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At least 127 records · Page 7Linked to original sources
PubMed2005

Pre-excimer laser and post-excimer laser refractive surgery measurements of scotopic pupil diameter using 2 pupillometers.

PURPOSE: To compare a digital infrared pupillometer with a handheld light amplification pupillometer for measuring scotopic pupil size and to evaluate if the postoperative refractive changes of the cornea can influence pupil measurements. DESIGN: Prospective noncomparative interventional case series. PARTICIPANTS: One hundred eyes, 50 myopic (mean spherical equivalent [SE] refraction [+/- standard deviation], -4.32+/-2.44 diopters [D]) and 50 hyperopic (mean SE refraction, +2.95+/-0.99 D), of 50 otherwise healthy subjects underwent photorefractive keratectomy or LASIK. INTERVENTION: The preoperative and postoperative scotopic pupil sizes were measured by 2 examiners (E1, E2) with both a handheld light amplification pupillometer (Colvard, Oasis Medical, Glendora, CA) and a digital infrared pupillometer (Eye World Pupillometer [EWP], Oculus Keratograph, Oculus Opikgerate GmbH, Wetzlar, Germany). The agreement and interrater repeatability were determined using the comparison method described by Bland and Altman. The paired Student's t test was used to evaluate the difference between the preoperative and postoperative measurements. MAIN OUTCOME MEASURES: Scotopic pupil diameter, topographic corneal refractive power, uncorrected visual acuity (VA), best spectacle-corrected VA, and manifest spectacle refraction. RESULTS: The preoperative mean scotopic pupil diameter was 6.12+/-0.90 mm with the EWP and 6.18+/-0.91 mm with the Colvard. After the surgery, mean SE refractions were -0.22+/-0.98 D (myopic patients) and +0.19+/-0.40 D (hyperopic patients). Postoperative mean scotopic pupil diameters were 6.12+/-0.89 mm (EWP) and 6.17+/-0.90 mm (Colvard). There was no statistically significant difference between preoperative and postoperative mean scotopic pupil sizes in either patient group. The limits of agreement between the 2 devices ranged from 2.24 mm (E1) to 2.12 mm (E2) preoperatively and from 2.27 mm (E1) to 2.08 mm (E2) postoperatively. The coefficient of interrater repeatability ranged from 0.56 mm (EWP) to 1.12 mm (Colvard) preoperatively and from 0.62 mm (EWP) to 1.14 mm (Colvard) postoperatively. CONCLUSIONS: The digital infrared pupillometer showed better preoperative and postoperative repeatability than the handheld light amplification pupillometer. In the present study, a mean correction of <3 D of the corneal refractive power did not seem to modify the preoperative scotopic pupil size measurements.

Adult↗
PubMed2002

A comparative study of stimulus-specific pupil responses in the domestic fowl (Gallus gallus domesticus) and the human.

Pupil responses triggered by specific stimulus attributes such as spatial structure, colour and light flux changes were measured in eight domestic fowl. Comparative experiments were also carried out in human subjects. The results were unexpected in that large increments in light flux caused only small constrictions of the pupil. A red stimulus, on the other hand, caused a relatively large pupil response, but a green stimulus was less effective. This finding suggests that the size of the pupil, apart from being controlled by well-described pretectal pathways that mediate luminance responses, is also subject to other inputs. The pupil response in the domestic fowl may therefore make an effective quantitative indicator of things of significance to the animal. In some ways these observations are similar to other findings in primates in that the processing of stimulus attributes such as colour and structure that are not normally associated with the light reflex pathway can cause a pupil response. The fowl pupil does however respond very fast when large light flux changes or red stimuli are involved. Results obtained with sinusoidally modulated light flux changes reveal a short response latency of 105 ms (SD=8.3). In contrast, human responses measured for similar stimulus conditions reveal a latency of 434 ms (SD=36). The speed of pupil response in the fowl is significantly higher than in humans, but the response amplitude is usually small. Another interesting observation is the lack of sustained response to changes in ambient illumination. These findings suggest that the input to the pupilloconstrictor neurones in the fowl consists largely of transient neurones with little sustained component.

