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At least 289 records · Page 16Linked to original sources
PubMed2005

Parametric characterization of the form of the human pupil from blurred noisy images.

The fluctuation of the human pupil is an important parameter in order to make non-invasive diagnosis of many different diseases and in several clinical applications. The relevant measurement device, the pupillometer, consists in a CCD camera, which shoots the pupil. We suppose that the measured image is blurred by a Gaussian kernel and corrupted by an additive white noise; moreover an elliptic shape for the pupil is assumed. We here present the extension of a multiscale approach for edge detection to identify some parameters of the pupil: the location of its centre, the length of the semi-axes and the orientation of the corresponding ellipse. The chosen method requires knowledge about the degradation parameters of the assumed model; so we first present a simple but efficient method to determine such quantities for the measured image. Then we apply the edge detection procedure to identify points close to the pupil edge, within a chosen probability. Finally we find the optimal ellipse fitting a suitable subset of the previously detected edge points. Results are presented, with comparisons to other approaches for edge finding.

Computer Simulation↗
PubMed2005

Brimonidine versus dapiprazole: Influence on pupil size at various illumination levels.

PURPOSE: To evaluate the influence of dapiprazole versus brimonidine on pupil size at various illumination levels. SETTING: Department of Ophthalmology, Johannes Gutenberg-University, Mainz, Germany. METHODS: In randomized prospective study, 19 healthy volunteers received 2 ophthalmic solutions, dapiprazole and brimonidine, 1 in each eye, for intraindividual comparison. Before and after application, pupil diameter was measured using an infrared binocular pupillometer at 3 illumination levels (0.03, 0.82, and 6.4 lux). RESULTS: Only slight pupil dilation was observed under scotopic conditions after application of both agents. After 20 minutes, the median reduction in pupil width was 1.4 mm for brimonidine and 0.9 mm for dapiprazole. These effects were statistically significant for both agents (both P < .001). The maximum effect was observed after 40 minutes and remained stable through the next measurement at 180 minutes. Under mesopic lighting conditions, only a slight effect (<1 mm) was seen. CONCLUSIONS: Pupil mydriasis at scotopic illumination levels was reduced by both drugs in a similar fashion. Because of the slightly stronger effect of brimonidine, application of this agent 20 minutes before activities in dimly lit areas or at night may be recommended for photic phenomena following refractive surgery.

Adrenergic alpha-Agonists↗
PubMed2006

Comparison of 2 multiple-measurement infrared pupillometers to determine scotopic pupil diameter.

PURPOSE: To compare a monocular and a binocular multiple-measurement digital infrared pupillometers for measuring scotopic pupil diameter. SETTING: Department of Ophthalmology, Loma Linda University, Loma Linda, California, USA. METHODS: Scotopic pupil size was measured after 1 minute of dark adaptation in 42 eyes of 21 volunteers. Measurements were taken twice each with 2 multiple-measurement digital infrared pupillometers, the monocular pupillometer (Neuroptics, Inc.), and the binocular pupillometer (P2000D, Procyon, Ltd.) Intraclass correlation coefficients (ICC) and limits of agreement (LOA) were used to measure repeatability and agreement of measures with each instrument and between instruments. The Wilcoxon signed rank test was used to compare variability of measurements within each instrument. RESULTS: The mean scotopic pupil size was 4.79 mm +/- 0.95 (SD) with the Procyon and 4.86 +/- 0.93 mm with the Neuroptics. Repeatability and agreement tests for the Procyon measures showed the following: ICC, 0.954; 95% confidence interval (CI), 0.916-0.975; LOA, -0.60 to 0.56; range, 1.16. The Wilcoxon signed rank test of variability gave a Z score of -2.53 (P = .01, 2 tailed). The repeated measures testing with the Neuroptics pupillometer showed the following: ICC, 0.985; 95% CI, 0.972-0.992; LOA, -0.39 to 0.26; range, 0.64; Z score, -1.15 (P = .25, 2-tailed). Repeatability and agreement tests for measures between instruments showed the following: ICC, 0.954; 95% CI, 0.916-0.975; LOA, -0.60 to 0.50; range 1.11. CONCLUSIONS: There was a high repeatability and agreement in scotopic pupil diameter for repeated measures within each device and measurements between the devices. Differences in variability in scotopic pupil diameter evaluated by the Wilcoxon signed rank test were significant only with the Procyon pupillometer.

