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PubMed1989

Consensual pupillary light reflex in the pigmented rat.

We measured the pupillary light reflex (PLR) in 5 pigmented, Long Evans rats (under urethan sedation) in three conditions: direct stimulation, consensual stimulation, and a control condition designed to measure the effects of stray light. The average constriction (maximal amplitude) produced by a ganzfeld stimulus delivering 1.6 log quanta absorbed per rod per sec for a duration of 3 sec was measured to be 0.78 +/- 0.07 mm for the direct PLR, 0.67 +/- 0.06 mm for the consensual PLR, and 0.07 +/- 0.029 mm for the control condition. We corrected the consensual measurement for each rat by subtracting the value of the control (stray-light induced) constriction. A comparison of the corrected consensual constriction to the direct constriction showed that, on average, the consensual constriction attained an amplitude of 78% of the direct constriction. Our findings contradict claims that the consensual pupillary light reflex is absent in rodents. Although our results are in agreement with findings showing bilateral projections of the retina to the pretectum (which subserves the pupillary light reflex) in the rat, the consensual-to-direct ratio we report is higher than might be expected from anatomical estimates of the overall proportion of uncrossed to crossed optic fibers in the rat.

Animals↗
PubMed1994

[Hand-held pupillometer for evaluating pupillary light reflex in general practice and at the bedside].

Owing to the sophisticated equipment currently required for the investigation of pupillary behavior, pupillographic procedures are still the preserve of a few specialized laboratories. To allow pupillographic measurements under ophthalmological office conditions, we designed a portable pupillometer that can also be used for bedside examinations. Following a defined light stimulus, the prototype presented in this paper records a direct pupillary light reflex on the basis of infrared reflex photometry. The latency of the pupillary reflex and the pupillary constriction time are determined and shown on a digital display.

Equipment Design↗
PubMed1995

[Long-term prolongation of direct pupillary light reflex latency and P100 latency of pattern visual evoked potential in unilateral optic neuritis].

We evaluated the visual functions of visual acuity, color sense, direct pupillary light reflex and pattern visual evoked potentials (P100) in five patients with unilateral optic neuritis whose visual acuity improved to 1.0 or better in order to assess the recovery of the impaired optic nerve fibers from the inflammatory process. During follow-up periods the direct light pupillary reflex was electropupillographically recorded and the P100 latency of visual evoked potentials was examined in both eyes. The temporal course of their differences showed a biphasic curve: the acute stage showed a rapid decrease of the differences and the chronic stage showed a flat line analysis of Pearson's correlation coefficient revealed that latency differences were mutually altered although there was a tendency for differences of direct pupillary reflex latency to decrease more rapidly at the acute stage than those of P100 latency. The present study demonstrated that the two different classes of the optic nerve fibers originating from the retinal ganglion cells, pupillary reflex-related fibers and form vision-related fibers, were damaged to the same degree by the inflammation, in spite of their morphological differences.

Adult↗
PubMed1999

Comparison of the effects of venlafaxine, paroxetine and desipramine on the pupillary light reflex in man.

RATIONALE: The time-course of the pupillary light reflex response is determined by the successive activation of the parasympathetic and sympathetic innervations of the iris, the latency and the amplitude reflecting parasympathetic and the recovery time mainly sympathetic activity. OBJECTIVE: To compare the effects of single doses of three antidepressants (venlafaxine: serotonin/noradrenaline reuptake inhibitor, paroxetine: selective serotonin reuptake inhibitor, and desipramine: tricyclic antidepressant) on resting pupil diameter and the pupillary light reflex response. METHODS: Fifteen healthy male volunteers participated in five weekly sessions, each of which was associated with one treatment (venlafaxine 75 mg or 150 mg, paroxetine 20 mg, desipramine 100 mg, or placebo) according to a double-blind, double-dummy, balanced, cross-over design. An infrared binocular television pupillometer was used for the recording of the resting pupil diameter and the pupillary light reflex in darkness, in previously dark-adapted eyes. Resting pupil diameter in darkness was recorded before and after treatment. The pupillary light reflex was elicited after treatment, with six light flashes (green, 565 nm peak wavelength) of 200 ms duration and of incremental illuminance (measured in the plane of the cornea): 3.0 x 10(-3) 8.5 x 10(-3) 2.5 x 10(-2), 7.0 x 10(-2), 0.18, 0.43 mW cm(-2). The parameters studied were: latency, amplitude and 75% recovery time. RESULTS: Analyses of variance followed by post hoc tests (least significant difference test or Dunnett's test; P < 0.05) revealed that both doses of venlafaxine produced a significant increase in resting pupil diameter, decrease in amplitude and shortening of the 75% recovery time of the light reflex response; venlafaxine 150 mg prolonged the latency, while the other treatments had no significant effects. CONCLUSIONS: The increase in resting pupil diameter could be indicative of parasympathetic inhibition and/or sympathetic activation. The shortening of the recovery time of the light reflex response is consistent with sympathetic potentiation resulting from noradrenaline uptake blockade in the iris. The prolongation of the latency and decrease of the amplitude of the light reflex response are indicative of a parasympatholytic effect of venlafaxine. However, as venlafaxine has negligible affinity for muscarinic cholinoceptors, this effect cannot be attributed to the blockade of cholinoceptors in the iris. A possible explanation for this finding is that it reflects a central rather than a peripheral effect of the drug: the blockade of noradrenaline uptake in the brain could lead to the potentiation of the noradrenergic inhibition of central parasympathetic (Edinger-Westphal) neurones. These results demonstrate the ability of therapeutically relevant single doses of venlafaxine to potentiate noradrenergic responses in man, consistent with the blockade of noradrenaline uptake.

