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Biomedical subjects

T R Hedges

Publications and source records attributed to T R Hedges.

At least 19 recordsLinked to original sources
PubMed2005

Optical coherence tomography of the retinal nerve fibre layer in mild papilloedema and pseudopapilloedema.

AIMS: To determine the degree to which optical coherence tomography (OCT) can distinguish differences in retinal nerve fibre layer (RNFL) thickness between eyes with mild papilloedema, pseudopapilloedema, and normal findings. METHODS: 13 patients with mild papilloedema, 11 patients with congenitally crowded optic nerves, and 17 normal subjects underwent neuro-ophthalmic examination, automated visual field testing, and fundus photography. Spinal fluid pressure measurements were obtained in a subgroup of five patients with pseudopapilloedema and 11 patients with mild papilloedema. Circular OCT scans using a diameter of 3.38 mm surrounding the optic disc were performed in each eye of patients and subjects. Fundus photographs were analysed by two observers who diagnosed crowding or papilloedema and graded amounts of swelling. Findings were assessed by descriptive statistics and variance analysis. RESULTS: RNFL thickness was greater in the superior and inferior quadrants and showed a high degree of correlation between each group of patients and subjects. A statistically significant difference was found in mean RNFL thickness between both groups of patients with optic disc swelling and normal subjects. However, there was not a statistical difference in mean nerve fibre layer thickness between patients with papilloedema and those with congenitally crowded optic nerves. CONCLUSIONS: OCT demonstrates measurable differences in nerve fibre layer thickness between normal subjects and patients with either papilloedema or pseudopapilloedema. However, OCT does not appear to differentiate between those individuals with congenitally crowded optic nerves and those with mild papilloedema caused by increased intracranial pressure.

Adolescent↗
PubMed2002

Flow velocity and pulsatility of the ocular circulation in chronic intracranial hypertension.

OBJECTIVES: The aim of this study is to examine the relationship of ocular blood flow velocities and pulsatility to intracranial pressure (ICP). METHODS: We measured arterial and venous flow velocities using color Doppler imaging (CDI) and calculated resistance indices for the central retinal (CRA) and the ophthalmic (OA) arteries from 16 patients (32 eyes) with chronic intracranial hypertension (ICH) and varying degrees of ICP and papilledema. The results were compared with normal data from 16 age-matched, healthy subjects. RESULTS: Arterial flow velocities were significantly decreased for the aggregate subject group compared with controls. A corresponding rise in arterial resistance with increasing ICP in the mild-moderate range was noted. Unexpectedly, with more severe elevations of ICP these trends reversed. CONCLUSIONS: In mild-moderate increased cerebrospinal fluid (CSF) pressure, a reduction of flow velocities may result because of increased vascular resistance. Paradoxically, in more severe chronic ICH, we hypothesize that local autoregulatory vascular changes and/or diversion of cerebral blood flow into the ophthalmic circulation may normalize these parameters. This phenomenon may partially underlie the relative sparing of visual function early in the course of pseudotumor cerebri (PTC), regardless of actual ICP levels.

Adult↗
PubMed2001

Optical coherence tomography demonstrates subretinal macular edema from papilledema.

OBJECTIVE: To evaluate macular changes in eyes with papilledema from increased intracranial pressure using optical coherence tomography (OCT). METHODS: Fifty-five patients with papilledema seen during 1998 and 1999 were studied with OCT of the optic nerve and retinal nerve fiber layer. Nineteen of these also had OCT of the macula during periods of acute, subacute, or recurrent papilledema and were evaluated in detail for this report. RESULTS: Seven patients had OCT evidence of subretinal fluid involving the macula. All had some reduction in visual acuity. The subretinal fluid appeared to arise from the peripapillary region, and all showed some improvement in central vision as the fluid resolved. CONCLUSIONS: Subretinal fluid accumulations can cause decreased visual acuity in patients with papilledema. Optical coherence tomography can demonstrate subretinal fluid and can be used to follow the course of this important visual complication of papilledema.

