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PubMed2003

Sustained improvement in vision in a recurrent growth hormone secreting macroadenoma during treatment with octreotide in the absence of marked tumour shrinkage.

Visual improvement following octreotide for growth hormone secreting pituitary macroadenomas is uncommon without tumour shrinkage. A 45-year old lady presented with blurred vision for 12 months. Visual assessment revealed a bitemporal hemianopia and CT scan demonstrated a large pituitary tumour with lateral and suprasellar extension. Acromegaly was confirmed by 75 g glucose tolerance testing. Primary transsphenoidal surgery was performed with normalisation of visual acuity and fields of vision. Post-operatively she had anterior pituitary hormone deficiency. As GH and IGF-1 levels remained elevated she underwent external pituitary irradiation. CT scanning demonstrated tumour shrinkage associated with a modest fall in GH levels. IGF-1 levels remained elevated falling to the age-related upper limit of normal after 5 years. At regular review she had stable visual acuity and fields of vision. She presented as an emergency 7 years from presentation with reduced vision and recurrence of bitemporal hemianopia. An MRI demonstrated a large pituitary adenoma. We therefore undertook a carefully monitored trial of octreotide with great caution with daily reassessment of acuity and fields. A decision was made to proceed to surgery in the event of deterioration or lack of improvement after a short trial over 5-7 days. We observed normalisation of visual acuity and perimetry within 3 days. She then commenced long-acting octreotide (Sandostatin LAR) 20 mg every 28 days. MRI after 1 week showed shrinkage of the tumour by a few millimetres. Five months later repeat MRI failed to show any further improvement in tumour size. However she remains well 29 months from treatment with normal vision and is being monitored carefully as her chosen form of therapy. Somatostatin analogues may be effective as therapy in a selected group of patients with acromegaly and visual loss who are not suitable for pituitary surgery. If used in this way the drug must be given cautiously with frequent detailed ongoing visual assessments. In this present case there has been a restoration of vision but the long-term outlook remains guarded without significant tumor shrinkage.

Adenoma↗
PubMed2006

The prevalence of low vision and blindness in Canada.

PURPOSE: The purpose of this study was to ascertain the prevalence and primary causes of visual impairment in a representative Canadian population. METHODS: We reviewed a representative sample of patients who attended ophthalmologists' offices in a medium-sized Canadian city between 1996 and 2001 in order to estimate the prevalence of visual impairment. Demographic data, visual diagnoses, best-corrected visual acuities (BCVA), and visual field information were recorded. Visual status was categorized based on accepted World Health Organization (WHO) and North American criteria. Population data were obtained from the Canadian census. RESULTS: The prevalence of low vision and blindness in our population was 35.6 and 3.8 per 10 000 individuals, according to the WHO classification, and 71.2 and 23.6 per 10 000 individuals, using the North American definition. Among individuals with some vision loss (vision worse than 20/40), cataract and visual pathway disease were the most common causes, together accounting for 40% of visual impairment. Age-related macular degeneration and other retinal diseases were the next most common causes of vision loss. Diabetic retinopathy and glaucoma were less frequently encountered as causes of visual impairment. CONCLUSION: The overall prevalence of low vision and blindness in Canada are in keeping with data from large population-based studies from other developed nations. Cataract, visual pathway disease, and macular degeneration are the leading causes of visual impairment. These results are important for enhancing our understanding of the scope of vision health in Canada and may direct future health planning and cost-utilization research.

Adolescent↗
PubMed1997

Motion parallax: effects of blur, contrast, and field size in normal and low vision.

Can people with different forms of low vision use motion parallax to improve depth judgments? We used a staircase method to compare depth thresholds using motion parallax and static viewing. We tested eighteen normal-vision subjects with a range of simulated deficits in acuity, contrast sensitivity, and simulated peripheral-field loss, and ten low-vision subjects with a wide range of acuity, contrast sensitivity, and field loss. Subjects viewed three vertical cylinders monocularly and indicated which one was at a different depth from the other two. For motion-parallax trials, observers moved their heads (in a viewing assembly on rollers) from side to side over a range of 6-12 cm. For static trials, the viewing assembly was fixed in place. Normal-vision subjects' depth thresholds with motion parallax were significantly smaller than those with static viewing by an average factor of 1.95 (p < 0.05) across all levels of acuity and contrast. For low-vision observers, the depth thresholds exhibited large individual differences; however, the motion-parallax thresholds were smaller than the static thresholds by an average factor of 2.05 (p < 0.01). These findings indicate that motion parallax can provide useful depth information for people with low vision.