Adrenergic Uptake Inhibitors↗
PubMed1995

The pupillary light reflex pathway of the primate.

BACKGROUND: Many studies of the pupillary light reflex pathway in mammals have indicated that the pretectum is important for this reflex. However, no single retinorecipient pretectal nucleus has been unequivocally identified as being involved in the light reflex pathway. In this study, anatomical studies in the rhesus monkey were carried out to identify the relevant retinorecipient pretectal nucleus and to better define the central pathway of this reflex. METHODS: An injection of Wheatgerm Agglutinin/Horseradish peroxidase, a neuroanatomical tracer, was placed under physiological guidance into the Edinger-Westphal nucleus. Intravitreal injection of the same tracer in another animal was used to define the pretectal retinal terminal fields. RESULTS: Following injection of tracer in the Edinger-Westphal nucleus, retrogradely labeled cells were found in only one retinorecipient nucleus, the pretectal olivary nucleus. Most labeled cells were located contralateral to the injection site. A few labeled cells were located ipsilaterally. Intravitreal injection of tracer resulted in anterograde labeling of all the retinorecipient pretectal nuclei, including the pretectal olivary nucleus. The retinal terminal field in the pretectal olivary nucleus coincided with the location of the cells that were retrogradely labeled by the injection of tracer into the Edinger-Westphal nucleus. CONCLUSIONS: These results demonstrate that there is a direct projection from the pretectum to the Edinger-Westphal nucleus, that it arises from only one retinorecipient pretectal nucleus, the pretectal olivary nucleus, and that cells in the pretectal olivary nucleus almost all appear to project to the contralateral Edinger-Westphal nucleus.

Animals↗
PubMed1984

The neural substrate for the pupillary light reflex in the pigeon (Columba livia).

The neural substrate of the pupillary light reflex in the pigeon was investigated using anatomical, stimulation, and lesion techniques. In birds, as in mammals, the sphincter pupillae muscle (which constricts the iris) is innervated by cells in the ciliary ganglion (Pilar and Tuttle, '82). These cells are in turn innervated by cells in the Edinger-Westphal nucleus (EW) (Cowan and Wenger, '68; Narayanan and Narayanan, '76; Lyman and Mugnaini, '80). The efferent link of the pupillary light reflex must therefore involve cells in EW. To study the central course of this reflex pathway, injections of horseradish peroxidase (HRP) were placed in EW. These injections labeled cells in a number of regions including a contralateral pretectal nucleus, area pretectalis (AP). Only a limited number of cells in AP project to EW. Injections of tritiated amino acids into AP labeled a discrete region of the contralateral EW. This projection is confined to a dorsolateral region of caudal EW and overlies the somata of approximately 100 cells. Tritiated proline was injected into the eye, and the results confirmed an earlier report (Reperant, '73) that AP receives retinal input from the contralateral eye. Immunohistochemical studies demonstrated fibers in AP that stained positively for substance-P-like, enkephalin-like and tyrosine-hydroxylase-like immunoreactivity. Injections of HRP were placed in AP to examine the retinal ganglion cells mediating the reflex. Cells with an average diameter of approximately 14 microns (5-25 microns range) were labeled and averaged approximately 6 microns greater in diameter than the retinal ganglion cells (mean = 7.3 microns) labeled by an optic chiasm injection. The cells labeled by AP injections were distributed unevenly throughout the retina with a higher concentration in the central and temporal retina and a paucity in the red field and fovea. Our results demonstrate that AP receives input from a distinct subpopulation of large retinal ganglion cells that comprises a very small percentage of the total population of retinal ganglion cells. Unilateral lesions of AP abolished the pupillary light reflex in the eye contralateral to the lesion; stimulation of AP elicited pupilloconstriction in the eye contralateral to the stimulation site. These results delineate the central course of the pupillary light reflex pathway in the pigeon and identify the retinal ganglion cells that subserve this reflex. They show that, at every point in the pathway, only a few cells mediate this simple reflex.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1976

