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Biomedical subjects

S E Feldon

Publications and source records attributed to S E Feldon.

At least 55 records · Page 3Linked to original sources
PubMed1988

Graves' ophthalmopathy: II. Correlation of clinical signs with measures derived from computed tomography.

Quantitative clinical and computed tomographic (CT) measures of Graves' ophthalmopathy were obtained in 76 patients. Significant correlation of several CT parameters of the mid-orbital axial CT slice with optic nerve involvement was established. By means of clinical measures, only limitation of ocular motility was found to correlate with the optic neuropathy. The results suggested that there were two distinct populations of patients with Graves' disease which could be segregated by CT scan and clinical evaluation, one which developed optic neuropathy and one which did not. Therefore simple measures performed on the mid-orbital slice of the CT scan are recommended for all patients with Graves' ophthalmopathy as an important adjunct to careful evaluation of extraocular muscle function, in order to identify patients at risk of developing optic neuropathy.

Adolescent↗
PubMed1988

Graves' ophthalmopathy: III. Effect of transantral orbital decompression on optic neuropathy.

Twenty-five patients (48 eyes) underwent transantral, surgical decompression of their orbits for treatment of Graves' ophthalmopathy with optic neuropathy. Visual acuity improved in 77%, remained unchanged in 17%, and worsened in 6%. Colour vision improved in 76%, remained unchanged in 20%, and worsened in 4%. Visual fields improved in 67%, remained unchanged in 12%, and worsened in 22%. In general the worse the vision preoperatively the greater the relative improvement postoperatively. Clinical and radiological findings failed to correlate with visual outcome of surgical intervention. The study shows surgery to be highly effective in restoring optic nerve function for patients with severe Graves' ophthalmopathy.

Adult↗
PubMed1987

Ophthalmic manifestations of maxillary sinus mucoceles.

Mucoceles involving any of the paranasal sinuses may present with ophthalmic disturbances. Maxillary antral mucoceles can encroach on the inferior orbit with ocular displacement and compression, proptosis or enophthalmos, lower lid distortion, tethering of extraocular muscles, and ptosis. Periocular pain, erosion of the inferior orbital rim, infraorbital nerve compression, epiphora, and inner canthal swellings are other important presentations. Postoperative mucoceles may involve only a portion of the antrum. Five illustrative cases are presented.

Adult↗
PubMed1987

Sources of artifact in infrared recording of eye movement.

A detailed analysis of recording artifacts present in normal horizontal saccadic eye movements was performed using infrared reflective oculography. The effects of diode displacement were assessed. Optimal recordings were obtained with infrared sensors displaced 1 mm scleral to the midlimbal position. Displacement of the infrared sensor toward the sclera resulted in an artifactual decrease in apparent peak saccadic velocity. Displacement of the infrared sensors toward the pupil resulted in complex nonlinear waveforms. Such artifacts were more apparent with increasing eccentricity of the eyes from primary position. The artifacts induced by poor positioning of the sensors were readily explained by changes in infrared reflectivity among sclera, iris, and pupil. Simultaneous independent recording from temporal and nasal sensors was recommended to separate truly anomalous saccadic trajectories from artifact.

Electricity↗
PubMed1985

Quantitative computed tomography of Graves' ophthalmopathy. Extraocular muscle and orbital fat in development of optic neuropathy.

Quantitative assessment of computed tomographic (CT) scans was performed on 98 orbits of 49 patients with Graves' ophthalmopathy. Extraocular muscle volume and orbital fat volume were determined, according to whether optic neuropathy was absent, had developed during follow-up, or was present at the time of scanning. No differences in muscle volume were found between the group already having optic neuropathy and the group in which optic neuropathy developed during follow-up. Both optic neuropathy groups, however, had significant increases in extraocular muscle volume compared with the group without optic neuropathy. The absolute amount of orbital fat was the same for all groups, but the relative amount of orbital fat tended to decrease as total orbital volume increased with development or presence of optic neuropathy. This study establishes a quantitative relationship between optic neuropathy and extraocular muscle enlargement in Graves' ophthalmopathy. Orbital fat, however, does not play an important role in the disease.

Adipose Tissue↗
PubMed1984

Retinal microangiopathy. Correlation of OCTOPUS perimetry with fluorescein angiography.

The capillary perfusion of 14 eyes with nonproliferative diabetic retinopathy and 14 eyes with retinal branch vein occlusion was assessed by wide-angle fluorescein angiography. Regional perfusion was directly correlated with visual sensitivity determined by OCTOPUS-automated static perimetry. Visual function was found to correlate linearly with capillary perfusion in both diseases. Occasional foci of decreased visual sensitivity that corresponded to a region of good capillary perfusion were found in the central fields of diabetics. Although capillary dropout appears to be the major cause of decreased visual sensitivity in microangiopathy, local metabolic factors may also play a role. Further studies are required to determine whether foci of decreased function are predictive of future capillary dropout or neovascularization.

Adult↗
PubMed1984

Clinical classification of Graves' ophthalmopathy. Identification of risk factors for optic neuropathy.

Clinical signs of Graves' ophthalmopathy were correlated with extraocular muscle volumes in 50 patients. Significant correlations were obtained for horizontal, vertical, and total extraocular muscle limitation, as well as periorbital swelling. Proptosis correlated to a lesser extent. Optic nerve involvement was found to be correlated with both total extraocular muscle volume and limitation of ocular motility. From this information, no risk, future risk, and immediate risk categories of disease were defined quantitatively. The results of the study imply that optic nerve involvement is more likely to occur in association with noncompliant, fibrotic muscle than with more supple muscle of the same total volume.

