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We show that irradiance-coding alone cannot explain the sustained pupillary constrictions evoked by chromatic and luminance variations in a stimulus. For example, stimulus modulations that decremented the contrasts in L- and M-cones as well as rods and melanopsin photoreceptors produced sustained constrictions rather than the predicted dilations. Although the sustained responses are unidirectional, we confirm that they are at least partially mediated by an L- and M-cone opponent interaction. We discuss the implications of sustained unidirectional chromatic responses in view of the function of the pupil to improve the clarity of vision.

Background: The photopigment melanopsin has been suggested to act as a dominant photoreceptor in nonvisual photoreception including resetting of the circadian clock (entrainment), direct tuning or masking of vital status (activity, sleep/wake cycles, etc.), and the pupillary light reflex (PLR). Pituitary adenylate cyclase-activating polypeptide (PACAP) is exclusively coexpressed with melanopsin in a small subset of retinal ganglion cells and is predicted to be involved extensively in these responses; however, there were inconsistencies in the previous reports, and its functional role has not been well understood., Methodology/principal Findings: Here we show that PACAP-deficient mice exhibited severe dysfunctions of entrainment in a time-dependent manner. The abnormalities in the mutant mice were intensity-dependent in phase delay and duration-dependent in phase advance. The knockout mice also displayed blunted masking, which was dependent on lighting conditions, but not completely lost. The dysfunctions of masking in the mutant mice were recovered by infusion of PACAP-38. By contrast, these mutant mice show a normal PLR. We examined the retinal morphology and innervations in the mutant mice, and no apparent changes were observed in melanopsin-immunoreactive cells. These data suggest that the dysfunctions of entrainment and masking were caused by the loss of PACAP, not by the loss of light input itself. Moreover, PACAP-deficient mice express an unusually early onset of activities, from approximately four hours before the dark period, without influencing the phase of the endogenous circadian clock., Conclusions/significance: Although some groups including us reported the abnormalities in photic entrainments in PACAP- and PAC(1)-knockout mice, there were inconsistencies in their results. The time-dependent dysfunctions of photic entrainment in the PACAP-knockout mice described in this paper can integrate the incompatible data in previous reports. The recovery of impaired masking by infusion of PACAP-38 in the mutant mice is the first direct evidence of the relationship between PACAP and masking. These results indicate that PACAP regulates particular nonvisual light responses by conveying parametric light information--that is, intensity and duration. The "early-bird" phenotype in the mutant mice originally reported in this paper supposed that PACAP also has a critical role in daily behavioral patterns, especially during the light-to-dark transition period.

The neurotransmitters and receptor types involved in the afferent arm of the human pupillary light reflex are unknown. We hypothesized that the pupillary light reflex is mediated in part by NMDA receptors and that it would be depressed by the NMDA antagonists, nitrous oxide and ketamine. To study this question, sixteen patients received general anesthesia with desflurane, fentanyl, and muscular relaxation with rocuronium. After a stable level of general anesthesia had been obtained and at least 1h after the start of the surgical procedure, ketamine 1mg/kg (N=8) or saline (N=8) was injected intravenously by random selection. Heart rate, pupil size, pupillary light reflex, BIS scores, and blood pressure were measured every 2min before and for 30min after drug administration. A similar study of sixteen patients was then conducted with either addition of 60% nitrous oxide or 60% nitrogen to the gas mixture. We observed that the pupillary light reflex was depressed by ketamine and nitrous oxide by approximately 50%. The BIS score, representing the processed electroencephalogram, was elevated by ketamine and unchanged with nitrous oxide. Heart rate, pupil size, and blood pressure were unchanged by the drugs when compared to the control groups. We conclude that the two NMDA antagonists ketamine and nitrous oxide depress the human pupillary light reflex during general anesthesia whereas other monitored parameters were either unchanged or paradoxically elevated by the drugs. These findings present evidence that glutamate NMDA receptor activation is involved in generating the human pupillary light reflex.

Objective: To identify clinical and pupillographic features of patients with a relative afferent pupillary defect (RAPD) without visual acuity or visual field loss caused by a lesion in the dorsal midbrain., Design: Experimental study., Participants and Controls: Four patients with a dorsal midbrain lesion who had normal visual fields and a clinically detectable RAPD., Methods: The pupil response from full-field and hemifield light stimulation over a range of light intensities was measured by computerized binocular pupillography., Main Outcome Measures: The mean of the direct and consensual pupil response to full-field and hemifield light stimulation was plotted as a function of stimulus light intensity., Results: All 4 subjects showed decreased pupillographic responses at all intensities to full-field light stimulation in the eye with the clinical RAPD. The pupillographic responses to hemifield stimulation showed a homonymous pattern of deficit on the side ipsilateral to the RAPD, similar to that observed in a previously reported patient with an optic tract lesion., Conclusions: The basis of a midbrain RAPD is the nasal-temporal asymmetry of pupillomotor input that becomes manifest when a unilateral postchiasmal lesion interrupts homonymously paired fibers traveling in the contralateral optic tract or midbrain pathway to the pupillomotor center, respectively. The pupillographic characteristics of an RAPD resulting from a dorsal midbrain lesion thus resemble those of an RAPD resulting from a unilateral optic tract lesion, but without the homonymous visual field defect., Financial Disclosure(s): The author(s) have no proprietary or commercial interest in any materials discussed in this article., (Copyright 2010 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Objective: To weight the rod-, cone-, and melanopsin-mediated activation of the retinal ganglion cells, which drive the pupil light reflex by varying the light stimulus wavelength, intensity, and duration., Design: Experimental study., Participants: Forty-three subjects with normal eyes and 3 patients with neuroretinal visual loss., Methods: A novel stimulus paradigm was developed using either a long wavelength (red) or short wavelength (blue) light given as a continuous Ganzfeld stimulus with stepwise increases over a 2 log-unit range. The pupillary movement before, during, and after the light stimulus was recorded in real time with an infrared illuminated video camera., Main Outcome Measures: The percent pupil contraction of the transient and sustained pupil response to a low- (1 cd/m(2)), medium- (10 cd/m(2)), and high-intensity (100 cd/m(2)) red- and blue-light stimulus was calculated for 1 eye of each subject. From the 43 normal eyes, median and 25th, 75th, 5th, and 95th percentile values were obtained for each stimulus condition., Results: In normal eyes at lower intensities, blue light evoked much greater pupil responses compared with red light when matched for photopic luminance. The transient pupil contraction was generally greater than the sustained contraction, and this disparity was greatest at the lowest light intensity and least apparent with bright (100 cd/m(2)) blue light. A patient with primarily rod dysfunction (nonrecordable scotopic electroretinogram) showed significantly reduced pupil responses to blue light at lower intensities. A patient with achromatopsia and an almost normal visual field showed selective reduction of the pupil response to red-light stimulation. A patient with ganglion cell dysfunction owing to anterior ischemic optic neuropathy demonstrated global loss of pupil responses to red and blue light in the affected eye., Conclusions: Pupil responses that differ as a function of light intensity and wavelength support the hypothesis that selected stimulus conditions can produce pupil responses that reflect phototransduction primarily mediated by rods, cones, or melanopsin. Use of chromatic pupil responses may be a novel way to diagnose and monitor diseases affecting either the outer or inner retina.

