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Biomedical subjects

H S Thompson

Publications and source records attributed to H S Thompson.

At least 19 recordsLinked to original sources
PubMed1991

Automated pupil perimetry. Pupil field mapping in patients and normal subjects.

The authors developed an automated method of pupil perimetry by linking an infrared video pupillometer to a Humphrey Field Analyzer. Software was developed to automatically analyze the pupil responses to focal light stimuli and display the results graphically. All 76 locations of Humphrey program 30-2 could be tested twice within 5.5 minutes and the relative sensitivity of the field was determined by comparing the amplitude of pupil constriction or latency time at each stimulus location. The mean pupil responses within annular areas at 3 degrees, 9 degrees, 15 degrees, 21 degrees, and 27 degrees were shown to be linearly related to log stimulus intensity over a 15 dB range under low level mesopic conditions (3.15 asb bowl background). In normal subjects, the superior temporal quadrant usually had the greatest mean pupillomotor response and the inferior nasal quadrant had the least. Pupil responses in the temporal field were larger than corresponding locations in the nasal field. Patients with visual field defects who underwent testing by pupil perimetry showed pupillary deficits in the same location within the field, providing evidence that pupil perimetry may be a useful, objective means of assessing visual field function.

Adolescent↗
PubMed1991

Pupillary constriction to darkness in a patient with blue-cone monochromatism.

A 17 year old male patient presented with bilateral photophobia, poor color vision, visual acuity 20/80-20/200, nystagmus, and showed normal fundi. Electroretinography revealed evidence of blue-cone monochromatism. This patient showed constriction of the pupils to darkness or the paradoxic pupillary phenomenon.

Adolescent↗
PubMed1990

Hydroxyamphetamine mydriasis in normal subjects.

Hydroxyamphetamine eyedrops are used to help localize the lesion in Horner's syndrome. Because normal variability in the response to the eyedrops may influence the interpretation of test results in patients with Horner's syndrome, we studied both the interocular variability of the drug's mydriatic effect within each normal subject and the variation between individuals. We used photographs to document the variability among 26 normal subjects. Hydroxyamphetamine hydrobromide 1% eyedrops (Paredrine) were placed in both eyes of normal subjects in the same way that patients with Horner's syndrome are tested. The drug produced a mean increase in pupil size of 1.96 mm (+/- 0.61 S.D.) in the 52 eyes tested. In normal subjects, the mydriatic effect of hydroxyamphetamine was symmetric in each pair of eyes. The mean interocular asymmetry of mydriasis as measured by the difference in dilation (right eye dilation minus left eye dilation) was -0.087 mm (+/- 0.29 S.D.). Thus, the variability of hydroxyamphetamine mydriasis from one eye to the other in a single subject was much lower than the variability between subjects.

Adult↗
PubMed1990

Hydroxyamphetamine mydriasis in Horner's syndrome.

We studied hydroxyamphetamine hydrobromide 1% (Paredrine) mydriasis in 54 patients with Horner's syndrome to determine its effectiveness in distinguishing preganglionic lesions from postganglionic lesions. The difference in pupillary dilation between the unaffected and affected sides was used as a measure of the hydroxyamphetamine effect. We found that patients who had clinical evidence of damage to the postganglionic neuron of the oculosympathetic pathway had less pupillary dilation on the affected side. In contrast, almost all patients judged to have clinical evidence of preganglionic lesions dilated more on the affected side. We determined the probability that a given difference in pupillary dilation between the involved and uninvolved side is the result of a postganglionic lesion.

Amphetamines↗
PubMed1990

Critical evaluation of the cocaine test in the diagnosis of Horner's syndrome.

We evaluated the effectiveness of the cocaine test for diagnosing Horner's syndrome. The test was administered to 119 patients with a diagnosis of Horner's syndrome and to 50 normal subjects. We compared the cocaine-induced anisocoria in the two groups by measuring photographs of the pupils. We found the cocaine test to be highly effective in separating normal subjects from patients with Horner's syndrome. The chances of having Horner's syndrome increased with the amount of cocaine-induced anisocoria. Through the use of logistic regression analysis, we determined the odds ratio of having Horner's syndrome compared with not having it for each 0.1-mm increment of anisocoria measured after cocaine administration. A postcocaine anisocoria value of 0.8 mm gave a mean odds ratio of approximately 1050:1 that Horner's syndrome was present (lower 95% confidence limit = 37:1). We found that simply measuring the postcocaine anisocoria provided a better prediction of Horner's syndrome than taking the trouble to calculate the net change in anisocoria. Odds ratios should help the clinician decide if the result of a cocaine test is indicative of Horner's syndrome.

Adult↗
PubMed1990

Use of infrared videography to detect and record iris transillumination defects.

