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Biomedical subjects

T A Cox

Publications and source records attributed to T A Cox.

At least 37 records · Page 2Linked to original sources
PubMed1997

Uveitis in the southeastern United States.

PURPOSE: Previous epidemiologic studies of uveitis have focused on predominantly Caucasian populations, and none have been based in the Southeast. We analyzed the epidemiology of uveitis among a referral population with a high percentage of African Americans in the United States. METHODS: We evaluated demographic data from 385 consecutive patients referred to the Duke Uveitis Clinic. RESULTS: Of the 385 patients, 120 (31%) were African American and 258 (67%) Caucasian; 237 (62%) were female and 148 (38%) male. The most common diagnoses among the 385 patients were idiopathic panuveitis (64 patients [17%]), idiopathic anterior uveitis (47 patients [12%]), pars planitis (46 patients [12%]), sarcoidosis (44 patients [11%]), and toxoplasmosis (39 patients [10%]). These diagnoses were also the most common among the 120 African American patients: 33 patients (28%) had idiopathic panuveitis, 30 (25%) had sarcoidosis, 10 (8%) had idiopathic anterior uveitis, 8 (7%) had toxoplasmosis, and 6 (5%) had pars planitis. Among the 258 Caucasian patients, the most common diagnoses were pars planitis (39 patients [15%]), idiopathic anterior uveitis (37 patients [14%]), toxoplasmosis (30 patients [12%]), idiopathic panuveitis (28 patients [11%]), and multifocal choroiditis and panuveitis (MCP) (17 patients [7%]). Categorizing diagnoses of all 385 patients by anatomic location, panuveitis was most frequent (148 patients [38%]), followed by anterior uveitis (97 patients [25%]), posterior uveitis (93 patients [24%]), and intermediate uveitis (47 patients [12%]). CONCLUSIONS: The higher frequency of sarcoidosis and idiopathic panuveitis than previously reported is related to our larger African American population base. The racial composition of the Southeast does not, however, account for differences such as our higher percentage of MCP; it is possible that other genetic or environmental factors play a role in this region.

Adolescent↗
PubMed1996

Condensation on polymethylmethacrylate, acrylic polymer, and silicone intraocular lenses after fluid-air exchange in rabbits.

PURPOSE: Condensation occurs rapidly on silicone intraocular lenses (IOLs) after vitrectomy and fluid-air exchange in the presence of a posterior capsulotomy, severely limiting the retinal view. Foldable IOLs made of an acrylic polymer are now available. The authors compare the condensation and subsequent retinal view degradation after vitrectomy and fluid-air exchange in rabbit eyes implanted with polymethylmethacrylate (PMMA), soft acrylic polymer (ACRYSOF), and silicone IOLs. METHODS: Thirty rabbits underwent bilateral lens removal. Twenty PMMA, 20 acrylic polymer, and 20 silicone IOLs were implanted into the capsular bag. After three-port vitrectomy, eyes were randomly assigned to undergo a posterior capsulotomy or to an intact posterior capsule. Fluid-air exchange was performed, and the amount of condensation on the IOL surface and resultant retinal view was graded. Surgical maneuvers then were performed to decrease the condensation. These maneuvers included wiping the IOL surface with a soft-tipped cannula and coating it with viscoelastic. RESULTS: No condensation occurred on IOLs in eyes with an intact posterior capsule. Significantly more condensation occurred on IOLs in eyes with a capsulotomy, regardless of IOL type (P < 0.014). Wiping the condensation resulted in significantly less condensation and improved retinal view on the PMMA and acrylic IOLs when compared with the silicone IOLs (P < 0.024). Condensation was eliminated on all three IOL types after viscoelastic was applied. However, increased distortion of the retinal view was induced by the viscoelastic on the silicone IOL as compared with the other IOLs. CONCLUSIONS: Condensation and subsequent retinal image degradation occurs uniformly after vitrectomy, posterior capsulotomy, and fluid-air exchange in eyes with PMMA, acrylic, and silicone IOLs. Because the condensation can be eliminated most easily on acrylic IOLs compared with silicone IOLs, when foldable IOL techniques are used it is likely that an acrylic polymer IOL would be advantageous for those patients at risk for future vitreous procedures requiring fluid-air exchange.

Animals↗
PubMed1996

Factors associated with visual acuity loss after noncontact transscleral Nd:YAG cyclophotocoagulation.