In this study, we measured aerial visual acuity in harbor seals. As a first approach to the hypothesis that harbor seals can obtain acute aerial visual acuity mediated by the interaction of the vertical slit-shaped pupil and the corneal flattening although refractive measurements had revealed aerial myopia, visual acuity was tested as a function of luminance and pupil dilation. We analyzed aerial visual acuity (minimal resolvable stripe width) in three harbor seals in a two-alternative-forced-choice discrimination experiment. Our results further support the hypothesis that harbor seals possess an aerial visual acuity comparable to the acuity in clear waters if the vertical slit pupil does not exceed the zone of corneal flattening in bright light. When the pupil dilates with decreasing luminance, visual acuity decreases which might be due to deflected light from the stronger curved peripheral cornea.

Purpose: To investigate the ability of a portable pupillometer, capable of 20-second binocular recordings of the swinging flashlight test (SFT), to detect relative afferent pupillary defects (rAPDs)., Methods: Pupillary response curves were recorded from both eyes in healthy volunteers (n = 22) with and without simulated rAPDs (using neutral density filters (NDFs)) and in abnormal patients (n = 24) with clinically graded rAPDs. The light stimulus (0.2 sec on and 1 sec off, or 2 sec on and 0.4 sec off) alternated between both eyes, simulating the SFT. Constriction amplitude (CA), constriction velocity (CV), and pupillary release were calculated by computer algorithm. In abnormal patients, NDFs were used to neutralize inter-eye differences., Results: Significant correlation (Spearman's rho 0.71, 0.73) between NDF strength and absolute inter-eye differences was seen for CA and CV in simulated rAPDs. All abnormal patients (15/15) having rAPDs greater than 0.5 log units were distinguished from normals using either the upper bound of the one-sided 95% confidence interval (95% CI) value of CA or CV as determined from 22 healthy volunteers. Inter-eye variability in some normals prevented confident distinction of six abnormal patients with 0.3 log unit rAPDs. Using NDFs, subtle rAPDs were predicted in three patients having questionable rAPDs on clinical examination. CA and CV were more sensitive than pupillary release for all comparisons., Conclusions: This binocular pupillometer identified all of our patients with > 0.5 log unit rAPDs. Using NDFs, all of our abnormal patients were accurately identified and their rAPDs quantified. Variability in some normals makes them indistinguishable from patients with subtle rAPDs.

Background: The aim of our study was to test in a small series of cases if pupil perimetry can prove real concentric visual field loss in retinal degeneration and distinguish from feigned visual field loss., Methods: By means of infrared-video-pupillography, light responses to perimetric stimuli were recorded. The stimulus pattern consisted of 41 stimuli presented in the central 30 degrees visual field. Stimulus intensity was 140 cd/m(2). 5 healthy subjects, 6 patients with retinitis pigmentosa and 2 patients with suspected functional visual field loss were examined., Results: Pupil perimetry was able to reproduce the visual field in retinitis pigmentosa very well. Normal subjects and patients with suspected feigned visual field loss showed normal pupillomotor fields, different from the findings in retinitis pigmentosa., Conclusions: This study provides sufficient evidence that pupil campimetry is applicable for differentiating between retinal dystrophy and functional concentric visual field loss. Possible residual light sensitivity of the blind retina due to melanopsin ganglion cells is obviously not sufficient to provide a pupillary light response to perimetric stimuli.

Light treatment has been used as a non-pharmacological tool to help mitigate poor sleep quality frequently found in older people. In order to increase compliance to non-pharmacological light treatments, new, more efficacious light-delivery systems need to be developed. A prototype personal light-treatment device equipped with low brightness blue light-emitting diodes (LEDs) (peak wavelength near 470 nm) was tested for its effectiveness in suppressing nocturnal melatonin, a measure of circadian stimulation. Two levels of corneal irradiance were set to deliver two prescribed doses of circadian light exposure. Eleven older subjects, between 51 and 80 yrs of age who met the selection criteria, were exposed to a high and a low level of light for 90 min on separate nights from the personal light-treatment device. Blood and saliva samples were collected at prescribed times for subsequent melatonin assay. After 1 h of light exposure, the light-induced nocturnal melatonin suppression level was about 35% for the low-light level and about 60% for the high-light level. The higher level of blue light suppressed melatonin more quickly, to a greater extent over the course of the 90 min exposure period, and maintained suppression after 60 min. The constant exposure of the low-light level resulted in a decrease in nocturnal melatonin suppression for the last sampling time, whereas for the high-light level, suppression continued throughout the entire exposure period. The present study performed with healthy adults suggests that the tested personal light-treatment device might be a practical, comfortable, and effective way to deliver light treatment to those suffering from circadian sleep disorders; however, the acceptance and effectiveness of personal light-treatment devices by older people and by other segments of the population suffering from sleep disorders in a real-life situation need to be directly tested.

Purpose: To determine the photopic pupil diameter and its determinants in a sample derived from a population-based survey in Tehran., Methods: In a cross-sectional study with a stratified random cluster sampling approach, 410 people age 14 years and over were selected from those residing in the first four municipality districts of Tehran after applying exclusion criteria, and 800 eyes (399 right eyes and 401 left eyes) were examined with the Orbscan II. The main outcome measure was the mean pupil diameter under photopic conditions, and possible correlations with potential determinants were evaluated through linear regression analyses. The design effect of a cluster sampling approach was observed and adjusted for., Results: The mean age of the participants was 40.6 +/- 16.8 years and 38.8% were male. The mean photopic pupil diameter (PPD) was 3.70 mm (range 2.30 to 5.10; 95% confidence interval (CI) 3.62 to 3.78). The mean PPD was 3.67 mm (95% CI, 3.54 to 3.81) in men and 3.72 mm (95% CI, 3.63 to 3.81) in women (p = 0.481). There was a significant reduction of 0.021 mm in PPD per year of aging (r = -0.49, p < 0.001). There was also a significant inverse correlation between PPD and spherical equivalent (r = -0.12, p = 0.034), while there was 0.66-mm increase in PPD with every 1.0-mm increase in the anterior chamber depth (ACD) (p < 0.001). Anisocoria, defined as a pupil diameter difference more than 0.4 mm between two eyes, was observed in 12.2% of the study population., Conclusion: While the mean PPD measured with the Orbscan II was 3.70 mm in a sample derived from a population-based survey in Tehran, the scarcity of similar studies and reports concerning the pupil diameter measured with the Orbscan II makes it difficult to draw eligible comparisons. The pupil diameter has reverse correlations with age and spherical equivalent, a direct correlation with ACD, but is not correlated with gender.

