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At least 235 records · Page 13Linked to original sources
PubMed1975

Respiratory fluctuations in pupil size.

Regular fluctuations in pupil size of the cat were measured and the properties, nervous pathways, and origin of these oscillations were investigated. The rhythm of pupil movements under control conditions appeared to be either locked to the central respiratory cycle or to the artificial ventilatory cycle. These movements were only seen in lightly anesthetized or tranquilized cats, but not in alert or deeply anesthetized cats (ether, halothane or pentobarbital). The fluctuations proved to be independent of sympathetic innervation but related to variations in parasympathetic outflow. At least two sources for pupil oscillations appeared to be involved: central respiratory activity and respiratory blood pressure fluctuations that modulated pupil width via sinoaortic baroreceptors. Lung movements per se, as a third possible factor, did not modulate pupil width, whereas electrical stimulation of the afferent lung vagi did; therefore the role of this mechanical factor is not clear. A review of the pertinent literature shows that in the organism there are many phenomena exhibiting respiratory oscillations. It seems likely that these oscillations have the same origin as the respiratory pupil fluctuations.

Anesthesia, General↗
PubMed2003

Modulation transfer functions in children: pupil size dependence and meridional anisotropy.

PURPOSE: This study quantified preschool children's optical quality in terms of their aberrations and modulation transfer function (MTF), and examined the dependence of MTF on pupil size and grating orientation. METHODS: Aberrometry was used to measure Zernike coefficients in 34 Chinese preschool children (18 males, 16 females; aged 4.95-6.89 years; mean, 5.91 +/- 0.56). For each subject, after mathematical correction for refractive error, these wavefront errors were used to calculate MTF (lambda = 550 nm) for pupil sizes from 1 to 5 mm and for gratings at orientations in 15 degrees intervals. RESULTS: Aberrations were correlated between right and left eyes, for wavefront RMS and some Zernike coefficients. Average aberrometry results showed that third-order terms predominated, in addition to some positive spherical aberration with an average higher order root mean square (RMS) of 0.20 micro m over a 5-mm pupil. Average MTFs were optimal for 3-mm pupil sizes at lower spatial frequencies (<69 cyc/deg) and slightly better than those found by similar techniques in young adults. Heights of MTFs were significantly related to higher order RMS (Spearman rho = -0.926). MTFs showed a small meridional anisotropy for 3-mm pupils, with average MTF for vertical gratings (horizontal modulation) being slightly, but significantly better than for horizontal gratings (vertical modulation). There was no evidence of an oblique effect in the optics of these children. CONCLUSIONS: In these children, ocular optical quality is pupil dependent, shows slight meridional anisotropy and is slightly better than that for young adults.

Anisotropy↗
PubMed2006

Pupillographic measurements with pattern stimulation: the pupil's response in normal subjects and first measurements in glaucoma patients.

PURPOSE: This study was undertaken to characterize the influence of contrast, luminance, and spatial frequency of a pattern stimulus on the pupil reaction of healthy subjects. First measurements with this technique in patients with glaucoma were compared with those in a control group. METHOD: Grating patterns were presented using a Maxwellian-view system to study series of contrast, luminance, and spatial frequency in three healthy subjects. The best two stimulus conditions were determined and were then used to examine 19 patients with open-angle glaucoma and 16 control subjects. RESULTS: In healthy subjects, an increasing contrast led to an increase in amplitude and a decrease in latency of the pupil reflex. Increasing luminance also resulted in an increase in the amplitude. The offset component of the pupil reflex was most pronounced at low spatial frequencies and the onset component at high spatial frequencies. When healthy subjects were compared with patients with glaucoma, control subjects generally had higher amplitudes, velocity, and acceleration of pupil constriction than did the patients with glaucoma. These differences were significant when the test was performed with a spatial frequency of 6.25 cyc/deg. CONCLUSIONS: Best stimulus conditions to elicit a pupil response to a pattern grating stimulus are 100% contrast and 55 cd/m(2) mean luminance. The choice of the spatial frequency determines which component of the pupil reflex is more pronounced. Differences between patients with glaucoma and healthy control subjects are demonstrable.

Contrast Sensitivity↗
PubMedDate not supplied

Pupil size in Jewish theological seminary students.