PURPOSE: To determine the factors associated with visual acuity loss following transscleral Nd:YAG cyclophotocoagulation (TYC). METHODS: The authors retrospectively studied 479 patients followed for a mean of 22 months after the initial TYC in one eye and analyzed the data with univariate and multivariate analysis for the factors associated with visual acuity loss. Data analyzed included age, race, sex, preoperative intraocular pressure (IOP) and visual acuity, type of glaucoma, total energy per treatment, number of retreatments, final IOP, and duration of follow-up. RESULTS: The preoperative factors associated with visual acuity loss after TYC as determined by both univariate and multivariate analysis were neovascular glaucoma (p = 0.001, odds ratio = 2.80) and black race (p = 0.044, odds ratio = 1.67). Postoperative hypotony and follow-up of > 6 months were also associated with visual acuity loss (p < 0.001, odds ratio = 6.68 and p = 0.046, odds ratio = 2.61, respectively). CONCLUSIONS: Transscleral Nd:YAG cyclophotocoagulation is associated with a greater risk of visual acuity loss in patients with neovascular glaucoma and in the black population. Postoperative hypotony is associated with a poor visual outcome, whereas the association with longer follow-up duration suggests that other factors, related to the patient's underlying disease, are also significant factors.

Adolescent↗
PubMed1993

Pathologic findings in the retinal pigment epitheliopathy associated with the amyotrophic lateral sclerosis/parkinsonism-dementia complex of Guam.

BACKGROUND: A pigment epitheliopathy that resembles ophthalmomyiasis interna occurs in approximately 10% of a large sample of the Chamorro population of Guam age 39 years or older; the rate is approximately 50% among those who have amyotrophic lateral sclerosis or Parkinsonism-dementia complex (lytico bodig). METHODS: Since publication of an earlier clinical report of affected patients, several of them have died of their neurologic disease, and their eyes were obtained for pathologic study. This is the first pathologic report of the retinal pigment epitheliopathy seen in the setting of amyotrophic lateral sclerosis/Parkinsonism-dementia complex of Guam and is based on examination of 13 eyes from 7 patients. RESULTS/CONCLUSION: Focal areas of attenuation of the retinal pigment epithelium in association with a reduced amount of intracellular pigment correlated with the funduscopic and gross appearance. No larvae were seen, and there was no evidence of inflammation. The pathogenesis of this pigment epitheliopathy remains undetermined.

Amyotrophic Lateral Sclerosis↗
PubMed1993

Acquired pendular nystagmus in multiple sclerosis: clinical observations and the role of optic neuropathy.

Thirty seven patients with pendular nystagmus due to multiple sclerosis were reviewed. Most developed nystagmus later in a progressive phase of the disease. All had cerebellar signs on examination and evidence of optic neuropathy. MRI in eight patients showed cerebellar or brainstem lesions in seven; the most consistent finding was a lesion in the dorsal pontine tegmentum. Dissociated nystagmus was seen in 18 patients: in these the signs of optic neuropathy were often asymmetric and the severity correlated closely with the side with larger oscillations. This suggests that dissociations in acquired pendular nystagmus may be due to asymmetries in optic neuropathy rather than asymmetries in cerebellar or brainstem disease.

Afferent Pathways↗
PubMed1992

Pupillary constriction during forceful eyelid closure.

Pupillary constriction during forceful eyelid closure was investigated in 30 normal subjects. The right eye of each subject was filmed with an infrared-sensitive television camera in darkness before, during, and after eyelid closure. Clinically detectable constrictions were found in nine of the 30 subjects (30%). No significant correlation was found between amplitude of constriction and age of subject or baseline pupillary diameter. Forceful eyelid closure should be considered as a technique to elicit pupillary constriction in patients with a poor near response, but many subjects will have no detectable constriction using this maneuver.

Adult↗
PubMed1992

Crystalluria in marathon runners. IV. Black subjects.

Crystal sizes (scanning electron microscopy) and distributions (Coulter Counter) as well as 24-h urinary sodium (Na) and calcium (Ca) excretions (flame atomic absorption) were determined in a group of black South African runners immediately after a marathon and again 3 weeks later. White runners and black and white control subjects were included in the study. Particle volume-size histograms for black controls and black runners were identical. There was no significant difference in the Na excretion of all the groups. However, while urinary Ca excretion was significantly raised in white runners relative to white controls, Ca excretion in black runners was unchanged relative to their controls. It is postulated that the lower rates of urinary Ca excretion may result from lower rates of Ca resorption from bone in response to the cyclical loading of running in black marathon runners. The results of this study suggest that black marathon runners are not prone to the same increased risk of renal stone formation as are white runners.