Aged↗
PubMed2003

Pupil dilation with intracameral 1% lidocaine during glaucoma filtering surgery.

PURPOSE: To evaluate pupil dilation from intracameral injection of nonpreserved 1% lidocaine. DESIGN: Observational case series of 25 consecutive phakic trabeculectomies. METHOD: Patients were evaluated in the operating room setting and given one drop of topical tetracaine preoperatively. Nonpreserved 1% lidocaine (0.1 cc) was injected intracameraly into the anterior chamber through a paracentesis site at the corneal limbus. Pupil diameter was measured after instillation of topical tetracaine, before injection of intracameral lidocaine. Postinjection measurements were made at 1, 3, and 5 minutes. RESULTS: The mean male pupil diameter was significantly greater than female dilation at every time point. The mean blue iris diameter was greater than brown at 1 and 3 minutes, but there was no difference at 5 minutes or more. There was no racial difference in the pupil dilation response to intracameral lidocaine. CONCLUSIONS: Nonpreserved intracameral 1% lidocaine produces immediate pupil dilation in previously undilated phakic patients during trabeculectomy surgery.

Anesthesia, Local↗
PubMed1992

Stray light in radial keratotomy and the influence of pupil size and straylight angle.

Glare is a major sequela of the radial keratotomy procedure. We used the straylight meter to measure intraocular light scatter, which is the cause of glare, in eyes after radial keratotomy. This apparatus uses a direct compensation method to assess the amount of intraocular light scatter. Nineteen patients were tested. Nine individuals served as controls. The mean postsurgery time was 60 months. The influence of the number of radial incisions, the pupil size, and the angle of light entering the eye were evaluated with the straylight meter. The results showed straylight values for normal pupil size (mean, 4 mm) to be statistically significantly higher (P = .0044) only for the smallest angle of light deflection studied (3.5 degrees). For dilated pupils (mean, 8 mm), straylight values were statistically significantly higher (P = .00005) for all three angles of light deflection studied. The number of incisions showed no statistically significant relationship to straylight values. Average stray light values were increased by a factor of 1.4 for 4-mm sized pupils and 2.0 for 8-mm sized pupils. There was an overlap in straylight values between the patient population and the control population.

Adult↗
PubMed1995

Tonic pupil and orbital glial-neural hamartoma in infancy.

PURPOSE/METHODS: Tonic pupils in early childhood are rare. We studied an otherwise healthy 31/2-month-old girl who had a right pupil that was poorly reactive to light, without other signs of oculomotor nerve palsy. RESULTS/CONCLUSIONS: Constriction of the right pupil after instillation of 0.125% pilocarpine eyedrops confirmed denervation hypersensitivity, consistent with a tonic pupil. There was no strabismus or proptosis. A magnetic resonance imaging scan demonstrated a right orbital mass, interposed between the lateral and inferior recti muscles. Biopsy was consistent with a benign, glial-neural hamartoma. Thus, in this young patient, a tonic pupil was associated with a benign orbital mass.

Child, Preschool↗
PubMed1989

The pupils of term and preterm infants.

We studied the pupils of 100 term and preterm infants between 26.5 and 46 weeks' postconceptual age. The mean (+/- S.D.) pupil diameter in a dark environment (less than 10 foot-candles of illumination) was 3.6 mm (+/- 0.9). Anisocoria of 0.5 to 1.0 mm was found in nine infants. The pupils did not consistently respond to 600 foot-candles of light before 32 weeks' postconceptual age, but responded increasingly thereafter. This progressive light response correlated significantly with postconceptual age, weight, Apgar scores, and corneal diameter (P less than .01). In the perinatal period, neurologic or radiologic examination may be warranted if the pupil diameter in a dark environment is less than 1.8 mm or greater than 5.4 mm or if the pupils do not respond to light challenge after 31 weeks' postconceptual age.

Cornea↗
PubMed1990

The fixed and dilated pupils of premature neonates.