Purpose: This study was conducted to determine the magnitude of pupil center shift between the illumination conditions provided by corneal topography measurement (photopic illuminance) and by Hartmann-Shack aberrometry (mesopic illuminance) and to investigate the importance of this shift when calculating corneal aberrations and for the success of wavefront-guided surgical procedures., Methods: Sixty-two subjects with emmetropia underwent corneal topography and Hartmann-Shack aberrometry. Corneal limbus and pupil edges were detected, and the differences between their respective centers were determined for both procedures. Corneal aberrations were calculated using the pupil centers for corneal topography and for Hartmann-Shack aberrometry. Bland-Altmann plots and paired t-tests were used to analyze the differences between corneal aberrations referenced to the two pupil centers., Results: The mean magnitude (modulus) of the displacement of the pupil with the change of the illumination conditions was 0.21+/-0.11 mm. The effect of this pupillary shift was manifest for coma corneal aberrations for 5-mm pupils, but the two sets of aberrations calculated with the two pupil positions were not significantly different. Sixty-eight percent of the population had differences in coma smaller than 0.05 microm, and only 4% had differences larger than 0.1 microm. Pupil displacement was not large enough to significantly affect other higher-order Zernike modes., Conclusions: Estimated corneal aberrations changed slightly between photopic and mesopic illumination conditions given by corneal topography and Hartmann-Shack aberrometry. However, this systematic pupil shift, according to the published tolerances ranges, is enough to deteriorate the optical quality below the theoretically predicted diffraction limit of wavefront-guided corneal surgery.

Purpose: To study the pupillary light reflex in patients with choroidal neovascularization due to age-related macular degeneration (AMD)., Methods: The study included 15 patients with AMD and 15 control subjects. A full recording of the pupil's reaction to light was registered and the following eight parameters were measured and reported: baseline pupil (R1), latency (T1), minimum pupil radius (R2), amplitude (AMP), maximum constriction velocity (VCmax), maximum constriction acceleration (ACmax), time for maximum velocity (T2), and time for maximum constriction (T3)., Results: All variables measured presented alterations in the AMD group and a number of them were significantly reduced in the AMD group., Conclusions: The presence of neovascular AMD significantly affects the pupil's response to light stimulus when compared to normal subjects.

Purpose: Contraction anisocoria describes a phenomenon in which the pupil of a directly illuminated eye constricts more than the pupil of the consensual (not illuminated) eye. The purpose of this study was to investigate the lateralization of contraction anisocoria in young female and male subjects., Methods: Infrared binocular pupillography was used to measure pupillary light reflex (PLR) in 44 healthy children (23 girls, 21 boys) from 6 to 16 years of age. Measurements were conducted in both light-adapted and dark-adapted conditions with different stimulus intensities. Relative constriction amplitude was obtained by dividing the maximal pupil area change by the initial static pupil area. Contraction anisocoria was calculated by subtracting relative constriction amplitude in the consensual eye from that of the direct eye. Values of contraction anisocoria obtained by stimulating a subject's right or left eye were compared to determine any potential lateralization., Results: It was found that stimulating the right eye led to larger contraction anisocoria than stimulating the left eye. Such right-side lateralization of contraction anisocoria is much greater in males than in females. In addition, the effects of sex were related to the ambient light level and stimulus intensity., Conclusions: These results provide evidence that contraction anisocoria is more laterally asymmetric in males than in females.

Purpose: To estimate the change in iris cross-sectional (CS) area with pupil dilation using anterior segment optical coherence tomography comparing eyes with angle closure (AC) to open angle glaucoma (OAG)., Methods: Sixty-five patients from the Wilmer Glaucoma service, 36 with definite or suspected OAG and 29 with definite or suspected AC, underwent anterior segment optical coherence tomography imaging under 3 conditions (pupil constriction to light, physiologic dilation in the dark, and after pharmacologic dilation). The nasal and temporal iris CS areas were measured with custom software, 3 times in each of 4 meridians. The principal outcome variables were iris CS area and change in iris CS area/mm pupil diameter change. The relation of these parameters to potential variables that would influence iris area was estimated by multivariate regression., Results: CS area was smaller in eyes with larger pupil diameter, those that had undergone trabeculectomy, and those of European-derived persons (P<0.05 for all in a univariate analysis). In a multivariate model with CS area as the dependent variable, larger pupil diameter (with a 0.19 mm decrease in CS area for each 1 mm of pupil enlargement, P=0.0002), and trabeculectomy remained significant factors. In a second multivariate model, AC irides had less change in CS area/mm pupil enlargement than OAG or OAG suspects (P=0.01). Change in iris CS area was essentially complete in 5 seconds (n=10 eyes)., Conclusions: The iris loses nearly half its volume from a pupil diameter of 3 to 7 mm, probably by eliminating extracellular fluid. Smaller iris CS area change with physiologic pupil dilation is a potential risk factor for AC. Dynamic iris CS area change deserves testing as a prospective indicator of AC.

A subset of retinal ganglion cells has recently been discovered to be intrinsically photosensitive, with melanopsin as the pigment. These cells project primarily to brain centres for non-image-forming visual functions such as the pupillary light reflex and circadian photoentrainment. How well they signal intrinsic light absorption to drive behaviour remains unclear. Here we report fundamental parameters governing their intrinsic light responses and associated spike generation. The membrane density of melanopsin is 10(4)-fold lower than that of rod and cone pigments, resulting in a very low photon catch and a phototransducing role only in relatively bright light. Nonetheless, each captured photon elicits a large and extraordinarily prolonged response, with a unique shape among known photoreceptors. Notably, like rods, these cells are capable of signalling single-photon absorption. A flash causing a few hundred isomerized melanopsin molecules in a retina is sufficient for reaching threshold for the pupillary light reflex.

Purpose: To evaluate the effect of 3 types of topically applied miotic eyedrops on the pupil diameter in normal eyes., Setting: Department of Neurosciences, Section of Ophthalmology, University of Pisa, Pisa, Italy., Methods: This prospective study comprised 60 eyes of 30 healthy volunteers treated with aceclidine 0.02%, brimonidine tartrate 0.20%, and dapiprazole 0.25%. Pupil diameter was measured under scotopic, mesopic (4 lux), and photopic (50 lux) conditions using an infrared pupillometer incorporated into a CSO topographer. The first measurement was obtained before single instillation of 1 type of miotic eyedrop. Subsequent measurements were taken after 30, 120, and 240 minutes. Each additional medication was tested after an interval of at least 6 weeks to avoid possible effects from the previously administered drug. All patients received a questionnaire and were asked to grade the tolerability of each eyedrop using a subjective scoring system., Results: Aceclidine 0.02% had no significant miotic effect. Brimonidine tartrate 0.20% caused significant miosis within 30 minutes and 120 minutes; after 240 minutes, the effect under all luminance conditions decreased to baseline levels without reaching the initial level. Dapiprazole 0.25% had a miotic effect similar to that of brimonidine but produced many side effects including hyperemia and burning, which many patients said caused significant discomfort., Conclusions: Brimonidine tartrate 0.20% had the best miotic effect of the 3 agents tested and was well tolerated by the patients. The reproducible miotic effect of brimonidine tartrate under all lighting conditions might benefit postoperative refractive patients who report night-vision difficulties related to large pupils.