We have developed a technique of detecting and recording iris transillumination defects using an infrared sensitive video camera. This method is useful for assessing the loss of posterior iris pigment in patients with the pigmentary dispersion syndrome and pigmentary glaucoma. Some patients with no transillumination defects on slit-lamp examination were noted to have discrete defects on infrared videography. This technique is a rapid, convenient, and reproducible method of permanently recording posterior iris pigment changes. These high-quality video images can then be followed to determine the natural course and the results of therapy in these patients.

Glaucoma, Open-Angle↗
PubMed1990

Could specific oral tolerance be a therapy for autoimmune disease?

Several experimental autoimmune diseases have been successfully suppressed by the induction of specific oral tolerance. Here, Stephen Thompson and Norman Staines review the nature and mechanisms of this form of tolerance and discuss its possible applications in the control of human autoimmune diseases.

Administration, Oral↗
PubMed1990

A unilateral cataract produces a relative afferent pupillary defect in the contralateral eye.

The relative afferent pupillary defect (RAPD) was measured with neutral density filters in ten patients, each of whom had a dense cataract in one eye only. In each instance, the cataract reduced visual acuity to counting fingers or worse, whereas visual acuity in the other eye was 20/25 or better. All patients with mature or nuclear cataracts had a measureable RAPD in the other eye (mean, 0.44 log unit). In each instance, after extraction of the cataract, the RAPD disappeared. Thus, a dense cataract causes an RAPD in the contralateral eye by increasing the pupillomotor effectiveness of the stimulus light and that this is the reason why even a brunescent cataract does not cause an RAPD in the same eye. In addition, two clinical cases are reported. One case records the development of a cataract in an eye with a preexisting RAPD resulting from optic neuritis; as the cataract became more opaque, the afferent defect became smaller and finally was reversed. The other case shows that a traumatic cataract can produce an RAPD in the contralateral eye. Thus, when an afferent pupillary defect is seen in an eye with a cataract, a visual pathway defect in that eye should definitely be suspected.

Adult↗
PubMed1990

Low affinity antibodies against collagen type II are associated with pathology in collagen-induced arthritis in mice.

The relationship between the functional affinity of antibodies against type II collagen (CII) and the development of arthritis was studied in mice with collagen-induced arthritis. The responses of DBA/1 strain mice were compared with those of mice selectively bred to produce antibodies of high functional affinity (HA mice) and low functional affinity (LA mice). HA and LA mice did not develop arthritis in response to immunization with CII whereas 86% of DBA/1 mice did, with 33% showing severe and 53% mild disease. Anti-CII antibodies of the highest titre, the lowest functional affinity, and the greatest affinity heterogeneity were associated with the development of the severest arthritis in DBA/1 mice: even in DBA/1 mice with moderate or no disease the amount of antibody and heterogeneity were higher and functional affinity lower than in either HA or LA mice. Antibodies of the G1, 2a, 2b and 3 subclasses were produced in all mice, and none of these alone accounted for the overall difference in IgG antibody titres or affinity in the groups of mice. Antibodies of the IgG2a subclass showed the closest association with the development of arthritis in the different groups. It is concluded that anti-CII antibodies of low functional affinity, and presumably also of the IgG2a subclass, influence the disease process in collagen arthritis.

Animals↗
PubMed1990

Seizure-induced miosis and ptosis: association with temporal lobe magnetic resonance imaging abnormalities.

Two patients with seizure-associated miosis and ptosis are described. In both there are magnetic resonance imaging abnormalities of the temporal lobe. In one patient, increased magnetic resonance imaging signal intensity is present in the temporal lobe contralateral to ptosis and miosis. In the other, there is temporal lobe asymmetry with the smaller temporal lobe ipsilateral to the miotic pupil and ptotic lid. The relevant human and experimental literature related to cortical control of pupil size and lid movement is reviewed. Based on the available literature and the findings in these two patients, it is proposed that the increased signal intensity in the temporal lobe of one patient represents an irritative stimulus causing contralateral miosis and ptosis, whereas the temporal lobe hypoplasia in the second patient permitted impulses from the contralateral normal temporal lobe to predominate, resulting in miosis and ptosis homolateral to the hypoplastic temporal lobe.

Adolescent↗
PubMed1989

Kestenbaum's number as an indicator of pupillomotor input asymmetry.

We compared the direct light response of both eyes in 90 patients who had anterior visual pathway disease using two different testing methods. We measured Kestenbaum's number in millimeters of pupillary diameter. Kestenbaum's number (K) is the difference in the pupil size attained in each eye under direct illumination while the other eye is occluded. We then measured the relative afferent pupillary defect (RAPD) in log units using neutral density filters. The two tests gave similar results (K = 0.88 x RAPD). Kestenbaum's number is the less precise measure, but it can be quickly and cheaply estimated even in dark brown eyes. The filter test requires a set of filters and at least one well-innervated iris sphincter. Kestenbaum's number can be measured without filters, but the iris sphincter and dilator muscles in both eyes must be normally innervated.

Filtration↗