Corneal Disorders
Ching-Yu Cheng, Tien Yin Wong in Ophthalmic Epidemiology, 2022
The cornea is a vital transparent structure that forms “the front window of the eye,” playing a key role in vision and ocular surface defense. Corneal damage from insults such as infection, inflammation, and trauma can lead to corneal opacity and resultant visual impairment. According to a recent World Health Organization (WHO) report, corneal opacity represents the fifth leading cause of blindness globally.1 It is estimated that around 4.2 million people were suffering from moderate to severe visual impairment secondary to corneal diseases in 2019.1 More importantly, avoidable corneal blindness has been shown to be significantly more prevalent (up to 90% of all blindness) in developing countries such as Africa (for example, Ethiopia), Myanmar, and many others, primarily attributed to poor sanitation, malnutrition, lower educational level, and limited access to healthcare facilities.2–4
Lasers in Medicine: Healing with Light
Suzanne Amador Kane, Boris A. Gelman in Introduction to Physics in Modern Medicine, 2020
The anatomy of the eye is shown in Figure 3.30a. The white of the eye is called the sclera. Light enters the eye through the cornea and the pupil, the opening of the iris. It then passes through the lens and the vitreous humor, a jellylike substance that fills the eyeball, and falls upon the inner lining of the eyeball, called the retina. Both the cornea and the lens refract entering rays of light in such a way as to project tiny images of the outside world onto the retina, which plays a role analogous to the image sensor in a camera. The retina is a complex structure consisting of many specialized layers, including the pigment epithelium, which contains specialized cells for sensing light, and choroid, which contains blood vessels and dark blue pigments to absorb stray light. Some layers hold the rod and cone cells that actually sense light, some provide circulation and support. In the regions of the retina known as the fovea and the macula, or yellow spot, visual acuity is highest because of a high concentration of light-sensing cells. The optic disc, or blind spot, is where the optic nerve enters the retina. Preserving the functioning of these regions is of especial concern during laser surgery.
Fundamentals
Arvind Kumar Bansal, Javed Iqbal Khan, S. Kaisar Alam in Introduction to Computational Health Informatics, 2019
Object based programming supports: 1) notion of nested class, 2) inheritance, 2) generic template of a class that can generate multiple active objects at runtime and 3) information hiding. The visibility of data and code can be hidden to promote modularity of a large software. Object-oriented programming supports complex nested relations, multimedia objects that involve multiple components and interoperability in text analysis involving the tree-structure of the ICD (International Classification of Diseases) codes. For example, eye is made of iris, retina, cornea and vitreous chamber. Each of them can have different diseases. All these diseases are eye-related diseases. Each component has subcomponents, and each subcomponent has multiple related diseases. There is an implicit tree-structure of subclasses: a disease in a component of an eye is also a disease in the eye.
Pathogenesis of Common Ocular Diseases: Emerging Trends in Extracellular Matrix Remodeling
Published in Seminars in Ophthalmology, 2023
Raziyeh Ghorbani, Mehdi Rasouli, Farshid Sefat, Saeed Heidari Keshel
In 2015, researchers estimated that more than 1 billion people worldwide suffer from eye disorders. The prevalence of these disorders including but are not limited to; cataracts, keratoconus, trachoma, and myopia is increasing dramatically. The compromised eye health of patients devastates the quality of life; therefore, identifying the underlying factors regarding the development of these disorders is pivotal for timely and efficient therapeutic intervention.1,2 The eye, one of the most important sensory organs of the body, has a very complex anatomy and function. Thus, a profound understanding of this structure and the identification of its various components can help in the treatment of pathological disorders.3 The eyeball in humans is composed of three layers: fibrous tonic, vascular tonic, and retina. It can be divided into anterior and posterior parts. The outermost layer is the fibrous tunic, which in addition to shaping the eye, protects the deeper parts of the eye. This layer is composed of the sclera and cornea.4 The choroid, ciliary body, pigmented epithelium, and iris are the constituents of the middle layer. The retina is the innermost layer of the eye that is sensitive to light and is made of light-receiving cells (cone and rod cells) and neurons.5,6 The term ocular diseases refers to disorders that impair the proper function of the eye and compromise a patient’s vision. Countless people around the world are suffering from various types of ocular diseases, commonly including myopia, cataracts, trachoma, keratoconus, glaucoma, etc.
Primary Tumour Type, Clinical Features, Treatment and Outcome of Patients with Iris Metastasis
Published in Ocular Immunology and Inflammation, 2022
Tao Liu, Feng Bai, Li Yang, Li Liu, Jun Xiao, Xiaoli Liu
Ocular metastases from malignant tumors in other parts of the body are common. An earlier study reported 230 cases of metastatic cancer, 12% of which metastasized to the eye and orbit1. Most intraocular metastases occur in the uvea, which is rich in blood vessels. Among all uveal metastases, choroidal metastases are the most common, and iris metastases are relatively rare. In 2018, among the 1111 cases of uveal metastasis, choroidal metastasis accounted for 90%, and iris metastasis accounted for only 8%2. But unlike other parts of the eye, the iris is a tissue that can directly be observed under the slit lamp, and an iris metastasis can readily be seen. It is worth noting that in some patients, iris metastasis occurs before the primary tumor is diagnosed. Some signs of iris metastases are similar to those of uveitis, an autoimmune disease; therefore, iris metastases are sometimes misdiagnosed as uveitis. Retrospectively studying the clinical characteristics of iris metastasis patients and summarizing the specific clinical manifestations of iris metastases will be helpful for the early clinical diagnosis and treatment of such diseases. We retrospectively reviewed the literature published over the past 79 years, described the characteristics of iris metastasis, and provide relevant clinical features, as well as diagnostic and treatment options.
The Vision Detroit Project: Visual Burden, Barriers, and Access to Eye Care in an Urban Setting
Published in Ophthalmic Epidemiology, 2022
Anju Goyal, Collin Richards, Vaama Patel, Sarah Syeda, John-Michael Guest, Ryan L. Freedman, Leo M. Hall, Chaesik Kim, Abdala Sirajeldin, Tannia Rodriguez, Samantha M. Arsenault, Joseph D. Boss, Bret Hughes, Mark S. Juzych
The most common eye disorders in the United States (U.S.) include cataracts, age-related macular degeneration, diabetic retinopathy, glaucoma, and refractive error.1,2 Dependent on access, advances in eye care have made vision loss due to many eye disorders treatable and preventable.3,4 In the U.S., the number of adults over 40-years-old affected by visual impairment is expected to rise from 3.4 million in 2004 to 5.5 million by 2050, with a large portion of eye disease remaining undetected.5 The Healthy People 2020 vision objectives have set goals to reduce visual impairment in the U.S. by 10% for uncorrected refractive error, diabetic retinopathy, glaucoma, cataracts, and age-related macular degeneration.6–8 Estimates indicate half of the 61 million adults at risk of vision loss have visited an eye doctor in the past year.8–10 Patients in the U.S. Midwest attend eye examinations at lower rates than other areas.11 Additionally, poor eye-health literacy in the Detroit population is associated with worse disease on presentation, lower compliance, and greater disease progression.12 To improve eye care in underserved settings, there is a need to increase access to initial eye exams and subsequent follow-up appointments for continuity of care.
Related Knowledge Centers
- Optic Nerve
- Visual Cortex
- Visual Perception
- Visual System
- Brain
- Neuron
- Iris
- Focus
- Lens
- Image