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At least 217 records · Page 12Linked to original sources
PubMed2007

Pupil dilation with intracameral lidocaine during phacoemulsification.

PURPOSE: To evaluate pupil dilation by an intracameral injection of nonpreserved lidocaine 1% during phacoemulsification cataract extraction and compare the results with those using conventional topical mydriatics. SETTING: Department of Ophthalmology, Rassoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran. METHODS: A prospective comparative case series study was conducted. The study included 57 patients who were given topical mydriatics (30 eyes) or intracameral lidocaine (27 eyes) to dilate the pupil for phacoemulsification and intraocular lens implantation. The topical group received 3 drops of cyclopentolate 1% and phenylephrine 5% given 5 minutes apart starting 60 minutes before surgery. The intracameral group received preservative-free lidocaine 1% (0.2 to 0.3 mL) injected just before the procedure began. No epinephrine was added to the irrigating solution. In both groups, the horizontal pupil diameter was measured before and after pupil dilation using the same caliper. Total surgical time, need for a mydriatic agent during the procedure, and subjective surgical performance were recorded. RESULTS: The mean age, sex, cataract density, baseline horizontal pupil diameter, and mean duration of the surgery were the same between the topical group and intracameral group. The mean pupil dilation was 4.52 mm +/- 0.08 (SD) in the intracameral group and 4.06 +/- 0.09 mm in the topical group; the difference between groups was statistically significant (P = .001). There was no significant difference between groups in the overall subjective surgical performance (P = .74). No patient in the intracameral group and 2 patients in the topical group required an intracameral mydriatic injection. CONCLUSION: During phacoemulsification, intracameral preservative-free lidocaine 1% provided rapid, effective mydriasis comparable that of topical mydriatics.

Aged↗
PubMed2005

Age related changes in the characteristics of the near pupil response.

Static and dynamic aspects of the near pupil response were studied in human subjects in the age range when accommodative amplitude steadily declines. Dynamic accommodative and pupillary responses to step stimuli were recorded in 66 subjects (ages: 14-45 years). Exponential fits to data provided amplitude, peak velocity and time constants. Accommodative amplitude decreased linearly with age (p < 0.05). Pupil constriction per diopter of accommodative response increased exponentially with age (p < 0.05). The amplitude of pupil constriction for a 2D stimulus decreased linearly with age (p < 0.05) and for a 5D stimulus did not change with age (p = 0.90). The latency of pupil constriction did not change with age (p = 0.65), while the mean peak velocity decreased linearly with age (p < 0.05). An increase in the amount of pupil constriction per diopter of accommodative response, but not per diopter of stimulus amplitude, suggests that the near effort per se does not increase with age. There is a slight reduction in the speed of near pupil response with age.

Accommodation, Ocular↗
PubMedDate not supplied

Colvard pupillometer measurement of scotopic pupil diameter in emmetropes and myopes.

PURPOSE: To prospectively compare the scotopic pupil size between emmetropes and myopes using a Colvard pupillometer. METHODS: The pupil diameters of 55 normal subjects and 55 healthy myopic subjects were measured with the Colvard pupillometer in a low-light situation that simulated the level of light encountered while driving at night. RESULTS: The mean (+/- SD) age of the emmetropic subjects was 30.78 years +/- 10.03 (range, 18-54 years) and the mean (+/- SD) age of the myopic subjects was 27.35 years +/- 8.43 (range, 21-52 years). The mean (+/- SD) scotopic pupil diameter was 6.46 +/- 0.90 mm (range, 4.5-8.0 mm) in the emmetropic group and 6.98 +/- 0.67 mm (5.5-8.5 mm) in the myopic group. The unpaired Student t-test showed that the difference in the scotopic pupil diameter between emmetropes and myopes was statistically significant (P =.0001). CONCLUSIONS: The mean scotopic pupil diameter in myopes was larger than that in emmetropes. Therefore, a large ablation zone of the cornea or an appropriate optical size of the phakic intraocular lens should be considered in refractive surgery. Preoperative scotopic pupil measurements may be necessary in all refractive patients.