Adult↗
PubMed1992

Pupillary escape.

I performed a pupillographic study of pupillary escape to determine its effectiveness in detecting optic nerve and retinal disease. Fourteen patients and 39 normal subjects were included in the study. Only one patient had abnormal pupillary escape, even though 13 patients had relative afferent pupillary defects. Testing for pupillary escape is not a reliable clinical technique.

Adult↗
PubMed1991

Stunned left ventricular myocardium after exercise treadmill testing in coronary artery disease.

Myocardial stunning (postischemic ventricular dysfunction) occurs in dogs after coronary stenosis following treadmill exercise. Less data are available in humans regarding development of stunned myocardium after exercise. Regional wall motion changes were evaluated in 22 patients with known coronary artery disease using 2-dimensional echocardiography and exercise treadmill testing. Wall motion was scored as 1 = normal, 2 = hypokinetic, 3 = akinetic, 4 = dyskinetic. At least 1 left ventricular segment with normal resting function developed an increase in wall motion score at 15 or 30 minutes compared with values at rest. The wall motion score in the midportion of the ventricular septum increased from 1.0 at rest to 1.6 (p less than 0.004) at 30 minutes after exercise; the basal inferior wall score worsened from 1.0 at rest to 1.9 (p less than 0.01) at 30 minutes after exercise. Coronary angiographic data in these patients revealed that left anterior descending narrowing correlated best with left ventricular septal wall motion abnormalities, whereas right coronary artery and circumflex narrowing best correlated with inferior and posterior wall motion abnormalities. Eight normal adult volunteers with no history of myocardial ischemia also underwent 2-dimensional echocardiography and exercise testing. No wall motion abnormalities were observed at any time after exercise. The present study suggests that in patients with coronary artery disease, exercise treadmill testing may induce regional wall motion abnormalities of the left ventricle that persist greater than or equal to 30 minutes after exercise, an observation consistent with the phenomenon of stunned myocardium.

Adult↗
PubMed1991

Delayed visual loss due to trauma of the internal carotid artery.

The group of six patients in this study experienced delayed visual loss following head trauma. Visual loss occurred from 1 day to 13 years after the initial injury. All patients suffered indirect trauma to the internal carotid artery resulting in formation of either an aneurysm or pseudoaneurysm or a carotid-cavernous fistula. Review of the radiologic and clinical findings was performed in six patients. The diagnosis was established by computed tomography, magnetic resonance imaging, and angiography. All patients had follow-up clinical evaluation and imaging studies. Treatment by neurosurgical or interventional neuroradiologic procedures resulted in significant visual improvement in five patients. Different pathophysiologic mechanisms could be correlated with the delayed visual loss produced by the two types of lesions. The pathologic changes associated with the aneurysms/pseudoaneurysms included direct compression of optic nerves and/or chiasm and intracranial hematoma. A carotid-cavernous fistula caused delayed visual loss by either hematoma at the orbital apex or compression of the chiasm and/or optic nerves by saccular dilatation of the cavernous sinus. The delayed onset of decreased vision following head trauma should alert the physician to the possibility of a traumatic aneurysm/pseudoaneurysm or a carotid-cavernous fistula. Different neuro-ophthalmologic symptoms can usually be correlated with the pathologic changes demonstrated by neuroimaging procedures.

Adolescent↗
PubMed1991

Tonic pupil and Czarnecki's sign following third nerve palsy.

A 71-year-old woman developed abnormal pupillary function in one eye after a third nerve palsy. Stimulation with light caused segmental constriction of the pupil, the near reflex was normal, and gaze upward elicited constriction of portions of the sphincter that were unreactive to light. This combination of findings has not been reported previously. We believe that this case supports the idea that a tonic pupil can be caused by aberrant reinnervation of the ciliary ganglion.

Aged↗
PubMed1991

The clinical significance of Tournay's pupillary phenomenon.

The act of lateral gaze in some normal individuals causes the pupil of the adducting eye to be smaller than that of the abducting eye. This phenomenon was described by Tournay more than 70 years ago, but it has generally been considered to have no clinical significance. We discuss two situations, episodic anisocoria and aberrant regeneration of the third nerve, in which Tournay's phenomenon should be considered by the clinician. We also describe familial occurrence of this interesting pupillary variant.

Adolescent↗