The cornea is the transparent front part of the eye that covers the iris, pupil, and anterior chamber. Along with the anterior chamber and lens, the cornea refracts light, accounting for approximately two-thirds of the eye's total optical power. In humans, the refractive power of the cornea is approximately 43 dioptres. The cornea can be reshaped by surgical procedures such as LASIK.
A pterygium of the eye is a pinkish, roughly triangular tissue growth of the conjunctiva onto the cornea of the eye. It typically starts on the cornea near the nose. It may slowly grow but rarely grows so large that it covers the pupil and impairs vision. Often both eyes are involved.
The corneal endothelium is a single layer of endothelial cells on the inner surface of the cornea. It faces the chamber formed between the cornea and the iris.
Corneal transplantation, also known as corneal grafting, is a surgical procedure where a damaged or diseased cornea is replaced by donated corneal tissue. When the entire cornea is replaced it is known as penetrating keratoplasty and when only part of the cornea is replaced it is known as lamellar keratoplasty. Keratoplasty simply means surgery to the cornea. The graft is taken from a recently deceased individual with no known diseases or other factors that may affect the chance of survival of the donated tissue or the health of the recipient.
A corneal ulcer, or ulcerative keratitis, is an inflammatory condition of the cornea involving loss of its outer layer. It is very common in dogs and is sometimes seen in cats. In veterinary medicine, the term corneal ulcer is a generic name for any condition involving the loss of the outer layer of the cornea, and as such is used to describe conditions with both inflammatory and traumatic causes.
Corneal ulcer, also called keratitis, is an inflammatory or, more seriously, infective condition of the cornea involving disruption of its epithelial layer with involvement of the corneal stroma. It is a common condition in humans particularly in the tropics and in farming. In developing countries, children afflicted by vitamin A deficiency are at high risk for corneal ulcer and may become blind in both eyes persisting throughout life. In ophthalmology, a corneal ulcer usually refers to having an infection, while the term corneal abrasion refers more to a scratch injury.
The corneal limbus is the border between the cornea and the sclera. It contains limbal stem cells in its palisades of Vogt. It may be affected by cancer or aniridia, among other issues. The PS ring is a visible dark ring around the iris of the eye composed of darkened areas of the corneal limbus.
Keratoprosthesis is a surgical procedure where a diseased cornea is replaced with an artificial cornea. Traditionally, keratoprosthesis is recommended after a person has had a failure of one or more donor corneal transplants. More recently, a less invasive, non-penetrating artificial cornea has been developed which can be used in more routine cases of corneal blindness. While conventional cornea transplant uses donor tissue for transplant, an artificial cornea is used in the keratoprosthesis procedure. The surgery is performed to restore vision in patients with severely damaged cornea due to congenital birth defects, infections, injuries and burns.
Macular corneal dystrophy, also known as Fehr corneal dystrophy, is a rare pathological condition affecting the stroma of cornea first described by Arthur Groenouw in 1890. Signs are usually noticed in the first decade of life and progress afterwards, with opacities developing in the cornea and attacks of pain. This gradual opacification leads to visual impairment often requiring keratoplasty in the later decades of life.
Gholam A. Peyman is an Iranian American ophthalmologist, retina surgeon, and inventor. He is best known for his invention of LASIK eye surgery, a vision correction procedure designed to allow people to see clearly without glasses. He was awarded the first US patent for the procedure in 1989.
Herpetic simplex keratitis is a form of keratitis caused by recurrent herpes simplex virus (HSV) infection in the cornea.
Reza Dana is the Claes H. Dohlman Professor of Ophthalmology, senior scientist and W. Clement Stone Clinical Research Scholar at Massachusetts Eye and Ear, Harvard Medical School, and director of the Harvard-Vision Clinical Scientist Development Program.
Jeewan Singh Titiyal is an Indian ophthalmologist, credited with the first live cornea transplant surgery by an Indian doctor. He was honoured by the Government of India, in 2014, by bestowing on him the Padma Shri, the fourth highest civilian award, for his services to the field of medicine.
Dorairajan Balasubramanian, popularly known as Professor Balu, is an Indian biophysical chemist and ocular biochemist. He is a former President of Indian Academy of Sciences and a director of research at the Prof. Brien Holden Eye Research Centre of L. V. Prasad Eye Institute, Hyderabad. A recipient of the National Order of Merit (France), Balasubramanian was honored by the Government of India, in 2002, with the fourth highest Indian civilian award of Padma Shri.
Mooren's ulcer is a rare idiopathic ocular disorder that may lead to blindness due to progressive destruction of the peripheral cornea. Although the etiology of Mooren's ulcer is poorly understood, recent evidence suggests that the pathogenesis of this disease appears to be the result of an autoimmune process directed against molecules expressed in the corneal stroma.
Limbal stem cells, also known as corneal epithelial stem cells, are unipotent stem cells located in the basal epithelial layer of the corneal limbus. They form the border between the cornea and the sclera. Characteristics of limbal stem cells include a slow turnover rate, high proliferative potential, clonogenicity, expression of stem cell markers, as well as the ability to regenerate the entire corneal epithelium. Limbal stem cell proliferation has the role of maintaining the cornea; for example, by replacing cells that are lost via tears. Additionally, these cells also prevent the conjunctival epithelial cells from migrating onto the surface of the cornea.
Anil Kumar Mandal is an Indian ophthalmologist and a consultant at L. V. Prasad Eye Institute, Hyderabad. Known for his research on glaucoma, Mandal is an elected fellow of the National Academy of Medical Sciences. The Council of Scientific and Industrial Research, the apex agency of the Government of India for scientific research, awarded him the Shanti Swarup Bhatnagar Prize for Science and Technology, one of the highest Indian science awards, for his contributions to Medical Sciences in 2003.
Santosh Gajanan Honavar is an Indian ophthalmologist and is currently the Honorary General Secretary of the All India Ophthalmological Society; Director of Medical Services ; Director, Department of Ocular Oncology and Oculoplasty at Centre for Sight, Hyderabad; and Director, National Retinoblastoma Foundation. He was the Editor of the Indian Journal of Ophthalmology and Indian Journal of Ophthalmology - Case Reports, the official journals of the All India Ophthalmological Society from 2017 to 2023.
Geeta Kashyap Vemuganti is an Indian ocular pathologist and the head of the department at the Ophthalmic Pathology Service and Stem Cell Laboratory of the L. V. Prasad Eye Institute (LVPEI). She is also a dean and professor at the school of medical sciences of the University of Hyderabad.
Peripheral Ulcerative Keratitis (PUK) is a group of destructive inflammatory diseases involving the peripheral cornea in human eyes. The symptoms of PUK include pain, redness of the eyeball, photophobia, and decreased vision accompanied by distinctive signs of crescent-shaped damage of the cornea. The causes of this disease are broad, ranging from injuries, contamination of contact lenses, to association with other systemic conditions. PUK is associated with different ocular and systemic diseases. Mooren's ulcer is a common form of PUK. The majority of PUK is mediated by local or systemic immunological processes, which can lead to inflammation and eventually tissue damage. Standard PUK diagnostic test involves reviewing the medical history and a completing physical examinations. Two major treatments are the use of medications such as corticosteroids or other immunosuppressive agents and surgical resection of the conjunctiva. The prognosis of PUK is unclear with one study providing potential complications. PUK is a rare condition with an estimated incidence of 3 per million annually.
