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Biomedical subjects

J C Townsend

Publications and source records attributed to J C Townsend.

At least 19 recordsLinked to original sources
PubMed2001

Amelanotic choroidal nevus and melanoma: cytology, tumor size, and pigmentation as prognostic indicators.

BACKGROUND: Choroidal nevi are fairly common lesions of the posterior pole that can sometimes transform into melanoma, and it is thought that most choroidal melanomas arise from preexisting nevi. Occasionally, these lesions present as nonpigmented or amelanotic variations of their pigmented counterparts. Recent studies suggest a relationship between tumor pigmentation and risk of growth and metastasis, with a better prognosis for lightly pigmented or amelanotic lesions. CASE REPORTS: A case of an amelanotic choroidal nevus and melanoma are presented. In Case 1, a 26-year-old white female was found to have a large amelanotic nevus in the right eye. After 7 years of periodic observation, the lesion has not changed. In Case 2, a 51-year-old white male was diagnosed with a large amelanotic melanoma in the left eye. Due to extensive involvement of the optic nerve, the patient underwent enucleation. Histological evaluation confirmed the lesion as a mixed-cell type malignant amelanotic melanoma. CONCLUSION: Management of choroidal nevi generally consists of periodic observation, and the most widely accepted management of choroidal melanoma is observation, radiotherapy, and transpupillary thermotherapy or enucleation. The therapeutic modality of choice for melanoma will vary depending on the size, growth, and location of the lesion. In addition, recent studies suggest an association between heavy tumor pigmentation, tumor size, cell type, and risk of metastasis. Although many variables will influence the final treatment option, pigmentation of the lesion should also be considered.

Adult↗
PubMed2001

Non-Hodgkin's orbital lymphoma.

BACKGROUND: The non-Hodgkin's lymphomas (NHL) are a group of neoplasms characterized by proliferation of malignant lymphocytes. Patients with NHL have a wide variety of presenting signs and symptoms, depending largely on the site of involvement and aggressiveness of the disease. Many organs in the body may be affected, including the eye and orbit. CASE REPORT: A 47-year-old male with a 3-year history of stage IV non-Hodgkin's lymphoma who had undergone recent monoclonal antibody therapy presented with a complaint of blur in the left eye with occasional diplopia. Significant ocular findings of the left eye included ptosis, mild proptosis, increased intraocular pressure, and choroidal folds. Magnetic resonance imaging of the orbit revealed an orbital lymphoma that completely resolved after 2400 rads of external beam irradiation therapy. Eight months later, the patient developed a secondary radiation retinopathy. CONCLUSION: The prevalence of NHL is on the rise, and orbital involvement may occur at any time during the course of the disease. The standard treatment for non-Hodgkin's orbital lymphoma is external beam irradiation therapy, although the optimal dose for obtaining local tumor control without complications remains to be determined. Non-Hodgkin's lymphoma, orbital lymphoma, and various treatment options are discussed.

Exophthalmos↗
PubMed2000

The normal optic nerve head.

BACKGROUND: The normal optic nerve head varies from one person to another, and there is often intraindividual variation as well. Factors such as race and age play an important role in distinguishing what may be considered normal variations in optic nerve head appearance. METHODS: A literature search and review of the latest studies on the optic nerve head was conducted. RESULTS: Results of recent studies showed that variations in the average cup-to-disc ratio exist for different races, and with age there is a gradual loss of nerve fibers leading to an overall increase in the cup-to-disc ratio. There is also evidence that congenitally larger optic nerves have larger cup-to-disc ratios and more nerve fibers. Smaller optic nerves, in contrast, have smaller cup-to-disc ratios and fewer nerve fibers. These findings are presented along with sample photographs depicting the normal variations in optic nerve head appearance. CONCLUSION: Over the past 30 years, technology has allowed for changing views about what may be considered normal in reference to the optic nerve head. This information is valuable to the eye care practitioner in helping to make appropriate patient care management decisions.

Aging↗
PubMed2000

Ocular toxicity of systemic medications: a case series.

