Major Cause Of Visual Impairment Research Articles

Current spectrum of oculomycosis in North India: A 5-year retrospective evaluation of clinical and microbiological profile

Oculomycosis is a major cause of visual impairment. Eye pain, redness, discharge, diminution and photophobia are presenting features. We collected corneal scraping, vitreous, aqueous fluids and conjunctival swabs after the slit-lamp examination. Ophthalmological findings were hypopyon, stromal congestion, conjunctival congestion and epithelial defect. Direct microscopy of 10% potassium hydroxide (KOH) wet mounts, gram staining, fungal and bacterial cultures were performed. Fungal isolates were obtained in 24% patients with equal number of both sexes and average age 49 years. KOH revealed fungi in 73% samples and 43.33% were positive on Gram staining. Fusarium spp. (36.66%), Aspergillus spp. (23.33%) and melanised fungi (20%) were common etiological agents. Fusarium spp. was more often associated with complications. Trauma was a predisposing factor in 65% cases and occurred mainly with vegetable matter. The majority responded to the conservative management with 5% natamycin and four patients required surgery.

What Does Genetics Tell Us About Age-Related Macular Degeneration?

Age-related macular degeneration (AMD) is a chronic degenerative disease of the central retina and a major cause of vision impairment and blindness with millions of people affected in the elderly population. In recent years, considerable efforts have been made to understand disease pathology with the long-term goal of designing novel and effective treatment options for this devastating disease. Although striking advances in treating the neovascular stage of late AMD have occurred, no therapy is available for almost half of all AMD patients, specifically those who are affected by the atrophic form of the disease. This review highlights current knowledge on the genetic factors associated with early- and late-stage forms of the disease. It also summarizes the findings regarding the extent to which these factors may play a role in the transition from one disease stage to another, and it emphasizes the need to explore further the underlying mechanisms for both development and progression of this disease as a starting point for designing innovative therapies for it.

Gliosis Can Impede Integration Following Photoreceptor Transplantation into the Diseased Retina.

Retinal degenerations leading to the loss of photoreceptor (PR) cells are a major cause of vision impairment and untreatable blindness. There are few clinical treatments and none can reverse the loss of vision. With the rapid advances in stem cell biology and techniques in cell transplantation, PR replacement by transplantation represents a broad treatment strategy applicable to many types of degeneration. The number of donor cells that integrate into the recipient retina determines transplantation success, yet the degenerating retinae presents a number of barriers that can impede effective integration. Here, we briefly review recent advances in the field of PR transplantation. We then describe how different aspects of gliosis may impact on cell integration efficiency.

Modeling transient retinal ischemia in mouse by ligation of pterygopalatine artery

Retinal ischemia is a major cause of visual impairment and blindness worldwide. The available therapeutic strategies have limited potential. In order to understand the pathophysiology and validating therapies for retinal ischemia, establishment of reproducible animal models is necessary. In the model discussed in this article, the pterygopalatine artery (PPA) is ligated along with the external carotid artery for 3.5 hours and thereafter allowed to reperfuse. Because PPA supplies the blood to the ophthalmic artery, the ligation of this artery causes retinal ischemia. This article describes the validation of retinal ischemia-reperfusion model in mouse through PPA ligation and its validation through fluorescein fundus angiography (FFA) and immunofluorescence staining for glial fibrillary acidic protein (GFAP), a glial injury marker. In conclusion this article describes the creation of mouse model of retinal ischemia-reperfusion injury which can be reproduced in a shorter time duration resulting in reduced mortality.

Diabetic Retinopathy: Retina-Specific Methods for Maintenance of Diabetic Rodents and Evaluation of Vascular Histopathology and Molecular Abnormalities.

Diabetic retinopathy is a major cause of visual impairment, which continues to increase in prevalence as more and more people develop diabetes. Despite the importance of vision, the retina is one of the smallest tissues in the body, and specialized techniques have been developed to study retinopathy. This article summarizes several methods used to (i) induce diabetes in mice, (ii) maintain the diabetic animals throughout the months required for development of typical vascular histopathology, (iii) evaluate vascular histopathology of diabetic retinopathy, and (iv) quantitate abnormalities implicated in the development of the retinopathy.