Acute Disease↗
PubMed2001

Optic neuropathy in children with Lyme disease.

Involvement of the optic nerve, either because of inflammation or increased intracranial pressure, is a rare manifestation of Lyme disease. Of the 4 children reported here with optic nerve abnormalities, 2 had decreased vision months after disease onset attributable to optic neuritis, and 1 had headache and diplopia early in the infection because of increased intracranial pressure associated with Lyme meningitis. In these 3 children, optic nerve involvement responded well to intravenous ceftriaxone therapy. The fourth child had headache and visual loss attributable to increased intracranial pressure and perhaps also to optic neuritis. Despite treatment with ceftriaxone and steroids, he had persistent increased intracranial pressure leading to permanent bilateral blindness. Clinicians should be aware that neuro-ophthalmologic involvement of Lyme disease may have significant consequences. If increased intracranial pressure persists despite antibiotic therapy, measures must be taken quickly to reduce the pressure.

Adolescent↗
PubMed2000

Parasite control methods used by horse owners: factors predisposing to the development of anthelmintic resistance in nematodes.

One hundred and fifty horse owners, primarily private owners and riding schools, replied to a questionnaire concerning the practices they used to control parasites. Twenty-seven had experienced a parasite problem. Faecal samples from 188 horses selected at random showed that worm control practices were generally successful; however, many owners were not following recommendations for slowing the development of resistant parasites. In 1996, 86 per cent of the owners were using either three or two classes of anthelmintic a year, and they used a median of six doses with a range from one to 11. Approximately half the owners, more commonly owners of up to five horses, picked up their horses' faeces at least once a week, but these owners also used more doses of anthelmintic a year than owners who did not pick up faeces. One-third of the owners manually removed Gasterophilus species eggs from the horses' hairs, but 94 per cent of them also used ivermectin. Many owners treated specifically for Anoplocephala species, cyathostome larvae and Gasterophilus species, and these owners were the most likely to use three classes of anthelmintic a year. One-hundred-and-seven owners replied to a second questionnaire asking for information about the factors that influenced their anthelmintic control practices. Many owners, particularly private owners, were not influenced by the cost of the anthelmintic. For the timing and frequency of treatment, and the choice of drug, owners were most influenced by advertisements, magazine articles and veterinary surgeons. In two magazines aimed at horse owners, the brands of drugs most frequently advertised were the brands most commonly used by the owners, and articles in the magazines recommended the use of three classes of drug per year. These results are discussed in relation to their influence on the development of anthelmintic-resistant nematodes.

Animal Husbandry↗
PubMed1999

Retinal findings in Takayasu's arteritis.

PURPOSE: To describe unusual as well as typical ocular findings in eight patients with Takayasu's disease. METHODS: The ophthalmic manifestations and clinical courses of eight patients with Takayasu's disease were evaluated. RESULTS: All patients had clinical and angiographic evidence of pulseless disease. Typical findings included retinal venous congestion, fluorescein staining, capillary drop-out, microaneurysms and arteriovenous shunting. Unusual findings included cotton wool spots, anterior ischemic neuropathy and retinal emboli. In one case microaneurysms disappeared after carotid bypass surgery. Several patients had profound, transient, visual loss with changes in head posture. CONCLUSION: Takayasu's disease can cause a variety of retinal manifestations. Less common findings include cotton wool spots, anterior ischemic optic neuropathy and retinal emboli.

Adolescent↗
PubMed1998

Effect of optic nerve head drusen on nerve fiber layer thickness.