Adolescent↗
PubMed2003

Pupil size and quality of vision after LASIK.

PURPOSE: To evaluate factors related to the quality of vision after LASIK. DESIGN: Survey study. PARTICIPANTS: One hundred consecutive patients. INTERVENTION: LASIK with a 6.0-mm elliptical ablation pattern without transition zone to treat mild to moderate myopia or astigmatism (preoperative manifest spherical equivalent [MSE], -4.79 +/- 1.33 diopters [D]; range, -2.88 to -9.25 D). The second eye was treated 1 month after the first. MAIN OUTCOME MEASURES: Completed questionnaires assessing night vision problems (glare, haze, and halo symptoms) before surgery and at 1, 3, and 6 months after surgery in 97, 75, 81, and 66 subjects, respectively. Mesopic pupil size and preoperative and postoperative variables were analyzed with questionnaire data using an analysis of variance (ANOVA) and multivariate regression analysis. RESULTS: Patients with large mesopic pupils had significantly more reports of glare, haze, and halo than did those with smaller pupils in the treated eye at 1 month after surgery (P=0.02, P=0.03, and P=0.02, respectively ANOVA) and of glare at 3 months (P=0.05). Significant predictors of symptoms at 6 months, identified through multivariate regression analysis, included preoperative MSE (for glare and haze), preoperative contrast acuity (glare), postoperative uncorrected visual acuity (UCVA; haze), and residual cylinder (haze). Together, these factors accounted for only 19% of the overall variability in glare and 37% of the variability in haze responses. No relationship between pupils and symptoms was noted at 6 months after surgery in either the ANOVA or regression analysis group. CONCLUSIONS: Patients with large pupils had more quality of vision symptoms in the early postoperative period, but no correlation was observed 6 months after surgery. Factors related to long-term symptoms include the level of treatment (preoperative myopia), preoperative contrast acuity, postoperative UCVA, and residual cylinder. Most of the variability in visual quality could not be explained by preoperative or clinical outcome measures, including pupil size.

Adult↗
PubMed2006

[Advantages of the autorefractometer and the Orbscan for measuring pupil diameter].

PURPOSE: We compared pupil size measurements obtained with the Orbscan and autorefractometer to the Colvard Infrared pupillometer in order to determine their respective clinical advantages. MATERIAL AND METHODS: We prospectively measured the pupil diameter in 94 eyes of 47 normal patients using the Colvard device, the Nikon NKR 8000 autorefractometer, and the Orbscan device. For each device, two successive measurements were taken to determine its reproducibility. We also studied the relationship with the contralateral eye (i.e., difference and correlation). The measurements obtained with the different devices in different light intensities were compared and studied using regression analysis. RESULTS: Pupil diameter measured using the Orbscan had the highest reproducibility (mean difference between the two successive measurements: 3.8% or 0.15mm) and showed the smallest difference between the two eyes (5.0% or 0.19mm) and the strongest correlation with the contralateral eye (r=0.93; p<0.001). Scotopic Colvard measurements and autorefractometer measurements with low light settings were not significantly different (5.86mm versus 5.86mm; p=0.48). Autorefractometer measurements with low light settings showed the strongest correlation with the scotopic Colvard measurements (r=0.84; p<0.001). The Orbscan measurements were less correlated with the scotopic or photopic Colvard measurements (r=0.73; p<0.001 and r=0.51; p=0.003, respectively). For the Colvard pupillometer, the correlation between photopic measurements and scotopic measurements was also poor (r=0.51; p<0.001). CONCLUSION: Pupil size measurements with the autorefractometer may be advantageous before refractive surgery. Measuring pupil size in photopic conditions, as with the Orbscan, cannot screen people with large pupils in mesopic conditions.

Adolescent↗
PubMed2002

Comparison of scotopic pupil measurement with slitlamp-based cobalt blue light and infrared video-based system.