We examined on a weekly basis the pupils of 30 preterm infants. In relative darkness (less than 10 foot-candles [ft.-c.] of illumination), the pupils measured a mean of 4.7 mm in the youngest infants (26 weeks' postconceptional age) when the corneal diameter was 7.0 mm. The pupils became progressively smaller, reaching 3.4 mm at 29 weeks' postconceptional age (P less than .001). The pupils did not constrict to the stimulating light (600 ft.-c.) until a mean of 30.6 weeks' (+/- 1 week) postconceptional age. Mydriasis should not be considered indicative of a central nervous system disorder, and a pupil unresponsive to light should not be considered suggestive of blindness until a preterm infant reaches at least 32 weeks' postconceptional age.

Aging↗
PubMedDate not supplied

Bilateral tonic pupils associated with neurosyphilis.

BACKGROUND: To describe 4 patients with bilateral tonic pupils in neurosyphilis. CASES: Four young men had pupillary abnormalities, which involved irregular shapes, large sizes, tonic reactions, and vermiform movements of both pupils with light-near dissociation. Cholinergic supersensitivity defined bilateral tonic pupils. OBSERVATIONS: Neurosyphilis was diagnosed in these patients on the basis of ocular and laboratory findings. CONCLUSIONS: Bilateral tonic pupils may be important as initial findings in neurosyphilis. We conclude that patients with bilateral tonic pupils should undergo serologic tests for syphilis.

Adult↗
PubMed1999

Optic disc topographic measurements after pupil dilation.

PURPOSE: To determine the effect of pupil dilation on topographic optic disc parameters measured with confocal scanning laser ophthalmoscopy. DESIGN: Prospective, comparative, observational case series. PARTICIPANTS: Thirty-eight subjects (25 glaucoma patients, 5 glaucoma suspects, and 8 normal subjects) representing a range of lens opacities participated in this study. METHODS: Topographic optic disc parameter measurements were obtained before and after pupil dilation with a confocal scanning laser ophthalmoscope (Heidelberg Retina Tomograph). Cataract severity was measured with the LOCS III grading system. Image quality was assessed using the standard deviation of the mean topography image and an image quality score. Multiple regression techniques were used to evaluate the effect of image quality, cataract density, and pupil size on the change in topographic parameters after dilation. MAIN OUTCOME MEASURES: Topographic optic disc parameter measurements. RESULTS: With dilation, mean change in most topographic optic disc parameters was not significantly different from zero. Changes in topographic optic nerve parameters tended to be relatively small when undilated images were of good quality and larger in images of relatively poor quality. The strongest predictor of the absolute value of change in topographic optic disc parameters was the standard deviation of the undilated mean topography image. CONCLUSIONS: When confocal scanning laser ophthalmoscope images are of good quality, topographic optic disc parameter measurements obtained with a dilated pupil are similar to those obtained with an undilated pupil. However, caution should be exercised when interpreting information from poor quality confocal scanning laser ophthalmoscopic images.

Aged↗
PubMed2000

Scotopic measurement of normal pupils: Colvard versus Video Vision Analyzer infrared pupillometer.

PURPOSE: To prospectively measure the scotopic pupil diameter in a normal population and to compare 2 infrared pupillometers for these measurements. SETTING: Johann Wolfgang Goethe-University, Department of Ophthalmology, Frankfurt am Main, Germany. METHODS: The Colvard infrared pupillometer was compared to the Video Vision Analyzer (VIVA) infrared pupillometer under scotopic light conditions in 33 participants (aged 19 to 55 years). Reliability was assessed by 2 independent examiners (E1, E2). Statistical analysis was performed using a comparison method by Bland and Altman. RESULTS: Mean pupil diameter was 6.16 mm +/- 1.20 (SD) (range 3.20 to 9.00 mm) with all measurements taken under scotopic illumination. The mean scotopic pupil diameter was 6.08 +/- 1.16 mm (range 3.2 to 8.4 mm) with the Colvard pupillometer and 6.24 +/- 1.28 mm (3.5 to 9.0 mm) with the VIVA pupillometer. The mean differences between the Colvard and VIVA were -0.27 mm (E1) and -0.05 mm (E2). Limits of agreement ranged from 1.4 (Colvard) to 2.4 (VIVA). The coefficients of repeatability ranged from 0.7 (Colvard) to 1.1 (VIVA). CONCLUSIONS: A mean scotopic pupil diameter of 6.15 mm with a maximal pupil size of 9.00 mm can be expected in a normal population; this should be considered in refractive corneal and refractive lens surgery. Measurements with the Colvard pupillometer were more reliable and precise than those with the VIVA pupillometer.