Purpose: To evaluate the effect of spherical aberration on visual function under natural pupil conditions after cataract surgery., Setting: Keio University Hospital, Tokyo, Japan., Methods: This study comprised cataract patients who had cataract extraction with implantation of an acrylic intraocular lens. Preoperative and postoperative visual acuity, higher-order aberration in the whole eye, contrast sensitivity function, and pupil diameter under photopic and mesopic conditions 1 month after surgery were measured. The area under log contrast sensitivity function (AULCSF) and spherical aberration corresponding to the individual pupil diameter under photopic and mesopic conditions were evaluated., Results: One hundred seven eyes of 79 patients (30 men, 49 women; mean age 68.0 years +/- 9.6 [SD]) were evaluated. The mean pupil diameter was 2.9 +/- 0.50 mm under photopic conditions and 3.6 +/- 0.57 mm under mesopic conditions. The mean spherical aberration was 0.03 +/- 0.04 mum (range -0.12 to 0.34 mum) under photopic conditions and 0.05 +/- 0.10 mum (range -0.14 to 0.55 mum) under mesopic conditions. The postoperative AULCSF without glare under photopic conditions was significantly negatively correlated with spherical aberration (P = .014). The postoperative AULCSF with and without glare under mesopic conditions was significantly negatively correlated with spherical aberration (P<.001 and P = .01, respectively)., Conclusions: Postoperative spherical aberration had a significant effect on visual function under photopic and mesopic conditions. This result indicates that reduced postoperative spherical aberration improves postoperative visual function under photopic and mesopic conditions.

Objective: Cardiac autonomic dysregulation has been reported in patients with schizophrenia. However, there are no definite data examining whether other branches of the autonomic nervous system are compromised as well and how they interrelate with cardiac function. In this study, we tested the hypothesis that the autonomic dysregulation at the heart is reflected in the regulation of the pupillary light reflex., Methods: We assessed heart rate variability and baroreflex sensitivity parameters as well as pupillographic measures in 28 unmedicated patients with schizophrenia and compared these measures to those of 28 controls. In addition, cardiovascular and pupillographic parameters were correlated in both groups., Results: The obtained cardiovascular parameters indicated decreased parasympathetic modulation. Patients showed a significantly increased resting pupil diameter as well as reduced relative amplitude, suggesting a dominance of sympathetic control and a lack of parasympathetic modulation at the pupil. Intriguingly, the parasympathetic latency of the pupil constriction was similar in both groups and correlated with several cardiovascular parameters. These correlations were in the opposite direction in patients compared to controls. Furthermore, shorter latencies of the pupil constriction were associated with symptom severity in patients., Conclusions: Overall, we found evidence for an autonomic dysregulation at the pupil and heart in patients with schizophrenia. Future studies are warranted to describe this complex interaction at different levels of the autonomic system., Significance: The interrelationship of both the systems indicates that the autonomic dysfunction affects the regulation in different branches of the autonomic network as well as their interaction in schizophrenia.

There are large inter-individual differences in pupil size and suppression of melatonin by exposure to light. It has been reported that melatonin suppression by exposure to light increases when pupils are pharmacologically dilated. However, the correlation between normal inter-individual difference in pupil size and melatonin suppression by exposure to light is not clear. Twenty-three healthy male subjects (22.6+/-2.7 years old) were exposed to light (1000 lx) for 2 h at night. The starting time of exposure to light was set to the ascending phase of melatonin concentration of each subject. Pupil area and saliva melatonin concentration were measured before exposure to light under dim light (15 lx) and during exposure to light. There were large inter-individual differences in melatonin suppression and pupil area. The mean and standard deviation of percentage of melatonin suppression 2 h after exposure to light was 57.2+/-22.1%. The mean and standard deviation of pupil areas before and 2 h after exposure to light were 30.7+/-7.9 mm2 and 15.9+/-4.8 mm2, respectively. The percentage of melatonin suppression by light was positively correlated with pupil area during light exposure (r=0.525, p<0.02). Interestingly, it was also correlated with pupil area measured before exposure to light, under dim light (15 lx) (r=0.658, p<0.001). These results suggest that inter-individual difference in pupil area positively correlates with melatonin suppression by light and that pupil area under dim light is a predictor of inter-individual differences in melatonin suppression by light.

Purpose: Retinal photocoagulation under poor visualization condition is often required. Transscleral infrared laser can be used as an alternative to regular transpupillary treatment. Based upon retinographic measurements, we proposed to estimate the reproducibility as well as ocular wall permeability rate for this treatment. Our primary goal was to evaluate whether this technique can deliver adequate photocoagulation at predetermined parameters without direct retinal visualization., Methods: In New Zealand pigmented rabbits, optimal transscleral infrared diode laser settings were administered to the right eye. With the same parameters, transpupillary photocoagulation was repeated in the left eye. Retinographic and clinical examinations were performed immediately and two months later., Results: Ocular wall permeability rate varied between 58.95 and 63.87%. Average permeability using a power of 300 mW (63.14%) was found to be higher than that encountered before its enhancement up to 500 mW (59.11%), (P<0.05)., Conclusions: Setting parameters showed dose-response effect. No retinal hole or retinal detachment was noticed in any rabbit. Transscleral infrared photocoagulation appeared to be a reproducible and secure method in the experimental model.

Rod and cone photoreceptors detect light and relay this information through a multisynaptic pathway to the brain by means of retinal ganglion cells (RGCs). These retinal outputs support not only pattern vision but also non-image-forming (NIF) functions, which include circadian photoentrainment and pupillary light reflex (PLR). In mammals, NIF functions are mediated by rods, cones and the melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). Rod-cone photoreceptors and ipRGCs are complementary in signalling light intensity for NIF functions. The ipRGCs, in addition to being directly photosensitive, also receive synaptic input from rod-cone networks. To determine how the ipRGCs relay rod-cone light information for both image-forming and non-image-forming functions, we genetically ablated ipRGCs in mice. Here we show that animals lacking ipRGCs retain pattern vision but have deficits in both PLR and circadian photoentrainment that are more extensive than those observed in melanopsin knockouts. The defects in PLR and photoentrainment resemble those observed in animals that lack phototransduction in all three photoreceptor classes. These results indicate that light signals for irradiance detection are dissociated from pattern vision at the retinal ganglion cell level, and animals that cannot detect light for NIF functions are still capable of image formation.

This case report describes the unusual finding of bilateral atonic pupils after cataract extraction by phacoemulsification in an 84-year-old woman with multiple cardiopulmonary risk factors.

Purpose: We aimed to evaluate the dynamic function of iris muscle in asymmetric pseudoexfoliation patients by videonystagmography., Methods: 15 patients with asymmetric pseudoexfoliation and 15 control subjects were included. The function of iris muscle was assessed by the pupillometry test of the videonystagmography by calculating the percent of change in pupillary diameter in unit time during fixation to an accommodative target, light reaction, convergence, and divergence., Results: There were significant differences between groups in the reaction during fixation (p: 0.01), in light reaction (p: 0.014), and in divergence-induced mydriasis (p: 0.003). In all of these, the difference between control eyes and pseudoexfoliative eyes of patients with PXS was significant., Conclusions: Pupillometry seems to be a promising noninvasive method to detect the clinical signs of PXS and may be useful for an accurate diagnosis.

