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30 eye-healthy subjects were being examined, with their pupils reacting, mydriatic or miotic. Their pattern reversal visual evoked cortical potentials (PRVECP's) were recorded under steady-state conditions. Test conditions allowed establishing a statistically significant influence of pupil size on the PRVECP.
The human pupillary control system is a paradigm for linearized biological control systems. It also exhibits a series of interesting nonlinear behaviors, particularly asymmetry, "pupillary escape," and "pupillary capture." We present a nonlinear model in which a signal dependent upon pupil size is fed back internally to cause a change in system parameters related to gains and rates of light adaptation. The model was simulated on a digital computer, a variety of experimental data was well matched, and improvements over previous pupil models demonstrated. A candidate physiological mechanism for adaptive components of the model might have the form of an inverse "Henneman coded" neuronal pool.
Different varieties of pupillary abnormalities have been described in Parkinson's disease but it is not clear if this is due to the disease itself or to the pharmacological treatment. In this study, pupil reactivity to various stimuli (dark/light adaptation, light reflex, near vision reaction and electrical sural stimulation) was investigated in 23 de novo parkinsonian patients (not on drugs) to assess pupillary abnormalities and investigate their pathophysiological mechanisms. Parkinsonian patients exhibited larger pupil diameter after light adaptation, as well as a reduced amplitude of contraction and a prolonged contraction time at light reflex. The data obtained confirmed the existence in Parkinson's disease of a pupillary imbalance mainly involving the parasympathetic system.
Alpha1-adrenoceptors mediate contraction of iris dilator smooth muscle and hence pupil dilatation. We compared the ability of i.v. bolus injections of alfuzosin, doxazosin, naftopidil, prazosin, tamsulosin and terazosin to antagonise phenylephrine-induced mydriasis relative to their potency for inhibiting phenylephrine-induced elevations of intraurethral pressure (IUP) in rabbits. Moreover, we compared the ability of these drugs to induce miosis in conscious rabbits in the absence of phenylephrine. All antagonists inhibited the effects of phenylephrine on pupil size and IUP, and the ratio of the respective ED50 values was close to unity in all cases. The doses required to induce statistically significant miosis in the absence of phenylephrine were 30- to 100-fold higher than those inhibiting phenylephrine-induced mydriasis for all antagonists, except for naftopidil. Moreover, the miotic effects of all alpha1-adrenoceptor antagonists were fully reversible within 8 h. We conclude that alfuzosin, doxazosin, naftopidil, prazosin, tamsulosin and terazosin inhibit phenylephrine-induced mydriasis in the same dose range as they inhibit elevations in IUP. Higher doses of all antagonists are required to induce miosis in the absence of an exogenous agonist, and such miosis is always reversible within hours.
BACKGROUND: The implantation of aspherical IOLs with negative spherical aberration should equalize the positive spherical aberration of the cornea. The aim of our study was the intraindividual comparison of higher order aberrations (HOA) after implantation of an aspherical and spherical IOL. PATIENTS AND METHODS: In ten patients we randomly implanted an aspherical IOL in one eye and a spherical IOL in the other. After 3 months, we used a Hartmann-Shack sensor to measure total HOA, 3rd to 5th order as well as spherical aberration Z4.0, in mydriasis. We compared all aberrations intraindividually for pupil diameters of 3.5-6 mm. RESULTS: For both IOLs, all aberrations rose with increasing pupil diameter. However, after implantation of the aspherical IOL total HOA, 4th order and spherical aberration Z4.0 were lower, for 4th order aberration and Z4.0 even significantly. For 3rd and 5th order aberrations, there was no difference between both IOLs. CONCLUSIONS: With implantation of aspherical IOLs, total HOA, 4th order and spherical aberration Z4.0 could be reduced compared to spherical IOLs.
BACKGROUND: Tonic pupil (TP) is a common disorder of parasympathetic innervation. In contrast to textbook recommendations, cranial imaging is still being performed in most of the patients with TP. The intention of the present study is to show that cranial imaging is of no benefit. PATIENTS AND METHODS: The medical records of 33 patients with TP were analyzed retrospectively. All patients had undergone a complete ophthalmological, orthoptic, and neurological investigation. Cranial imaging was performed by computed tomography or magnetic resonance imaging. Serology tests were carried out in some of the patients. RESULTS: Diagnostic imaging provided no additional data revealing the underlying cause of TP. CONCLUSIONS: Cranial imaging in isolated tonic pupil is not helpful. Because of therapeutic implications, diagnostic evaluation can be recommended only in patients older than 50 years to exclude giant cell arteritis and syphilis.
