Dark Iris Research Articles

Consistent contrast between eyelid and iris brightness supports a role for vigilance signalling in ducks

Signalling self‐ability to maintain vigilance may help in securing a mate, while providing accurate information about vigilance status may result in conspecifics adjusting their own scanning rate of the environment, potentially to the individual's benefit. In birds, vigilance is often associated with head‐up postures adopted within a bout of head‐down activity, and this can be used by conspecifics to assess the vigilance of their flock mates. However, vigilance behaviour is not always obvious and other cues may then be used to assess vigilance rates of conspecifics. Here we assess whether iris/eyelid/face patterns from 43 duck species are consistent with the hypothesis that eyelid brightness has evolved so as to contrast with iris brightness, which may then help in signalling individual vigilance status. Ducks generally flock when resting during the day, and because of their wide visual fields, individuals can monitor their environment while remaining in a resting head‐down position. Ducks also show a wide variety of plumage and iris patterns, with both light‐headed and dark‐headed species. Matching our prediction, most ducks with dark irises had pale eyelids, irrespective of head colour. Furthermore, the smaller number of species with a pale iris generally have darker eyelids. A phylogenetic analysis shows a clear and significant association in the evolution of eyelid and iris brightness patterns in both males and females. These data therefore provide support for the hypothesis that eyelid brightness has evolved to act as a contrast with iris brightness. Further studies are now needed to examine the extent to which and the way this is used in vigilance information transfer between individuals.

Prediction of Eye Color from Genetic Data Using Bayesian Approach*

Prediction of visible traits from genetic data in certain forensic cases may provide important information that can speed up the process of investigation. Research that has been conducted on the genetics of pigmentation has revealed polymorphisms that explain a significant proportion of the variation observed in human iris color. Here, on the basis of genetic data for the six most relevant eye color predictors, two alternative Bayesian network model variants were developed and evaluated for their accuracy in prediction of eye color. The first model assumed eye color to be categorized into blue, brown, green, and hazel, while the second variant assumed a simplified classification with two states: light and dark. It was found that particularly high accuracy was obtained for the second model, and this proved that reliable differentiation between light and dark irises is possible based on analysis of six single nucleotide polymorphisms and a Bayesian procedure of evidence interpretation.

Perceived Direction of Gaze from Eyes with Dark vs. Light Irises

Much of the previous research on the perceived direction of gaze has not specified eye color or pupil visibility. This study tests whether the lightness or darkness of a gazer's irises (typically brown vs. blue) affects their perceived direction of gaze. Twenty-five observers judged the direction of horizontal gaze from a model whose LCD-imaged head gazed toward points on the plane of the observer's face. The model's head was displayed with its natural brown irises and also with its irises digitally altered to look blue without pupils, blue with centered pupils, and blue with nasally decentered pupils. True gaze location was compared with the judged gaze location for each type of iris. For all iris types, observers judged that monocular gaze was biased outward from its true direction for all gaze locations, including central, whereas binocular gaze was close to centered and had a greater slope. Blue eyes with no pupil and blue eyes with a centered pupil exaggerated this perceived outward deviation for monocular gaze but binocular gaze remained the same. When the pupils were nasally decentered by a typical amount, straight monocular as well as binocular gaze appeared to be centered. The direction of monocular gaze from eyes that differ in the darkness of their irises is perceived differently, and, within the blue irises, small differences in pupil centration made surprisingly large differences in the perceived directions of gaze.

