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At least 145 records · Page 8Linked to original sources
PubMed1981

The pupillary light reflex in normal subjects.

In 19 normal subjects the pupillary reflex to light was studied over a range of stimulus intensities by infrared electronic pupillography and analysed by a computer technique. Increasing stimulus intensity was associated with an increase in direct light reflex amplitude and maximum rate of constriction and redilatation. Latency from stimulus to onset of response-decreased with increasing stimulus intensity. The normal range for each of these parameters is given and the significance of these results in clinical pupillary assessment discussed.

Adolescent↗
PubMed1995

Efferent projections of the olivary pretectal nucleus in the albino rat subserving the pupillary light reflex and related reflexes. A light microscopic tracing study.

The olivary pretectal nucleus is a primary visual centre sensitive to luminance changes. It is involved in the pupillary light reflex, the consensual pupillary light reflex and related reflexes, such as the lid closure reflex whereby pupillary constriction takes place. Since the olivary pretectal nucleus is a small nucleus, previous studies using degeneration, horseradish peroxidase and radioactive amino acid tracing were limited regarding to the exclusiveness of the projections from the olivary pretectal nucleus. In the present study the position of the olivary pretectal nucleus in the rat was first localized by physiological recording of the neurons upon luminance stimulation. Subsequently, an anterograde tracer Phaseolus vulgaris leucoagglutinin was injected iontophoretically. This allows a much more precise localization of the olivary pretectal nucleus projections. Ascending and descending pathways originating from the olivary pretectal nucleus were observed. Ascending fibres project bilaterally to the intergeniculate leaflet, the ventral part of the lateral geniculate nucleus and ipsilaterally to the anterior pretectal nucleus. In addition, contralateral projections were observed to the zona incerta and the fields of Forel. Descending fibres project bilaterally to the periaqueductal gray, the nucleus of Darkschewitsch, the interstitial nucleus of Cajal, the Edinger-Westphal nucleus and the intermediate gray layer of the superior colliculus. Also a contralateral projection to the oculomotor nucleus and an ipsilateral projection to the pontine nucleus and the nucleus of the optic tract were found. Furthermore, the contralateral olivary pretectal nucleus received a small projection. Retrograde tracing experiments using two fluorescent dyes revealed that the fibres projecting to the contralateral olivary pretectal nucleus and to the contralateral interstitial nucleus of Cajal are collaterals. The projection from the olivary pretectal nucleus to the facial nucleus which has been described to receive an input in cats could not be confirmed for the rat. The fact that the Edinger-Westphal nucleus, the interstitial nucleus of Cajal and the superior colliculus receive an input from the olivary pretectal nucleus suggests that this primary visual centre is not only involved in the pupillary light reflex, but also in controlling eye and head position and saccadic eye movements. Although visual acuity largely depends on receptive field sizes of retinal ganglion cells and their central connections, the stronger sympathetic influence during the pupillary light reflex in animals with frontally placed eyes compared to animals with laterally placed eyes may also contribute to the higher visual acuity in animals with frontally placed eyes.

Afferent Pathways↗
PubMed1990

Autonomic components of the human pupillary light reflex.

To investigate the autonomic components of the pupillary light reflex in humans, we used infrared pupillometry combined with a partial local cholinergic (tropicamide) or alpha-adrenergic (thymoxamine) blockade. The pupillary response curve was analyzed using parameters identical or similar to those employed previously to study the autonomic components of the pupillary light reflex. Tropicamide increased baseline pupil area and affected five of the eight measured parameters. Thymoxamine lowered baseline pupil area but did not affect any of the parameters. We found the expected cholinergic contribution to the constrictive phase of the pupillary light reflex but no evidence for peripheral alpha-adrenergic activity during redilation. We propose that redilation primarily involves parasympathetic relaxation, modulated by cholinergic inhibition of the dilator muscle and central sympathetic inhibition of the Edinger-Westphal nucleus.

Adult↗
PubMed1995

Oval pupil in patients with diabetes mellitus: examination by measurement of the dark-adapted pupillary area and pupillary light reflex.

Determination of the dark-adapted pupillary area (DAPA) by infrared photography revealed that some diabetic patients show corectopia (oval pupil) in addition to the small DAPA as pupillary abnormalities. The prevalence and clinical details of oval pupil were compared between diabetic patients and healthy subjects. Pupillary light reflexes were also analyzed with an infrared videopupillography in some of the diabetic patients. The healthy subjects were examined for the influence of age on the ratio of the pupillary diameter of the major and minor axes. The ratio was 1.04 +/- 0.02 (mean +/- S.D.) in the healthy subjects, and cases in which the ratio was +2 S.D. or higher than the mean ratio were defined as oval pupil. Oval pupil was observed in 21 (24%) of 86 diabetic patients, and was correlated with heart rate variation (P < 0.05) and DAPA (P < 0.01), which represent an autonomic dysfunction. Quantitative analysis of pupillary light reflexes with an infrared videopupillography revealed that the dark-adapted pupillary area before photic stimulation (P < 0.01) and the maximum %-velocity of constriction (P < 0.05) were significantly less in the oval pupil group than in the round pupil group. Cranial magnetic resonance imaging revealed no abnormalities in the oval pupil group. From these results, a peripheral autonomic disorder was implicated in the etiology of oval pupils in diabetic patients.

Adult↗