BACKGROUND: There are many visually threatening conditions that may result from long-term use of systemic medications. Many of these adverse side effects can be greatly reduced or prevented with close monitoring of patients. In view of current knowledge, updated clinical guidelines for appropriate monitoring of ocular toxicity from systemic medications need to be developed for the eye care practitioner. CASE REVIEW: There have been many reports of ocular toxicity from isoniazid, thioridazine, steroids, and amiodarone therapy. Clinical cases illustrating possible adverse ocular side effects are presented, which include INH-induced optic neuropathy, phenothiazine-induced retinopathy, steroid-induced glaucoma, and vortex epitheliopathy secondary to amiodarone. CONCLUSION: Optometrists should be aware of the potential for ocular side effects from systemic medications. Eye care guidelines for monitoring ocular side effects from thioridazine, INH, steroids, and amiodarone use are suggested.

Adult↗
PubMed2000

Case presentations of retinal artery occlusions.

BACKGROUND: Retinal artery occlusions typically result in sudden, unilateral painless loss of vision and may have varying presentations. They are associated with systemic diseases such as atherosclerosis, hypertension, and valvular heart disease. Additional risk factors include diabetes mellitus, cigarette smoking, giant-cell arteritis, and hyperlipidemia. They most often occur in persons 60 to 80 years of age. METHODS: Four patients have come to our clinics with varying degrees of visual loss as a result of retinal artery occlusions. The types of arteriolar occlusions presented include: precapillary arteriole occlusion, cilioretinal artery occlusion, branch retinal artery occlusion, and central retinal artery occlusion. RESULTS: Patients were followed for their ocular involvement, but also included was medical management of the underlying systemic disease condition. Workup of retinal artery occlusion included laboratory testing, carotid duplex scans, and echocardiograms to uncover the possible systemic etiologies of the artery occlusion. CONCLUSION: Optometrists should recognize the signs and symptoms of the various arterial obstructions and refer patients for systemic treatment as indicated. Patients who manifest retinal or pre-retinal artery occlusions should undergo thorough systemic evaluations for vascular disease, including: atherosclerotic disease, hypertension, and valvular heart disease.

Aged↗
PubMed1998

Retinitis pigmentosa inversa.

BACKGROUND: Retinitis pigmentosa (RP) is one of the most common inherited retinal diseases, with a prevalence of about 1 in 3500 to 4500. Retinitis pigmentosa inversa is a rare variant of this disorder characterized by areas of choroidal degeneration with pigment migration and bony spicule formation in the macular area. In contrast to more typical forms of RP, this anomaly destroys central vision, leaving peripheral vision intact. CASE REPORT: A 47-year-old white male was followed for about 7 years with evidence of progressive retinal pigment epithelial atrophy and hyperpigmentation affecting both maculae. Since 1970, he had noted difficulty seeing at night as well as an acquired hearing deficit that appeared to be getting worse, ultimately impairing his ability to safely drive a truck. Medical history was positive for either chloroquine or hydroxychloroquine use for 2 to 3 years as malaria prophylaxis while he served in Vietnam. In addition, his father in Louisiana had visual loss of unknown cause. During the 7-year period, the condition progressed rapidly. The patient became virtually blind secondary to visual acuity loss with dense central and paracentral scotomas. The peripheral visual fields remained intact. After several years of extensive examinations, including laboratory, electroretinography, and genetic testing, a definitive diagnosis of RP inversa was made. DISCUSSION: RP inversa is a rare form of tapetoretinal degeneration that is characterized by decreased central vision with normal peripheral vision. A recessive form of inheritance has been postulated but never substantiated. Although there is currently no treatment, recent studies have indicated that 15,000 IU of vitamin A palmitate daily may slow the progression of retinitis pigmentosa; however, it is unknown whether this treatment would be effective for the inverse form of RP. Differential diagnoses include Leber's congenital amaurosis, central gyrate atrophy, central areolar choroidal sclerosis, progressive cone-rod dystrophy, syphilitic retinopathy, retinal toxicity from phenothiazine use, and chloroquine/hydroxychloroquine retinopathy.

Adult↗
PubMed1998

Weber's syndrome secondary to subarachnoid hemorrhage.