Effect of low-level stimulus features on attention to faces

Event Abstract Back to Event Effect of low-level stimulus features on attention to faces Esther Eijlers1*, Ignace Hooge1 and Chantal Kemner1 1 Utrecht University, Netherlands The attention to features of a face can be influenced in many ways. This study examined whether low-level stimulus features, such as iris-color, have an effect on which parts of the face people attend to. Participants looked at gray-scale pictures of faces while their eye-movements were tracked. The stimuli consisted of photographs of six individuals with emotionally neutral and fearful expressions, on which the eyes were manipulated in three different ways (eye-region contrast, iris-color-, pupil size). For the first manipulation, faces with high or low contrast in the eyes, and region surrounding the eyes, were compared. For the second, faces with dark and light colored irises, and for the third, faces with small pupils and large pupils were compared. For each of the three manipulations, a 2 x 2 repeated measures ANOVA with eye-feature and emotion (neutral, fearful) as factors was conducted, with relative number of fixations to the eyes as dependent variable. There was a significant interaction between iris-color (light or dark) and emotion. Planned comparisons showed that this effect was caused by the difference between the means for the fearful faces, while there was no difference for the neutral faces. For the other two manipulations, there were no significant effects. These results indicate that when attention is already distributed to the eye region, as is the case in observation of fearful faces, the high-contrast boundary between the dark iris and the white sclera can act to further attract or help sustain attention to the eyes. This, then, suggests that boundary detection might be an important factor in guiding attention to different parts of the face. Keywords: Attention to faces, emotion Conference: XI International Conference on Cognitive Neuroscience (ICON XI), Palma, Mallorca, Spain, 25 Sep - 29 Sep, 2011. Presentation Type: Poster Presentation Topic: Poster Sessions: Emotion, Motivation and the Social Brain Citation: Eijlers E, Hooge I and Kemner C (2011). Effect of low-level stimulus features on attention to faces. Conference Abstract: XI International Conference on Cognitive Neuroscience (ICON XI). doi: 10.3389/conf.fnhum.2011.207.00161 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 18 Nov 2011; Published Online: 28 Nov 2011. * Correspondence: Ms. Esther Eijlers, Utrecht University, Utrecht, Netherlands, e.eijlers@uu.nl Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Esther Eijlers Ignace Hooge Chantal Kemner Google Esther Eijlers Ignace Hooge Chantal Kemner Google Scholar Esther Eijlers Ignace Hooge Chantal Kemner PubMed Esther Eijlers Ignace Hooge Chantal Kemner Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Iris color and texture: A comparative analysis of real irises, ocular prostheses, and colored contact lenses

AbstractIn this work, we analyzed the color and texture of irises, ocular prostheses, and cosmetic colored contact lenses measured by means of a multispectral system, which provides the CIE L*a*b* colorimetric coordinates of a high resolution image pixel by pixel. The same subject, who has dark brown irises, participated in the measurement of all the contact lenses. The CIE L*a*b* colorimetric coordinates were analyzed to classify the samples into three major groups (brown, blue and green) using a new algorithm developed for this purpose. This classification allowed us to carry out a comparison of the color associated with each set of samples, using the corresponding color gamuts in the CIE L*a*b* color space. Furthermore, we analyzed the iris color reproduction achieved by prostheses and contact lenses in terms of CIEDE2000 color differences, and obtained closer results with prostheses. In addition, we performed an analysis of texture by means of the color spatial distribution of all samples. This was achieved by means of two statistical approaches: first order statistics of image histograms and second order statistics using co‐occurrence matrices. The results suggest that the texture associated with real irises, ocular prostheses and colored contact lenses is very different. This study provides useful information about the color and texture of irises that may help to establish a strategy for improving the techniques used in the manufacturing process of prostheses and colored contact lenses to obtain a better and more realistic appearance. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011

Occupational exposure to electromagnetic fields and sex-differential risk of uveal melanoma

ObjectivesThe association between occupational exposure to electromagnetic fields (EMF) and the risk of uveal melanoma was investigated in a case–control study in nine European countries.MethodsIncident cases of uveal melanoma and...

Impact of iris pigment and pupil size in ultraviolet radiation cataract in rat

To investigate the effect of iris pigment and pupil size in ultraviolet radiation (UVR)-induced cataract. Brown-Norway rats (pigmented) and Fischer-344 rats (non-pigmented) were unilaterally exposed in vivo to 5 kJ/m(2) UVR. Each strain was split into two groups, each receiving either mydriatic (tropicamide) or miotic (pilocarpine) eye-drops. One week after exposure, the degree of ocular inflammation and damage in the anterior segment was determined. The lenses were extracted, photographed and the degree of forward light scattering (cataract) was quantified. The cataract types differed between the two strains. All Fischer rats developed macroscopically identifiable UVR cataract while only 41% of Brown-Norway rats did so. All groups except the miotic Brown-Norway developed significant light scattering. The Fischer rats developed 3-4-fold more lens light scattering than the Brown-Norway rats. The miotic Fischer group exhibited significantly more light scattering than the mydriatic Fischer group. There was no significant difference in light scattering between the two Brown-Norway groups. There was a correlation between ocular inflammation and degree of light scattering, with Brown-Norway rats exhibiting less inflammation and lens light scattering. Pigmented rats develop less UVR cataract and less ocular inflammation than non-pigmented rats. Pupil size plays a smaller role in UVR cataract development in pigmented rats than in non-pigmented. The role of UVR-induced ocular inflammation in cataract development is still ambiguous.