Adult↗
PubMed1998

Comparative pupil dilation using phenylephrine alone or in combination with tropicamide.

OBJECTIVE: A prevalence survey of actinic and other eye diseases was conducted in Nambour, Queensland, Australia, in 1992. Pupils were dilated with phenylephrine alone for cataract identification because there were concerns that patient discomfort, due to cycloplegia occurring with the usual dilating agents of tropicamide and phenylephrine, may influence future compliance in an associated intervention study. This validation study was undertaken to measure the possible underestimation of cataract prevalence in this community study, which may have occurred because of inadequate dilation from phenylephrine alone. DESIGN: The study design was a repeated measures experimental design. PARTICIPANTS: Forty-seven normal subjects participated in the study. Both eyes were tested. INTERVENTION: Pupil diameter after dilation with three drops of 10% phenylephrine alone was compared with pupil diameter after dilation with three drops of 10% phenylephrine together with three drops of 1% tropicamide. The two regimens were given to the same subjects 1 week apart. Reversal was attempted with thymoxamine hydrochloride 0.5%. MAIN OUTCOME MEASURES: Pupil diameter was assessed using a Neitz cataract camera, and accommodation reserve also was measured. Subjects' subjective appreciation of return of ocular function was assessed by a questionnaire. Repeated measures analysis of variance, paired t test, McNemar's test, and Wilcoxon signed rank test were used to analyze outcomes. RESULTS: Mean maximum pupil size with 10% phenylephrine and 1% tropicamide was significantly larger than pupil size after the use of 10% phenylephrine alone (F1,19 = 18.99, P = 0.0003). However, there was no significant difference between the two dilation regimens when comparing the proportion of subjects who dilated to 6 mm or more (McNemar's X(2)1 = 2.7, P > 0.1). Compared with 10% phenylephrine and 1% tropicamide, pupil diameters were significantly smaller (t46 = 16.77, P = 0.0001), and accommodation reserve greater (t46 = 4.14, P = 0.0001), 40 minutes after reversal with thymoxamine in the group dilated with 10% phenylephrine alone. CONCLUSION: Pupil dilation with 10% phenylephrine alone, if allowed at least 40 minutes to act, will be as satisfactory for the identification of cataracts in a normal population as 10% phenylephrine and 1% tropicamide and is more acceptable because of reduced problems with glare and accommodation.

Accommodation, Ocular↗
PubMed2001

Effect of brimonidine tartrate ophthalmic solution 0.2% on pupil size in normal eyes under different luminance conditions.

PURPOSE: To evaluate the effect of brimonidine tartrate ophthalmic solution 0.2% (Alphagan) on pupil size in normal eyes. Three luminance conditions were used to assess the potential use of brimonidine in postoperative refractive patients who experience nighttime vision problems related to large pupil size. SETTING: McDonald Eye Associates, Fayetteville, Arkansas, USA. METHODS: Pupil size was measured in 16 eyes of 16 participants with the Colvard pupillometer under 3 luminance conditions. One drop of brimonidine 0.2% was administered to each patient. Pupil size was then measured using the same technique 30 minutes and 4 and 6 hours after drop administration. RESULTS: Under scotopic conditions, 100% of the pupils showed significant miosis at 30 minutes (P <.05). The effect continued in all eyes for 4 hours. At 6 hours, a miotic effect was still present in 81.3%. However, under photopic luminance, there was no significant effect on pupil size in all 16 eyes (P >.05). The pupil size in 5 eyes (31.2%) was not affected at 30 minutes or 4 or 6 hours. At 6 hours, 15 eyes (93.8%) had returned to their preinstillation size. CONCLUSION: Brimonidine tartrate 0.2% had a significant effect in decreasing pupil size under scotopic conditions. The results indicate that the drug can decrease night-vision difficulties such as halos, star bursts, glare, and monocular diplopia in postoperative refractive patients.

Adrenergic alpha-Agonists↗
PubMed1992

Preoperative pupil fatigue.