BACKGROUND: Since a large intracranial hemorrhage is a space-occupying mass, it may cause the brain to shift, resulting in neurologic deficits both at the location of the bleeding and at a site distal to the hemorrhage. A parietal lobe hemorrhage may push the brain downward, causing the uncus of the temporal lobe to herniate through the tentorial notch, compressing the midbrain. The signs of parietal lobe damage, uncal herniation, and several midbrain syndromes that effect ocular motility are discussed. CASE REPORT: A 66-year-old Hispanic man came to us with a history of a subarachnoid hemorrhage that involved the right parietal lobe. Several signs of damage to both the right parietal lobe and midbrain were evident, including an ipsilateral third nerve paresis with contralateral hemiplegia, Weber's syndrome. CONCLUSION: A patient who survives a subarachnoid hemorrhage may demonstrate permanent residual neurologic deficits subsequent to the acute event. The presentation is particularly complex when the hemorrhage is large and damage occurs at multiple locations. Damage at the level of the midbrain is evident when the findings include Weber's syndrome, which is one of several syndromes that involves the oculomotor nerve.

Aged↗
PubMed1998

Acute vision loss resulting from complications of ethanol abuse.

BACKGROUND: Alcoholism affects about 10% of men and 3% to 5% of women in their lifetime. It is a primary chronic disease with genetic, psychosocial, and environmental factors that influence its development and manifestations. METHODS: A 47-year-old alcoholic male manifested mild nutritional optic atrophy, chronic anemia, pancreatitis, and previous gastrojejunostomy and pancreaticojejunostomy. After an acute episode of hypovolemic blood loss from peptic ulceration, there was increased bi-temporal optic nerve head pallor with permanent vision loss, central scotoma, and an acquired red-green color vision defect. RESULTS: The genetic, psychosocial, and systemic effects of ethanol abuse--including anemia, cardiomyopathy, gastric/duodenal ulceration, pancreatitis, and neurologic deficits--are reviewed. Appropriate treatment and management of ocular manifestations and complications from alcoholism are discussed. Prophylactic topical therapy may be indicated to restore the balance between intraocular tension and optic nerve head perfusion in an attempt to prevent further axonal loss. CONCLUSION: Alcohol-induced nutritional optic neuropathy should not be viewed as an isolated ocular entity, but rather as a potentially treatable neurologic problem. An interdisciplinary approach is essential optimal in the management of the alcoholic patient.

Acute Disease↗
PubMed1997

Choroidal metastases resulting from carcinoma of the lung.

BACKGROUND: Choroidal metastases, the most commonly observed tumors of the choroid, are a frequent sequela of lung cancer. Carcinoma of the lung is the most common cancer. Choroidal metastatic tumors can be observed before or after the definitive diagnosis of a lung carcinoma. METHODS: A 42-year-old man, examined 1 month after reporting an ache and blurry vision in his left eye, was found to have an elevated, irregular-shaped choroidal lesion in the eye. The second patient, a 53-year-old man, was examined 1 week after reporting dim vision in the left eye. Diagnosed with non-small-cell lung carcinoma 5 months earlier, he was found to have bilateral choroidal lesions. RESULTS: The first patient was diagnosed with choroidal metastasis from adenocarcinoma of the lung 8 months after the initial presentation, confirmed after a fine-needle aspiration biopsy. The second patient had bilateral choroidal metastases from disseminated lung carcinoma. CONCLUSIONS: Metastases to the eye or orbit develop in approximately 0.7% to 12% of patients with lung cancer. Treatment regimens depend on the size and extent of the choroidal tumor, number of tumors, laterality, the visual status of the affected or nonaffected eye, the stage of cancer, and the age and general health of the patient. Prognosis is contingent on vital organ involvement and response to therapy. Preserving the patient's visual status may enhance the quality of remaining life.

Adenocarcinoma↗
PubMed1997

Optometric management of patients with Alzheimer's disease.

BACKGROUND: The earliest symptoms of Alzheimer's disease (AD) may be visual. AD is an age-related, progressive dementia. At least 7% of Americans over 65 years of age are afflicted, and it ranks as the fourth leading cause of death in the United States. A review of the literature was performed to delineate the visual manifestations of Alzheimer's disease. RESULTS: Abnormal visual perception and visuospatial processing are common among patients with AD Visual acuity, pupillary light reflexes, and the ocular fundus do not appear to be specifically affected by AD. Whether AD impairs color vision is controversial. Stereopsis may also be affected. True visual-field defects are rarely found. Although not universally reported, some studies of contrast sensitivity functions show abnormal sensitivity possibly at low spatial frequencies. The electroretinogram is normal, while the visual evoked response is frequently abnormal. CONCLUSIONS: As primary eye care providers, optometrists must properly identify and refer individuals with suspected Alzheimer's disease to the appropriate specialist, as well as manage their visual welfare.