Heterochromia Iridis and Pertinent Clinical Findings in Patients with Glaucoma Associated with Sturge–Weber Syndrome

To examine the clinical and gonioscopic findings in patients with glaucoma associated with Sturge-Weber syndrome. Retrospective review of clinical findings of all patients with Sturge-Weber syndrome who presented between January 1978 and December 2003. Koeppe gonioscopy was performed under general anesthesia and findings were photographed when feasible. Iris color was documented by color sketch or photograph at initial presentation. Fisher exact test was used to determine whether the presence of heterochromia was statistically higher in the glaucomatous group. Fifty-five patients who met inclusion criteria were identified, of whom 44 (80%) had glaucoma. Unilateral glaucoma was diagnosed in 30 eyes and bilateral glaucoma in 14 eyes, yielding 58 eyes with glaucoma and 52 eyes without. Gonioscopic examination revealed distinct anatomic abnormalities in the anterior chamber angle in 32 (55%) of the glaucomatous eyes in contrast to the normal fellow eyes in patients with unilateral glaucoma and to the patients without glaucoma. Heterochromia iridis with darker iris on the glaucomatous side was present in 11 of the 30 patients with unilateral glaucoma (37%, P < .001) but in none of the patients without glaucoma. The characteristics observed in the anterior chamber angle in this large, uniquely examined series are the first reported to the authors' knowledge and may support a role for neural crest derived anomalies in the pathogenesis of glaucoma in these infant eyes. Careful examination for heterochromia iridis may be judicious in these patients.

Tear secretions and the stimulating effects of 1% and 2% pilocarpine concentrations on dark iris black subjects

The aim of this study was to observe the effect of topical pilocarpine on tear flow rate. Schirmer’s strip was employed in the measurement of tear flow rate. There was a significant difference between the basal tear flow rate and that obtained after the instillation of 1% pilocarpine (critical t = 1.96 and calculated t = 3.52) and 2% pilocarpine showed also a significantdifference with the basal tear flow rate (calculated t = 6.46). There was no significant difference in the initial tear flow rates between the sexes in the examined population. There was a significant difference between 1% and 2% pilocarpine effects on tear flow rate (calculated t = 3.11), at 95% confidence level. It was observed that tear flow rate decreased with age and the use of topical pilocarpine served as temporary remedy in increasing tears secretion. The age groups between 31 years and above were more tolerant to the stinging effect of pilocarpine.

Optical Functional Properties of the Boston Keratoprosthesis

To evaluate the optical characteristics of the Boston Keratoprosthesis (KPro), identify glare sources, evaluate possible glare control, and examine the benefit of implantation when the fellow eye has normal vision. Computed and optical-bench-measured point spread function (PSF) and glare sources were compared. A translucent plastic cornea was used to determine the impact of glare caused by scatter in the cornea and its control with a dark-iris tinted contact lens. The effect of glare in implanted eyes was measured with a brightness acuity test (BAT), with and without the dark-iris contact lens. Computed and measured visual fields were compared. Stereopsis was measured in patients with an intact fellow eye. Computed and measured modulation transfer functions for the KPro were found to be very close to the diffraction limit. Both the model-eye measurements and patients' BAT glare responses identified that the hazy corneal graft surrounding the KPro is the main source of glare and can be controlled with a dark-iris contact lens. The lid effectively blocks the light that would be scattered in the hazy cornea of patients in whom the type II KPro was implanted. An intact fellow eye remains the dominant eye, with better acuity, and the KPro eye supports only minimal stereo ability and does not expand the binocular visual field. Glare can be reduced significantly with the use of a contact lens with a dark iris. Implanting the KPro in a patient whose fellow eye has normal or near normal vision does not seem to improve visual function.