PURPOSE: To determine the accuracy and reproducibility of scotopic pupil measurements with a slitlamp-based cobalt blue light. SETTING: University of Texas Health Science Center-San Antonio, San Antonio, Texas, USA. METHODS: In a prospective experimental study, 2 independent observers measured 16 subjects' pupils with a standard slitlamp-based cobalt blue light. In the same setting, the accuracy and reproducibility of the measurements were compared with those obtained with an infrared video-based system. RESULTS: Measurements of pupil size using the infrared video-computer system were highly reproducible. With the slitlamp-based cobalt blue light, the 2 measurements obtained by observer 2 (n = 16) were very close to each other (mean difference 0.09 mm +/- 0.23 [SD]; P =.12), whereas those obtained by observer 1 (n = 16) were slightly different from each other (mean difference 0.18 +/- 0.33 mm; P =.043). The mean pupil diameter measured with cobalt blue light was not significantly different between the 2 observers (P >.05), and the measurements were highly correlated with each other (r = 0.96, P <.01). The mean difference between the measurements using cobalt blue light and the infrared video-computer system was 0.21 +/- 0.54 mm for observer 1 (P =.47) and 0.06 +/- 0.47 mm for observer 2 (P =.85). Good correlation was noted between the measurements taken from each measuring device for both observers (r = 0.87 and 0.90, P <.01). CONCLUSIONS: Slitlamp-based cobalt blue light provided a reasonably good measurement of scotopic pupil size. It correlated well with the infrared video system when used at the lowest setting by experienced personnel. However, the observed difference between the measurements obtained by the 2 devices indicates that the cobalt blue light should be used cautiously in the refractive surgery preoperative evaluation of patients with large pupils.

Color↗
PubMed2003

Quality of vision after laser in situ keratomileusis: influence of dioptric correction and pupil size on visual function.

PURPOSE: To determine the influence of pupil size and the amount of ablation on visual performance and on the patient's perception of glare or halo after laser in situ keratomileusis (LASIK). SETTING: Department of Ophthalmology, National Taiwan University Hospital, Taipei, Taiwan. METHODS: This study included a random cross-section of 50 eyes of 32 patients with "uniform" topography at least 6 months after LASIK and 51 eyes of 28 patients who had normal corneas. Each LASIK patient completed a survey rating adverse effects such as symptoms of night glare and halo. Pupil diameter and best spectacle-corrected visual acuity (BSCVA) were measured under photopic and scotopic conditions. Contrast sensitivity was measured with an MCT 8000 (Vistech Consultants, Inc.) under daytime and nighttime and with night glare conditions. A Technomed C-scan (Technomed Technology) was performed, and the potential corneal visual acuity (PCVA) was calculated after the settings for the pupil size were changed to the values measured under bright-light or dim-light conditions. RESULTS: No significant difference was found between the post-LASIK and normal cornea groups in photopic or scotopic BSCVA (P>.05). In cases of moderate myopia, the post-LASIK group had decreased PCVA and contrast sensitivity (P<.05). In cases of high myopia, the post-LASIK group had decreased contrast sensitivity at spatial frequencies of 1.5 cycles per degree (cpd) under daytime conditions and 3 cpd under nighttime conditions (P<.05). Glare or halo symptoms did not correlate with scotopic BSCVA, PCVA, or nighttime contrast sensitivity with or without glare (P>.05). Pupil size was not significantly correlated with glare or halo symptoms, BSCVA, or contrast sensitivity under scotopic or photopic conditions (P>.05). In moderate myopia, the amount of attempted correction of the spherical equivalent (SE) was correlated with halo symptoms (P<.05; adjusted r(2) = 0.17). In high myopia, the amount of attempted astigmatism correction was correlated with the development of glare symptoms (P<.05; adjusted r(2) = 0.16). CONCLUSIONS: There was a decrease in contrast sensitivity in post-LASIK eyes. The amount of attempted correction of the SE or astigmatism was correlated with the development of glare and halo symptoms. Pupil size was not significantly correlated with glare or halo symptoms, BSCVA, or contrast sensitivity in post-LASIK patients with "uniform" topography who had scotopic pupils not larger than 7.0 mm.

