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Biomedical subjects

J C Townsend

Publications and source records attributed to J C Townsend.

At least 37 records · Page 2Linked to original sources

Clinical pearls in optometric management of the geriatric patient.

BACKGROUND: Painstaking attention to detail is absolutely necessary for optometrists to provide the appropriate clinical management of the geriatric patient. METHODS: Clinical management techniques (pearls) are discussed which aid in the diagnosis and treatment of problems specific to geriatric patients. Factors noted in patient presentation are stressed and include physical appearance, ability to move about, and use of other senses. The most commonly occurring eye anomalies occurring in the geriatric population are discussed including iatrogenic drug side effects, pupillary anomalies, extraocular palsies, dry eye, corneal degenerations, refractive error changes, lenticular changes, glaucoma, age-related maculopathy, vitreoretinal disease, and ocular manifestations of systemic disease (vascular occlusive disease, diabetes, ischemic optic neuropathy, other neuro-ophthalmic disease). RESULTS: Conditions relatively rare in the young population occur with regularity in the elderly population and often must be assumed to be present in concert with some typical patient presentations in the geriatric population. CONCLUSIONS: Optometrists as primary health care providers often provide the only avenue individuals with blinding and sometimes life threatening conditions have in managing these conditions. Optometrists managing geriatric patients are required to know what happens to this population from an ocular disease as well as other function and dysfunction standpoint.

Aged↗

Malignant melanoma of the choroid with literature review.

A 67-year-old white male presented for an eye examination with history of difficulty reading. Upon routine dilation, an unsuspected malignant melanoma of the choroid was discovered. Binocular indirect ophthalmoscopy, B-scan ultrasonography, and visual field testing helped confirm the initial diagnosis. Uveal malignant melanoma is the most common primary intraocular malignant tumor occurring in adults. Controversial issues regarding proper management of choroidal malignant melanoma are discussed.

Aged↗

Traumatic optic neuropathy complicated by thyroid eye disease.

BACKGROUND: Thyroid eye disease is the most common orbital disorder found in adults. Ocular changes may occur with or without systemic hyperthyroidism. Blunt orbital trauma can affect the eye in many ways and can confound and alter the natural course of thyroid eye disease. METHODS: A 76-year-old patient with a number of ophthalmic findings and associated symptoms which could have been related to previous blunt ocular trauma. Careful optometric evaluation, systemic laboratory testing, and review of the ocular and medical findings demonstrated the onset of thyroid dysfunction. RESULTS: Thyroid disease was diagnosed on the basis of the presence of enlarged extraocular muscles by CT scan and elevated tensions on attempted upgaze. The patient demonstrated an elevated T3 uptake and low TSH levels for which he was treated with propylthiouracil. The occurrence of thyroid disease and damage from blunt trauma confounded the diagnosis because forced duction testing and optic atrophy could well have been the result of previous blunt trauma. CONCLUSIONS: This case elucidates the many differential diagnoses and complications that result from the combination of previous blunt trauma and the occurrence of new thyroid disease with ophthalmic findings.

Aged↗

Superior quadrant visual field loss secondary to temporoparietal craniectomy for brain abscess.

BACKGROUND: Visual field defects occur from a variety of causes. As a result, the differential diagnosis of visual field defects and their etiology is important. METHODS: A 64-year old white male was examined in follow up related to the surgical removal of a right temporal lobe abscess secondary to a childhood right side mastoidectomy. The patient underwent ophthalmic examination, which suggested possible changes in his field of vision, and neurobehavioral evaluation related to his visual field defect, a left homonymous superior quadrant defect. RESULTS: Computed tomography (CT) scan of the head without contrast enhancement confirmed the ophthalmic diagnosis and correlated with the patient's medical history. However, neurobehavioral evaluation revealed a number of deficits that were believed to be associated with alcohol abuse. CONCLUSIONS: Visual field loss with changing vision symptoms and a complex history can confound the differential diagnosis of visual field defects. Frequently careful and complete evaluation can confirm and reveal subsequent diagnoses.

Brain Abscess↗

Central serous chorioretinopathy complicated by subsequent occipital lobe infarction and sinusitis in a drug abuser.

BACKGROUND: The presence of multiple occurring, simultaneously complicated clinical findings can be challenging. METHODS: A 39-year-old white male presented initially with central serous chorioretinopathy. Later, the patient reported a great deal of pain over his left eye with nasal vision loss. Comprehensive ophthalmic evaluation and neurologic consultation were invaluable in the diagnosis and management of the patient. RESULTS: Neurologic consultation along with computed tomography (CT) of the head with and without contrast enhancement along with magnetic resonance imaging (MRI) with and without gadolinium revealed lesions in the left occipital lobe, right cerebellum, and left thalamus area. In addition, bilateral maxillary and ethmoidal sinusitis were observed. CONCLUSIONS: Multiple events affecting vision are often related, sometimes not. However, co-existing factors can confound and obscure accurate diagnoses. Careful patient clinical and laboratory investigations are frequently necessary to elucidate correct diagnosis.

Adult↗

Support for the vasogenic theory of glaucoma: case reports and literature review.

BACKGROUND: The influence of systemic disease, vascular abnormalities, hematologic and rheologic factors, pulsatile ocular blood flow, perfusion pressure, autoregulation, optic disc hemorrhage and the results of optic nervehead fluorescein angiographic studies are reviewed in the context of supporting evidence for the vasogenic theory of glaucoma. METHODS: Two case reports of patients with confirmed carotid artery occlusive disease and one case report of a patient with a history of hypovolemic blood loss are presented. RESULTS: These cases illustrate the importance of hypotensive crisis, perfusion pressure, collateral blood flow and the optic nerve head vascular autoregulatory mechanism in the pathogenesis of glaucoma and the differential diagnosis of pseudoglaucoma. CONCLUSIONS: Evaluation and consideration of both mechanical and vasogenic causes of the glaucomas is essential in the management of the glaucomas. It is also necessary to differential diagnose the "pseudo-glaucomas," and to manage them correctly.