Multiple ocular diseases detection based on joint sparse multi-task learning.

In this paper, we present a multiple ocular diseases detection scheme based on joint sparse multi-task learning. Glaucoma, Pathological Myopia (PM), and Age-related Macular Degeneration (AMD) are three major causes of vision impairment and blindness worldwide. The proposed joint sparse multitask learning framework aims to reconstruct a test fundus image with multiple features from as few training subjects as possible. The linear version of this problem could be casted into a multi-task joint covariate selection model, which can be very efficiently optimized via kernelizable accelerated proximal gradient method. Extensive experiments are conducted in order to validate the proposed framework on the SiMES dataset. From the Area Under Curve (AUC) results in multiple ocular diseases classification, our method is shown to outperform the state-of-the-art algorithms.

The Prevalence and Pattern of Refractive error in Ogun State, Nigeria

Objective: To determine the prevalence and pattern of refractive errors in Ogun State, Nigeria. The prevalence of blindness was also determined.
 Method: A cross sectional descriptive survey. Participants aged 15years and above were randomly selected from 1125 attendees of different community medical outreaches conducted in 5 Local government areas of Ogun State between August 2012 and March 2013. Participants underwent ocular examination and refraction (automated objective and subjective assessments).
 Results: The sample consisted of 780 participants. Their mean age was 49.14 (±18.37), and 52.8% were females. About two-thirds [67.7%] had presenting visual acuity [VA] of at least 6/18, while 14.3% were legally blind [VA worse than 3/60].Astigmatism was the most prevalent refractive error [40%] but on conversion tospherical equivalents, hyperopia [28.5%] became the most prevalent error. Apart from refractive errors, cataract and glaucoma were found to be the other major causes of visual impairment amongst the respondents.
 Conclusion: The prevalence of refractive errors and blindness in the study population was higher than previously documented with hyperopia being the most prevalent spherical equivalent refractive error. An urgent integration of primary eye care into the existing primary health care system for prevention of blindness is advocated.

Receptor mediated disruption of retinal pigment epithelium function in acute glycated-albumin exposure

Diabetic macular edema (DME) is a major cause of visual impairment. Although DME is generally believed to be a microvascular disease, dysfunction of the retinal pigment epithelium (RPE) can also contribute to its development. Advanced glycation end-products (AGE) are thought to be one of the key factors involved in the pathogenesis of diabetes in the eye, and we have previously demonstrated a rapid breakdown of RPE function following glycated-albumin (Glyc-alb, a common AGE mimetic) administration in monolayer cultures of fetal human RPE cells. Here we present new evidence that this response is attributed to apically oriented AGE receptors (RAGE). Moreover, time-lapse optical coherence tomography in Dutch-belted rabbits 48 h post intravitreal Glyc-alb injections demonstrated a significant decrease in RPE-mediated fluid resorption in vivo. In both the animal and tissue culture models, the response to Glyc-alb was blocked by the relatively selective RAGE antagonist, FPS-ZM1 and was also inhibited by ZM323881, a relatively selective vascular endothelial growth factor receptor 2 (VEGF-R2) antagonist. Our data establish that the Glyc-alb-induced breakdown of RPE function is mediated via specific RAGE and VEGF-R2 signaling both in vitro and in vivo. These results are consistent with the notion that the RPE is a key player in the pathogenesis of DME.

A functional approach to cerebral visual impairments in very preterm/very-low-birth-weight children.