Adult↗
PubMed2004

Estimation of pupil size by digital photography.

PURPOSE: To evaluate a digital photography method of pupil size estimation over a broad range of illumination conditions and to compare this method with common clinical techniques. SETTING: College of Optometry, Ohio State University, Columbus, Ohio, USA. METHODS: Two examiners measured the pupil diameter in 45 right eyes at 3 illumination levels: <0.63 lux (dark), 5 lux (dim), and 1000 lux (bright). Estimation by infrared video recording, the reference standard, was compared with measurements by digital photography, ruler, semicircular templates, and the Colvard pupillometer. Masked graders measured pupil size from infrared video recordings and digital photographs. RESULTS: The repeatability of the measurement method determined by the mean intraclass correlation coefficients was highest for video recording across conditions (0.86-0.97), followed by digital photography (0.76-0.94), Colvard pupillometry (0.63-0.82), ruler (0.71-0.85), and templates (0.70-0.83). An analysis of variance showed a significant difference in pupil size by method (P<.001). All methods except digital photography estimated smaller pupil sizes under dark and dim illumination than infrared video measurements (all P<.01). Under bright illumination, the ruler measurements were significantly smaller (-0.15 mm) and the Colvard pupillometer measurements were greater (+0.30 mm) than the reference (P<.01). The 95% limits of agreement (LoA) between examiners were smallest for video measurements at all light levels. The remaining measures ranked from best to worst by 95% LoA were digital photography, Colvard pupillometry, ruler, and templates. CONCLUSIONS: Estimation of pupil size by digital photography was more repeatable and accurate than estimates by common clinical techniques over a wide range of illumination. Although not as quick as other methods, digital photography is relatively inexpensive, permits lasting documentation, and allows independent grading suitable for clinical research purposes.

Adult↗
PubMed2003

Use of concurrent pupil dilation assessment to inform interpretation and analysis of fMRI data.

Potential contributions of concurrently acquired pupil dilation data to functional magnetic resonance imaging (fMRI) experiments were examined. Sixteen healthy participants completed a working memory task (digit sorting) during measurement of pupil dilation outside the fMRI environment and during concurrent 3T fMRI assessment. Pupil dilation increased parametrically with task difficulty inside and outside the scanner, on a similar time course, suggesting that task demand was similar in both environments. The time course of pupil dilation during digit sorting was similar to the time course of the fMRI signal in the middle frontal gyrus, suggesting that middle-frontal gyrus activity indexed the engagement working memory processes. Incorporating individual differences in pupil dilation improved the sensitivity and specificity of general linear modeling analyses of activity in the middle frontal gyrus, above and beyond standard analytic techniques. Results suggest concurrent pupil dilation during fMRI assessment can help to (1) specify whether task demand is the same inside and outside the fMRI environment, (2) resolve the extent to which fMRI signals reflect different aspects of event-related designs, and (3) explain variation in fMRI data due to individual differences in information processing.

Adult↗
PubMed2003

Effect of pupil size on multifocal pattern visual evoked potentials.

The purpose of this study was to investigate the influence of pupil diameter on the amplitude and latency of multifocal visual evoked potentials (mfVEP). The multifocal objective perimeter (Accumap; Objectivision) was used to stimulate the visual field at 56 sites extending to 32 degrees using a pseudo-random pattern stimulus. The mfVEP were recorded using bipolar occipital electrodes, 7 min/eye. Ten normal subjects were recruited from the community and one eye was randomly selected for testing. The mfVEP were recorded at four different pupil diameters (2 mm, 4 mm, 6 mm, 8 mm), obtained by applying tropicamide (0.5%) or pilocarpine (2%) in different dilutions. Appropriate refractive correction was provided to overcome cycloplegia and achieve a visual acuity of 6/7.5 or better. Analysis revealed that at most pupil diameters the normalized full field amplitude did not show significant variation, except at the most miotic pupil diameter (2 mm), where the amplitude became reduced, based on 2-way anova and Tukey's T method. There was, however, significant correlation between latency and pupil area (correlation coefficient: upper field -0.63, lower field -0.76). The results suggest that even in the presence of mydriatics or miotics, the mfVEP test can be used to assess diseases that affect amplitude, provided near correction is used. The interpretation of latency, however, must be made with caution, as a borderline conduction defect with a dilated pupil may appear normal.