Adolescent↗
PubMed2004

Color vision testing.

The science of color vision testing has evolved since its inception in the late 1700s. Since then, the rudimentary technique of comparing color names has been replaced by more sophisticated methods. Commonly used tests in clinical practice today include isochromatic plates, arrangement tests, anomaloscopes, and lantern tests. Each category has unique attributes that make it suitable for a particular clinical situation. The clinician should be aware of the requirements for administering and grading each test type. Factors such as the quality of the illuminant and the size of the field of view are important elements in setting up a proper color vision laboratory. Currently, no treatment exists for congenital color vision defects. However, studies show that diagnosis of these defects early in life may help children adjust better to tasks at school and may help adults understand their limitations at work. Acquired color vision defects are often used as markers of ocular pathology in the clinical setting. Different color vision tests are appropriate for diagnosing the different categories of defects. Sometimes, a battery of tests may be appropriate. This paper is a review of the current knowledge in the field of color vision testing.

Color Perception↗
PubMed2001

Chalazion as a cause of decreased vision after LASIK.

PURPOSE: To describe a post-LASIK patient with decreased vision and a chalazion of the upper eyelid. METHODS: A 46-year-old man was referred with decreased vision of 1 month's duration. He underwent bilateral uncomplicated LASIK for myopic astigmatism 1.5 years and bilateral enhancements 1 year previously. He had 20/20 uncorrected vision in both eyes after those procedures. He developed a chalazion of his right central upper eyelid 1 month prior with simultaneous blurring of vision. On our examination, his uncorrected visual acuity was 20/60 in the right eye. Complete eye examination including refraction, computerized corneal topography, and pachymetry were done. RESULTS: With a manifest refraction of +1.25 +0.50x80, the visual acuity in the right eye improved to 20/20. Computerized corneal topography revealed circular central corneal flattening in both eyes, much greater in the right eye than the left eye. The location of the chalazion with the right eye closed corresponded to the area of central corneal flattening. The central power from the corneal topography was 39.4 D OD and 40.8 D OS. He was diagnosed as having acquired hyperopia associated with chalazion-induced central corneal flattening of the right eye. Chalazion-induced hyperopic change on topography disappeared, and his uncorrected vision improved to 20/20 in the left eye as the chalazion resolved completely. CONCLUSION: In post-LASIK patients with decreased vision and topography changes late after surgery, periocular masses should be considered in the differential diagnosis. Decreased corneal thickness and rigidity after LASIK might be a predisposing factor to external compression-induced curvature changes.

Astigmatism↗
PubMed1994

Clinical low vision resource usage prediction.

In an era of increased demands and constrained budgets, it is necessary to make the best use of all available resources. This is difficult when specialized vision care, such as low vision clinical assessment, is involved because of the heterogeneity of the patient populations seen by such clinics. PURPOSE. This research attempts to discover if these diverse patient populations can be identified and clustered into groups based upon similarity of clinical resources use. Specifically, the inquiry examines the potential for a low vision patient resource utilization classification scheme at the Low Vision Clinic (LVC) in the Centre for Sight Enhancement (CSE), University of Waterloo. METHODS. From a sample of 99 patients consulting the LVC in a 3-month period, retrospective data collection involved abstracting and coding medical records containing information detailing each patient's demographic, diagnostic, therapeutic, and resource utilization characteristics. Cluster analysis using Hartigan's block clustering algorithm was then applied to the data. A replication study was completed using a sample of 99 patients visiting the LVC 1 year later. RESULTS. Patients can be classified into five iso-resource groups, hereby termed low vision patient resource groups (LVPRGs). The clusters represent a resource consistent and clinically coherent scheme for classifying low vision patients based upon resource requirements. As a measure of repeatability, the groups reemerged in the replication study. CONCLUSIONS. If the groupings demonstrate robustness in a field test, clustering algorithms in general, and LVPRGs in specific, may offer useful tools to enhance resource utilization in the LVC setting.

Adult↗
PubMed2004

Vision screening for children: current trends, technology, and legislative issues.