Cerebral visual impairment (CVI) is a major cause of visual impairment, with very preterm birth/very low birth weight (VP/VLBW) being a major risk factor. There is no generally accepted definition of CVI. This study aims to investigate the usefulness of an empirically-based functional definition of CVI. One-hundred-five VP/VLBW children and 67 controls participated. CVI was defined after comprehensive oculomotor, visual sensory and perceptive assessment, and validated against vision problems in daily life and in terms of intellectual, behavioral, emotional and social functioning, as well as use of therapeutic services. Twenty-four per cent of the VP/VLBW children met criteria for CVI, compared to 7% of controls (P = 0.006, OR: 3.86, 95% CI: 1.40-10.70). VP/VLBW children with CVI had lower performance IQ, but not verbal IQ, than those without CVI. Visual problems in daily life were confirmed in VP/VLBW children classified with CVI. Additionally, difficulties in behavioral and social functioning were most prominent among VP/VLBW children with CVI. In VP/VLBW children, CVI defined in terms of visual function deficits is accompanied by intellectual, behavioral, and social impairments, validating our operational definition of CVI. CVI might act as a marker for developmental problems in VP/VLBW children.

Baseline traits of patients presenting at a low vision clinic in Shanghai, China.

BackgroundLow vision, along with cataract, trachoma, onchocerciasis, childhood blindness and refractive error, is one of the priorities in the global initiative, VISION 2020-The Right to Sight. The purpose of this study was to characterize the traits of patients presenting at a low vision clinic in China.MethodsA retrospective study was conducted of the records of 299 patients who visited the Low Vision Clinic of Eye and ENT Hospital Affiliated to Fudan University from January 2009 to May 2014. Reviewed parameters included age, gender, education, occupation, cause of visual impairment and types of low vision aids (LVAs) dispensed.ResultsOf all the patients (193 male; aged from 3 to 96 years, with a mean of 29.74 ± 25.23 years), 43.48% experienced moderate visual impairment, 25.42% had severe visual impairment and 21.07% were blind. The four major causes of visual impairment were congenital cataract (14.38%), degenerative myopia (13.71%), juvenile macular degeneration (9.36%) and retinitis pigmentosa (9.36%). The most common causes of visual impairment were congenital cataract (22.67%) in 0-19-year-olds, retinitis pigmentosa (20.62%) in 20-59-year-olds, and age-related macular degeneration (36.54%) in the 60+ group. With the help of LVAs, a significant improvement of distance and/or near vision or visual field was observed in 243 patients, of whom 185 accepted LVAs and 58 patients refused due to high price, inconvenience, young age (≤6 y), clumsy appearance and ignorance. The most commonly dispensed LVAs were stand magnifiers (21.57%) followed by spectacle-type LVAs (19.21%).ConclusionsThe majority of the patients in our low vision clinic were young, the main causes of visual impairment were congenital and hereditary diseases. Stand magnifiers were the most commonly dispensed LVAs. High price was the major reason for refusing LVAs.

Progress in histopathologic and pathogenetic research in a retinitis pigmentosa model.

Retinitis pigmentosa is a major cause of visual impairment and blindness, affecting millions of people worldwide. The mechanisms of and effective treatments for the disease, however, remain to be further investigated. The Royal College of Surgeons rat is one of the most widely used animal models for the study of retinal degeneration diseases. The mutation in the mer tyrosine kinase proto-oncogene of this model leads to deficient phagocytosis in the retinal pigment epithelium cells and the accumulation of photoreceptor out segments in the subretinal space, ultimately resulting in retinal degeneration. The retina begins to change as early as 17 days after birth and becomes gradually thinner with the death and remodeling of cells and blood vessels. Retinal cell apoptosis plays a dominant role in this degeneration, with some cells being activated by the secondary alterations of the retinal neurotransmitter and other related factors.