Purpose: To evaluate a method of surgically treating presbyopia in hyperopic patients having laser in situ keratomileusis (LASIK) by selecting excimer ablation optical zone diameters based on the photopic pupil., Setting: Private practice, Beverly Hills, California, USA., Methods: This prospective analysis comprised 46 patients having hyperopic LASIK for presbyopia. The distance-dominant eye was treated with a standard 6.0 mm optical and 9.0 mm outer zone for full distance correction with no nomogram adjustment from the final preoperative manifest refraction. In the nondominant eye, an algorithm was used to select the optical and blend zone diameters and the optical zone size-dependent programmed amount of correction augmentation. Variables evaluated at the 6-month postoperative visit included preoperative and postoperative manifest refractive spherical equivalent (MRSE), refractive cylinder, and monocular and binocular near and distance uncorrected visual acuities. Patient satisfaction and spectacle dependence were also evaluated., Results: In the near-corrected eye, the mean preoperative and postoperative MRSE was +1.10 diopters (D) +/- 1.20 (SD) and -1.30 +/- 0.56 D, respectively, and the mean refractive cylinder, -0.76 +/- 0.91 D and -0.36 +/- 0.33 D, respectively (P<.05). The mean uncorrected near acuity in the near-corrected eye was J10 preoperatively and J1 postoperatively (P<.0001) and the binocular mean uncorrected near acuity, J10 and J1, respectively (P<.0001). The mean uncorrected logMAR distance acuity in the near-corrected eye was +0.38 +/- 0.31 (20/50) preoperatively and +0.36 +/- 0.25 (20/50) postoperatively (P>.05). The mean binocular uncorrected logMAR distance acuity was +0.30 +/- 0.30 (20/40) and +0.01 +/- 0.08 (20/20) (P<.0001), respectively. The mean overall patient satisfaction score was 8.8 (scale 1 to 10). After LASIK, no patient reported using spectacles full time for near or distance and 15% reported part-time use., Conclusion: Photopic pupillometry-guided LASIK may be an effective option when considering surgical treatment of presbyopia in hyperopic patients.

Mammalian retinal photoreceptors form an irradiance detection system that drives many nonvisual responses to light such as pupil reflex and resetting of the circadian clock. To understand the role of pupil size in circadian light responses, pupil diameter was pharmacologically manipulated and the effect on behavioral phase shifts at different irradiance levels was studied in the Syrian hamster. Dose-response curves for steady-state pupil size and for behavioral phase shifts were constructed for 3 pupil conditions (dilated, constricted, and control). Retinal irradiance was calculated from corneal irradiance, pupil size, retinal surface area, and absorption of ocular media. The sensitivity of photic responses to retinal irradiance is approximately 1.5 log units higher than to corneal irradiance. When plotted against corneal irradiance, pharmacological pupil constriction reduces the light sensitivity of the circadian system, but pupil dilation has no effect. As expected, when plotted against retinal irradiance all dose-response curves superimposed, confirming that the circadian system responds to photon flux on the retina. Pupil dilation does not increase the circadian response to increasing irradiance, since the response of the circadian system attains saturation at irradiance levels lower than those required to induce pupil constriction. The main finding shows that due to the different response sensitivities, the effect of pupil constriction on the light sensitivity of the circadian system in the hamster under natural conditions is virtually negligible. We further suggest the existence of distinct modulating mechanisms for the differential retinal irradiance sensitivity of the pupil system and the circadian system, which enables the different responses to be tuned to their specific tasks while using similar photoreceptive input.

Aim: To compare the pupil signs in patients with bilateral pupillotonia caused by Holmes-Adie syndrome or generalised peripheral neuropathy., Methods: Infrared video pupillographic techniques were used to measure a number of pupil variables in patients with Holmes-Adie syndrome, generalised neuropathy (various aetiologies) and healthy age-matched control subjects., Results: Regardless of aetiology, the patients generally had pupil signs typical of pupillotonia (small dark diameters, large light diameters, tonic near responses, attenuated light responses with light-near dissociation, and sector palsy). However, significant differences were found in the prevalence and magnitude of several pupil variables in the two patient groups. In particular, sector palsy and anisocoria exceeding 1 mm (in the light) were seen much more commonly in Holmes-Adie patients than patients with generalised neuropathy. The presence of both these pupil signs can be used to distinguish between these diagnoses with a sensitivity of 58% and a specificity of 90%., Conclusions: The tonic pupils of patients with Holmes-Adie syndrome are significantly different to those found in patients with generalised neuropathy; recognition of these differences may allow distinction between these diagnoses.

The recovery of visual performance and pupil responses were investigated in patients with demyelinating optic neuritis (ON) and multiple sclerosis (MS). The pupil constriction amplitude and the time delay (latency) of the pupil response were measured in 14 patients with a history of unilateral ON in response to either achromatic (luminance) or chromatic (isoluminant) stimulus modulation. Five of these subjects were diagnosed later with MS. In addition, we measured detection thresholds for achromatic stimuli using standard visual field perimetry and chromatic thresholds using a new colour assessment and diagnosis (CAD) test that isolates the use of colour signals. The results show that, despite significant improvements in visual function following the acute phase (as assessed using visual acuity and fields), significant pupil response deficits remain. The findings also demonstrate that accurate measurements of pupil responses and chromatic thresholds can reveal deficits that remain undetected with more conventional techniques. These preliminary findings suggest that the techniques described here can provide useful information about remitting and relapsing demyelinative phases, often observed during MS and ON.

Purpose: To describe the use of anterior segment optical coherence tomography (OCT) in studying the dynamic dark-light changes of the anterior chamber angle., Methods: Thirty-seven normal subjects with open angles on dark-room gonioscopy and 18 subjects with narrow angles were analyzed. The dynamic dark-light changes of the anterior-chamber angle were captured with real-time video recording. The angle opening distance (AOD500) and trabecular iris space area (TISA500) of the nasal angle and the pupil diameter in each of the representative serial images were measured. Linear regression analysis was performed to investigate the association between AOD500/TISA500 and pupil diameter. Demographic and biometry measurements associated with the AOD difference (AOD500((light)) - AOD500((dark))) and TISA difference (TISA500((light)) - TISA500((dark))) were analyzed with univariate and multivariate regression models., Results: The AOD500/TISA500 measured in the light in the open-angle and the narrow-angle groups were 694 +/- 330 microm/0.24 +/- 0.10 mm(2) and 265 +/- 78 microm/0.10 +/- 0.03 mm(2), respectively. These values were significantly greater than the AOD500/TISA500 measured in the dark (492 +/- 265 microm/0.16 +/- 0.08 mm(2) and 119 +/- 82 microm/0.05 +/- 0.04 mm(2), respectively, all with P < 0.001). The ranges of the AOD/TISA difference were 13 to 817 microm/0.011 to 0.154 mm(2), with an average of 180 microm/0.073 mm(2). Multivariate regression analysis identified a positive correlation between anterior chamber depth and the AOD/TISA difference. Fifty eyes showed significant correlations between AOD/TISA and pupil diameter, whereas one eye showed no association. Four eyes in the narrow angle group developed appositional angle closure in the dark., Conclusions: The dynamic dark-light changes of the anterior chamber angle can be imaged and analyzed with anterior segment OCT. Although the angle width generally decreased linearly with increasing pupil diameter, the differences of the angle width measured in the dark and in the light varied substantially among individuals.