PURPOSE OF REVIEW: The purpose of this review is to examine current trends in vision screening for children. RECENT FINDINGS: Literature within the past year regarding children's vision screening has been dominated by clinical validation studies of autorefractors or photoscreeners that allow the detection of amblyogenic refractive errors, misalignment of the eyes, or media opacities. New technologies reported include wave-front analysis for amblyogenic factors and a visual evoked potentials-based screening tool for the preverbal child. Studies evaluating the goals of the screening program, the target population, and the physical limitations of the screening environment have prompted multipronged or hybrid studies designed to more accurately detect vision problems, particularly in the preschool child, in whom cooperation and cognitive development affect reliability of results. State and federal legislation in the United States has been proposed or adopted to regulate and partially fund pediatric vision screening and comprehensive examinations. SUMMARY: Through improvements and new developments in technology, study design, the efforts of organized medicine, and legislative initiatives, vision screening for children continues toward the goal of bringing all children with eye disease or vision problems to treatment in a timely fashion.

Child↗
PubMed2004

Will visual discomfort among visual display unit (VDU) users change in development when moving from single vision lenses to specially designed VDU progressive lenses?

PURPOSE: Three types of progressive additions lenses (PAL) specially designed for VDU-work and one single vision lens were compared in a prospective field study. The aim was to investigate if these progressive lenses created a difference in the development of visual discomfort compared to single vision lenses when working on an optimized VDU-workstation. METHODS: The study had a prospective, parallel group design, with four groups of VDU-workers. Approximately 40 subjects in each group, selected after careful task analysis with special attention towards the visual angles and distances to the work tasks. The groups were followed over one year. A questionnaire concerning visual conditions, working conditions, discomfort in different body areas, the status of the subjects' optometric corrections, psychological factors both at work and at home, amount, frequency and duration of VDU-work etc. was filled in before the intervention, after six months and after one year. No other contact was made with the subjects. The VDU-lenses included were Interview (Essilor), Gradal RD (Zeiss) and Technica (American Optical). Pain intensity and duration were assessed on a 100 mm Visual Analogue Scale (VAS) before the intervention, and six and twelve months after the intervention. All subjects were given a complete optometric examination. RESULTS: Only small changes in the development of headache and visual discomfort were registered. However, the subjective evaluation of area of clear vision and overall satisfaction was significantly improved for the Interview and Gradal RD lens (p < 0.05). There were no significant changes for Technica and single vision lenses. CONCLUSION: Lens designs that cover viewing distances from near and out to approximately 2 meters work well compared to lens designs trying to cover greater range of clear vision. When tasks analysis shows that single vision correction may be used, this is still an acceptable solution.

Computer Terminals↗
PubMed2006

Citation patterns in the optometric and ophthalmologic clinical binocular vision literature.

PURPOSE: The purpose of this study is to compare citation patterns in the clinical binocular vision literature of optometry and ophthalmology. METHODS: The author conducted citation analysis of two current clinical binocular vision textbooks from optometry and two from ophthalmology and of articles published in the years 2000 to 2004 in optometry and ophthalmology journals. Topical parameters for inclusion of sources were diagnosis and management of nonstrabismic binocular vision disorders, diagnosis and management of nonpresbyopic ocular accommodation disorders, and procedures for examining such conditions. These topical parameters were chosen because they are areas in which the diagnostic procedures and treatment options available to members of the two professions are not delineated by their respective scopes of practice. RESULTS: The most frequently cited journals in the optometric publications were optometry journals (63% of citations in the optometry textbooks and 58% in the optometry journal articles). The most frequently cited journals in the ophthalmology publications were ophthalmology journals (79% of citations in the ophthalmology textbooks and 49% in the ophthalmology journal articles). Each discipline also cited a greater variety of journals from within its own field than was cited by the other discipline. The journal with the highest total number of citations was Optometry and Vision Science (280) followed by Ophthalmic and Physiological Optics (73), American Journal of Ophthalmology (68), Investigative Ophthalmology and Visual Science (62), and Optometry (61). CONCLUSIONS: Optometry and ophthalmology sources show more citations to materials from their own discipline than from their fellow discipline in the area of nonstrabismic binocular vision disorders and nonpresbyopic accommodative disorders. Reasons may include lack of awareness of the literature of the other discipline, bias toward the literature of one's own discipline, or bias against the literature of another discipline. It is also likely that the diagnostic and management strategies of the two professions are significantly different, although scope of practice would not constrain the range of strategies for the conditions chosen as the topical matter for consideration in this study. The journals found to be most frequently cited in this study should help to identify the core journals in this area of clinical binocular vision.