OBJECTIVE: The purpose of the study was to evaluate the effect of optic nerve head drusen (ONHD) on nerve fiber layer (NFL) thickness by visual field testing, red-free photography of NFL, and optical coherence tomography (OCT). DESIGN: The study design was a prospective clinical study. PARTICIPANTS: Twenty-three eyes of 15 consecutive patients with ONHD and 27 eyes of 27 age-matched control subjects participated. INTERVENTION: Ophthalmologic examination, color and red-free photography, automated Humphrey visual field testing, and OCT were performed. Each of the drusen study eyes were graded on a scale of 0 to III based on the amount of visible ONHD. Grade 0 represented the absence of clinically visible ONHD, and grade III represented an optic nerve head with abundant drusen. MAIN OUTCOME MEASURES: Findings from clinical evaluation and color optic nerve head photographs and NFL evaluation by red-free photography, visual fields, and OCT were measured. RESULTS: The number of study eyes with visual field defects increased with the higher grade drusen discs, corresponding both with progressively thinner NFL measurements by OCT and NFL loss shown by NFL photography. The NFL evaluation showed NFL thinning by red-free photography in 12 (71%) of 17 eyes with visible drusen (grades I-III discs) and visual field defects in 9 (53%) of 17 eyes in this group. By OCT measurements, the superior and inferior NFLs were significantly thinner in the eyes with visible ONHD compared with those of control eyes in the superior quadrant (P < 0.001) and inferior quadrant (P = 0.004). Compared with grade 0 discs, grades I through III discs showed statistically significant thinning of the NFL superiorly (P < 0.001). No statistical significant thinning of the NFL was seen in grade 0 discs compared with those of control subjects. CONCLUSIONS: Optical coherence tomography is able to detect NFL thinning in eyes with ONHD and appears to be a sensitive and early indicator of NFL thinning. Increased numbers of clinically visible ONHD correlated with NFL thinning shown by OCT measurements and both visual field defects and NFL loss seen by red-free photography.

Female↗
PubMed1998

Cancer-associated retinopathy in a patient with non-small-cell lung carcinoma.

Cancer-associated retinopathy (CAR) is a paraneoplastic syndrome most often associated with small-cell lung carcinoma (SCLC), and it has been reported in patients with other malignancies. Antibodies against recoverin, a 23-kDa protein, have been found in patients with CAR suggesting an autoimmune phenomenon. Herein is the first report of a patient with non-small-cell lung cancer (NSCLC) in whom anti-recoverin antibodies were detected in the serum. Steroid therapy, chemotherapy, and radiation therapy did not help the patient's vision. Progressive loss of vision in patients with lung cancer should, potentially, be tested for CAR.

Aged↗
PubMed1998

Retinal ischemia in aortic arch atheromatous disease.

Retinal ischemia is often caused by emboli arising from the cardiac chambers or the common carotid artery bifurcation; the latter are often composed of cholesterol. However, in many patients no lesions are identified after evaluation of these sources of emboli. Two patients were observed who had retinal ischemia and emboli originating from aortic atheromatous plaques that were visualized by transesophageal echocardiography. Cardiac, carotid, and intracranial sources of emboli were excluded. The embolic nature of retinal ischemia was further corroborated by the presence of microembolic signals during transcranial Doppler insonation of the middle cerebral artery on the side ipsilateral to the symptomatic retina. In patients with Hollenhorst plaques the aortic arch can be a potential source of emboli. Transesophageal echocardiography should be considered in these patients when the initial evaluation does not identify a cardiac or carotid lesion.

Aged↗
PubMed1997

Orbital color Doppler imaging in carotid occlusive disease.

OBJECTIVE: To define orbital circulation abnormalities identified by color Doppler imaging in patients with severe carotid occlusive disease. PATIENTS: Twenty-four patients referred to a hospital-based neuro-ophthalmology service with hemodynamically significant carotid occlusive disease (> 75% stenosis) were prospectively studied. Eight had signs of ocular ischemic syndrome; 12 of the 24 patients underwent endarterectomy. MAIN OUTCOME MEASURES: Peak systolic velocity of the central retinal, posterior ciliary, and ophthalmic artery and pulsatility indexes as determined by color Doppler imaging. METHODS: Color Doppler imaging was performed using a 7.5-MHz probe. Both eyes were studied in all patients and carotid duplex imaging was obtained. RESULTS: All patients with hemodynamically significant carotid occlusive disease had lower mean peak systolic velocities in the central retinal, posterior ciliary, and ophthalmic arteries and higher pulsatility indexes compared with normal control patients. Endarterectomy improved peak systolic velocities. Reversal of ophthalmic flow direction as a separate variable was unassociated with altered mean central retinal or posterior ciliary artery flow velocities. Patients with ocular ischemic syndrome may have similar orbital color Doppler imaging findings compared with patients with severe carotid occlusive disease without overt manifestations of chronic ocular ischemia. CONCLUSION: Orbital circulation is highly adaptable even when faced with severe compromise in proximal blood flow.