Adult↗
PubMedDate not supplied

Modified stretch technique for small pupil phacoemulsification with topical anesthesia.

I present an atraumatic technique for small pupil phacoemulsification using topical anesthesia. Fifty consecutive small pupil phacoemulsification cases were performed with topical anesthesia and mild intravenous sedation. Viscoelastic combined with a modified two instrument stretch was used for pupillary enlargement adequate for phacoemulsification. After preoperative cycloplegia, two or more multidirectional stretches were used for 3.0 to 5.0 mm pupils; three or more multidirectional stretches were used for pupils less than 3.0 mm. Pain and proprioceptive responses were avoided by reducing the stretch length, leaving the angle structures and ciliary body untouched. Sodium hyaluronate (Healon GV) created additional expansive power. Of 50 successfully implanted cases, 45 (90%) had acceptable pupillary form and function postoperatively. The 5 (10%) with enlarged, atonic pupils had past injury or inflammatory disease. This technique minimizes anterior segment trauma, instrumentation, and operating time.

Anesthesia, Local↗
PubMed2005

Accuracy of GDx variable corneal compensation polarization measurements in normal human eyes: effect of accommodation, cycloplegia, focus, pupil size, and eye selection on reproducibility.

PURPOSE: To evaluate the reproducibility of variable corneal compensation (VCC) and the effect of accommodation, cycloplegia, eye selection, focus, and pupil size on this measurement of polarization. METHODS: Using a GDx scanning laser polarimeter, multiple measurements of the VCC were obtained from each eye of 33 healthy, young adults under differing conditions. Pupil size and refraction were independently measured with a pupillometer and an autorefractometer. The effects of eye, instrument focus, pupil diameter, cycloplegia, and accommodation were statistically assessed. RESULTS: The reproducibility of a single retardation measurement and its axis, as determined by the standard deviations (SD) of repeated measurements, is +/-1.58 nm and 2.10 degrees , respectively. There is a difference in retardation between right and left eyes, of 5.26+/-9 nm, P=0.002. Increasing pupil size increases retardation. Cycloplegia or defocusing decreases retardation, and pharmacologically induced accommodation has no effect on retardation. CONCLUSIONS: The retardation and its axis are highly reproducible measurements when the pupil is of physiologic size and the GDx is properly focused. There is a consistent difference in VCC retardation between the paired right and left eyes. This difference may reflect equipment-induced measurement artefact and/or an anatomic asymmetry between the paired eyes of the subjects studied. Clinicians should be cautious when comparing interocular VCC measurements between paired right and left eyes and using data pooled from both eyes for age-adjusted, normalized standards.

Accommodation, Ocular↗
PubMed2001

Effect of different dose schedules of latanoprost on intraocular pressure and pupil size in the glaucomatous Beagle.