Aged↗
PubMed1997

Traumatic porencephalic cyst of the brain.

BACKGROUND: A porencephalic cyst is a cavity within the cerebral hemisphere, filled with cerebrospinal fluid, that communicates directly with the ventricular system. It is a rare condition probably caused by vascular occlusion resulting from an insult during fetal development or an injury occurring later in life. Porencephaly is often associated with various ophthalmic and neurologic signs, including visual-field defects, abnormal pupillary responses, optic nerve hypoplasia, decreased vision, nystagmus, strabismus, hemi-inattention, seizures, and mental deficiencies. CASE REPORTS: Two cases are presented of patients in whom porencephalic cysts developed as a result of traumatic head injuries. Both had demonstrable visual-field defects, with diagnosis of porencephaly verified by computed tomography scans of the head. CONCLUSIONS: Visual-field defects resulting from porencephalic cysts can mimic those observed with strokes or brain tumors. A thorough case history and complete neurologic workup can assist with differential diagnosis. The clinical features of porencephaly, different theories of brain recovery after trauma, and treatment options are discussed.

Adult↗
PubMed1996

Colloid cyst of the third ventricle.

BACKGROUND: Colloid cyst of the third ventricle has rarely been reported in the ophthalmic literature. The incidence is about one per 1000 in asymptomatic patients and accounts for 0.55 to 2 percent of all intracranial tumors. Although it is an uncommon benign tumor, nearly half of symptomatic patients present with papilledema and hydrocephalus. Consideration of this intracranial tumor should be included in the differential diagnosis of papilledema and apparent unilateral disc edema. METHODS: A patient with highly asymmetrical papilledema and vague visual symptomatology involving the right eye was studied. Computer axial tomography (CT) without contrast enhancement revealed a colloid cyst of the third ventricle. Typical symptoms of the condition include headaches, nausea, vomiting, visual obscuration, transient diplopia and weakness of the lower extremities, which are due to acute hydrocephalus caused by increased intracranial pressure from cystic obstruction of the foramen of Monro. Intermittency of symptoms is characteristic of this lesion. RESULTS: The patient underwent frontal craniotomy with total tumor excision and reopening of the cerebrospinal fluid pathway. CONCLUSIONS: Colloid cyst of the third ventricle discovered incidentally on CT in asymptomatic patients with no evidence of hydrocephalus can be monitored periodically. If symptomatic, neurosurgery is usually indicated since prolonged increased intracranial pressure can lead to mental and physical deterioration as well as sudden death.

Brain Diseases↗
PubMed1996

Presumed ocular tuberculosis in an AIDS patient.

BACKGROUND: Prior to the advent of anti-tuberculosis medications, ocular manifestations of tuberculosis, including choroidal tubercles, were common. METHODS: A 46-year-old Hispanic male with a history of AIDS, tuberculosis and treated neurosyphilis presented for examination complaining of decreased vision in the left eye. Ophthalmoscopy revealed a large, elevated, juxtapapillary lesion consistent with a choroidal tubercle or an intraocular lymphoma. RESULTS: During follow-up, the lesion responded well to systemic anti-tuberculosis therapy. CONCLUSIONS: With the recent increase in incidence of tuberculosis in both th general population and AIDS patients, ocular manifestations of tuberculosis once thought to be rare may be increasing. Ocular tuberculosis should be considered in the differential diagnosis of patients presenting with intraocular masses, especially in individuals at high risk for exposure.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Circumscribed choroidal hemangioma.