Adult↗
PubMed1997

Juvenile pilocytic astrocytoma masquerading as amblyopia.

PURPOSE: A healthy 13-year-old girl, previously diagnosed with amblyopia in her right eye, was seen in consultation after her vision continued to decrease. METHODS: A complete ophthalmologic examination including visual field testing and optic nerve photography was performed in the neuro-ophthalmologic clinic. Magnetic resonance imaging study was also obtained. RESULTS: Visual sensory deficits and pale optic nerves were noted on clinical examination. Visual field testing showed a chiasmatic junctional defect. Magnetic resonance imaging verified a large chiasmatic mass, histologically proven to be a juvenile pilocytic astrocytoma. CONCLUSION: Early recognition of signs and symptoms of chiasmatic lesions is essential for preventing visual loss.

Adolescent↗
PubMed1996

Anterior clinoid mucocele masquerading as retrobulbar neuritis.

Mucoceles arising from the anterior clinoid is rare. Although intrinsically benign, mucoceles in the sphenoid sinus (anterior clinoid variant) can lead to complications due to their proximity to other structures. We present a case of a young man whose visual complaints were typical for retrobulbar optic neuritis. Results of radiologic tests for diagnosis led us to the early detection of a surgically treatable condition, a sphenoid sinus mucocele (anterior clinoid variant). Early surgery was helpful in ameliorating the symptoms, leading to full recovery of visual function. The clinician should be aware of this rare entity with its presentation in a wide variety of signs and symptoms.

Adult↗
PubMed1996

Retinal nerve fiber layer abnormalities in Alzheimer's disease.

Retinal nerve fiber layer (RNFL) photographs from 26 patients with Alzheimer's disease and 23 normal, age-matched, control subjects were reviewed for quality and abnormalities by two observers. A higher proportion of Alzheimer's patients showed RNFL abnormalities when compared to control subjects. There was some disagreement between the two observers regarding quality and frequency of abnormalities, reflecting suboptimal quality of the photographs obtained in patients with advanced Alzheimer's disease. Although these findings add to the clinical and histopathological evidence that ganglion cell degeneration occurs in Alzheimer's disease, the difficulty in obtaining and evaluating retinal nerve fiber layer photographs, especially in advanced cases, may limit the clinical usefulness of retinal nerve fiber layer analysis in such patients.

Aged↗
PubMed1995

Central retinal artery occlusion in a child with T-cell lymphoma.

PURPOSE/METHODS: Central retinal artery occlusion occurs infrequently in children. We treated a child with central retinal artery occlusion before a systemic disease was discovered. RESULTS/CONCLUSION: Vision improved after paracentesis and anticoagulation. Systemic T-cell lymphoma was subsequently diagnosed. In contrast to older patients in whom atheromatous disease is a common etiologic factor, children frequently have more obscure systemic or ocular associations. Lymphoma should be considered as a possible systemic association in cases of central retinal artery occlusion, especially in younger patients who are less at risk for the more common causes.

Antineoplastic Agents↗
PubMed1995

Reversible abnormalities in the ophthalmic arteries detected by color Doppler imaging.