Optical qualities of the Boston keratoprosthesis

Abstract Purpose To evaluate the optical characteristics of the Boston Keratoprosthesis (KPro) in relation to visual function. To determine glare sources and evaluate possible glare control. To explore the feasibility of fundus imaging. To examine the binocular consequences of implanting the device when the fellow eye has normal vision. Methods The computed and optical bench measured point spread function and corresponding modulation transfer function (MTF), as well as glare sources, were compared. A model eye construct was used to determine the relative impact of different sources of glare and its control. The effect of glare in eyes implanted with a KPro was measured with a Brightness Acuity Test (BAT) with and without a dark iris contact lens (dCL) for 8 eyes with Type I and 2 eyes with Type II KPro. Computed and measured visual fields were compared. The power of a lens that provides a wide field view of the fundus was calculated. Images with a fundus camera and lenses were obtained. Stereopsis was measured in 5 Type I KPro patients with an intact fellow eye. Results The computed and measured MTF for the KPro were found to be very close to the diffraction limit. Both the model eye and patients testing identified the hazy corneal graft as the main source of glare, which was controlled with a dCL. In 3 patients with an intact fellow eye, modest stereo acuity was gained with KPro implantation. Binocular visual field is not expanded when implanting a patient with normal fellow eye. Good image quality of the fundus is achieved in eyes with clear media. Conclusion Disability glare can be reduced with the use of a dCL. Implanting the KPro in a patient with an intact fellow eye only marginally improves visual function. Adequate fundus imaging can be obtained.

Iris pigmentation and susceptibility to noise-induced hearing loss

The purpose of this retrospective study is to examine the possible association between iris pigmentation and susceptibility to noise-induced hearing loss in 2407 noise-exposed workers. The workers were between 16 to 65 years of age and were exposed to 2 to 42 years of work-related noise. Results demonstrated that dark-eyed workers presented a greater percentage of normal pure-tone thresholds than fair-eyed workers. Fair-eyed workers had threshold averages of 25.1 dB (right ear) and 26.0 dB (left ear) at 3, 4, and 6 kHz, which were significantly worse than workers with dark irises, with threshold averages of 15.8 dB and 17.2 dB in the right and left ear, respectively (p<0.01). Fair-eyed workers with less than 10 years of noise exposure had the same audiometric pattern as the dark-eyed workers exposed for more than 10 years. Workers not exposed to noise did not present significant differences in their audiometric pattern as a function of eye colour. These results suggest that iris pigmentation may be an additional indication of susceptibility to noise-induced hearing loss.

Retained intraocular foreign body masquerading as malignant melanoma of the iris

Dear Editor, Several non-neoplastic lesions of the iris, such as anterior staphyloma, iris stromal atrophy, iris nevus, iris cysts, Cogan-Reese syndrome, peripheral anterior synechia, inflammatory iris mass and prostaglandin-induced iris pigmentation can clinically look like a malignant melanoma of the iris [1–3]. Failure to recognize such a process could lead to excessive or superfluous therapy. We would like to present a 45-year-old male who visited our department with complaints of photophobia, hyperemia of the right eye and a small peripheral located melanocytic iris lesion. Findings from slit-lamp and dilated fundoscopic examination of the right eye were unremarkable, apart from a slightly mild inflamed anterior chamber and a 0.9×2.0mm elevated and heavily pigmented lesion, which was in close proximity with the chamber angle (Fig. 1). Gonioscopic examination revealed a pigmented mass in the angle with no spread to the iris. On stringent questioning, our patient recalled being hit in the right eye 30 years earlier with a heavy metal fragment. Archived files confirmed a deep-seated corneal erosion in 1976 and, at that time, a foreign body could not be found. On re-examination, the tumor pattern presented more as a sharp linear lesion than as a foreign body. There was no evidence for ocular siderosis. Echo-B 50 MHz ultrasound examination revealed a high-reflective lesion in the chamber angle without extension, highly indicative of a metallic foreign body. In day care, the foreign body was removed microscopically via corneal route from the anterior segment (Fig. 2). This case emphasizes the importance of careful history taking, gonioscopic examination and imaging modalities. When ocular history and slit-lamp examination does not reveal any evidence for ocular trauma, the diagnosis of foreign body may be difficult. Techniques such as orbital X–ray, ultrasound biomicroscopy and computed tomography looking for atypical features are essential in such situations [4, 5]. When confronted with a dark iris lesion with characteristics which are not in accordance with features normally seen in iris melanoma diagnosis, a foreign body should be considered in the differential diagnosis, even if the incident may have occurred years ago. Shields et al. reported that iris foreign bodies accounted up to 4.5% of pseudomelanomas in a clinical Graefes Arch Clin Exp Ophthalmol (2008) 246:623–624 DOI 10.1007/s00417-007-0702-6