Adult↗
PubMed2001

[Effect of pupil size on longitudinal focal distribution after photorefractive keratectomy ].

BACKGROUND: Optical aberrations induced by the transition zone of a myopic photorefractive keratectomy (PRK) may degrade the image quality. The subjectively evaluated visual acuity and contrast sensitivity may be reduced significantly especially with mydriasis. The purpose of this study was to calculate the image forming properties of the eye using raytracing techniques of a spot light source based on topographic height data of a scanning slit videokeratoscope. METHODS: Refractive surfaces were calculated from raw height data sets of the anterior and posterior corneal surface measurements (Orbscan, Orbtec, USA). The characteristics of the residual refractive surfaces were derived from Navarro's eye model. The focal distance was calculated using the exact raytracing calculation. Point spread function was determined at the focal plane and at 5 (delta = 0.2 mm) parafocal planes in front of and behind the focal distance in accordance to the pupil diameter (2, 3 and 6 mm). The algorithm was applied to 11 selected eyes (6 left, 5 right) of 8 patients before and after PRK with myopia (n = 6) and myopic astigmatism (n = 5). RESULTS: Before PRK the focal distance did not decrease significantly with increasing pupil size (2 to 6 mm), but decreased significantly after PRK (-0.41 +/- 0.12 mm, p = 0.02). Preoperatively, the variance of the point spread function did not differ significantly between a 2 mm (0.046 +/- 0.015 mm) and a 6 mm (0.055 +/- 0.021 mm) pupil size but was affected significantly by the pupil size postoperatively (2 mm: 0.049 +/- 0.018 mm, 6 mm: 0.096 +/- 0.045 mm, p = 0.04). CONCLUSIONS: Raytracing of corneal topography height data based on refined eye models with the option of calculation of the focus has the potential of tracing the optical resolution of the eye as a function of the pupil size. Due to of the altered surface geometry of the cornea after myopic PRK, both the variance of the point-spread function and the depth of focus increase with pupil size. This may be an explanation for impaired subjective refractometry and reduced contrast sensitivity of the patient after conventional keratorefractive surgery.

Adult↗
PubMed2003

Effect site concentrations of remifentanil and pupil response to noxious stimulation.

BACKGROUND: Opioid drugs block reflex pupillary dilatation in response to noxious stimulation. The relationship between the target effect site concentration (Ce(T)) of remifentanil and the pupil diameter and reactivity in response to a standard noxious stimulus were evaluated. METHODS: Anaesthesia was induced with propofol TCI to obtain loss of consciousness (LOC) in 12 ASA I/II patients. Thereafter, remifentanil Ce(T) was titrated by increments of 1 up to 5 ng ml(-1). In the awake state, at LOC and at each plateau level of remifentanil Ce(T), arterial pressure, heart rate, and BIS (A2000) were recorded. Pupil size and dilatation after a 100 Hz tetanic stimulation (T100) were measured at LOC and at each plateau level of remifentanil Ce(T). RESULTS: LOC was observed at a mean propofol Ce(T) of 3.53 (SD 0.43) microg ml(-1). Arterial pressure and heart rate decreased progressively from LOC to 5 ng ml(-1) remifentanil Ce(T) without any statistical difference between each incremental dose of remifentanil. Mean BIS values decreased from 96 (2) in the awake state, to 46 (12) at LOC (P<0.05) and then remained unchanged at all remifentanil Ce(T). Pupil dilatation in response to 100 Hz tetanic stimulation decreased progressively from 1.55 (0.72) to 0.01 (0.03) mm and was more sensitive than pupil diameter measured before and after 100 Hz tetanus. An inverse correlation between pupil dilatation in response to 100 Hz tetanus and an increase in remifentanil Ce(T) from 0 to 5 ng ml(-1) was found (R(2)=0.68). CONCLUSIONS: During propofol TCI in healthy patients, the decrease in pupil response to a painful stimulus is a better measurement of the progressive increase of remifentanil Ce(T) up to 5 ng ml(-1) than haemodynamic or BIS measurements.