Pupils are frequently dilated on the day before cataract surgery and for retinal detachment surgery so the fundus can be examined. This may, however, interfere with pupil mydriasis on the day of surgery. This study looked at the effect of pupil dilation with tropicamide 1% and with cyclopentolate 1% on pupil mydriasis 24 hours later, using phenylephrine 10% and cyclopentolate 1%, in 40 cataract patients. The pupils dilated with cyclopentolate one day previously demonstrated a mean reduction in subsequent mydriasis of 0.73 mm compared with pupils that had been dilated with tropicamide (P less than .0001). The magnitude of this difference was not related to the patient age (P = .12) or to iris color (P = .21). If it is necessary to dilate pupils on the day before surgery, tropicamide 1% rather than cyclopentolate 1% should be used, as it is less likely to interfere with the pupil mydriasis produced with cyclopentolate 1% and phenylephrine 10% on the day of surgery.

Aged↗
PubMed2004

An evaluation of pupil size standards used by police officers for detecting drug impairment.

BACKGROUND: The Drug Evaluation and Classification (DEC) program was developed to detect, arrest, and convict drivers impaired by drugs other than alcohol. The DEC program is a training program designed to prepare police officers and other qualified persons to serve as Drug Recognition Experts (DREs). PURPOSE: The purposes of this study were: (1) to determine normative values and ranges for pupillary responses using the specific DEC program protocols for pupil testing in nonimpaired persons, and (2) to appraise the suitability of the 3.0- mm to 6.5-mm pupil range as a potential sign of impairment under three conditions. METHODS: Trained DRE officers measured pupi sizes using standardized DEC protocols. Pupil measurements were taken under three light levels: room light, near-total darkness, and direct light. The subjects were 250 volunteers, with an average age of 29.2 years (+/-6.1). All subjects were healthy, nonimpaired, and free of visual, and/or neurological problems. RESULTS: For each pupil measured (N= 500), the mean (SD) for each of the three test conditions were: room light 3.86 (0.93) mm; near-total darkness 6.41(1.55) mm; and direct light 3.35 (0.72) mm. CONCLUSIONS: This study determined normative values and potential ranges for pupillary responses using the specific DEC program protocols for pupil testing in non-impaired persons. When the presently approved DEC program pupil size range (3.0 to 6.5 mm) is compared with the results of this study, it appears that the DEC range for pupil size might be too sensitive. However, when determining impairment related to drug(s), the DRE reviews the results of all tests and draws a conclusion based on the totality of the evidence, not only on a variation in the pupil size.

Adult↗
PubMed1956

The responses of the pupil of Gekko gekko to external light stimulus.

1. The responses of the pupil of a nocturnal gecko (Gekko gekko) to external light stimulus were studied. 2. The responses of the pupil are determined by light entering the pupil and not by light acting directly on the iris. 3. The responses of the pupil are very uniform in sensitivity including spectral sensitivity for light coming in different directions to the eye. 4. The possible change in area of the pupil is more than 300-fold and probably represents an effort to shield the pure rod retina from saturating light intensities. 5. The pupil continues to contract sharply for changes in external light intensity which give retinal illuminations corresponding to 10(6) quanta/sec. striking a retinal rod. 6. There is a large degree of spatial summation of the response; circular external light fields subtending 5 and 140 degrees giving the same illumination at the pupil give approximately the same pupil response. 7. The spectral sensitivity curve agrees with the absorption curve of an extracted pigment from a closely related gecko described by Crescitelli in the followig paper. It is similar to the human scotopic curve but its maximum is displaced about 20 to 30 mmicro towards the red end of the spectrum. The fall in sensitivity towards the red end of the spectrum is described by the equation See PDF for Equation

Humans↗
PubMed2001

Unilateral fixed dilation of the pupil as a false-localizing sign with intracranial hemorrhage: case report and literature review.