[Adie's syndrome].

The author has investigated patients suffering from disorders of the pupillary reflexes and of the tendon reflexes of the lower limbs which come under the heading of tonic pupil. Forty-five patients were followed up over a period of 15 years. The tendon reflexes of the lower limbs were recorded graphically and showed a very characteristic retardation of the second phase of the patellar reflex. The aetiopathogenesis of Adie's syndrome is discussed. The pathogenesis of Adie's syndrome has so far not been definitely established. We have merely tried to point out a few of the features which permit its early diagnosis and have drawn attention to the basic problem of the pathogenesis of certain neuro-muscular disorders on the basis of secondary considerations involved in this uncommon syndrome.

Adie Syndrome↗
PubMed1995

Pupillary light reflex.

A wealth of new information has recently come to light concerning the pupillary response to various types of visual input. Much of this information is recent, and has either been published in the last year, is in press, or has just been reported at meetings. This new information is important because it is resulting in reexamination of the pupillary input pathways and the clinical role for using pupillary movements to understand the physiology and pathology of the visual system. This review will focus on this new information and its clinical implication. The review is organized in the following sections: 1) the pupillary response to full-field, global light stimuli; 2) "pupil perimetry" or the pupillary response to focal light stimuli; 3) the pupillary response to isoluminant stimuli, eg, color spatial frequency, motion; 4) receptive field organization in the pupillary light reflex pathway.

Humans↗
PubMed1989

The pupillary light reflex in diabetes mellitus: evaluation of a newly developed infrared light reflection method.

Pupillary light reflexes were measured in 18 diabetic patients without clinical signs of neuropathy and in 18 control subjects, using a newly developed infrared light reflection technique called IRIS. This method has some important advantages. Apart from being non traumatic, it enables the recording of dynamic pupillary light reflexes simultaneously in both eyes. Furthermore, it has a large amplitude and time resolution (1 ms), permitting accurate determination of latency values. It was found that 78% of the diabetic patients show a significantly prolonged latency of the constriction reaction, while 39% of the diabetic patients show an abnormally prolonged dilatation latency. All patients with an abnormally prolonged dilatation latency also show a prolonged constriction latency. This finding suggests that in diabetes mellitus the parasympathetic system is affected before abnormalities of the sympathetic nervous system can be demonstrated. Assessment of the pupillary light reflex, using the sensitive IRIS method, is an easily applicable and reliable method for detection of subclinical autonomic nervous system dysfunction associated with diabetes mellitus. The method may also provide an objective tool for the assessment of therapy results in diabetic neuropathy.

Adult↗
PubMed2006

Ultraviolet light-induced and green light-induced transient pupillary light reflex in mice.

PURPOSE: To study UV light-induced and green light-induced pupillary light reflex (PLR) in mice and to measure the illumination thresholds of rod-mediated and cone-mediated PLR responses. METHODS: We measured dark-adapted transient PLR- in C57BL/6 mice elicited with ultraviolet and green light over an intensity range of 9 log units. To assist in isolating the responses mediated by rods and cones, we studied the PLRs in mouse models presenting pure cone and pure rod functions. We also characterized ERG signals in these mice under the same experimental conditions. RESULTS: The UV light-induced transient PLR has identical intensity-response curves as green light-induced PLR in all the three mice strains. The threshold (5% PLR) of rod-driven PLR is 107 approximately 108 photons cm2 s-1, which is 1 approximately 2 log units lower than the dark-adapted ERG b-wave. The threshold of cone-driven PLR is approximately 1012.5 photons cm-2 s-1 and is similar to that of the cone ERG. CONCLUSIONS: We demonstrated that mice have PLR responses under UV stimulation. The cone-elicited PLRs have a threshold that is approximately 5 log units higher than that of rod-elicited PLR at both UV and green wavelengths. We observed a divergence between the spectra responses in PLR and ERG. However, the mechanism and implications of this phenomenon are yet to be identified.