Visual Outcome in Ocular Toxoplasmosis: A Case Series of 30 Patients from Ghana

Purpose: To determine visual outcome (low vision and blindness) in patients with inactive ocular toxoplasmosis. Methods: This study employed a cross sectional design involving a series of 30 patients with inactive toxoplasmic ocular lesions. Ophthalmic assessment including best corrected visual acuity (BCVA) measurement, slit lamp biomicroscopy, and dilated fundus examination by indirect ophthalmoscopy was performed on all participants. Ocular toxoplasmosis was diagnosed based on characteristic retinal lesions in addition to a positive serologic testing using commercial ELISA kits. Visual impairment (VI) was determined based on the International Classification of Diseases. Results: Their ages ranged from 16-59 years (mean age of 34.2 ± 14.19), with 19 (63.3%) males and 11 (36.7%) females. There were 33 infected eyes in all (3 patients had bilateral cases). The most common complaint (77%) was blurred vision in the infected eyes. 11 (33%) eyes had mild or no visual impairment (VI category 1), 22 (67%) eyes had low vision (VA<6/18), and 11 (33%) eyes were blind (VA<3/60). Posterior pole (p<0.001) and larger retinal lesions (p=0.04) were the major causes of visual impairment. However, there was no association between visual impairment and the number of lesions occurring in the infected eyes (χ2=3.52, p=0.11). Older patient age was significantly associated with: posterior pole lesions (0.003), larger retinal lesion sizes (p=0.001) and multiple lesions (p=0.001). Only three cases each of strabismus and bilateral involvement suggest that acquired infection is more common in this Ghanaian population. Conclusion: Low vision and blindness were common in Toxoplasma eye infection in our Ghanaian population and that posterior pole and larger retinal lesions rather than multiple lesions were the major causes of reduced vision.

Pathogenesis of Common Ocular Diseases.

Pathogenesis of Common Ocular Diseases.

Approach to the Geriatric Patient

As of 2012, over one in eight Americans is over the age of 65, and this number is rising, particularly in the 85+ age group. This segment of the population has a rate of hospitalization three times higher than that for persons of all ages. General internists and family medicine physicians provide a large portion of care for this age group and should therefore be comfortable using a comprehensive approach to geriatric assessment. This review describes general considerations regarding geriatric care, including the process of taking a functional history and clinical implications of geriatric care. The geriatric assessment process is discussed in terms of physical, cognitive, social, and medical domains. The benefits of geriatric assessment in primary care, specialty care, and hospitalized patients are described. Tables outline activities of daily living, sensory changes with aging, major causes of visual impairment in the geriatric population, major neurocognitive disorder diagnostic criteria, medications to avoid or use with caution based on Beers criteria and Screening Tool of Older individuals’ Potentially inappropriate Prescriptions criteria, U.S. Preventive Services Task Force–recommended services relevant to older adults, and vaccinations in older adults. Figures illustrate the key vulnerabilities of older adults; outcomes linked to functional dependence; common disorders associated with cognitive concerns; domains of cognition and examples of impairment in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition; the social and medical domains of geriatric assessment; barriers to medication adherence in older patients; and resources for medication appropriateness in older adults. This review contains 8 highly rendered figures, 8 tables, 110 references, and 5 MCQs.

Approach to the Geriatric Patient

As of 2012, over one in eight Americans is over the age of 65, and this number is rising, particularly in the 85+ age group. This segment of the population has a rate of hospitalization three times higher than that for persons of all ages. General internists and family medicine physicians provide a large portion of care for this age group and should therefore be comfortable using a comprehensive approach to geriatric assessment. This review describes general considerations regarding geriatric care, including the process of taking a functional history and clinical implications of geriatric care. The geriatric assessment process is discussed in terms of physical, cognitive, social, and medical domains. The benefits of geriatric assessment in primary care, specialty care, and hospitalized patients are described. Tables outline activities of daily living, sensory changes with aging, major causes of visual impairment in the geriatric population, major neurocognitive disorder diagnostic criteria, medications to avoid or use with caution based on Beers criteria and Screening Tool of Older individuals’ Potentially inappropriate Prescriptions criteria, U.S. Preventive Services Task Force–recommended services relevant to older adults, and vaccinations in older adults. Figures illustrate the key vulnerabilities of older adults; outcomes linked to functional dependence; common disorders associated with cognitive concerns; domains of cognition and examples of impairment in the Diagnostic and Statistical Manual of Mental Disorders, fifth edition; the social and medical domains of geriatric assessment; barriers to medication adherence in older patients; and resources for medication appropriateness in older adults. This review contains 8 highly rendered figures, 8 tables, 110 references, and 5 MCQs.

Prevalence and causes of visual impairment and rate of wearing spectacles in schools for children of migrant workers in Shanghai, China.