The purpose of the present study was to elucidate the existence of individual differences of pupil response to light stimulation, and to confirm the reproducibility of this phenomenon. Furthermore, the relationship between the individual differences in nocturnal melatonin suppression induced by lighting and the individual differences of pupillary light response (PLR) was examined. The pupil diameter and salivary melatonin content of 20 male students were measured at the same period of time (00:00-02:30 hr) on different days, accordingly. Illumination (530 nm) produced by a monochromatic light-emitting diode (LED) was employed as the light stimulation: pupil diameter was measured with 4 different levels of illuminance of 1, 3, 30 and 600 lux and melatonin levels were measured at 30 and 600 lux (respective controls were taken at 0 lux). Oral temperature, blood pressure and subjective index of sleepiness were taken in experiments where melatonin levels were measured. Changes of the pupil diameter in response to light were expressed as PLR and light-induced melatonin suppression was expressed as a control-adjusted melatonin suppression score (control-adjusted MSS), which was compared to the melatonin level measured at 0 lux. In the PLR, the coefficients of variation obtained at 30 lux or less were large (51.5, 45.0, 28.4 and 6.2% at 1, 3, 30 and 600 lux, respectively). Correlations of illuminance of any combination at 30 lux or less were statistically significant at less than 1% level (1 vs. 3 lux: r=0.68; 1 vs. 30 lux: r=0.64; 3 vs. 30 lux: r=0.73), which showed the reproducibility of individual differences. The control-adjusted MSS at 600 lux (-1.14+/-1.16) was significantly (p<0.05) lower than that registered at 30 lux (-0.22+/-2.12). PLR values measured at 30 and 600 lux were then correlated with control-adjusted MSS; neither indicated a significant linear relationship. However, the control-adjusted MSS showed around 0 under any of the illuminance conditions in subjects with high PLR. In control-adjusted MSS of low values (i.e., melatonin secretions were easily suppressed), subjects indicated typically low PLR. In subjects with low control-adjusted MSS (n=3), characteristic changes in the autonomic nervous system, such as body temperature and blood pressure, were noted in subjects exposed to low illuminance of 30 lux. The fact that the relationship between PLR and control-adjusted MSS portray a similar pattern even under different luminance conditions suggests that MSS may not be affected in those with high PLR at low illuminance, regardless of the illuminance condition.

Purpose: To determine the relative contributions of inner and outer retinal photoreception to the pupillary light response., Methods: Wild-type, retinal degenerate (rd/rd), and melanopsin mutant (opn4(-/-)) mice were tested for pupillary light responsiveness by video pupillometry before, during, and after exposure to supersaturating light intensities. Similar lighting protocols were used to probe responses of intrinsically photosensitive retinal ganglion cells (ipRGCs) recorded with multielectrode arrays ex vivo., Results: Both outer retinal photoreceptors (rods and cones) and inner retinal photoreceptors (intrinsically photosensitive retinal ganglion cells [ipRGCs]) are sufficient to drive the pupillary light response in mice. After supersaturating light exposure, rather than bleaching or adapting, rd/rd mice showed paradoxical potentiation of responses to subsaturating light exposure. opn4(-/-) mice, in contrast, could not sustain pupillary constriction under continuous bright illumination, and showed desensitization after bright-light exposure. Both the intensity of light necessary to induce potentiation and the spectral sensitivity for sustained and potentiated responses differed from that necessary to trigger pupillary constriction, suggesting that photopotentiation is dependent on a pigment-state distinct from that triggering the pupillary light response itself. Multielectrode array recordings of ipRGCs from rd/rd retinas demonstrated persistent cell firing under continuous light exposure but did not show potentiation., Conclusions: Unique photoreceptive properties of intrinsically photosensitive RGCs confer resistance to bleaching and/or adaptation under continuous bright illumination to the pupillary light response and suggest the presence of a photopigment with multiple absorption states.

Analysis of human eye pupil reactivity is a very valuable diagnostic method used mainly for evaluation of the condition of the autonomic nervous system and the visual system. The paper presents an experimental pupillometer built in the Institute of Physics of the Wroclaw University of Technology. The apparatus makes it possible to record and analyze pupillary light reflex and spontaneous changes in the pupil diameter during a session in the dark. The detector system used in the pupillometer allows us to record the pupil diameter at a rate of 90 Hz with a linear accuracy of 0.008 mm. In this paper, the proposed detection method, the principle of operation and calibration of the apparatus and the possibilities of the measurement system are presented.

Purpose of Review: The role of scotopic pupil size as a factor in predicting night vision complaints is controversial. This review summarizes reports in the literature, some that have found and some that have failed to find a correlation with scotopic pupil size and night vision complaints., Recent Findings: Pupil-measuring devices are discussed along with informed consent issues and reports showing that wavefront aberrations increase with increasing pupil size. A new objective measuring device (Larson) showed a correlation with postoperative starbursts and pupil size and a decrease in starbursts with wavefront-guided treatments compared with conventional excimer laser treatments. Cortical adaptation allows many patients to adapt to their new night vision. Treatment options for those who remain symptomatic include drops to reduce pupil size and wavefront-guided retreatments., Summary: Reports in the literature are conflicting, and refractive surgeons would be wise to inform their patients that large scotopic pupil size is a potential risk factor for night vision complaints. By doing this they will follow the recommendations in recent patient information brochures of both VISX (Santa Clara, California) and Alcon (Orlando, Florida) and on the United States Food and Drug Administration web site.