BACKGROUND: A study was carried out to ascertain, in ophthalmologically normal subjects, the short-term effects of dipivefrin hydrochloride 0.1% on visual performance and make comparisons with pilocarpine. METHODS: Twelve normal volunteers aged 20-26 years attended on three occasions. One eye, randomly selected, received one drop of either pilocarpine 2%, dipivefrin or saline 0.9%. High- and low-contrast LogMAR acuity at 6 m and pupil diameter (measured by infra-red pupillometry) were recorded at baseline (T0) and at intervals up to 90 min following instillation of drops. Program 30-2 of the Humphrey Visual Field Analyzer (HFA) was run at T0 and at 60 min after treatment instillation (T60). Saline was always instilled at visit 1, to allow for learning effects. On visits 2 and 3 either pilocarpine or dipivefrin was randomly instilled into the treated eye. RESULTS: Pilocarpine significantly worsened the field global indices mean deviation (P < 0.001) and pattern standard deviation (P < 0.01) compared with T0. There was no significant change with dipivefrin. A significant (P = 0.01) pupil dilation from 5.44 mm (SD 0.79) at T0 to 6.19 mm (SD 1.09) at T90 occurred with dipivefrin. Pilocarpine caused significant miosis. No significant changes in LogMAR values were found with dipivefrin. Pilocarpine significantly (P < 0.01) increased LogMAR values (i.e. reduced acuity) compared with dipivefrin. At T30 the mean increase in LogMAR was 0.76 (SD 0.30) for high and 0.83 (SD 0.11) for low contrast. By T90 recovery of acuity was virtually complete. CONCLUSIONS: In normals dipivefrin causes mydriasis but does not affect the central visual field global indices (as assessed by STATPAC), or high- and low-contrast LogMAR acuity. Pilocarpine adversely affects the visual field and both measures of acuity. Knowledge of these effects is of value in glaucoma therapy and when monitoring the progression of visual loss.
The Argyll Robertson pupil, a miotic pupil that fails to react to direct light, has been described for more than a century. Originally associated with tabes dorsalis, the sign has now been found in a number of conditions with lesions in the area of the nucleus of Edinger-Westphal. Magnetic resonance imaging studies have localized the lesion in patients with sarcoidosis and multiple sclerosis. With the declining incidence of neurosyphilis, the sign is increasingly likely to indicate another cause, although an assiduous search for lues should also be undertaken.
The manually adjustable pupil has two diameters: one constricted, the other dilated. The patient may select the appropriate diameter for the existing light conditions by moving a small magnet over the surface of the prosthesis. In the discerning patient this prosthesis will eliminate the need for two separate prostheses, which are commonly provided today. Patient privacy and hygiene are maintained because the prosthesis need not be removed to alter pupil size.
Chromostereopsis has been attributed previously to interocular differences in foveal transverse chromatic aberration (TCA). We tested this hypothesis by measuring chromostereopsis as a function of the separation of small artificial pupils. We also measured the monocular transverse chromatic aberration under the same conditions. Our results show that chromostereopsis with small pupils can be precisely accounted for by the interocular difference in monocular transverse chromatic aberration. This relationship is closely predicted by a simple water eye model.
An instrument for making dynamic measurements of the human pupil is described. The device uses a 100-element linear self-scanning photodiode array and a Z80A microprocessor system. The eye is imaged using infrared radiation. The instrument has both analogue and digital outputs of pupil diameter, which are accurate to better than +/- 2.5% of full scale. By compensating for the inherent nonuniformities in the photodiode array, the microcomputer maintains the accuracy and reliability of the system at low irradiance levels. A simple means of implementing a two-dimensional measuring system is proposed.
The problem of determining the pupil morphological parameters from pupillometric data is considered. These characteristics are of great interest for non-invasive early diagnosis of the central nervous system response to environmental stimuli of different nature, in subjects suffering some typical diseases such as diabetes, Alzheimer disease, schizophrenia, drug and alcohol addiction. Pupil geometrical features such as diameter, area, centroid coordinates, are estimated by a procedure based on an image segmentation algorithm. It exploits the level set formulation of the variational problem related to the segmentation. A discrete set up of this problem that admits a unique optimal solution is proposed: an arbitrary initial curve is evolved towards the optimal segmentation boundary by a difference equation; therefore no numerical approximation schemes are needed, as required in the equivalent continuum formulation usually adopted in the relevant literature.