Adult↗
PubMed1993

Effects of target distance and pupil size on letter contrast sensitivity with simultaneous vision bifocal contact lenses.

Using simulated presbyopia we measured the effects of target vergence and pupil size on letter contrast sensitivity while subjects wore accurately centered simultaneous vision bifocal contact lenses. These experiments examined the increase in depth of focus provided by two bifocal contact lenses, and the effects of pupil size on near and distance vision. Monocular contrast sensitivity was assessed with three different designs of soft contact lenses. First, as a single vision control, we measured contrast sensitivity with a Bausch & Lomb, Optima 38 lens corrected for distance. We then measured contrast sensitivity with an Allergan Optical, Hydron Echelon, which is a diffractive simultaneous bifocal and a CIBA Vision, Spectrum, which is a concentric design, center-near, two-zone simultaneous vision bifocal. In general both bifocal contact lenses improved contrast sensitivity at near but decreased contrast sensitivity at distance (when compared to the single vision lens). With a fixed 3.5-mm artificial pupil, the Echelon lens had two clear peaks of sensitivity, one at distance (0.00 D) and one at near (-2.00 D), but the Spectrum lens had no clear peaks. Performance of the Spectrum lens depended on its center zone size. Near (-2.00 D) and distance (0.00 D) contrast sensitivity was measured with pupil sizes that ranged from 1 to 6 mm. The results showed that visual performance with a diffractive lens was almost independent of pupil diameter up to 3 to 4 mm but, as predicted, performance with the two-zone lens depended critically on pupil size.

Contact Lenses, Hydrophilic↗
PubMed1999

Effect of yellow filters on pupil size.

The purpose of this study was to investigate the size of the pupil while viewing through yellow and neutral density (ND) filters. Previous studies have shown that the pupil of the human eye is relatively more sensitive to short wavelengths than indicated by the photopic luminosity curve. We first measured the consensual horizontal pupil diameter of 11 observers as a function of luminance (0.144 to 18,150 cd/m2) to establish the luminance-response function for each observer. We then measured the pupil diameter while the observer viewed through a Corning Photochromic Filter (CPF) 550 lens and two ND filters (ND 0.5 and 1.0). The pupil diameters obtained with each filter were compared to the diameters at an equivalent luminance based upon each observer's luminance-response function. Our results show that the pupil diameter is larger with the yellow lens than when viewing a broad spectrum white field at an equivalent luminance. We speculate that our results may explain some, but not all, of the well-known subjective brightness enhancement that occurs when viewing through yellow filters.

Color↗
PubMed2006

Influence of pupil size and cataract on retinal nerve fiber layer thickness measurements by Stratus OCT.