Objective: To determine the percent decussation of pupil input fibers in humans and to explain the size and range of the log unit relative afferent pupillary defect (RAPD) in patients with optic tract lesions., Design: Experimental study., Participants and Controls: Five patients with a unilateral optic tract lesion., Methods: The pupil response from light stimulation of the nasal hemifield, temporal hemifield, and full field of each eye of 5 patients with a unilateral optic tract lesion was recorded using computerized binocular infrared pupillography. Six stimulus light intensities, separated by 0.5-log unit steps, were used; 12 stimulus repetitions were given for each stimulus condition., Main Outcome Measures: For each stimulus condition, the pupil response of each eye was characterized by plotting the mean pupil contraction amplitude as a function of stimulus light intensity. The percentage of decussating afferent pupillomotor input fibers was calculated from the ratio of the maximal pupil contractions elicited from each eye. The RAPD was determined pupillographically from full-field stimulation to each eye., Results: In all patients, the pupil response from the functioning temporal hemifield ipsilateral to the tract lesion was greater than that from the functioning contralateral nasal hemifield. This temporal-nasal asymmetry increased with increasing stimulus intensity and was similar in hemifield and full-field stimuli, eventually saturating at maximal light intensity. The log unit RAPD did not correlate with the estimated percentage of decussating pupil fibers, which ranged from 54% to 67%., Conclusions: In patients with a unilateral optic tract lesion, the pupillary responses from full-field stimulation to each eye are the same as comparing the functioning temporal field with the functioning nasal field. The percentage of decussating fibers is reflected in the ratio of the maximal pupil contraction amplitudes resulting from stimulus input between the two eyes. The RAPD that occurs in this setting reflects the difference in light sensitivity between the intact temporal and nasal hemifields. Its magnitude does not correlate with the difference in the number of crossed and uncrossed axons, but its sidedness contralateral to the side of the optic tract lesion is consistent with the greater percentage of decussating pupillomotor input.

Objective: To determine the pathogenesis of the bullous keratopathy that is frequently observed in patients after argon laser iridotomy (ALI) by comparing the changes in aqueous flow after ALI with those that follow peripheral iridectomy in rabbit eyes., Methods: Silicone particles were injected into the anterior chamber of rabbit eyes as tracers to monitor aqueous flow. Particle tracking velocimetry with image analysis was used to determine the direction and speed of aqueous flow in 5 pigmented rabbits that underwent ALI and 5 that underwent peripheral iridectomy., Results: In the ALI group, silicone particles were found to stream through the iridotomy window against the corneal endothelium immediately after the pupil was constricted by a light stimulus. The mean +/- SD speed of the particles was 2.97 +/- 1.51 mm/s. In contrast, the mean +/- SD flow rate through the iridectomy window in the peripheral iridectomy group was significantly slower at 0.36 +/- 0.30 mm/s (P = .01)., Conclusion: Constriction of the pupil elicited marked aqueous streaming through the ALI window against the corneal endothelium. Clinical Relevance The mechanical stress to the corneal endothelium by the abnormal aqueous stream may be partially responsible for the corneal decompensation that follows ALI.

Background: The aim of this study was to characterise the changes of the dynamic pupillary light reflex in patients with unilateral Horner's syndrome by appropriate pupillographic parameters., Methods: The dynamic changes of pupillary diameter in response to light flashes of 100 ms were recorded in darkness with two infrared video cameras in 15 patients., Results: Significant changes in the pupillary light reflex of the affected side were observed only during the phase of redilatation. The decelerated redilatation was defined by the following parameters: (1) time parameters (percentage of redilatation after 4 s and after 5 s, time to reach 67% and 75% of redilatation) and (2) amplitude-adjusted velocity parameters (relative velocity at 67% and at 75% of redilatation)., Conclusion: A slowed pupil redilatation in patients with Horner's syndrome can be detected also after short light flashes and is characterised by prolonged redilatation time parameters and reduced amplitude-adjusted redilatation velocity parameters.

Purpose: To evaluate the effectiveness of the pupil center as an anatomic landmark for excimer laser treatments., Setting: Sekal-Microchirurgia-Rovigo Centre, Rovigo, Italy., Methods: Pupillometry with the Costruzione Strumenti Oftalmici S.R.L. (CSO) pupil-measuring module (incorporated in Eye Top videokeratoscope) was performed in 52 patients with a diagnosis of myopia and in 25 patients with a diagnosis of hyperopia. Measurements both in mesopic and photopic conditions consisted of pupil diameters, spatial shift of the pupil center, and the distance between the pupil center and keratoscopic axis., Results: The mean pupil diameter in photopic conditions of illumination in myopic eyes was 3.52 mm +/- 0.56 (SD), while in mesopic conditions it was 5.37 +/- 0.78 mm; in hyperopic eyes the mean photopic pupil diameter was 3.01 +/- 0.46 mm, while the mean mesopic diameter was 5.12 +/- 0.48 mm. The mean spatial shift of the pupil center in myopic eyes was 0.086 mm (maximum 0.269 mm), while in the hyperopic eyes it was 0.095 mm (maximum 0.283 mm). The mean distance between the pupil center and keratoscopic axis in myopic eyes was 0.226 +/- 0.13 mm (maximum 0.75 mm), while in hyperopic eyes it was 0.45 +/- 0.19 mm (maximum 0.8 mm)., Conclusions: The mean of the measured pupil sizes was greater in myopic eyes than in hyperopic eyes. The spatial shift of the pupil center, as the pupil dilates, was relatively small in all groups; therefore, the pupil center is a good anatomic landmark for both traditional refractive surgery and wavefront-guided treatments. The mean distance between the keratoscopic axis and pupil center was greater in the hyperopic group than in the myopic group. Therefore, centration of any laser treatment on the basis of the keratoscopic analysis should be done carefully, especially in hyperopic eyes and in cases in which the pupil center is meaningfully shifted from keratoscopic axis, even in photopic conditions of illumination.

Purpose: To evaluate the influence of the pupillary diameter, ciliary muscle tone, and room light on nerve fiber layer measurements with the scanning laser polarimeter (GDx)., Methods: One randomly selected eye of ten normal volunteers was examined with the GDx in a two-day protocol under eight testing conditions (pilocarpine 1%, phenylephrine 10%, tropicamide 1%, or no drops with room lights on or off). The twelve parameters, obtained by the GDx, were compared under the eight testing conditions, using two way ANOVA for repeated measurements and Tukey HSD post hoc test., Results: Ten of the twelve parameters were statistically significantly different (P < 0.05) when measured under the three medication or no medication conditions, controlling for the ambient light status. There were no significant differences when measured with the light on or off, controlling for use of drops., Conclusions: Nerve fiber layer measurements with the GDx were influenced by drugs affecting pupillary diameter, but not by the status of room light or ciliary muscle tone.

Rodents blind from outer retinal (rod and cone) degeneration still retain several light-dependent phenomena, including entrainment of the circadian clock and pupillary light responsiveness. This paradox is explained by the presence of intrinsically photosensitive retinal ganglion cells in the inner retina. These cells have unique properties, including a novel action spectrum, resistance to bleaching and adaptation under continuous light, and resistance to vitamin A depletion. Two candidate classes of photopigment have been proposed: melanopsin and cryptochromes. Physiologic analysis of circadian entrainment and pupillary light responsiveness in mice lacking these proteins leads to three conclusions: (1) outer and inner retinal photoreceptors provide partially redundant information to the inner retina, (2) melanopsin is required for inner retinal phototransduction in the absence of rod and cone signaling, and (3) cryptochromes contribute to the amplitude of inner retinal phototransduction but are not strictly required.