PURPOSE: To determine the distribution of the difference between the horizontal and vertical dark-adapted entrance pupil diameters (PDs) in normal individuals. SETTING: Texas Tech University Health Sciences Center, Lubbock, Texas, USA. METHODS: In this observational cohort study, high-magnification infrared pupil photography was performed of the right eye of 26 normal volunteers from 20 to 47 years of age. The horizontal and vertical PDs were measured using commercially available digital-image software, taking into account the effect of photographic parallax. RESULTS: In 24 subjects (85%), the vertical PD was larger than the horizontal PD; in 8 subjects (31%), it was 0.30 mm to 0.50 mm larger. In 2 subjects, the horizontal diameter was slightly larger but the difference was <0.10 mm. The mean horizontal to vertical PD ratio was 0.97. CONCLUSIONS: In this study population, the vertical PD was larger than the horizontal PD in most subjects. Although the difference was a fraction of the total PD, it may be important for laser refractive surgery planning and preoperative risk counseling of some patients.
PURPOSE: To determine the individual variability of the dark-adapted pupil diameter over 6 months using a standardized dark-adaptation protocol. SETTING: Texas Tech University Health Sciences Center, Lubbock, Texas, USA. METHODS: This prospective observational cohort study comprised volunteers with no history of ocular disease, surgery, or injury other than requirement for refractive correction. The right eye was tested. A standardized dark-adaptation protocol was used that controlled for accommodation and patient alertness. Infrared, still digital photographs were taken after 10 minutes of dark adaptation at 1 lux and were analyzed using digital image software. Testing was performed at baseline in the afternoon, at 3 months in the afternoon, and at 6 months in the morning. Lifestyle factors such as diet and exercise were not controlled. RESULTS: Mean intersession differences were 0.04 mm (95% confidence interval [CI]: -0.68-0.146), 0.15 mm (95% CI: -0.001-0.297), and 0.09 mm (95% CI: -0.048-0.236) for baseline-3 month, baseline-6 month, and 3 month-6 month comparisons, respectively. None of these differences was significantly different from zero (P>.05, 2-tailed Student t tests). The likelihood that the mean intersession difference was >.25 mm was negligible for all comparisons (P=.9996, .9099, and .9829 respectively, 1-tailed Student t tests). CONCLUSION: When a consistent dark-adaptation protocol that controls for alertness and accommodation is used, normal young individuals showed no significant variation in the dark-adapted pupil diameter over a 6-month period.
In patients with unilateral Adie's syndrome, we compared the relative supersensitivity of the tonic pupil to methacholine hydrochloride (Mecholyl 2.5%) and pilocarpine 0.125%. We tested a large series of patients and photographed the pupils before and 30 minutes after the eyedrops. In a group of 36 patients, Mecholyl was positive in 64% of the tests; and in a group of 20 patients, pilocarpine 0.125% was positive in 80% of the tests. Eight patients who failed to show supersensitivity with Mecholyl were tested with pilocarpine and five of the eight were shown to be supersensitive. We concluded that pilocarpine, in this concentration is not only an adequate substitute for Mecholyl 2.5%, but is a more sensitive testing substance in unilateral cases, simply because it has a slightly stronger miotic action.
INTRODUCTION: Adie's syndrome is usually a disease of unknown origin. We report two cases secondary to Sjögren syndrome. CASE REPORTS: A 26-year-old man developed in few months a sensitive neuropathy with a bilateral tonic pupil. A 50-year-old woman complained of sensitive signs probably related to a ganglionopathy and dysautonomic disorders affecting sudomotor and vasomotor functions. Adie syndrome had been diagnosed three years earlier. In both patients, the systemic signs and the results of the complementary tests led to the diagnosis of Sjögren's syndrome. Corticosteroids had limited effects on the sensitive signs and no influence on the tonic pupils. CONCLUSION: Adie syndrome, isolated or accompanied by other dysautonomic disorders, may reveal or precede the diagnosis of Sjögren's syndrome.
INTRODUCTION: In third cranial nerve palsy, the lack of mydriasis evokes a noncompressive mechanism. Case report. We report a case of a slightly painful, pure extrinsic third-nerve palsy, complete except for the partial ptosis secondary to the compression by an intracavernous carotid aneurysm. Percutaneous endovascular embolization was followed by complete regression of the palsy within 4 weeks. The pupil may have been spared by the mechanism of compression after the separation of the pupillomotor and extrinsic fibers or the ischemia of the third nerve by its arterial trunk lesion. CONCLUSION: This case report underlines that brain radiological explorations are necessary in some third-nerve pupil-sparing palsies.
The pupil response of Porichthys notatus to different intensities of illumination is described and compared to that of P. myriaster, Cephaloscyllium ventroisum, and a human. While the fully dark adapted pupil is round, at the highest light intensities it consists of only two small, almost independent, apertures with a total area 4.9% of that observed in the fully dilated animal. The response is at least partially consensual and occurs, albeit at a much reduced rate, in isolated eyes. P. notatus also displays retinomotor movements comparable to those seen in most teleosts, suggesting that, contrary to most previous assumptions, pupillary responses and retinomotor migrations are not mutually exclusive.