Glaucoma is the leading cause of irreversible blindness worldwide, with its primary risk factor arising from elevated intraocular pressure (IOP) due to an imbalance between aqueous humor production and outflow. This study aims to establish quantitative correlations among IOP, iris mechanical properties, channel microstructures, and aqueous humor dynamics through three-dimensional modeling and finite element analysis, overcoming the limitations of conventional experimental techniques in studying aqueous flow within the trabecular meshwork (TM) outflow pathway. A three-dimensional fluid-structure interaction (FSI) model incorporating the layered TM structure, Schlemm's canal (SC), iris, and other anterior segment tissues was developed based on human ocular anatomy. FSI simulations were performed to quantify the effects of IOP variations and iris Young's modulus on tissue morphology and aqueous humor dynamics parameters. The computational results demonstrated that axial iris deformation showed significant correlations with IOP and iris Young's modulus. Although elevated IOP exhibited minimal effects on hydrodynamic parameters in the anterior and posterior chambers, it markedly suppressed aqueous flow velocity in the TM region. Additionally, wall shear stress in SC and collector channels displayed high sensitivity to IOP variations. These findings reveal that the tissue mechanics-FSI mechanism modulates outflow resistance by regulating aqueous humor dynamics, offering valuable references for developing clinical therapies targeting IOP reduction in glaucoma management.
Humans ; Trabecular Meshwork/anatomy & histology* ; Finite Element Analysis ; Aqueous Humor/metabolism* ; Intraocular Pressure/physiology* ; Glaucoma/physiopathology* ; Iris/anatomy & histology* ; Computer Simulation ; Models, Biological

OBJECTIVETo investigate the facial aging analysis of 1200 Han adult people in Dalian with iris diameter, so as to provide reference for facial rejuvenation in Han people.

METHODS1200 facial digital photographs from the second-generation ID card of China were stratified randomly selected as the research sample, excluding facial deformity, tattooing eyebrow, tattooing lid margin, ptosis, lip grain and eyebrow deformity cases, as well as the cases whose join point of upper eyelid and lower eyelid not exposed at the nasal side. These photos were divided into six cohorts: female aged 18, 38, and 68 years old; and male aged 18, 38, and 68 years old, with 200 cases in each cohort. The individual iris diameter was divided into 20 equal parts in each photograph, with each part marked one unit as individual iris diameter ruler. Ten values were made from a horizontal plane between the medial canthus to ten points at one face ( the line between two medial canthus is used as the horizontal line, circumocular and facial soft tissue were measured with individual iris diameter ruler on the photographs), then the results were analyzed with Adobe Photoshop software.

RESULTSThere are statistically significant differences in eyebrow height (36.42 ± 4.22 unit in 18 years old male group, 40.22 ± 6.90 unit in 38 years old male group, 34.83 ± 9.39 unit in 68 years old male group; 37.59 ± 6.72 unit in 18 years old female group, 41.09 ± 5.15 unit in 38 years old female group, 36.84 ± 9.45 unit in 68 years old female group), palpebral fissure height, physiognomic external canthus height, palpebral fissure width, pupil height and other items (P < 0.05).

CONCLUSIONS(1) The brow position rises to the peak level at middle age (38 years old group), then drops down gradually with aging. (2) The physiognomic external canthus moves towards the nasal side and caudal side with aging. (3) Eyeball moves towards caudal side with aging. (4) The soft tissue around bilateral angle of mouth, nasal tip and submaxilla moves towards caudal side with aging. (5) The measurement of individual iris diameter ruler can apply to analyze the aging changes of facial soft tissue, and is more suitable for the case when facial photographs are taken at different distances.

Adolescent ; Adult ; Age Factors ; Aged ; Aging ; China ; ethnology ; Cohort Studies ; Eye ; anatomy & histology ; Eyebrows ; anatomy & histology ; Face ; anatomy & histology ; Female ; Humans ; Iris ; anatomy & histology ; Lip ; anatomy & histology ; Male ; Nose ; anatomy & histology ; Photography ; Rejuvenation ; Sex Factors

Objective evaluation of driver drowsiness is necessary toward suppression of fatigued driving and prevention of traffic accident. We have developed a new method in which we utilized pupillary diameter variability (PDV) under spontaneous pupillary fluctuation conditions. The method consists of three main steps. Firstly, we use a 90s long infrared video of pupillogram infrared-sensitive CCD camera. Secondly, we employed edge detection algorithm based on curvature characteristics of pupil boundary to extract a set of points of visible pupil boundary, and then we adopted these points to fit a circle to obtain the diameter of the pupil in current frame of video. Finally, the values of PDV in 90s long video is calculated. In an experimental pilot study, the values of PDV of two groups were measured. One group rated themselves as alert (12 men), the other group as sleepy (13 men). The results showed that significant differences could be found between the two groups, and the values were 0.06 +/- 0.005 and 0.141 +/- 0.042, respectively. Taking into account of the knowledge that spontaneous pupillary fluctuation is innervated by autonomic nervous system which activity is known to change in parallel with drowsiness and cannot be influenced by subjective motive of people. From the results of the experiments, we concluded that PDV could be used to evaluate driver fatigue objectively.
Algorithms ; Automobile Driving ; Fatigue ; diagnosis ; physiopathology ; Humans ; Iris ; anatomy & histology ; Monitoring, Physiologic ; methods ; Pupil ; physiology

As the infrared image gray distribution of nystagmus video is uneven, the accuracy of pupil edge detection could not be high enough. A pupil location method based on morphology and Canny algorithm was presented in this paper. Some meaningless regions were removed by morphology, and target was smoothed. The connected regions were separated, and the largest connected region-pupil was found. Then the pupil edges were extracted by the designed Canny edge detection algorithm. The coordinates of pupil for each frame images were calculated and the pupil movement tracking was fitted. Finally, desired clinical diagnostic information would be obtained from the tracking. Experimental results showed that the method could be adapted to different gray values for different objects, and could accurately detect the edge of the pupil. As the pupil was tracked well, the experimental results could reflect the eye movement. The method provides a practical way for the pupil location of existing domestic researches in video-nystagmograph.
Algorithms ; Electronystagmography ; instrumentation ; methods ; Eye Movements ; physiology ; Humans ; Infrared Rays ; Iris ; anatomy & histology ; Nystagmus, Pathologic ; diagnosis ; Videotape Recording

Iris image quality evaluation plays a very important part in iris computer recognition. An iris image quality evaluation method was introduced into this study to distinguish good image from bad image caused by pupil distortion, blurred boundary, two circles appearing not concentric, and severe occlusion by eyelids and eyelashes. The tests based on this method gave good results.
Humans ; Image Enhancement ; methods ; Image Interpretation, Computer-Assisted ; Iris ; anatomy & histology ; Pattern Recognition, Automated ; methods ; Photogrammetry ; methods ; standards