OBJECTIVE AND IMPORTANCE: Although other focal signs may prove "false localizing," it is a neurosurgical axiom that unilateral fixed dilation of the pupil occurs ipsilateral to a supratentorial mass. CLINICAL PRESENTATION: A 25-year-old man collapsed with a dense right hemiplegia and a Glasgow Coma Scale score of 6 (eye opening, 1; motor, 4; verbal, 1) after rupture of a left middle cerebral artery aneurysm associated with an intrasylvian hematoma. Initially, both pupils had remained equal-sized and reactive: however, within hours, the right (contralateral) pupil became fixed and dilated (i.e., false localizing). For some time, the left (ipsilateral) pupil remained small and reactive; at emergency craniotomy, this also became fixed and equally dilated. INTERVENTION: After evacuation of the clot and wrapping of the aneurysm, both pupils rapidly became equal-sized and reactive. Twenty-four hours later, concurrent with massive left hemispheric swelling and a midline shift, the left (ipsilateral) pupil became unilaterally fixed and dilated (i.e., false localizing). Eventually, the right (contralateral) pupil also became fixed and dilated, concurrent with cardiovascular collapse. Death occurred within 10 hours. CONCLUSION: Unilateral fixed dilation of the pupil in patients with hemispheric mass lesions may be false localizing. Furthermore, disparate "herniating mechanisms" can arise despite mass effect emanating from the same side. Because such mechanisms cannot be witnessed, their nature remains speculative. An extensive review is contained in this article.

Adult↗
PubMed1979

The effect of pupil size on visual acuity in uncorrected and corrected myopia.

The effect of pupil size on the relation between Snellen visual acuity and corrected and uncorrected myopia was examined for 22 young subjects with degrees of myopia ranging from 0.75 D to 7.5 D. Effective pupil size was varied by inducing mydriasis and then placing artificial pupils of between 1.0 and 8.0 mm diameter before the eye. Both a constant chart luminance of 120 cd/m2 and a constant retinal illuminance of 2150 trolands were used. There was little difference in results for the two lighting conditions. For the corrected myopes considered as a group, maximum visual acuity occurred for 2--3 mm diameter pupils, but larger pupils reduced acuity only marginally. For the uncorrected myopes, variation in pupil size produced a large variation in visual acuity, and for refractive errors greater than about 1.5 D, the optimum pupil diameter was less than 1 mm. For uncorrected myopes of 3.0 D or less, visual acuity was nearly as good with a 1-mm pupil as for corrected myopes. The presented data are a useful guide to the clinician.

Adult↗
PubMedDate not supplied

Dependence of wave front refraction on pupil size due to the presence of higher order aberrations.

PURPOSE: Propagation of light through the optical pathway within the eye can lead to a deformation of the wave front that might affect objective but also subjective refraction depending on pupil size. The aim of this study was to investigate the change in wave front refraction that is calculated on the basis of second order Zernike polynomials when varying the pupil size from 6 mm to 3 mm. The change was correlated with the amount of fourth and sixth order spherical aberration and fourth and sixth order astigmatism. METHODS: Wave front aberrations were measured in 130 eyes by means of a Tscherning wave front sensor at a pupil size of 6 mm. Wave front aberrations in terms of Zernike coefficients up to sixth order were approximated for 6 mm and 3 mm pupil size. The wave front refraction was calculated based on the second order Zernike coefficients for both pupil diameters. Resulting differences in wave front refraction (sphere or cylinder) due to the change in pupil size were correlated with the initial higher order aberrations determined for the 6.0 mm pupil by means of a linear regression (Spearman rank correlation coefficient). RESULTS: The correlation between the change in sphere and cylinder on one hand and the spherical aberration and higher order astigmatism on the other hand was found to be highly significant (p<0.001), with a correlation coefficient of R = 0.96 for sphere and R = 0.85 for cylinder. CONCLUSIONS: Calculating the wave front refraction on the basis of second order Zernike polynomials is plagued with the influence of the higher order aberration preexisting in the individual eye. This is one reason why this method does not represent precisely enough subjective refraction. Other methods that calculate the refraction based on wave front measurement independent from the pupil size should be established in the ophthalmic community.