Adolescent↗
PubMed1992

Optic neuritis in children with poor recovery of vision.

We reviewed the records of 10 children with optic neuritis in whom recovery of vision was poor or incomplete. Our cases were otherwise similar to those described in previous studies in that they were always bilateral, often accompanied by a viral prodrome (seven of 10), and usually associated with disc oedema (seven of 10). Seven of twenty eyes had a final visual acuity of 6/60 or worse and only one patient regained 6/6 vision in either eye. In three patients the best vision in either eye was 6/60 or worse. Recovery of vision was often slow, taking up to six years. Five of 10 patients have developed multiple sclerosis (MS), and one child had acute disseminated encephalomyelitis (ADEM) with optic neuritis. Optic neuritis in children does not always carry a good prognosis for recovery of vision; however, the failure of vision recovery in a short period of time does not necessarily indicate a poor outcome. Some children with optic neuritis develop MS, which can develop even when optic neuritis follows a viral illness.

Adolescent↗
PubMed2005

Diagnosing protan heterozygosity using the Medmont C-100 colour vision test.

BACKGROUND: A surprisingly high 15 per cent of women in Caucasian societies are carriers of the genes for abnormal colour vision but there is no clinical method to identify them. It has long been known that heterozygotes for the protan colour vision deficiencies can demonstrate a reduced luminous sensitivity to red light. This is known as Schmidt's sign, which is thought to arise from mosaicism (Lyonisation). The Medmont C-100 colour vision test measures relative spectral sensitivity using flicker photometry to differentiate protans and deutans. It should be able to diagnose Schmidt's sign. METHOD: We tested six known protan heterozygotes (four whose sons have a protan colour vision deficiency and two whose fathers are protan) with the Medmont C-100 test. RESULTS: All six heterozygotes made average settings of -1.75 or more negative at the Medmont C-100 test, settings which are at or beyond the boundary of the distribution of settings made by observers with normal colour vision. There have been two previous cases reported in the literature of protan heterozygotes, who made protan settings on the Medmont C-100 or its predecessor test, the OSCAR. We also tested six daughters of the known heterozygotes, 50 per cent of whom are likely to be heterozygotes. Four of the six (66 per cent) made protan settings on the Medmont C-100. The other two made normal 0.0 settings. CONCLUSION: We conclude that the Medmont C-100 can be used clinically to diagnose carriers of protan colour vision deficiency.

Color Perception Tests↗
PubMed2006

Color vision and macular recovery time in epileptic adolescents treated with valproate and carbamazepine.

Visual dysfunction has been reported in patients diagnosed with epilepsy. Some of these visual disturbances may be attributable to either the disease process, or the anticonvulsant therapy prescribed to control the seizures. The aims of our study were to evaluate whether color vision and macular function are impaired in epileptic adolescents, to study if the monotherapy with valproic acid (VPA) and carbamazepine (CBZ) can affect color vision and macular function and to determine the possible relationship between color vision, retinal function and antiepileptic drugs (AEDs) dosage and their serum concentrations. We examined 45 (16 male and 29 female, mean age +/- SD, 15.71 +/- 2.01 years) Caucasian epileptic patients suffering from various types of cryptogenic epilepsy before the beginning of therapy and after 1 year of VPA or CBZ monotherapy and 40 sex- and age-matched healthy controls. Color vision was assessed by Farnsworth Munsell (FM) 100-hue test and total error score (TES) was evaluated. This test consists of colored caps: the testee has to arrange the caps according to their colors macular function was assessed by nyctometry evaluating initial recovery time (IRT) and summation method (SM). This test evaluates visual acuity after a period of intense illumination of macula. Analysis of variance was used to evaluate the difference between controls and patients; moreover, Pearson's correlation test have been performed. Before the beginning of therapy, there were no differences in color vision and macular function between controls and epileptic patients. After 1 year, the patients, treated with VPA or CBZ, showed a deficit in FM 100-hue test. At nyctometry, all patients showed no significant variation of macular function between baseline evaluation and second evaluation at end of the follow-up. Our study demonstrates that, in our group of epileptic patients, epilepsy per se does not affect color vision and retinal function. In contrast, after 1 years of therapy with VPA and CBZ these patients showed a deficit in FM 100-hue test although nyctometry evaluation continued to be normal allowing to exclude an impairment in macular function. Further investigations are required to determine the pathophysiological alteration(s) that are at the basis of color perception defects.