Eye↗
PubMed1982

Oculomotor effects of intermittent conduction block in myasthenia gravis and Guillain-Barré syndrome. An oculographic study with computer simulations.

Five abnormal oculographic patterns were identified in eight patients with either myasthenia gravis or Guillain-Barré syndrome (GBS). These could be differentiated into three intrasaccadic and two postsaccadic abnormalities. From our studies of computer simulations, and considering the established pathophysiology of myasthenia gravis and GBS, we believe that our oculographic findings were a consequence of defects in peripheral neural and neuromuscular conduction, together with a simple adaptive increase in duration of the saccadic burst of central innervation. We conclude that the eye movement abnormalities we observed are explained by intermittent block of peripheral conduction, and suggest that any disease causing intermittent blockage of neural signals to extraocular muscles will produce similar abnormalities of eye movement.

Adolescent↗
PubMed1982

Graves' ophthalmopathy evaluated by infrared eye-movement recordings.

Thirteen patients with varying degrees of Graves' ophthalmopathy were examined using high-resolution infrared oculography to determine peak velocities for horizontal eye movements between 3 degrees and 30 degrees. As severity of the orbital disease increased, peak velocities became substantially lower. Vertical-muscle surgery failed to have any effect on peak velocity of horizontal eye movements. In contrast, orbital decompression caused notable improvement in peak velocity of eye movements. Eye-movement recordings, which provide a measure of extraocular muscle function rather than structure, may provide a safe, sensitive, and accurate method for classifying and following up patients with Graves' ophthalmopathy.

Adult↗
PubMed1982

Clinical and computed tomographic findings in the Foster Kennedy syndrome.

A 52-year-old man had progressive loss of visual acuity in his left eye associated with anosmia of five years duration. Clinical findings included papilledema in the right eye and optic atrophy in the left eye. A diagnosis of Foster Kennedy syndrome was made. Careful attention to the ophthalmoscopic appearance of the left eye disclosed optic disk swelling in regions without significant atrophy as well as dilated retinal veins. Both of these signs suggested increased intracranial pressure, rather than a primary anterior ischemic optic neuropathy. High resolution computed tomographic scanning confirmed the presence of a large subfrontal meningioma and an expanded right optic nerve sheath, consistent with the papilledema noted clinically.

Frontal Lobe↗
PubMed1980

Monocularly and binocularly evoked visual responses to patterned half-field stimulation.

Visual evoked responses to half-field stimulation were recorded in 18 normal subjects to determine the most suitable techniques for use in detecting hemianopic deficits. The most consistent results were obtained by recording from a transverse array of electrodes using the midfrontal region as reference and stimulating with a reversing checkerboard pattern, each check subtending 50 min of visual angle. Responses recorded from electrodes ipsilateral to the half-field stimulated consisted of an N70, P105, N165 complex. Responses from contralateral electrodes demonstrated the presence of an N100 which divided the P105 seen ipsilaterally into a P85 and a P120. The contralateral predominance of the N100 was further documented by plotting the ratio of the N100 to the immediately preceding P wave. Consideration of the ipsilateral P105 and the contralateral N100 together was found to be more reliable in detecting lateralization of the visual evoked potential than either wave alone. Crossed and uncrossed pathways made equal contributions to the visual evoked potential produced by half-field stimulation. Good correspondence was found between algebraic summation of homonymous monocular hemifield responses when compared to binocular hemifield stimulation. This finding supports the use of binocular hemifield stimulation for the detection of subtle congruous homonymous field defects.

Adult↗
PubMed1980

Disordered inhibition in internuclear ophthalmoplegia: analysis of eye movement recordings with computer simulations.

High resolution infra-red oculographic recordings were obtained in 19 patients with clinically evident internuclear ophthalmoplegia. The major findings were attenuated phasic and tonic components of adducting saccades, fractionated phasic components of abducting saccades, equally long durations for phasic components of adducting and abducting saccades with refixation, and nasal drift of the abducting eye which initiated abducting nystagmus. Ipsilateral gaze paresis and abduction lag were occasionally associated with primarily unilateral cases of internuclear ophthalmoplegia. These findings were interpreted using available anatomical, electromyographic and oculographic data as well as computer simulations of internuclear ophthalmoplegia. We concluded that deficient excitation of the ipsilateral medial rectus was due to interruption of burst-tonic neurons within the medial longitudinal fasciculus which mediate horizontal eye movements. This resulted in a decreased pulse height and step of the agonist neural controller signal. We were also able to determine that variably slowed fractionated abducting saccades were caused by deficient intrasaccadic inhibition of the antagonist medial rectus. When medial rectus excitation was more deficient than medial rectus inhibition of the opposite eye, then a typical internuclear ophthalmoplegia resulted; when the amount of medial rectus excitation was equal to the amount of medial rectus inhibition of the opposite eye, then a gaze paresis occurred; and when medial rectus excitation was less deficiennt than medial rectus inhibition of the opposite eye, abduction lag resulted in the oculographic appearance of internuclear ophthalmoplegia of abduction. Abducting nystagmus appeared to be initiated by a tendency for the abducted eye to drift nasally from the increased level of tonic inhibition of the antagonist medial rectus. Some oculographic patterns were attributed to higher level adaptive changes in innervation. These changes were a consequence of disordered excitatory and inhibitory controller signals at the lower, internuclear level. Possible anatomical pathways which might carry these inhibitory controller signals were discussed. High resolution eye movement recordings of patients with internuclear ophthalmoplegia were interpreted directly and by computer simulations as being most consistent with disordered inhibitory and excitatory control of the medial rectus motor pool during rapid eye movements and eccentric gaze.

Adolescent↗