PURPOSE: To investigate the authors' clinical impression that pupil size among myopic Jewish theological seminary students is different from pupil size of similar secular subjects. METHODS: This cross-sectional study was conducted on 28 male Jewish theological seminary students and 28 secular students or workers who were matched for age and refraction. All participants were consecutively enrolled. Scotopic and photopic pupil size was measured by means of a Colvard pupillometer. Comparisons of various parameters between the groups were performed using the two-sample t-test, Fisher exact test, a paired-sample t-test, a two-way analysis of variance, and Pearson correlation coefficients as appropriate. RESULTS: The two groups were statistically matched for age, refraction, and visual acuity. The seminary students were undercorrected by an average of 2.35 diopters (D), while the secular subjects were undercorrected by only 0.65 D (p<0.01). The average pupil size was larger in the religious group under both scotopic and photopic luminance. This difference was maintained when the two groups were compared according to iris color under both conditions, reaching a level of statistical significance (p<0.0001). There was a significant difference in photopic pupil size between dark and light irises (p=0.049), but this difference was not maintained under scotopic conditions. CONCLUSIONS: The average pupil size of young ultraorthodox seminary students was significantly larger than that of matched secular subjects. Whether this is the result of intensive close-up work or of apparently characteristic undercorrection of the myopia is undetermined.

Adult↗
PubMed1986

Tonic pupils in neurosyphilis.

Of 60 patients with tonic pupils, 29 had serologic tests for syphilis. Five patients had positive blood serology and confirmatory tests; four had other manifestations of neurosyphilis and positive CSF serology. All seropositive patients had bilateral tonic pupils with light-near dissociation and denervation hypersensitivity. Of the 10 tonic pupils, only 1 was miotic and 1 dilated. Although tonic pupils tend to become small and bilateral, they should be distinguished readily from Argyll Robertson pupils, which react briskly, not tonically, to near stimuli. Patients with bilateral tonic pupils should have serologic tests for syphilis.

Diagnosis, Differential↗
PubMed2006

Pupil shapes and lens optics in the eyes of terrestrial vertebrates.

Animal eyes that are primarily used under low-light conditions usually have optical systems of short depth of focus, such that chromatic defocus may lead to considerable blurring of the images. In some vertebrates, the problem is solved by multifocal lenses having concentric zones of different focal lengths, each of which focuses a different relevant spectral range onto the retina. A partially constricted circular pupil would shade the peripheral zones of the lens, leading to the loss of well-focused images at relevant wavelengths. The slit pupil, however, allows for use of the full diameter of the lens even in bright light. We studied species of terrestrial vertebrates from a variety of phylogenetic groups to establish how widespread multifocal lenses are and how pupil shapes are adapted to the optical systems. We found that multifocal lenses are common from amphibians to mammals, including primates. Slit pupils were only present in animals having multifocal optical systems. Among the felids, small species have multifocal lenses and slit pupils, while large species have monofocal lenses and round pupils. The Eurasian lynx, a cat of intermediate size, has an intermediate eye design. The functional significance of the absence of multifocal optical systems in large felids remains mysterious, because such systems are present in other large-eyed terrestrial vertebrates. Multifocal optical systems in nocturnal prosimians suggest that those animals have colour vision despite being described as cone monochromats.

Animals↗
PubMed2001

Influence of Stiles-Crawford effect apodization on spatial visual performance with decentered pupils.

Using theoretical estimates of the optical-transfer function and line-spread function as image-quality criteria, we predicted the influence of the Stiles-Crawford effect (SCE) on both optical performance of the eye and subjective measurements of transverse aberrations when pupils are decentered. The SCE was modeled as a pupil apodization. The SCE appears to improve image quality by providing compensation for aberrations induced by pupil decentration, but this improvement is usually small. When a criterion of the placement of the image is used as the centroid of the line-spread function, an average SCE reduces the influence of pupil decentration on subjective transverse chromatic aberrations (TCA's) for 5-mm-diameter pupils by 30%. This reduction is much less than that obtained by previous experimental studies of TCA, and possible reasons for this discrepancy are discussed. Decentering the SCE produces an appreciable shift in subjective TCA for 5-mm-diameter pupils of 1.4 arc min per 1-mm decentration (at wavelengths 433 and 622 nm).