Adolescent↗
PubMed2005

Near vision impairment predicts cognitive decline: data from the Hispanic Established Populations for Epidemiologic Studies of the Elderly.

OBJECTIVES: To estimate the association between sensory impairment and cognitive decline in older Mexican Americans. DESIGN: A prospective cohort study. SETTING: The Hispanic Established Populations for Epidemiologic Studies of the Elderly from five southwestern states. PARTICIPANTS: The sample consisted of 2,140 noninstitutionalized Mexican Americans aged 65 and older followed from 1993/1994 until 2000/2001. MEASUREMENTS: The outcome, cognitive function decline, was assessed using the Mini-Mental State Examination blind version (MMSE-blind) at baseline and at 2, 5, and 7 years of follow-up. Other variables were near vision, distance vision, hearing, demographics (age, sex, marital status, living arrangements, and education), depressive symptoms, hypertension, diabetes mellitus, stroke, heart attack, and functional status. A general linear mixed model was used to estimate cognitive decline at follow-up. RESULTS: In a fully adjusted model, MMSE-blind scores of subjects with near vision impairment decreased 0.62 points (standard error (SE)=0.29, P=.03) over 2 years and decreased (slope of decline) 0.13 points (SE=0.07, P=.045) more per year than scores of subjects with adequate near vision. Other independent predictors of cognitive decline were baseline MMSE-blind score, age, education, marital status, depressive symptoms, and number of activity of daily living limitations. CONCLUSION: Near vision impairment, but not distance vision or hearing impairments, was associated with cognitive decline in older Mexican Americans.

Aged↗
PubMed1993

Colour vision in diabetic patients after photocoagulation treatment. A five-year follow-up.

Colour vision of 60 diabetic patients (60 eyes) was studied after photocoagulation treatment in 1986-87. For the follow-up study 5 years later in 1991-92, 32 of the patients were available. The ages of the patients in the follow-up study varied from 28 to 64 years, the duration of diabetes from 19 to 35 years, the amount of laser spots from 200 to 3174, and the visual acuity from 0.4 to 1.0. As colour vision tests, the Standard Pseudo-isochromatic Plates part 2, Lanthony Tritan Album, Farnsworth Panel D 15, and box III of the Farnsworth-Munsell 100 hue test were used. Of the 32 eyes, 22 (68.8%) had the same results in the colour vision tests, 4 (12.5%) had better results, and 6 (18.8%) had worse results than 5 years earlier. Between Group 1 (colour vision the same or better than 5 years earlier, 26 eyes) and Group 2 (colour vision worse than earlier, 6 eyes) there was a significant difference in the age and in the level of the visual acuity of the patients. The changes in the lens, fundus or visual acuity during 5 years did not seem to have an effect in colour vision.

Adult↗
PubMed1998

The contribution of low birth weight to severe vision loss in a geographically defined population.

AIMS: To describe the birthweight specific rate of severe vision loss among babies born between 1 January 1984 and 31 December 1987 to mothers resident in a geographically defined area, to classify the causes of vision loss by time of origin, and to describe the associated sensory and motor impairments and disabilities. METHODS: Cases were identified from a population register of children with early childhood impairment, which uses multiple sources of ascertainment. Further clinical information was retrieved from hospital records and by asking ophthalmologists caring for the children. RESULTS: 166 (1.25/1000 live births) children with severe vision loss diagnosed by the age of 5 years were identified. The rate among babies born weighing less than 1500 g at birth was 26 times higher than the rate for babies between 2500 g and 3499 g. These very low birthweight babies contribute 17.5% of all severely visually impaired children. Almost two thirds of children with severe vision loss have a lesion of prenatal origin. Other sensory or motor deficits are present in 69% of the children. Retinopathy of prematurity accounted for 5.4% of all visually impaired children and seven of the 166 children met the criteria for perinatal asphyxia. CONCLUSIONS: Although the contribution made by babies with a low birth weight to overall severe vision loss in the community is small, many of these children have additional impairments and probably place considerable demands on health and educational services and families. Reduction in the frequency of vision problems in the preschool population as a whole is unlikely to occur until there are major advances in the understanding of the aetiology and prevention of eye conditions of genetic, prenatal, and developmental origin.