Animals↗
PubMed2005

Effects of tobacco smoking on the kinetics of the pupillary light reflex: a comparison between smokers and non-smokers.

BACKGROUND: The time course of the pupillary light reflex (PLR) is determined by the successive activation of parasympathetic and sympathetic innervations of the iris, latency and amplitude reflecting parasympathetic activity and recovery time showing mainly sympathetic activity. OBJECTIVE: To determine the effects of tobacco cigarette smoking on the PLR in smokers after an abstinence period of at least 12 h. METHODS: Ten smokers (mean 15.7 cigarettes/day) and 10 non-smokers participated in a randomised, non-intervention controlled, cross-over study that included a parallel control group. Smokers underwent two sessions with a time interval between 3 and 8 days; two recordings were taken at each session, separated by 20 min: session 1, without smoking, and session 2, smoking 3 cigarettes within a 30-min period. Non-smokers underwent one session; two recordings were taken separated by 20 min. At each recording, in both groups, PLR was elicited with four light flashes of increasing luminance. RESULTS: The relationship between PLR parameters and light intensity was linear in each subject. The slope of the regression line for relative amplitude increase versus intensity was significantly flatter in abstinent smokers than in non-smokers (p=0.033); the slope returned significantly after smoking (p=0.043). No other significant effects were obtained. CONCLUSIONS: Kinetic parameters of PLR provide a sensitive pharmacological test to detect cholinergic neurotransmission manipulation effects, as they seem to detect changes in moderate smokers after 12 h of abstinence, and their reversal on return to smoking. These results suggest an enhancement in the suppression of the parasympathetic oculomotor reflex arc rather than a facilitation of the sympathetic drive to the iris.

Adult↗
PubMed1998

Changes in the pupillary light reflex of pigmented royal college of surgeons rats with Age.

We studied the latency and amplitude of the pupillary light reflex response of the Royal College of Surgeons rat from 10 to 52 weeks of age. The responses of these dystrophic rats were diminished compared to those of normal, non-dystrophic rats at all ages examined. This was most marked at the dimmest light intensity studied here and for the latency of dystrophic animals' responses. The latency deteriorated over the course of 52 weeks, although there was some evidence of improvement beyond 36 weeks of age. The amplitude of the dystrophic animals' responses also suggested some deterioration occurring up to 36 weeks of age, but with a substantial improvement beyond this time. In addition to these parameters, we also observed a break in the constriction phase of the pupillary light reflex that was unique to the dystrophic animals' responses. The frequency with which the anomaly occurred decreased in a light-dependent manner with age. The improvement of the pupillary light reflex at older ages, even when very few photoreceptors remain, may reflect compensatory events occurring in the inner retinal layers and/or in the central connections of the pupillary light reflex pathway. We suggest that the break in the constriction phase is a reflection of dual inputs driving the response, one of which is affected more by the degenerative events. This study provides baseline data on the effect of degeneration on function over time which can be used to evaluate the efficacy of repair strategies such as transplantation.

Aging↗
PubMed1987

Pupillary light reflex in patients with hemispheric cerebrovascular disease.

Pupillary dynamics were investigated in 41 patients with hemispheric CVD by means of computerized open-loop videopupillography. The patients were alert and showed either abnormal high- or low-density areas on CT scan. Fourteen cases were examined in the acute stage (within 7 days from onset), 28 cases in the subacute stage (between 8 and 28 days) and 11 cases in the chronic stage (over 29 days). In the acute stage, the parasympathetic nervous functions (maximum velocity and acceleration of pupillary constriction) were hyporeactive and showed no significant differences between the ipsilateral and contralateral side of the lesion. In the subacute stage, these functions were significantly more hyperreactive on the ipsilateral side than on the contralateral side, that is, the parasympathetic functions of the healthy hemisphere became significantly improved in comparison with those in the acute stage. In the chronic stage, no significant differences were observed between the two sides. In contrast, the sympathetic nervous function (maximum velocity of dilatation) showed no differences with respect to either laterality or the time course after onset. The above data suggest that bilateral parasympathetic hypofunctions exist in the acute stage of hemispheric CVD, with an ipsilateral improvement of these functions with the passage of time, and that such autonomic dysfunctions may play some role in the pathophysiology of CVD.

Aged↗
PubMed1979

Possibilities of simultaneous analysis of phasic pupillary light reflex and visual evoked potentials.