Color Perception↗
PubMedDate not supplied

The pupil dark response in normal volunteers.

A new semi-automatic videopupillometer with a two-channel video integrator uses prismatic displacement of pupil images for binocular recording with a single infrared-sensitive video camera. The video integrator graphically records pupil area or diameter during testing and can reanalyze and plot information from videotape recordings of pupil responses. This new pupillometer was used to evaluate the pupil dark response in 178 eyes of 89 normal human volunteers (ages 18-75 years). The time course of pupil dilation was similar in volunteers of all ages, even though the average pupil area became progressively smaller with increasing age.

Adolescent↗
PubMed2003

Acceleration effects on pupil size with control of mental and environmental factors.

BACKGROUND: Using still photography and cinematography, early studies reported that pupils dilate immediately on exposure to acceleration and the dilation persists during sustained +Gz. Due to the lack of control for mental and environmental factors and poor sampling rate in early techniques, we re-examined the effects of increased acceleration on pupil size in the human centrifuge. METHODS: Eight volunteers were dark adapted for 20 min by fixating on a 2.5 mm LED disk, 1 m away in otherwise complete darkness. Pupil diameters and horizontal and vertical eye movements were recorded binocularly in real time using an eye-tracking and pupillometry system. The recording sequence consisted of 1 min at +1 Gz, followed by transition to +3 Gz at 0.1 G x s(-1) 2 min at sustained +3 Gz, return to +1 Gz at 1 G x s(-1), and finally maintained at +1 Gz for another minute. During this sequence, the subject's heart rate was also monitored and the subject was instructed to subtract 2 from 1000 to maintain mental alertness. RESULTS: All subjects showed a significant decrease in pupil diameter (p < 0.05) and increase in heart rate (p = 0.02) during +3 Gz and regained the baseline level on sustained acceleration ranged from 0.6 to 3.3 mm. CONCLUSION: Our findings suggest that pupils constrict during hypergravity. It appears that the reflex regulation of pupil size is attributed to parasympathetic action through fibers originating in Edinger-Westphal's nucleus in the mesencephalon, which receives direct input from the otoliths.

Acceleration↗
PubMed2005

[The influence of pupil center shift on wavefront-guided laser in situ keratomileusis].

OBJECTIVE: To evaluate the pupil center shift quantitatively after pupil dilation and to investigate its influence on the outcome of wavefront guided LASIK. METHODS: Sixty-three eyes in 32 myopic patients with order RMS higher than 0.35 or were divided into groups A and B, and the Zyoptix LASIK was applied to the patients of both groups In group A, pupil center was used as the center of ablation, while in group B the ablation center was adjusted based on the pupil center shift. RESULTS: A (0.173 +/- 0.114) mm mean pupil center shift was observed in this study, with the maximum 0.51 mm. At 3 months after the operation, there was no significant difference in visual acuity and refraction power between the two groups. However, the reduction of coma was (0.025 +/- 0.137) microm and (0.097 +/- 0.118) microm in groups A and B respectively (t = 2.131, P = 0.037). The change in spherical aberration was significantly different between the two groups. CONCLUSIONS: Pupil center shift after dilation is common. Adjustment of ablation center based on the shift may improve the correction of coma.

Corneal Topography↗
PubMed1991

Effects of topical administration of timolol maleate on intraocular pressure and pupil size in dogs.

Effects of topical administration of a single dose of timolol maleate on intraocular pressure (IOP) and pupil diameter were evaluated in normotensive eyes of 11 clinically normal dogs over 12 hours (7:00 AM to 7:00 PM). Mean (+/- SEM) normal IOP was 15.5 (+/- 1.1) mm of Hg and diurnal fluctuation was observed, with the highest IOP seen in the morning. Mean normal pupil diameter was 8.5 (+/- 0.3) mm. Topical treatment with 0.5% timolol resulted in reduction of IOP in the treated and nontreated eyes. Mean reduction of IOP in the treated eye was 2.5 mm of Hg, a reduction of 16.1%, with maximal reduction of 3.7 mm of Hg. Mean reduction of IOP in the nontreated eye was 1.4 mm of Hg, a reduction of 9.0%. The treated eye had reduced pupil diameter at 30 minutes after treatment, which persisted throughout the 12 hours of the study. Mean reduction of pupil diameter in the treated eye was 2.9 mm, a reduction of 34.1%. In addition, a contralateral effect on pupil diameter was seen in the nontreated eye, with mean reduction of 1.2 mm, a reduction of 14.1%. Topical administration of timolol maleate resulted in reduction of IOP and pupil diameter in treated and contralateral eyes, thus supporting the use of timolol for treatment of glaucoma in dogs. Miosis indicates possible beta-adrenergic inhibition or alpha-adrenergic activation of the sphincter muscle. beta-Adrenergic blockade would then result in miosis.