Birth Injuries↗
PubMed2000

Implementation methods for vision related quality of life questionnaires.

AIM: To determine the most reliable and consistent method and time interval over which to implement a vision impairment quality of life assessment tool. METHODS: 117 patients with low vision aged 9-101 years were assigned into three age, sex, and visual function matched groups (n = 39 in each) to answer the Low Vision Quality of Life (LVQOL) questionnaire by post, telephone, or in person. The LVQOL questionnaire was completed on four occasions, each separated by four weeks. RESULTS: Postal implementation was the most cost effective method, showed the highest internal consistency of LVQOL items, but resulted in a lower apparent quality of life score than either telephone or in-person interviews (p<0.001). There was no difference in test-retest reliability between the three methods of implementation (p = 0.12). The profile of LVQOL scores showed a trend towards reduced quality of life scores 3 months after the baseline measures, although this was not significant. CONCLUSION: Posting may be the method of choice for clinical measurement of vision related quality of life. Patients with greater visual impairment were no less likely to complete a questionnaire when implemented by post and there was no apparent bias from other people assisting them. The quality of life measure can occur at any time up to 2 months after low vision rehabilitation for the progressive nature of conditions causing low vision not to cause a decreased baseline score. The LVQOL was shown to be a highly internally consistent and reliable method for measuring quality of life in the visually impaired.

Adolescent↗
PubMed2002

Acquired colour vision deficiency in patients receiving digoxin maintenance therapy.

BACKGROUND/AIMS: Disturbances of colour vision are a frequently reported sign of digoxin toxicity. The aim of this study was to investigate the incidence of acquired colour vision deficiency in elderly hospitalised patients receiving maintenance digoxin therapy. METHODS: 30 patients (mean age 81.3 (SD 6.1) years) receiving digoxin were tested using a battery of colour vision tests (Ishihara, AO Hardy Rand Rittler plates, City tritan test, Lanthony tritan album, and the Farnsworth D15). These were compared to an age matched control group. Serum digoxin concentrations were determined from venous blood samples. RESULTS: Slight to moderate red-green impairment was found in approximately 20-30% of patients taking digitalis, and approximately 20% showed a severe tritan deficiency. There was no correlation between colour vision impairment and serum digoxin level. CONCLUSIONS: Formal colour vision testing of elderly patients taking digitalis showed a high incidence of colour deficiency, suggesting that impairment of retinal function can occur even at therapeutic drug levels. As a result, colour vision testing in this population would have limited value for the detection of drug toxicity.

Aged↗
PubMed1997

Deficient colour vision and interpretation of histopathology slides: cross sectional study.

OBJECTIVE: To determine whether histopathologists with deficient colour vision make more errors in slide interpretation than those with normal colour vision. DESIGN: Examination of projected transparencies of histopathological slides under standardised conditions by subjects whose colour discriminating ability was accurately assessed. SETTING: Departments of histopathology in 45 hospitals in the United Kingdom. SUBJECTS: 270 male histopathologists and medical laboratory scientific officers. MAIN OUTCOME MEASURES: Number of slides correctly identified by subjects whose colour vision was measured on the Ishihara, City University, and Farnsworth-Munsell 100 hue tests. RESULTS: Mean (SD) scores (out of 10) for doctors with colour deficient vision were 9.4 (0.7) v 9.9 (0.4) for controls (P < 0.01) and 7.5 (1.6) v 9.4 (0.7) for scientific officers (P < 0.001). When subjects with colour deficient vision were categorised into severe, moderate, or mild, there was a significant trend towards those with severe deficiency making more mistakes (P < 0.001). CONCLUSIONS: Histopathologists and medical laboratory scientific officers should have their colour vision tested; if they are found to have a severe protan or deutan deficiency, they should be advised to adopt a safe system of working.

Clinical Competence↗