Objective: The pupil response to light flux increments is abnormal in severe optic neuritis, but little is known about the effects of this condition on the pupil colour response. The aim of this study was to examine how optic neuritis affects pupil responses to light flux and colour modulation and the extent to which such pupil responses mirror the loss and recovery of vision., Methods: A new pupil examination technique that makes use of sinusoidal modulation of either luminance contrast or chromatic saturation was employed. This technique enables the automatic extraction of both pupil response amplitude and latency and achieves a high signal to noise ratio with fewer averages., Results: The study reveals a greater loss of pupil response amplitude and significantly longer latencies to chromatic modulation (i.e. approximately 80 ms). Stimulation of the unaffected eye in the optic neuritis group results in smaller response amplitudes when compared to the normal group for both light flux and colour modulation., Conclusions: Pupil response components can be affected differently in optic neuritis. These findings suggest that the pupil colour response, in particular, may provide a useful, objective estimator to judge the extent of damage and recovery in diseases of the optic nerve.

Purpose: The mouse eye has a bright retinal image (f/number <1) but low optical quality (visual acuity about 0.5 cpd) that may render emmetropization unnecessary. However, this species is potentially a powerful model to study eye growth and myopia because its genome can be readily manipulated and has been completely sequenced. We have investigated how precisely eyes of mice can be refracted and tested whether deprivation myopia can be induced by frosted diffusers., Methods: An automated eccentric infrared photorefractor was adapted to refract eyes of two mouse strains--C57BL/6 (B6) and DBA/2 (D2)--during Tropicamide cycloplegia without anesthesia. Axial lengths were measured in highly magnified video images of freshly excised eyes. Plastic hemispherical diffusers were applied between postnatal days and 29 and left attached for 7 or 14 days., Results: (1) Trial lenses ranging from +10 to -10 D produced high correlations between the brightness slope in the pupil and applied lens power (r = 0.81 and r = 0.87), demonstrating reliable refraction. Five repeated measures in 12 eyes showed an average standard deviation of 3.0 D, equivalent to an axial length change <10 microm (derived from schematic eye modeling). (2) Deprivation produced a significant shift toward myopia, relative to untreated eyes, but only after 14 days and only in B6 mice (p = 0.02 with or p = 0.00038 without one outlier; N = 9). In contrast, DBA/2J were unaffected by occlusion, perhaps due to mutations that target eye, lens, or anterior segment. (3) Both eyes of untreated animals often had axial lengths that differed markedly. Surprisingly, we detected no significant correlation between refractive error and axial length after treatment., Conclusions: The infrared refraction technique is sufficiently sensitive to resolve equivalent changes in axial length of only +/- 10 microm in alert mice. Prolonged occlusion produces a significant myopic shift in B6 mice, but not in D2 mice. Even among isogenic B6 mice, the response is variable for reasons that presumably trace back to subtle developmental, environmental, and technical factors.

A usual approximation in Hartmann-Shack aberrometry is that the centroid displacements are proportional to the spatial averages of the wave-front slopes at the sampling subapertures. However, these spatial averages are actually weighted by the local irradiance distribution across each microlens. The irradiance across the eye pupil is not uniform in usual reflectometric aberrometers, which is due to several factors including retinal scattering and cone waveguiding directionality. It is shown that neglecting this fact in usual least-squares reconstruction procedures gives rise to a biased estimation of the aberration coefficients. The magnitude of this bias depends on the actual irradiance distribution across the eye pupil, the mode being estimated, the detailed modal composition of the aberrated wave front, and the geometry of the wave-front sampling array. Order-of-magnitude calculations suggest that this bias may well be in the range 5%-10% for relatively smooth irradiance distributions. The systematic nature of this error makes it advisable to check for its presence and, if required, to compensate for it by an adequate choice of the least-squares reconstruction matrix.

Purpose: To evaluate the efficacy and safety of diode laser transscleral cyclophotocoagulation in the treatment of chronic angle-closure glaucoma., Patients and Methods: A prospective, non-comparative interventional pilot study was conducted. Fourteen eyes of 14 Chinese patients with chronic angle-closure glaucoma whose intraocular pressures were greater than 21 mm Hg on medications were treated with diode laser transscleral cyclophotocoagulation using the G-probe at the United Christian Hospital between February 2000 and May 2001. The inferior 270 degrees quadrant (from 2 to 11 o'clock for right eye and from 1 to 10 o'clock for left eye) was treated and the patients were followed up regularly. The initial laser energy was set at 2,000 mWatt with a duration of 2 seconds. The post-treatment anti-glaucoma medications were adjusted according to the intraocular pressure. If medications failed to lower the intraocular pressure to below 21 mm Hg, cyclophotocoagulation to the same inferior 270 degrees quadrant was repeated., Results: All patients completed a 12-month follow-up period. The total success rate defined as IOP < 21 mm Hg with or without medication(s) was 85.7% at 1 year of follow-up review. The mean +/- SD intraocular pressure decreased from pre-treatment level of 36.9 +/- 11.7 mm Hg to 18.9 +/- 6.5 mm Hg at 1 year after treatment. The difference was statistically significant (P < 0.001) (Paired t test). The mean +/- SD number of IOP-lowering eyedrops was significantly reduced from 1.9 +/- 0.7 before cyclophotocoagulation to 0.4 +/- 0.8 at 1 year after treatment (P = 0.0002) (Paired t test). Two eyes required repeat treatment. Seven eyes (50%) had atonic pupil following the laser treatment., Conclusion: Diode laser transscleral cyclophotocoagulation is effective in lowering the intraocular pressure in chronic angle-closure glaucoma and its effect lasts for at least 1 year.

Background: The spectral sensitivity of the pupillary mechanism is reported to be greater in the blue part of the visible spectrum compared to the sensitivity of the visual system as defined by V(lambda) for a two-degree field. This means that blue light gives rise to smaller pupils compared to those that occur with light of other colours of the same luminance. This has been interpreted as indicating that there may be a rod input to pupil response even at photopic levels of illumination. An alternative explanation is that the smaller pupil size for blue light is an artefact arising from the use of the CIE V(lambda) function which is based on the spectral sensitivity of the eye to a two-degree field. In most investigations of pupil response, the adapting luminous field is much larger than two degrees., Method: The size of the static pupil was measured using an entoptic method when the eye was adapted to a large 'Ganzfeld' field of wavelengths of 624, 580, 521, 467 and 429 nm and luminances ranging from mesopic to photopic., Results: The pupil is smaller for light of shorter wavelengths compared to that for light of longer wavelengths of the same luminance. This effect disappears at photopic luminances when luminance is calculated using the V(10 degrees ) (lambda) function instead of the V(2 degrees ) (lambda) function but is still evident at mesopic levels. When pupil size is plotted against equivalent luminance for a 10-degree field V(10 degrees ) (lambda, L(eq)) pupil size is independent of wavelength., Conclusion: The apparent enhanced sensitivity of the pupil to blue light at photopic levels is an artefact arising from the inappropriate use of the V(2 degrees ) (lambda) for the measurement of luminance when the adapting field in pupil response measurements is a large field. Pupil size is a simple linear function of the log of equivalent luminance calculated for large fields for adapting luminances from photopic to mesopic and is independent of the wavelength of the adapting field for the whole range of adapting luminances.