BACKGROUND: Circumscribed or solitary choroidal hemangioma is a relatively rare, benign vascular tumor. Because its appearance may mimic more serious intraocular lesions, eye care practitioners should be familiar with differential diagnosis and treatment options. METHODS: A patient presented with an asymptomatic, elevated, red-orange lesion above the macula in the right eye and a history of longstanding unexplained visual acuity loss in the eye. Intraocular lesions such as amelanotic melanoma, metastatic tumor, choroidal osteoma, disciform scar, serous detachment, and central serous chorioretinopathy can appear similar to circumscribed choroidal hemangioma (CCH) on ophthalmoscopy, but may be differentially diagnosed with fluorescein angiography, ultrasonography, and periodic observation. RESULTS: CCH requires various therapeutic options. Until the patient becomes symptomatic from visual loss secondary to serous macular detachment or subretinal neovascular membrane formation, no treatment is necessary. Laser photocoagulation is the preferred therapeutic intervention, and most patients will require a minimum of two sessions. A small percentage of individuals will progress to complete retinal detachment with profound visual loss regardless of therapy. Most CCHs remain stable in size and do not undergo malignant transformation. CONCLUSIONS: CCHs may be overlooked because of their initial subtle clinical appearance with no associated cutaneous or systemic anomaly. Even though CCH is a benign tumor, it may mimic more serious intraocular lesions and require a combination of ancillary tests for proper diagnosis. Depending on visual symptoms or potential threat to vision, management options include periodic observation, laser photocoagulation, cryotherapy, microwave therapy, and possible enucleation. CCH has little or no growth potential, but visual prognosis remains guarded due to significant secondary retinal changes that can occur over the tumor's surface. CCH must be considered in the differential diagnosis of an elevated intraocular lesion.

Aged↗
PubMed1995

Clinical implications of intra- and inter-reader agreement in four different automated visual fields.

BACKGROUND: This study was designed and conducted to examine the degree of inter- and intra-reader agreement when four readers evaluate visual fields in patients known to have glaucoma and patients known to not have glaucoma. METHODS: Fifty-three patients known to have glaucoma and 60 patients known not to have glaucoma were selected randomly from a population at the University of Alabama at Birmingham School of Optometry. Four visual fields were performed on each patient, non-dilated, with the proper correction in place. The fields were performed on three different instruments by technicians who were unaware of the diagnostic status of the patient. Four independent (blinded) clinicians read the visual fields and judged them as: "glaucoma field defect," "no glaucoma field defect," and "poor reliability-cannot judge." RESULTS: Statistical analysis revealed that a single reader's interpretation of four different types of visual fields are very different from, are poorer than, and are more consistent than are the four readers' interpretations of a single type of visual field. The analysis also shows that the readers consistently underestimated the number of glaucoma patients with one instrument and overestimated the number with another. CONCLUSIONS: This results suggest that a single visual field will discriminate patients with glaucoma with an accuracy in the 70 to 75 percent range. For one of the instruments, the shorter protocol was almost as effective in discriminating glaucomatous fields as the longer protocol. This study also suggests that repeating the visual fields or analysis of a single field by two readers improves reliability.

Aged↗
PubMed1995

Retinal nerve fiber layer defects and microtalc retinopathy secondary to free-basing "crack" cocaine.

BACKGROUND: There have been several reports in the literature documenting ocular manifestations of cocaine abuse. None have discussed the potential retinal complications stemming from cocaine inhalation. METHODS: Approximately 60 patients with a history of free-basing "crack" cocaine were examined at the Optometry Clinic. Threshold visual field testing and fundus photographs were obtained and later reviewed. RESULTS: Microtalc retinopathy and associated retinal nerve fiber layer "rake" or "slit" defects were detected exclusively in patients who had free-based "crack" cocaine. Some of these patients manifested visual field changes that mimic glaucoma. Several cases are presented that demonstrate the findings typical of those observed in the patients examined at the Optometry Clinic. CONCLUSIONS: Microtalc retinopathy and associated glaucoma-like retinal nerve fiber layer defects indicate the presence of permanent microvascular changes in the eyes, as well as the lungs, brain, and probably other peripheral organs. Optometrists should be aware of these new findings in order to properly manage patients who free-base "crack" cocaine.

Adult↗
PubMed1994

Papilledema secondary to metastatic prostate disease.

BACKGROUND: Prostate cancer increases in incidence with age, and is common in older men. If allowed to progress or detected late, prostate cancer readily metastasizes to bone and accounts for about 11 percent of all cancer deaths. Associated conditions with prostate metastatic disease are anemia, pathological bone fractures, and paraplegia. Occasionally, prostate cancer may metastasize to the skull or spinal cord and result in papilledema. Two cases presenting with papilledema secondary to metastatic prostate disease are discussed.

Adenocarcinoma↗