when the dioptric power of the spectacle was between +11.0 D and +13.75 D. This system was then applied to 78 eyes (61 patients) with visual acuity of 20/100 or less. Subjective improvement of vision was found in 55% of those patients' eyes. Eight patients out of 26 patients whose better eye acuity was 20/100 or less wanted to use this system and received prescription to result in the visual improvement, as evidenced by their continued use. This system can provide aid for low vision correction for distance.

Adolescent↗
PubMed2003

Comparative randomised controlled clinical trial of a herbal eye drop with artificial tear and placebo in computer vision syndrome.

A comparative randomised double masked multicentric clinical trial has been conducted to find out the efficacy and safety of a herbal eye drop preparation, itone eye drops with artificial tear and placebo in 120 patients with computer vision syndrome. Patients using computer for at least 2 hours continuosly per day having symptoms of irritation, foreign body sensation, watering, redness, headache, eyeache and signs of conjunctival congestion, mucous/debris, corneal filaments, corneal staining or lacrimal lake were included in this study. Every patient was instructed to put two drops of either herbal drugs or placebo or artificial tear in the eyes regularly four times for 6 weeks. Objective and subjective findings were recorded at bi-weekly intervals up to six weeks. Side-effects, if any, were also noted. In computer vision syndrome the herbal eye drop preparation was found significantly better than artificial tear (p < 0.01). No side-effects were noted by any of the drugs. Both subjective and objective improvements were observed in itone treated cases. So, itone can be considered as a useful drug in computer vision syndrome.

Adult↗
PubMed2003

[Disorders of color vision].

This review gives a summary of all colour vision disorders (dyschromatopsias) and diagnostic methods and tests. Colour vision is inadequately treated in current literature with regard to the choice of diagnostic methods and the interpretation of results for a single disorder, which contributes to wrong dyschromatopsia diagnosing seen every day in specialist practice. Examination for colour disorders is usually outpatient and is carried out by ophthalmology or neurology departments or occupational health services under the supervision of an ophthalmologist to prevent misinterpretation of results and wrong occupational choices. The problem is very serious, and proper education should be able to provide guidelines for correct and early diagnosis of dyschromatopsia. As the examination is not well defined, it is very important to set unique criteria in diagnosing any single colour vision disorder.

Color Perception Tests↗
PubMed2004

Color vision changes in young subjects acutely exposed to 3,000 m altitude.

INTRODUCTION: Performance of mountaineers, civil aircraft pilots, and of the personnel involved in many military operations in high mountains may rely on color discrimination at these moderate levels. The authors aimed at investigating the effects of moderate altitude (3000 m) exposure on color vision. METHODS: Sixteen high school students, ages ranging between 14 and 17 yr, were enrolled in this study. Their color vision was examined with the Farnsworth-Munsell 100-Hue (FM-100 Hue) test at 1060 and 3000 m above the sea level and the total number of errors (all 4 sectors together) compared. Number of errors was also calculated for each of 4 sub-sectors and compared between these two altitudes. RESULTS: There was a statistically significant increase in total number of errors (p = 0.001) as well as in number of errors in sector 1 (p = 0.007) and sector 3 (p = 0.013) at 3000 m when compared with 1060 m. CONCLUSIONS: Moderate altitude (3000 m) adversely affected the total number of errors on FM-100 Hue color vision testing of an acclimatized group of young individuals in a photopic environment and this deterioriation was significant in the blue-yellow range.

Adolescent↗
PubMed2004

Virtual vision loss simulator.

Vision loss is common among people over the age of 65 and the condition is irreversible in most cases. Our simulator is a means to effectively and accurately inform people about the nature of common vision problems, initially limited to medically accurate simulations of cataract and macular degeneration. Using an eye tracker that continuously determines the subject's fixation point, a systematically degraded digital image displayed on an HMD can be a powerful educational tool. This article presents our Virtual Vision Loss (VVL) simulator and the developed simulation techniques based on calibration from 27 subjects.

Adult↗