Administration, Topical↗
PubMed1990

[Pupil--recent development of investigation].

This paper introduces recent development of investigation in the pupil system, in the Department of Ophthalmology, Kitasato University. Firstly, normal pupil parameters among various age groups (10 years to 70 years old) were studied by a new infrared videopupillography (Iriscorder C-2515). The parameters studied were pupil area in darkness, and other various parameters followed by photic stimulation (3000 troland) of the eye. Secondly, the pupil was studied by photographic method using infrared film under ordinary illuminated (500-800 Lux) room, and drug response especially pilocarpine of the pupil was studied and reviewed. Thirdly, a new information about pupil response followed by 0.06% pilocarpine instillation in patients under the brain death has been proposed. Denervation supersensitivity was obvious in 70% of the patient under brain death. Clinical significance of this pharmacological study has been emphasized especially for the determination of the brain death under comatose state of a given patient.

Adolescent↗
PubMed1989

[Inhibition of acetylcholinesterase at pupil-related central nuclei by organophosphorus pesticide (fenthion)--an experimental study].

An organophosphorus pesticide (OP) inhibits acetylcholinesterase (AChE) of various organs, especially in cholinergically innervated organs. Pupil constriction is a major sign of an ocular symptom in the patient with acute OP intoxication, but the etiology is unknown. The present experiments were intended to elucidate a central mechanism of pupil size in which AChE and OP are involved. Fenthion (dimethyl 4-methylthion-m-tolyl phosphorothionate) of 5mg/day body weight) was subcutaneously administered dorsally in Wistar rats for 14 days consecutively in the longest group. Histochemical staining and microspectrophotometry were used to analyze the intensity of the AChE activity in the iris, the pretectal nucleus and Edinger-Westphal (EW) nucleus on the 2nd, 4th, 6th, 10th and 14th day of administration. The pupil was measured after 20 minutes of dark adaptation. The pupil constricted on the 6th day and most remarkably on the 10th day. The AChE activity in the iris decreased remarkably on the 4th day. Miosis was not seen on the 4th day. The AChE activity in the pretectal nucleus decreased remarkably on the 6th day. The AChE activity in the EW nucleus reduced gradually from the 6th day and 62% reduction of initial value was seen on the 14th day. Intense miosis was seen on the 10th day. In conclusion inhibition of AChE activity was detected first in the iris, thereafter in the pretectal nucleus and the EW nucleus in close correlation with the miotic pupil. Therefore, miosis associated with OP intoxicated patients may parallel the central inhibition of AChE in pupil-related centers.

Acetylcholinesterase↗
PubMed1979

[The role of the pupil's size in the perception of other persons].

Studies by Hess (1975) show that the pupil serves as a source of information in perception of the emotional state of another person. Large pupils are interpreted in a positive sense. Basing on the results of Hess, the hypothesis that pupil size does not become a relevant variable in person perception until after puberty, was formed. The following result would be interpreted as supporting the hypothesis: since girls reach puberty before boys, more girls should react to pupil size than boys of the same age. 121 students between the ages of 11 and 16 years judged in several statements which of two face photos of a teacher expressed a greater degree of positive attention and esteem towards the students. The two face photos were identical with the exception of pupil size. All age groups rated the photos with larger pupils more positively. Sex differences occurred in the ratings of the 11 to 12-year-olds. Some basic differences between this experiment and that of Hess are discussed.

Adolescent↗
PubMed1984

Permanent alterations in muscarinic receptors and pupil size produced by chronic atropinization in kittens.