BackgroundTo assess the prevalence of visual impairment and rate of wearing spectacles in schools for children of migrant workers in Shanghai, China.MethodsChildren from grade 1 to 5 in schools for children of migrant workers were randomly chosen for ocular examinations. All children were screened for uncorrected visual acuity and presenting visual acuity. After screening, the children whose uncorrected visual acuity was 20/40 or less received ocular motility evaluation, cycloplegic refraction/non-cycloplegic refraction, and external eye, anterior segment, media, and fundus examinations.ResultsA total of 9673 children were enumerated and 9512 (98.34%) participated in this study. The prevalence of uncorrected, presenting, and best-corrected visual acuity of 20/40 or worse in the better eye were 13.33%, 11.26%, and 0.63%, respectively. The rate of wearing spectacles of the children with visual impairment in one or both eyes was 15.50%. Of these, 26.05% were wearing spectacles with inaccurate prescriptions. Refractive error was a major cause of visual impairment, accounting for 89.48% of all the visual impairment causes. Other causes of visual impairment included amblyopia accounting for 10.12%; congenital cataract, 0.1%; congenital nystagmus, 0.1%; ocular prosthesis, 0.1%; macular degeneration, 0.05%; and opaque cornea, 0.05%.ConclusionsThis is the first study of the prevalence and causes of visual impairment in schools for children of migrant workers in Shanghai, China. The visual impairment rate in schools for children of migrant workers in suburbs of Shanghai in the best eye before vision correction was lower than those of urban children in mainstream schools in Guangzhou in 2012, and higher than students in rural of Beijing in 1998 and in suburb of Chongqing in 2007. The refractive error was the principal cause of the visual impairment of the children of migrant workers. The rate of wearing spectacles was low and the percentage of inaccurate prescriptions, among those who wore spectacles, was high. Uncorrected refractive error was a significant cause of visual impairment in migrant children.

Prevalence of refractive error and visual impairment among rural school-age children of Goro District, Gurage Zone, Ethiopia.

Refractive error is one of the major causes of blindness and visual impairment in children; but community based studies are scarce especially in rural parts of Ethiopia. So, this study aims to assess the prevalence of refractive error and its magnitude as a cause of visual impairment among school-age children of rural community. This community-based cross-sectional descriptive study was conducted from March 1 to April 30, 2009 in rural villages of Goro district of Gurage Zone, found south west of Addis Ababa, the capital of Ethiopia. A multistage cluster sampling method was used with simple random selection of representative villages in the district. Chi-Square and t-tests were used in the data analysis. A total of 570 school-age children (age 7-15) were evaluated, 54% boys and 46% girls. The prevalence of refractive error was 3.5% (myopia 2.6% and hyperopia 0.9%). Refractive error was the major cause of visual impairment accounting for 54% of all causes in the study group. No child was found wearing corrective spectacles during the study period. Refractive error was the commonest cause of visual impairment in children of the district, but no measures were taken to reduce the burden in the community. So, large scale community level screening for refractive error should be conducted and integrated with regular school eye screening programs. Effective strategies need to be devised to provide low cost corrective spectacles in the rural community.

Cost-Effectiveness Analysis of Latanoprost Compared with Dorzolamide/Timolol Fixed Combination for the Treatment of Open-Angle Glaucoma and Ocular Hypertension Patients in Korea.