PURPOSE: To demonstrate dynamic, reversible abnormalities in ophthalmic artery blood flow velocity identified with color Doppler imaging (CDI) in patients with clinical findings of ocular ischemia with and without carotid artery stenosis. METHODS: One patient with ocular ischemia and normal carotid arteries had abnormal ophthalmic artery velocities demonstrated by CDI. Two other patients with reversed ophthalmic artery flow and critical internal carotid artery stenosis were studied before and after carotid endarterectomy. Peak systolic and diastolic velocities as well as pulsatility indices of ophthalmic, posterior ciliary, and central retinal arteries were calculated. RESULTS: The patient who had ocular ischemic syndrome without carotid artery stenosis showed increased ophthalmic artery velocities initially, and reversal of flow within the ophthalmic artery subsequently developed. Clinical findings and symptoms improved gradually as ophthalmic artery, posterior ciliary, and central retinal artery velocities increased. The patients with critical internal carotid artery stenosis had reversed ophthalmic artery blood flow initially which reverted to normal after carotid endarterectomy. CONCLUSION: Ocular ischemic syndrome may occur due to abnormal blood flow in the ophthalmic artery in the absence as well as in the presence of carotid artery stenosis. Flow dynamics in the ophthalmic artery and its branches can be shown by CDI to revert toward normal as the clinical findings improve spontaneously or after opening an occluded carotid artery.

Aged↗
PubMed1995

Color Doppler imaging of normal orbital vasculature.

BACKGROUND: Color Doppler imaging has become a useful adjunctive tool in diagnosing ophthalmic vascular disease. However, a paucity of information exists regarding normal values. This investigation was conducted to generate a database of normal retrobulbar circulatory parameters. METHODS: The authors prospectively studied the retrobulbar hemodynamic parameters of 53 normal eyes from 32 healthy individuals of various ages, all without risk factors for the development of systemic vascular disease. Preliminary Doppler spectral analysis was used to demonstrate normal carotid arterial, carotid siphon, and ophthalmic vascular anatomy. RESULTS: Mean hemodynamic values were recorded for each retrobulbar vessel. Diastolic blood pressure significantly correlated with ophthalmic arterial end-diastolic velocity (P < 0.05) and pulsatility index (P < 0.05). Although end-diastolic velocity significantly decreased (P < 0.05) and vascular resistance significantly increased (P < 0.05) as a function of age in the posterior ciliary and central retinal arterial circulation, no such correlation was identified in the ophthalmic artery which demonstrated significantly more hemodynamic variability among individuals (P < 0.00001). No significant differences in blood flow or vascular resistance were noted between sexes, fellow orbits, or the nasal and temporal branches of the posterior ciliary artery within individual orbits. CONCLUSION: Orbital hemodynamic parameters do not appear to be sex dependent or variable between fellow orbits. These data suggest that age and diastolic blood pressure may affect normal orbital blood flow and vascular resistance patterns. Significant interindividual variability is limited only to ophthalmic arterial blood flow.

Adult↗
PubMed1995

Retinal nerve fiber layer changes and visual field loss in idiopathic intracranial hypertension.

PURPOSE: The authors retrospectively analyzed changes in the retinal nerve fiber layer in patients with idiopathic intracranial hypertension and studied their relation to visual field loss to determine the clinical usefulness of retinal nerve fiber analysis in the clinical management of patients with papilledema. METHODS: Retinal nerve fiber layer photographs and visual fields from 36 eyes of 21 patients with papilledema due to idiopathic intracranial hypertension were analyzed for abnormalities in a masked fashion. RESULTS: Nerve fiber layer changes were found in 67% of eyes studied. Superior areas within the nerve fiber layer were affected 5.4 times more frequently than inferior regions. Visual field loss was more prevalent in eyes with diffuse nerve fiber layer loss (89%) than in eyes with slit defects (29%). The location of the nerve fiber layer changes correlated with corresponding areas of visual field loss. Nerve fiber layer changes were as common in mild to moderate as in atrophic papilledema; however, slit defects predominated in patients with mild to moderate papilledema, and diffuse loss predominated in atrophic papilledema. CONCLUSIONS: Changes in the retinal nerve fiber layer observed in patients with idiopathic intracranial hypertension provide objective information regarding the status of their optic nerve and may improve their clinical management.

Adolescent↗