Adolescent↗
PubMedDate not supplied

Influence of exposure time and pupil size on a Shack-Hartmann metric of forward scatter.

PURPOSE: To determine the influence of exposure time and pupil size on a Shack-Hartmann (S/H) derived metric of forward scatter (MAX_SD) using a physical model of nuclear cataract. METHODS: A physical model eye was developed and mounted to a S/H wavefront sensor. The eye model consisted of a lens, variable pupil, simulated cataract, and retina. Located behind the pupil, a cuvette contained one of five polystyrene microsphere solutions simulating five levels of nuclear cataract severity. Cataract severity was described using a S/H derived metric of forward scatter (MAX SD), which measures aspects of forward scatter contained in the S/H lenslet point spread functions (PSF). To determine the impact of exposure time and pupil size, measurements of MAX_SD were regressed against cataract severity for three different exposure times and three different pupil sizes. RESULTS: MAX_SD was well correlated to cataract severity. Exposure time had the largest influence, and pupil size had the smallest influence on the forward scatter metric. When pupil size and exposure time were allowed to vary and image saturation was allowed to occur, MAX SD explained 83% of the variance in cataract severity. Excluding images where saturation occurred, holding optimal exposure time constant, and varying pupil size, MAX_SD explained 97% of the variance in cataract severity. CONCLUSIONS: The ability of the forward scatter metric derived from S/H measurements to predict cataract severity for a longitudinal study is optimized by selecting a patient-specific exposure at the initial cataract assessment to avoid saturation and maximize the dynamic range of the system. This patient-specific exposure should be used in all future visits.

Cataract↗
PubMed2001

Comparison of pupil perimetry and visual perimetry in normal eyes: decibel sensitivity and variability.

PURPOSE: To compare the sensitivity and variability of pupil perimetry with visual perimetry at the same retinal locations in normal subjects. METHODS: Pupil perimetry was performed on the right and left eyes of 10 normal subjects using a computerized infrared pupillometer equipped to present perimetric light stimuli and record pupil light reflexes. Eleven locations were tested at different intensities along the horizontal meridian of each eye, and the decibel sensitivity of the pupil light reflex was compared with the visual threshold at the same location. RESULTS: The shape and height of the hill of vision (retinal sensitivity) was very similar between the right and left eyes of each individual using either pupil perimetry (R2 = 0.69) or standard threshold perimetry (R2 = 0.62) but was less similar between subjects. Comparisons between pupil and visual sensitivity revealed a lack of correlation at the same retinal location in normal eyes (R2 = 0.19). CONCLUSIONS: The high intereye correlation for either pupil or visual sensitivity may provide an important tool for detecting focal or asymmetric visual field damage. Although the basic shape of the sensitivity profile of pupil and visual responses was similar under the conditions of testing, the two did not correlate well within each eye among the normal subjects. This highlights that similarities do exist in the sensitivity profile of the two pathways, but they do not seem to vary in the same proportion between normal individuals.

Adult↗
PubMed2003

Effects of pupil diameter on light detection and temporal modulation.

PURPOSE: This study compared the effects of pupil variation on light detection and temporal modulation across the central visual field. METHODS: Light detection sensitivity (LDS) and low flickering frequency (6 Hz) temporal modulation sensitivity (TMS) of 20 young subjects were measured from the central visual field of the right eyes using an autumated perimeter (Medmont M600). The measurements were taken under 3 artificial pupils, i.e. 3 mm, 4.3 mm and 6 mm diameters. The sensitivities were grouped and averaged for different retinal eccentricities (3 degrees, 6 degrees, 10 degrees, and 15 degrees). RESULTS: TMS and LDS were reduced with increasing retinal eccentricities (P < 0.001) and decreasing pupil diameters (P < 0.001). TMS collected from all pupil diameters were significantly different from each other (P < 0.001). Similarly, LDS under 3 mm pupil was statistically different from those of 4.3 mm and 6 mm (P < 0.003). Comparison of the hills of vision showed that pupil variation resulted in significantly different slopes (P = 0.001). The slopes were also found to be significantly different between TMS and LDS (P = 0.012). CONCLUSIONS: The data showed that dilated pupil resulted in significantly higher sensitivities than those of smaller pupil for both visual functions. The difference in the slopes of hills of vision also suggested that the variation in retinal illumination affected the visual responses differently at various retinal eccentricities for TMS and LDS.