Glaucoma is a major cause of visual impairment and a chronic disease requiring treatment for lifetime. Management of intraocular pressure (IOP) is the main focus of treatment, and many pharmacological treatment agents are recommended and available in Korea. This study was conducted to facilitate efficient allocation of limited resources amongst various pharmacological agents. The objective of this study was to evaluate costs and effectiveness of two most commonly used drugs in Korea which are latanoprost and dorzolamide/timolol fixed combination. A decision analytic model was developed from a payer perspective to evaluate clinical effectiveness, costs and utility values of latanoprost and dorzolamide/timolol fixed combination. The model was constructed based on a one-month cycle with a time horizon of one year. The treatment success to measure effectiveness was defined as achieving a ≥20% reduction IOP from baseline. Costs of medication, diagnostic fees, physician and pharmacy visitation fees, and surgery fees were included in the study. Utility values according to the severity of glaucoma were also incorporated in the model. Treatment success and failure rates as well as utility for each health state were obtained from previously published literature and local market analysis data. Cost information was obtained from Korea-specific data sources. The result of this study was expressed in an incremental cost-effectiveness ratio (ICER). One-way sensitivity analysis was conducted to evaluate different clinical parameters. The final effectiveness values for latanoprost and dorzolamide/timolol fixed combination were 0.9098 and 0.9089 in quality-adjusted life year (QALY), and the final costs were 550,737 KRW and 534,789 KRW respectively. Latanoprost displayed an ICER of 17,500,246 KRW/QALY compared to dorzolamide/timolol fixed combination. Under the currently implied ICER threshold in Korea, latanoprost can be interpreted as a cost-effective treatment option compared to dorzolamide/timolol fixed combination on the treatment of glaucoma.

Diagnosis of diabetic retinopathy by employing image processing technique to detect exudates in retinal images

Diabetic retinopathy (DR) is a microvascular complication of long-term diabetes and it is the major cause of visual impairment because of changes in blood vessels of the retina. Major vision loss because of DR is highly preventable with regular screening and timely intervention at the earlier stages. The presence of exudates is one of the primitive signs of DR and the detection of these exudates is the first step in automated screening for DR. Hence, exudates detection becomes a significant diagnostic task, in which digital retinal imaging plays a vital role. In this study, the authors propose an algorithm to detect the presence of exudates automatically and this helps the ophthalmologists in the diagnosis and follow-up of DR. Exudates are normally detected by their high grey-level variations and they have used an artificial neural network to perform this task by applying colour, size, shape and texture as the features. The performance of the authors algorithm has been prospectively tested by using DIARETDB1 database and evaluated by comparing the results with the ground-truth images annotated by expert ophthalmologists. They have obtained illustrative results of mean sensitivity 96.3%, mean specificity 99.8%, using lesion-based evaluation criterion and achieved a classification accuracy of 99.7%.

Visual Consequences of Refractive Errors in the General Population

To study the frequency and causes of visual impairment in relation to refractive error. Population-based cohort study. A total of 6597 participants from Rotterdam Study I (baseline and 4 follow-up examinations) and 2579 participants from Rotterdam Study II (baseline and 2 follow-up examinations), all 55 years or older, were included. Participants underwent an extensive ophthalmic examination, including best-corrected visual acuity and objective refraction, fundus photography, visual field perimetry, and optical coherence tomography imaging of macula and optic disc. We calculated cumulative risks and odds ratios of visual impairment for various refractive error categories and determined causes by using all screening information as well as medical records. Unilateral and bilateral low vision (World Health Organization [WHO] criteria, VA < 0.3 and VA ≥ 0.05; United States (US) criteria, VA < 0.5 and VA ≥ 0.1) and blindness (WHO criteria, VA < 0.05; US criteria, VA < 0.1). Cumulative risks of visual impairment ranged from virtually 0 in all refractive error categories at 55 years of age to 9.5% (standard error, 0.01) for emmetropia and 15.3% (standard error, 0.06) for high hyperopia to 33.7% (standard error, 0.08) for high myopia at 85 years of age. The major causes of visual impairment in highly hyperopic persons were age-related macular degeneration (AMD), cataract, and combined causes (each 25%); in highly myopic persons, the major cause was myopic macular degeneration (38.9%). The major causes of visual impairment for the other refractive error categories were AMD and cataract. Compared with those with emmetropia, those with high myopia had a significantly increased lifetime risk of visual impairment; those with -6 diopters (D) or less and -10 D or more had an odds ratio (OR) risk of 3.4 (95% confidence interval [CI], 1.4-8.2) of visual impairment; those with less than -10 D had an OR of 22.0 (95% CI, 9.2-52.6). Of all refractive errors, high myopia has the most severe visual consequences. Irreversible macular pathologic features are the most common cause of visual impairment in this group.