OBJECTIVE: To evaluate the changes in intraocular pressure and pupil size in glaucomatous dogs after instillation of 0.005% latanoprost (Xalatan, Pharmacia and Upjohn, Kalamazoo, MI, USA) once in the morning, or once in the evening, or twice daily in five-day multiple-dose studies. Animals studied Eight Beagles with the moderate stage of inherited primary open-angle glaucoma. PROCEDURES: Applanation tonometry (IOP) and pupil size (PS) measurements were obtained at 8 am, 10 am, 12 noon, 2 pm, and 4 pm in eight glaucoma dogs. Methylcellulose (0.5% as placebo) was instilled in the control eye, and 0.005% latanoprost was instilled in the opposite drug eye. Control and drug eyes were selected using a random table. For these three studies, 0.5% methylcellulose and 0.005% latanoprost were instilled the second through the fifth days with instillations in the morning (8.30 am), or evening (8 pm), or twice daily (8.30 am and 8 pm). Statistical comparisons between drug groups included control, placebo, and treated (0.005% latanoprost) eyes for three multiple-dose studies. RESULTS: In the 8-am latanoprost study, the mean +/- SEM diurnal declines in IOP for the placebo and drug eyes for the first day were 6.5 +/- 3.6 mmHg and 8.4 +/- 4.0 mmHg, respectively. The mean +/- SEM diurnal changes in IOP after 0.005% latanoprost at 8 am once daily for the next four days were 23.3 +/- 5.0 mmHg, 25.4 +/- 2.1 mmHg, 25.7 +/- 1.7 mmHg, and 26.1 +/- 1.7 mmHg, respectively, and were significantly different from the control eye. A significant miosis also occurred starting 2 h postdrug instillation, and the resultant mean +/- SD pupil size was 1.0 +/- 0.1 mm. In the first day of the second latanoprost study, the mean +/- SEM diurnal changes in the placebo and drug eye IOPs were 11.6 +/- 3.8 mmHg, and 12.0 +/- 4.4 mmHg, respectively. For the following four days with latanoprost instilled at 8 pm, the mean +/- SEM diurnal changes in IOP in the drug eyes were 24.9 +/- 2.1 mmHg, 22.4 +/- 1.8 mmHg, 21.6 +/- 1.9 mmHg, and 26.6 +/- 2.2 mmHg, respectively. Compared to the fellow placebo eyes, the diurnal changes in IOP were significantly different. Significant changes in pupil size were similar to the IOP changes, with miosis throughout the day and return to baseline pupil size the following morning before drug instillation. In the last study, the mean +/- SEM diurnal changes in IOP for the placebo and drug eyes for the first day were 6.6 +/- 2.1 mmHg and 9.4 +/- 2.8 mmHg, respectively. For the four subsequent days with latanoprost instilled twice daily, the mean +/- SEM diurnal IOP changes were 19.6 +/- 1.5 mmHg, 19.1 +/- 1.4 mmHg, 19.9 +/- 1.7 mmHg, and 20.3 +/- 0.7 mmHg, respectively, and were significantly different from the placebo eyes. The mean changes in PS were 3.1 +/- 0.7 mm. CONCLUSION: 0.005% latanoprost instilled once daily (am or pm) as well as twice daily produces significant decreases in IOP and PS in the glaucomatous Beagle. The evening instillation of 0.005% latanoprost produced less daily fluctuations in IOP than when the drug was instilled in the morning. 0.005% latanoprost instilled twice daily produced the greatest decline in IOP with the least daily fluctuations, but longer duration miosis.

Animals↗
PubMed2003

The effect of pupil size on binocular summation at suprathreshold conditions.

PURPOSE: To determine the influence of retinal illuminance on monocular or binocular visual reaction time (VRT). METHODS: On two normal subjects, uniform circular stimuli were presented with respect to a reference stimulus at the fovea under suprathreshold conditions, and the detection of positive and negative luminance variations was recorded. Binocular and monocular reaction times were measured (by the index finger pressing on a mouse key) for viewing with both natural and artificial pupils. RESULTS: Binocular reaction times were shorter than monocular reaction times; nevertheless, this binocular-summation effect was less marked in trials with the artificial pupil. Analyses of binocular-summation ratios for contrast changes for both pupil types indicated maximum and minimum binocular-saturation values depending on contrast variations in both positive and negative luminance changes. CONCLUSIONS: Binocular summation can be influenced by pupil size under suprathreshold conditions. Results are discussed in terms of retinal illuminance and cortical pupil response mechanisms.

Adult↗
PubMed1997

Time-dependent changes in heart rate and pupil size during desflurane or sevoflurane anesthesia.