Contrast Sensitivity↗
PubMed1992

Nucleofractis phacoemulsification through a small pupil.

A small pupil is an added risk with any technique for cataract extraction. A prospective study involving 1880 consecutive cataract procedures performed by one surgeon between January and June 1990 was carried out to determine the incidence of small pupils (preoperative diameter of 4 mm or less) and the surgical risk with phacoemulsification and implantation of an intraocular lens (IOL) "in the bag." Thirty eyes (1.6%) were found to have a small pupil. All 30 eyes received an in-the-bag posterior chamber IOL, with no intraoperative complications such as anterior or posterior capsule tears. The need for iris-enlarging surgery was correlated with pupil size: such surgery was done in O of the 10 eyes with pupils measuring 4 mm, 1 of the 12 eyes with pupils measuring 3 to 3.5 mm and 4 of the 8 eyes with pupils measuring 2 to 2.5 mm. The author proposes that opening the capsule with a continuous tear and removing the cataract by means of phacoemulsification with nuclear fracturing (nucleofractis) constitutes safe, efficient surgical management of eyes with small pupils undergoing cataract extraction.

Cataract Extraction↗
PubMed2006

Single dose of 1% tropicamide and 10% phenylephrine for pupil dilation.

OBJECTIVE: To compare the efficacy of pupil dilation between a single dose and three doses of 1% tropicamide and 10% phenylephrine for binocular indirect ophthalmoscopy. MATERIAL AND METHOD: A prospective randomized double-blind clinical controlled trial was conducted. All patients underwent the binocular indirect ophthalmoscopy and met the inclusion criteria were randomized into two groups using block randomization. Group A received a single dose of 1% tropicamide and 10% phenylephrine eye drops, and Group B received three doses of the same drugs. The primary outcome was the horizontal pupil diameter measured by slit-lamp biomicroscope (Haag-Streit model 900) before and at 10, 15, 20, 25 and 30 minutes after eye drop instillation. The clinical equivalence of the efficacy of pupil dilation between the two groups was defined as the difference of less than or equal to 1 mm (-1 mm to + 1 mm). RESULTS: Eighty patients (160 eyes) were randomized into 40 patients (80 eyes) in group A and 40 patients (80 eyes) in group B. The mean pupil sizes at baseline of group A were 3.51 +/- 0.63 mm in the right eye and 3.39 +/- 0.67 mm in the left eye. Those in group B were 3.61 +/- 0.67 mm in the right eye and 3.66 +/- 0.72 mm in the left eye. The mean pupil diameters at 30 minutes of group A were 7.34 +/- 0.51 mm in the right eye and 7.41 +/- 0.56 mm in the left eye, whereas those of group B were 7.49 +/- 0.45 mm in the right eye and 7.51 +/- 0.40 mm in the left eye. The mean difference of the pupil size between the two groups was 0.15 mm (p = 0.175) in the right eye and 0.l0 mm (p = 0.362) in the left eye. The 95% confidence intervals of the difference in pupil size were -0.36 to 0.07 mm in the right eye and -0.32 to 0.12 mm in the left eye. CONCLUSION: The 95% confidence interval of the difference in pupil size lay entirely within the range of equivalence. The single dose of 1% tropicamide and 10% phenylephrine was clinically equivalent to the three doses of the same drugs.

Adult↗
PubMed1989

[Subacute sensory neuropathy manifestated by tonic pupils associated with small cell carcinoma of the lung].