A Role for Eyebrows in Regulating the Visibility of Eye Gaze Direction

The human eye is unique amongst those of primates in having white sclera against which the dark iris is clearly visible. This high-contrast structure makes the gaze direction of a human potentially easily perceptible to others. For a social creature such as a human, the ability to perceive the direction of another's gaze may be very useful, since gaze usually signals attention. We report data showing that the accuracy of gaze deviation detection is independent of viewing distance up to a certain critical distance, beyond which it collapses. This is, of itself, surprising since most visual tasks are performed better at closer viewing distances. Our data also show that the critical distance, but not accuracy, is affected by the position of the eyebrows so that lowering the eyebrows reduces the critical distance. These findings show that mechanisms exist by which humans could expand or restrict the availability of their gaze direction to others. A way to regulate the availability of the gaze direction signal could be an advantage. We show that an interpretation of eyebrow function in these terms provides a novel explanation for several well-known eyebrow actions, including the eyebrow flash.

Influence of eye colors of Caucasians and Asians on suppression of melatonin secretion by light

This experiment tested effects of human eye pigmentation depending on the ethnicity on suppression of nocturnal melatonin secretion by light. Ten healthy Caucasian males with blue, green, or light brown irises (light-eyed Caucasians) and 11 Asian males with dark brown irises (dark-eyed Asians) volunteered to participate in the study. The mean ages of the light-eyed Caucasians and dark-eyed Asians were 26.4 +/- 3.2 and 25.3 +/- 5.7 years, respectively. The subjects were exposed to light (1,000 lux) for 2 h at night. The starting time of exposure was set to 2 h before the time of peak salivary melatonin concentration of each subject, which was determined in a preliminary experiment. Salivary melatonin concentration and pupil size were measured before exposure to light and during exposure to light. The percentage of suppression of melatonin secretion by light was calculated. The percentage of suppression of melatonin secretion 2 h after the start of light exposure was significantly larger in light-eyed Caucasians (88.9 +/- 4.2%) than in dark-eyed Asians (73.4 +/- 20.0%) (P < 0.01). No significant difference was found between pupil sizes in light-eyed Caucasians and dark-eyed Asians. These results suggest that sensitivity of melatonin to light suppression is influenced by eye pigmentation and/or ethnicity.

Is renal impairment a predictor of the incidence of cataract or cataract surgery?: Findings from a population-based study

To explore the relationship between creatinine clearance, an estimate of glomerular filtration rate, and 5-year incidence of cataract and cataract surgery. Population-based cohort study. Of the 3654 participants (aged 49 years or older) of the Blue Mountains Eye Study (BMES I) baseline examination (during 1992 to 1994), 2334 (75%) were reexamined after 5 years from 1997 to 1999 (BMES II). Risk factor data were collected for all participants at baseline (BMES I). Assessment of renal function was based on estimated creatinine clearance (C(Cr)) calculated with the Cockcroft-Gault formula, adjusted for body surface area, and expressed in ml/minute/1.73 m2. Cataract incidence was determined from graded photographs. The association between renal function and incidence of cataract and cataract surgery was analyzed by logistic regression. Incidence of nuclear, cortical, and posterior subcapsular cataract, and cataract surgery. Mean C(Cr) +/- standard deviation was 60+/-13 ml/minute/1.73 m2. The overall 5-year incidence of nuclear, cortical, and posterior subcapsular cataract was 35.7% (417 of 1167 participants at risk), 16.7% (274 of 1641), and 4.3% (77 of 1790), respectively. Cataract surgery was performed in 6.8% (144 of 2123) of participants. There were no significant associations of renal function with incident nuclear (odds ratio [OR], 1.0; 95% confidence interval [CI], 0.99-1.02), cortical (OR, 1.0; CI, 0.98-1.01), and posterior subcapsular cataract (OR, 1.0; CI, 0.99-1.04) after adjusting for multiple risk factors. After adjusting for age, gender, and dark brown iris color, moderate or worse renal impairment (C(Cr) <60 ml/minute/1.73 m2) compared with normal or mildly impaired function (C(Cr) > or =60 ml/minute/1.73 m2) was significantly associated with incident cataract surgery (P<0.05), but the effect depended on age. Participants younger than 60 years of age with moderate to severe renal impairment had increased odds of incident cataract surgery (OR, 2.75; CI, 1.06-7.14), but this OR decreased with age. In participants 80 years old or older, the OR was 0.34 (CI, 0.11-1.10). There were no significant effects of renal function on the incidence of cataract of any type. The effect of moderate or worse renal impairment on incident cataract surgery depended on age. However, the interpretation of this effect is uncertain because of additional factors that may be involved in patients having surgery.