UNLABELLED: To better characterize alterations in autonomic function associated with prolonged anesthesia, we tested the hypothesis that the time-dependent effects of sevoflurane and desflurane differ. We studied seven male volunteers, each anesthetized for 8 h with 1.25 minimum alveolar anesthetic concentration desflurane on one study day and with 8 h sevoflurane on another. These volunteers did not undergo surgery and were minimally stimulated during the study. Measurements included blood pressure, heart rate, pupillary size and light reactivity, concentrations of serum catecholamines, and carbon dioxide production. Over time, heart rate and pupil size increased significantly. During 6 of the 14 anesthetics (45%), heart rate at some point exceeded 95 bpm; similarly, pupil size at some time exceeded 5 mm during 8 anesthetics (57%). In contrast, plasma catecholamine concentrations and carbon dioxide production remained unchanged, and blood pressure remained nearly constant. There are thus substantial time-dependent changes in autonomic functions during prolonged anesthesia, even in unstimulated, nonsurgical volunteers, but we could not detect a difference in these changes during desflurane compared with sevoflurane anesthesia. IMPLICATIONS: Pupil size and heart rate changes are used to guide the delivery of anesthesia. In volunteers, pupil size and heart rate increased with increasing duration of constant desflurane or sevoflurane anesthesia. Thus, anesthetic duration alters heart rate and pupil size independent of surgery and changes in anesthetic delivery.

Anesthesia, Inhalation↗
PubMed2001

The transfer half-life of morphine-6-glucuronide from plasma to effect site assessed by pupil size measurement in healthy volunteers.

BACKGROUND: Clinical and experimental data suggested a long delay between the plasma concentration versus time course of morphine-6-glucuronide and the time course of its central opioid effects. This study was aimed at the quantification of the transfer half-life (t(1/2,ke0)) of this delay. METHODS: Pupil size was used as a measure of central opioid effect. Eight healthy volunteers (four men, four women) participated in that single-blind randomized crossover study. Median dosages administered intravenously were 0.5 mg morphine as loading dose followed by 10.7 mg given as infusion over a period of 4.7 h, and 10.2 mg M6G as loading dose followed by 39.1 mg M6G given over a period of 3.7 h. The duration of the infusion was tailored to achieve submaximum pupil constriction. The pupil diameter was assessed every 20 min for approximately 18 h. Values of t(1/2,ke0) were obtained by semiparametric pharmacokinetic-pharmacodynamic modeling. RESULTS: The estimated median t(1/2,ke0) of M6G was 6.4 h (range, 2.9-16.2 h), and that of morphine was 2.8 h (range, 1.8-4.4 h). The individual t(1/2,ke0) of M6G was always longer than that of morphine. Judged by the concentration at half-maximun effect (EC50) values of the sigmoid pupil size at maximum constriction (Emax) model describing concentration-response relation, M6G was apparently 22 times less potent than morphine (EC50 = 740.5 nm [range, 500-1,520 nm] for M6G and 36.2 nm [range, 19.7-43.3 nm] for morphine). The steepness of the sigmoid Emax model did not significantly differ between morphine and M6G (gamma = 1.9 and 2.6, respectively). To produce similar pupil effects, the M6G dose had to be 2.8 times greater than the morphine dose. CONCLUSIONS: The reported numerical value of the t(1/2,ke0) of M6G in humans obtained after direct administration of M6G is a step toward a complete modeling approach to the prediction of the clinical effects of morphine. The study raises questions about the high interindividual variability of the transfer half-life between plasma and effect site (ke0) values and the apparent low potency of M6G.

Adult↗
PubMed1991

Acuities through annular and central pupils after radial keratotomy.

The corneal radius of curvature after radial keratotomy (RK) increases centrally in the surgery-free area while remaining relatively unchanged paracentrally and peripherally in the surgical areas. These corneal topography changes suggest that the imaging properties of the cornea should vary with the area of the cornea allowed to participate in image formation. To test this hypothesis visual acuities were measured both through a central and an annular pupil for normals and RK patients as a function of time after surgery. Annular acuities were decreased significantly after RK and remained decreased over time. Best corrected central acuity increased as a function of time after surgery, becoming significantly better than presurgery acuities but not as good as normals with similar low refractive corrections. Clinical implications include: (1) variations in visual performance (e.g., acuity, contrast sensitivity, glare) and optical quality measures (e.g., refraction, higher-order aberrations) as a function of pupil size; (2) use of a large a surgery-free area as possible; (3) careful centering of the surgery-free area on the natural pupil; (4) new contact lens designs for correcting RK patients' residual refractive error; and (5) counseling patients in general, and patients with naturally large pupils in particular, concerning possible variation in visual function with pupil size. In summary, this study indicates that postsurgery RK paracentral/peripheral corneal optics experience a loss in optical quality as compared to either normal eyes with a low refractive correction or the same eye before surgery.

Adult↗