AIM: To investigate whether retinal nerve fiber layer (RNFL) thickness, as measured by optical coherence tomography (OCT), is influenced by pupil size and cataract. METHODS: RNFL thickness was measured by means of Stratus OCT (RNFL Thickness 3.4 acquisition protocol) in a group of consecutive patients undergoing phacoemulsification and intraocular lens implantation. Measurements were taken preoperatively without pupil dilation (PR1), preoperatively with pupil dilation (PR2), and 1 month postoperatively without pupil dilation. RESULTS: Twenty-five eyes of 25 patients were enrolled in the study and underwent statistical analysis. Pupil dilation caused RNFL thickness measurements to increase slightly in PR2 compared with PR1; the difference showed to be statistically significant in the 360-degree average measurement (P=0.0456) and in the nasal quadrant (P=0.032), but not in the remaining quadrants. Postoperative measurements were higher than those of PR1 in all quadrants (temporal P=0.011; superior P=0.0098; nasal P<0.0001; inferior P=0.0081) and in 360 degrees average (P<0.0001), suggesting that the presence of cataract significantly influences RNFL thickness as measured by Stratus OCT. More advanced degrees of lens opacity were correlated to a higher decrease in RNFL thickness values (r=0.4071, P=0.0434). CONCLUSIONS: While pupil size only marginally affects RNFL measurements performed by Stratus OCT, the presence and degree of cataract seem to have a significant impact. This effect should be taken in consideration when using this technology for the diagnosis of glaucoma and other neuro-ophthalmologic disorders possibly affecting the RNFL.

Aged↗
PubMed2006

Irene E. Loewenfeld, PhD Physiologist of the pupil.

Irene E. Loewenfeld, PhD has devoted a long and vigorous professional life to understanding the workings of the pupil of the human eye. Her interest in the pupil began in 1940 when she went to work as a technician in the pupillography laboratory of Professor Otto Lowenstein at New York University. It culminated in her widely admired textbook The Pupil, published in 1993. Among her many contributions, Loewenfeld provided rigorous observations about Adie tonic pupil, anisocoria in optic tract lesions, Argyll Robertson pupil, oculomotor paresis with cyclic spasms, and innovations in electronic recordings of pupil movement.

History, 20th Century↗
PubMed2007

Adjunct devices for managing challenging cases in cataract surgery: pupil expansion and stabilization of the capsular bag.

PURPOSE OF REVIEW: Patients anticipate favorable surgical outcomes when having cataract surgery. The modern-day cataract surgeon should employ all necessary means to achieve this result. A working knowledge of adjunct devices for pupil expansion and capsular-bag stabilization can significantly improve surgical outcomes. RECENT FINDINGS: Adjunct devices for pupil expansion include the Beehler pupil dilator, nylon iris hooks, and pupillary rings, including the Perfect Pupil, the Graether 2000, and the Morcher pupil dilator. Capsular-bag stabilization can be accomplished with capsular tension rings, capsular tension segments or iris hooks. The recent literature on these devices is reviewed. SUMMARY: Impaired visualization through a small pupil and poor tissue stabilization increases the chance of tissue damage, retained nuclear material, and vitreous loss. Fortunately, inadequate mydriasis and instability of the capsular bag can be managed safely with the use of adjunct tools. Preoperative planning, familiarity with available tools, and accessibility of these devices in the operative setting is necessary.

Animals↗
PubMed2006

ApoE allelic variability influences pupil response to cholinergic challenge and cognitive impairment.

Exaggerated pupil response to dilute tropicamide has been suggested as an early biological marker for Alzheimer's disease. The current study links apolipoprotein E (ApoE) allelic variability to the magnitude of pupil response in a sample of community-dwelling elderly without a diagnosis of Alzheimer's disease or dementia. Possession of an epsilon 4 allele influences both the likelihood of exhibiting an exaggerated pupil response above a predetermined cut-off (13% above baseline diameter) and the absolute overall magnitude of the response. Allelic variability was also shown to correlate with cognitive impairments in memory and attention. The data in this study further elucidate the nature of the biological bond between an exaggerated pupil response and the pathology of Alzheimer's disease. ApoE allelic variability is probably linked to pupil response through its influence on tau hyperphosphorylation. The early Alzheimer's pathology seen in the Edinger-Westphal area of cranial nerve III, a major centre for pupil control, is primarily tau-based with significant cell loss in this nucleus leading to central denervation hypersensitivity even in elderly who are clinically silent but who have early pathology.

Administration, Topical↗