Chronic mydriasis was induced in six kittens (four monocular, two binocular) and two adult cats (both monocular) by the daily topical application of atropine. Both the kittens and the adult cats were atropinized for a 13-week period with the treatment regimen beginning at the time of eye opening for the kittens. Pupil size measurements, obtained 1 year after the atropinization were discontinued, revealed that, although the pupils of the adult cats were normal, the pupils of the kittens' treated eyes were consistently smaller than pupils in control eyes. The status of the muscarinic receptors in the kittens' irides was investigated using 3H-QNB binding assays. In comparison with iris muscle homogenates from the control eyes, those from the treated eyes demonstrated an eightfold increase in the number of receptor binding sites. The results indicate that pupil size can be altered permanently by chronic mydriasis initiated early in the life of a kitten and that the permanent change in pupil size may result, in part, from a type of permanent supersensitivity response in the muscle following chronic blockade of muscarinic transmission by atropine.

Age Factors↗
PubMed1997

Limbus versus pupil center for ocular alignment measurement with corneal reflexes.

PURPOSE: To investigate the accuracy of ocular misalignment measurement, using corneal reflections. METHODS: Corneal reflex positions were measured relative to two landmarks, the limbus center and the entrance pupil center, using high-resolution digital images for cyclopean gaze angles from 0 degree to 18.8 degrees (34.04 prism diopters; PD) to the right and to the left in 10 subjects. Distance h from the center of the corneal curvature to each landmark was determined from linear regressions and showed significant differences between both conditions: mean hlimbus was 5.243 mm, and mean hpupil was 4.884 mm. From these, limbus- and entrance-pupil-center-related Hirschberg ratios were determined as 11 degrees/mm (19.43 PD/mm) and 11.82 degrees/mm (20.92 PD/ mm), respectively; and ocular alignment was calculated for both conditions. Simulated angles of strabismus were calculated as the binocular difference between ocular alignment of the right and left eyes (condition 1), and as the monocular difference between the ocular alignment of right eyes and left eyes separately (condition 2). RESULTS: Condition 1: Errors in simulated angles of strabismus were approximately twice as large for entrance pupil center compared with those in limbus-center-based evaluation; in the primary position, the 95% pupil-related confidence interval of the binocular difference was +/- 5.217 degrees (9.1 PD), compared with +/- 3.174 degrees (5.5 PD) for the limbus-related option. Condition 2: Errors were approximately equal. CONCLUSIONS: The entrance pupil center is a less reliable landmark than is the limbus center for measuring ocular alignment by using corneal reflections, because of unreliable positions of the entrance pupil center; different mean Hirschberg ratios should be used in both conditions.

Blinking↗
PubMed2005

Pupil ovalization after phakic intraocular lens implantation is associated with sectorial iris hypoperfusion.

OBJECTIVE: To investigate iris perfusion in patients with and without pupil ovalization after phakic intraocular lens implantation. METHODS: Comparative retrospective randomized case series of 6 participants, each with a regular pupil, and 6 participants with pupil ovalization after phakic intraocular lens implantation for high myopia were included in the study. Indocyanine green angiography was performed between 20 and 40 months (mean +/- SD, 26 +/- 6.1 months) after lens implantation. RESULTS: Iris perfusion defects were found in 5 of 6 patients with pupil ovalization. No perfusion deficits were noted in patients with round pupils. CONCLUSION: Iris ovalization after phakic intraocular lens implantation may be associated with a lack of iris perfusion and with secondary ischemia. Patients with these lenses and pupil ovalization should be followed regularly.

Adult↗
PubMed1977

Sex differences in behavior ratings: male and female teachers rate male and female pupils.

Male and female primary school teachers rated their male and female pupils using a 16-item classroom behavior rating scale (Modified AML). Male pupils were generally rated more poorly than femal pupils by both male and female teachers. Male teachers rated both male and female pupils more conservatively than did female teachers on the separate factors of the AML scale. There was no difference in ratings by male and femal teachers of the overall adjustment of pupils, where the extreme scale point called for a professional decision as to whether the child should be referred to child guidance services. The findings have methodological implications for epidemiological studies, and for longitudinal studies. The findings fail to support the view that male pupils have more difficulty in school because they are taught by female teachers.

Aggression↗