北海道釧路支庁管内白糠町におけるコクマルガラスの観察記録

A single Daurian Jackdaw (Corvus dauuricus) was observed on 6 February and 16 March 2003, at farmland in Shiranuka, Hokkaido. The bird has pied plumage, a dark iris, and was half the size of a Carrion Crow (C. corone). This is a first observation record of this species in Kushiro Subprefecture, Hokkaido.

Macular Pigment Optical Density in a Chinese Sample

Purpose: Extensive efforts have been devoted to determining the macular pigment optical density (MPOD) in Caucasian subjects. Unfortunately, no such data in ethnic groups with naturally dark irises are currently available. In this study, we report the values in a sample of Chinese subjects. Methods: The MPOD was measured psychophysically using a densitometer at 0.25°, 0.50°, 1.00°, and 2.00° eccentricity from the foveal center in 92 Chinese subjects. Results: The spatial profile for the averaged MPOD was approximately exponential in form and showed a decline with age (r = −0.23). Subjects aged below 60 years had significantly higher averaged MPOD than those aged 60 years or above. Significant gender differences, in favor of males, were also found in the middle-age groups. Conclusions: Our study reports for the first time the MPOD in a Chinese population. Baseline information on MPOD would aid future research in preventive measures against age-related macular degeneration.

A Generic Diagnosis for the Southeast Asian Scincid Lizard Genus Tropidophorus Duméril and Bibron, 1839 with Some Additional Comments on Its Morphology and Distribution

The scincid genus Tropidophorus is diagnosed by a suite of derived morphological characters, one of which is newly recognized: the corners of the eyelid form within one scale instead of between two. This character occurs elsewhere only in the distantly related Cophoscincopus and may be related to semiaquatic habits of both taxa. For Tropidophorus, we also report a novel arrangement of supraciliary scales in some species, which is potentially useful in inferring intrageneric relationships; a deeply bifurcated hemipenis, confirming the taxon as a member of the Sphenomorphus group of lygosomine skinks; further details of the taxonomic and sexual occurrence of postanal pores in the genus, and the presence of a pale iris, which contrasts with the dark iris of most other members of the Sphenomorphus group. We also note patterns of endemism in the genus and an unusual disjunction in the distribution.

Efficacy of latanoprost and timolol maleate in black and white patients

The purpose of this study was to assess the efficacy of latanoprost 0.005% and timolol maleate 0.5% in black and white patients with elevated intraocular pressure (IOP). This double-masked, randomized, 2-period crossover study included 39 eyes in 22 patients with primary open-angle glaucoma or ocular hypertension. After a 2- to 4-week washout period, patients were randomly assigned to receive either vehicle placebo in the morning and latanoprost in the evening or timolol maleate twice daily for 6 weeks. Then, after a 4-week washout period, patients received the opposing treatment for 6 weeks. Both latanoprost and timolol maleate significantly lowered IOP from baseline in both black and white patients. Latanoprost treatment was associated with lower mean IOP compared with timolol treatment in black patients (P = .013 at 8 AM, P = .19 at 10 AM). At 10 AM at the end of the treatment period, the mean +/- SD change from baseline IOP in black patients receiving latanoprost was significantly greater than that of white patients (-10.2 +/- 7.0 and -5.9 +/- 2.5 mm Hg, respectively; P = .042). The mean +/- SD change from baseline IOPs in black patients was not significantly different from that in white patients at 8 AM at the end of the treatment period for the latanoprost group and at 8 AM and 10 AM at the end of the treatment period for the timolol maleate group. In white patients, the change from baseline IOP in light (grade 1) irises was not significantly different from dark (grade 5) irises after treatment with either latanoprost or timolol maleate. In summary, intraocular pressure after treatment with latanoprost was lower than that after timolol treatment in black patients with primary open-angle glaucoma or ocular hypertension, and at 1 of 2 timepoints, latanoprost caused a significantly greater reduction of IOP in black patients than in white patients.