A report of first results of a simultaneous analysis of the phasic pupillary light reflex and visual evoked potentials (VEP). It is shown that combination of pupillography with VEP analysis can be of some use in the diagnosis of conductive defects of the optic nerve (e.g. optic neuritis). Furthermore, the simultaneous analysis allows distinction between subclinical disturbances of the afferent and efferent arcs of the pupillary light reflex. Assuming a lesion of the afferent arc secondary to damage to the optic nerve, an increase of both the pupillomotor and the VEP latencies is seen. With lesions of the efferent arc (e.g. in the case of a third nerve palsy) only the pupillomotor latency is altered. Potentialities and disadvantages of the method are discussed.

Adult↗
PubMed1989

Cardiovascular and pupillary light reflexes in subjects with abnormal glucose tolerance.

It is well known that in diabetes mellitus autonomic neuropathy frequently develops. This is usually determined by the cardiovascular reflex. Furthermore, even in borderline cases that have not become overt diabetes, we have already reported the presence of autonomic neuropathy as assessed by the pupillary light reflex. However, a relationship between the impairments of the cardiovascular and pupillary light reflexes is not clear, especially in people with abnormal glucose tolerance. In the present study diabetics were divided into three groups according to the results of their cardiac beat-to-beat variation (BBV) tests and Schellong tests; group I had no abnormality of these cardiovascular reflexes, group II had abnormal BBV scores and normal Schellong test scores, and group III had abnormal responses to both tests. People with borderline diabetes (B-DM) were free from any impairment of their cardiovascular reflexes. We examined their pupillary light reflexes. Age-matched non-diabetics were also studied as a control. The following results were obtained. (1) Compared to controls, (a) diabetics, but not borderline diabetics, had smaller pupils before photic stimulation (A1) and lower maximum dilatation velocities (VD). These illustrate sympathetic function; (b) diabetics and borderline diabetics had lower amplitudes of constriction (A3) and maximum constriction velocities (VC). These illustrate parasympathetic function; (c) borderline diabetics and those diabetics belonging to group III experienced a lower pupillary constriction rate.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed2006

[Dynamics of the pupillary light reflex in unilateral Horner's syndrome].

BACKGROUND: The aim of this study was to characterise the changes of the dynamic pupillary light reflex in patients with unilateral Horner's syndrome by appropriate pupillographic parameters. METHODS: The dynamic changes of pupillary diameter in response to light flashes of 100 ms were recorded in darkness with two infrared video cameras in 15 patients. RESULTS: Significant changes in the pupillary light reflex of the affected side were observed only during the phase of redilatation. The decelerated redilatation was defined by the following parameters: (1) time parameters (percentage of redilatation after 4 s and after 5 s, time to reach 67% and 75% of redilatation) and (2) amplitude-adjusted velocity parameters (relative velocity at 67% and at 75% of redilatation). CONCLUSION: A slowed pupil redilatation in patients with Horner's syndrome can be detected also after short light flashes and is characterised by prolonged redilatation time parameters and reduced amplitude-adjusted redilatation velocity parameters.

Adolescent↗
PubMed1995

The intensity of the pupillary light reflex does not correlate with the number of retinal photoreceptor cells.

The purpose of this study was to determine if the pupillary light reflex (PLR) can serve as an indicator of the number of photoreceptor cells present in the rat retina to a sufficient degree of precision to be useful for testing the functional effects of retinal transplantation. The PLR was measured as percentage constriction of normal Fischer 344 rats (n = 14) and compared to the PLR of light-damaged (1300 luxes/30 days exposure) Fischer rats (n = 13). Additionally, the PLR of RCS-rdy+ (congenic) rats (n = 8) was compared to the PLR or RCS dystrophic rats (n = 7). Three eyes from each group were randomly chosen for morphometry. The number of photoreceptor nuclear profiles per 60 microns of retinal length was counted at six predetermined loci and averaged. The mean PLR of Light-Damaged F344 group (64%) was significantly different from the mean PLR of the Normal F344 group (75%) (P = 0.003). However, the mean PLR of the RCS Dystrophic group (72%) did not differ from the mean PLR of the RCS Congenic group (71%) (P = 0.82). Morphometry revealed that the mean number of photoreceptor nuclear profiles within each group of animals was vastly different: Normal F344 = 138, Light Damaged F344 = 19, Congenic RCS = 93, and Dystrophic RCS = 1. No correlation was found between intensity of PLR and number of photoreceptors present (r = 0.11, P = 0.78).(ABSTRACT TRUNCATED AT 250 WORDS)

Aging↗