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Thomas R Hedges

Publications and source records attributed to Thomas R Hedges.

11 recordsLinked to original sources
PubMed2006

Multifocal visual-evoked potential in unilateral compressive optic neuropathy.

AIM: To evaluate the effects of unilateral compressive optic neuropathy on amplitude and latency of multifocal visual evoked potentials (mfVEPs). METHODS: Static automated perimetry and mfVEP recordings were obtained from six patients with presumed meningiomas affecting one optic nerve. Monocular and interocular amplitude and latency analyses were performed and compared with normal control subjects. RESULTS: The change in the mfVEP amplitude agreed with visual field findings with regard to topography and severity of deviation from normal. The delay in recordable responses from affected eyes ranged from 7.6 to 20.7 ms (interocular analysis) and 7.9 to 13.9 ms (monocular analysis). CONCLUSIONS: Compressive optic neuropathy decreases the amplitude and increases the latency of the mfVEP. The changes in latency were similar to those seen in optic neuritis but larger than those in ischaemic optic neuropathy and glaucoma.

Aged↗
PubMed2005

Multifocal visual evoked potential in nonorganic visual field loss.

OBJECTIVE: To evaluate the use of multifocal visual evoked potentials in the diagnosis of nonorganic visual field loss. METHODS: Five patients with unexplained visual field loss underwent full neuro-ophthalmic examination, Humphrey visual field testing, and multifocal visual evoked potential testing using the Accumap objective perimeter (ObjectiVision Pty Ltd, Sydney, Australia). RESULTS: In all 5 cases, the results of the ophthalmic examination did not correlate with the degree of visual field loss seen on Humphrey visual field testing. Multifocal visual evoked potentials testing showed essentially normal tracings. CONCLUSIONS: Multifocal visual evoked potentials may be useful in cases of difficult to prove functional visual field loss or in cases in which objective documentation of normal function is needed.

Adolescent↗
PubMed2004

Multifocal visual evoked potential, multifocal electroretinography, and optical coherence tomography in the diagnosis of subclinical loss of vision.

Multifocal VEP and mfERG techniques show promise for routine clinical use in neuro-ophthalmology. OCT is now used in many subspecialty areas of ophthalmology, especially in studies of the retina and glaucoma. Although neuro-ophthalmologists must still rely on time-consuming history taking and careful clinical examination, the three modalities described herein can provide objective proof regarding clinical diagnoses in selected cases, saving time and avoiding costly neurologic investigations.

Electroretinography↗
PubMed2003

Amiodarone optic neuropathy--review.

The antiarrhythmic agent, amiodarone (Cordone), Pacerone), has been reported to cause optic neuropathy. However, the clinical manifestations are similar to non-arteritic anterior ischemic optic neuropathy (AION), which makes diagnosing amiodarone optic neuropathy difficult. There is controversy whether or not amiodarone optic neuropathy actually exists as a distinct entity. The clinical manifestations and the proposed pathophysiology of amiodarone optic neuropathy are discussed.

Amiodarone↗
PubMed2002

Association between sleep apnea syndrome and nonarteritic anterior ischemic optic neuropathy.

OBJECTIVE: To determine if patients with nonarteritic ischemic optic neuropathy (NAION) have sleep apnea syndrome (SAS), an entity characterized by repetitive upper airway obstructions during sleep, inducing hypoxia and sleep disruption. METHODS: We recruited 17 patients with NAION and 17 age- and sex-matched controls from patients referred for treatment because of suspected restless legs syndrome. We performed overnight polysomnography and determined the respiratory disturbance index during night sleep, a value used to diagnose and grade SAS. We compared the proportions of patients with SAS among patients with NAION and matched controls using the chi(2) test. Additionally, we compared the proportions of patients with SAS among patients with NAION and a large SAS prevalence study using the binomial test. RESULTS: Twelve (71%) of 17 patients with NAION had SAS. According to the respiratory disturbance index, 4 patients (24%) had mild, 4 patients (24%) had moderate, and 4 patients (24%) had severe SAS. Only 3 (18%) of 17 controls had SAS (P =.005). In the 45- to 64-year age group, 4 (50%) of 8 patients with NAION had SAS; 51 (11.9%) of 430 of the random sample in the prevalence study had SAS (P =.005). In the group older than 64 years, 8 (89%) of 9 patients with NAION had SAS; 18 (24%) of 75 of the random sample in the prevalence study had SAS (P<.001). CONCLUSIONS: We found a high prevalence of SAS in patients with NAION, which supports previous case reports suggesting that such an association exists. This association may explain why approximately 75% of all patients with NAION discover visual loss on first awakening or when they first use vision critically after sleeping. Our findings indicate that SAS may play an important role in the pathogenesis of NAION.

Aged↗
PubMedDate not supplied

Charles Bonnet, his life, and his syndrome.

Charles Bonnet (1720-1792) was an eminent naturalist and philosopher whose contributions to botany and philosophy were highly regarded and honored by his contemporaries in the scientific community of his era in France and England. In1760 he first described and analyzed formed visual hallucinations experienced by his grandfather. The syndrome was named after Bonnet in 1937 by George de Mosier, another native of Geneva, Switzerland.

Hallucinations↗
PubMedDate not supplied

Evaluation of hydroxychloroquine retinopathy with multifocal electroretinography.

BACKGROUND AND OBJECTIVE: To describe the changes revealed by multifocal electroretinography (ERG) in patients taking hydroxychloroquine. PATIENTS AND METHODS: Six patients being treated for various inflammatory conditions with hydroxychloroquine for periods ranging from 8 months to 7 years were consecutively evaluated. Each examination included measurement of Snellen visual acuities, Amsler grid assessment, and automated visual field testing. In some cases, funduscopic examinations were complimented by photography and fluorescein angiography. Multifocal ERG was performed for all patients. RESULTS: Three patients (six eyes) were found to have distinctive abnormalities on multifocal ERG consisting of pericentral depression of ERG signals. The abnormalities on multifocal ERG corresponded with the patients' subjective descriptions and the visual field depiction of their pericentral scotomas. All affected patients had been taking hydroxychloroquine for at least 7 years. One patient with generalized depression on multifocal ERG had possible hydroxychloroquine retinopathy. Two patients (three eyes) had relatively normal results on multifocal ERG. CONCLUSION: Multifocal ERG objectively demonstrates depression of signals in the perifoveal region in visually symptomatic patients with long-term hydroxychloroquine use. Even patients with normal visual acuity and no fundus abnormalities can have abnormal results. Although we have not yet identified patients with abnormalities on multifocal ERG before the onset of symptoms, multifocal ERG may be useful in monitoring patients at risk and may provide an earlier opportunity to identify maculopathy.

Adult↗