Aged↗

Visual field loss secondary to radiation-induced cerebral necrosis.

Radiation-induced cerebral necrosis has been well documented in the literature. Because radiation induced cerebral necrosis can occur to any part of the central nervous system that falls within the irradiated area, the visual pathway is highly susceptible to damage as it passes from the eye to the visual cortex. With proper visual field testing and interpretation, optometrists may serve as primary diagnosticians in radiation-induced cerebral necrosis and actively participate in the long-term management of these patients. This case presents a patient with visual field loss secondary to a temporal lobe lesion whose etiology was thought to be radiation-induced. The incidence, pathophysiology, and clinical features of radiation-induced cerebral necrosis as well as other differential diagnoses are discussed.

Aged↗

Parietal and bi-occipital lobe infarction confounded by ethanol-induced optic neuropathy.

A frequent occurrence in geriatric and chronically ill patients is the exhibition of several simultaneously occurring and confounding health problems. This paper reports the case of a 61-year-old-white male who presented with an extensive history of multiple brain infarcts, hemiparesis, personality changes and varied visual complaints. Tests in the neurooptometric work-up for this patient included static automated perimetry, stereoacuity and optokinetic nystagmus evaluation. The results were suggestive of multiple cerebrovascular accidents which included the right and left occipital lobes as well as the right parietal lobe. This clinical picture was complicated by the presence of nutritional or ethanol-induced optic neuropathy. Emphasis was placed on a detailed sequential history of events and a complete neurological and optometric evaluation to ascertain the multiple foci of cortical infarction. Corroboration of clinical findings was obtained by computerized axial tomography (CT scan).

Alcoholism↗

Localization of visual field defects in multiple sclerosis.

Demyelinating plaques can occur throughout the central nervous system in multiple sclerosis, possibly involving the visual pathways at any location. The proper evaluation of visual field defects in multiple sclerosis patients enables the optometrist to become a part of the health care team in monitoring the severity and progression of the disease. Three case reports are presented which illustrate the variable presentations and the proper interpretation of findings to localize demyelinating plaques in the visual pathways.

Adult↗

Congenital optociliary shunt vessels.

Congenital optociliary shunt vessels have rarely been reported in the literature. Three cases of congenital optociliary shunt vessels are presented: two with unilateral shunt vessels and one with bilateral shunt vessels. All three patients were asymptomatic with good visual acuity and essentially normal visual fields with no apparent change in visual function over time. Associated with congenital optociliary shunt vessels is an anomalous bifurcation of the vasculature. Diagnostic implications of optociliary shunt vessels include 1) congenital variations, or 2) acquired secondary to a long-standing venous congestive event as occurs with optic nerve sheath meningioma, central retinal vein occlusion, papilledema, hyaloid bodies of the optic nervehead, dysthyroid optic neuropathy, and papillophlebitis.

Aged↗

Establishment of an external quality-assessment scheme for amino acid analyses: results from assays of samples distributed during two years.

Ten different samples of lyophilized plasma and two of liquid urine were distributed during two years to 26 laboratories performing quantitative amino acid analyses in a scheme designed to provide external quality assessment. After each distribution, statistical summaries and performance scores based on delta standard deviations and percentage biases from the all-laboratory trimmed means were returned to participants, who also received annual performance summaries based on their accumulated results. Coefficients of variation calculated from returns across all the samples ranged from 13% for glycine to 65% for methionine. Automated ion-exchange amino acid analyzers with ninhydrin detection appeared to perform better than other methods, although there was no clearly superior method and no model of analyzer clearly outperformed the others. These exercises demonstrate that there is room for improvement in the performance of quantitative amino acid analyses and that individual expertise may be more important in maintaining good performance than the choice of method or analyzer.

Amino Acids↗

Corneal arcus as an indicator of hypercholesterolemia.

For many years, corneal arcus has been documented as a normal, age-related change. Recent literature implies that corneal arcus is associated with elevated cholesterol, especially in the young, but that the association is not apparent in the elderly. This study demonstrates corneal arcus, regardless of age, as an indicator of elevated serum cholesterol, and as such, a sign of increased risk for cardiovascular disease.

Adult↗

Ocular effects of second generation oral hypoglycemic agents.

Second generation oral hypoglycemic agents, such as glyburide and glipizide, are often the treatment of choice in non-insulin dependent diabetes mellitus. These sulfonylureas are more potent osmotic agents than their predecessors and may give rise to crystalline lens changes and refractive error shifts in the absence of blood glucose variation. Such a case is presented, as is a detailed description of the mechanism of action of commonly prescribed oral hypoglycemic agents.

Administration, Oral↗

Albumin to creatinine ratio: an unreliable index of 24 h albumin excretion in healthy adults.

The urine albumin to creatinine ratio was studied on four timed collections during a 24 h period in a group of 30 healthy volunteers. The results show large within and between subject variation not explained by exercise, and the absence of a predictable diurnal pattern. It was not possible to predict the 24 h excretion of albumin from the albumin to creatinine ratio of a separately collected random urine sample. The large variations of the ratio observed in healthy subjects stress the need for 24 h urine collections rather than random samples when assessing albumin excretion.

Adult↗