Only a few cases of carcinomatous neuropathy with tonic pupils have been reported. In the present paper we described a 53-year-old woman with subacute sensory neuropathy who had presented with bilateral tonic pupils. She noticed numbness over the medial aspect of the left thigh in March, 1988, and then developed dysesthesia over the left forearm and hand, mild weakness of left upper and lower extremities and urinary disturbance. Neurological symptoms were subacutely progressive and she was bed-ridden in May. She was admitted to our hospital in June, 1988. On examination, she had body-weight loss of 6 kg during the last six months and general status was otherwise unremarkable. She had anisocoria; the left pupil was larger in daylight than the right, while smaller in dim light. The left pupil scarcely reacted to light, but promptly constricted to near vision. The right pupil constricted normally to light and near vision. An instillation of 0.0625% pilocarpine solution showed supersensitive response of both pupils. An instillation of 1.25% epinephrine solution demonstrated mild dilation of both pupils. Thus, it was conceivable that she had postganglionic ciliary nerve damage characteristic of tonic pupil as well as the lesion of sympathetic nerve innervating pupillary dilator. She had severe sensory ataxia and pseudoathetosis of the hands. Weakness was mild to moderate in extremities. Almost all deep tendon reflexes were absent. All modalities of sensation, particularly on deep sense, were severely involved with sea-level-type distribution below Th7, and over C2 to C3 regions on the left side.(ABSTRACT TRUNCATED AT 250 WORDS)

Autonomic Nervous System Diseases↗
PubMed1994

Factors affecting light-adapted pupil size in normal human subjects.

PURPOSE: To investigate the effect of age, gender, refractive error, and iris color on light-adapted pupil size in humans. METHODS: Pupil diameters of 91 subjects (age range, 17 to 83 years) with normal, healthy eyes were measured using an objective infrared-based continuous recording technique. Five photopic ocular illuminance levels were used (2.15 to 1050 lumens m-2), and the accommodative status of each subject was precisely controlled at a constant level. RESULTS: Pupil size decreased linearly as a function of age at all illuminance levels. Even at the highest illuminance level, there was still a significant effect of age upon pupil size. The rate of change of pupil diameter with age decreased from 0.043 mm per year at the lowest illuminance level to 0.015 mm per year at the highest. In addition, the variability between pupil sizes of subjects of the same age decreased by a factor of approximately two as luminance was increased over the range investigated. Pupil size was found to be independent of gender, refractive error, or iris color (P > 0.1). CONCLUSIONS: Of the factors investigated, only chronologic age had a significant effect on the size of the pupil. The phenomenon of senile miosis is present over a wide range of ocular illuminance levels.

Accommodation, Ocular↗
PubMed1998

Normal variation in, and effect of 2% pilocarpine on, intraocular pressure and pupil size in female horses.

OBJECTIVE: To determine normal variation in, and effect of 2% pilocarpine hydrochloride on, intraocular pressure (IOP) and pupil size in female horses during a specified period. ANIMALS: 10 female horses with normotensive eyes. PROCEDURE: IOP and horizontal and vertical pupil size were measured on a single day between 8 AM and 8 PM at hours 0, 0.5, 1, 2, 4, 6, 8, 10, and 12. Measurements were repeated after single- dose application of 2% pilocarpine to both eyes. IOP and pupil size were measured at 8 AM and noon in a 5-day experiment of twice-daily application of 2% pilocarpine. RESULTS: Variation in IOP and pupil size was not significant between 8 AM and 8 PM. Change in IOP or pupil size after a single dose of 2% pilocarpine also was not significant. In the multiple-dose experiment, the IOP at noon on the fifth day was significantly higher than the IOP in the morning on the first and second days. The IOP in the morning on the fifth day was significantly higher than the IOP in the morning and at noon on the first and second days. The IOP at noon on the fourth day was significantly higher than the morning IOP on the first and second days and at noon on the first day. The decrease in vertical pupil size was significant. CONCLUSIONS: Between 8 AM and 8 PM, variation in IOP and pupil size in normotensive eyes of horses is not significant. Two percent pilocarpine does not significantly change IOP between 8 AM and 8 PM in clinically normal horses after a single dose or multiple twice-daily applications. After multiple twice-daily applications, a trend toward an increase in IOP was seen, and the decrease in vertical pupil size was significant.

Animals↗