|
Photophthalmia
Photophthalmia ( pho·toph·thal·mia (''fōt″of-thal´me-ah'') ) is ophthalmia or inflammation of the eye, especially of the cornea and conjunctiva due to exposure to intense light of short wavelength (as Ultraviolet, ultraviolet light), as in snow blindness. It involves occurrence of multiple epithelial erosions due to the effect of ultraviolet rays, especially between 311 and 290 nm. Snow blindness occurs due to reflection of ultraviolet rays from snow surface. Photoretinitis is another form that can occur due to infra-red rays (eclipse burn of retina). Presentation It can present with the following: * severe burning pain * lacrimation * photophobia * blepharospasm * swelling of palpebral conjunctiva * retrotarsal folds Usually the effect of UV exposure is felt after 6-8 hours from exposure. With severe irritation, the eyes become blood red. In minor cases, avoid rubbing and wash the eyes thoroughly with water until the irritation subdues. Always consult an eye specialist ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ophthalmia
Ophthalmia (also called ophthalmitis) is inflammation of the eye. It results in congestion of the eyeball, often eye-watering, redness and swelling, itching and burning, and a general feeling of irritation under the eyelids. Ophthalmia can have different causes, such as infection from bacteria, viruses, fungi, or may result from a physical trauma to the eye, chemical irritation, and allergies. A bacteria infection can result in a mucus and [pus] secretion. Severe cases of ophthalmia can cause blindness if not treated, especially in newborns, who contract it from the environment in the womb. Treatments vary according to the nature of the cause, with minor irritations going away on their own. Types Types include sympathetic ophthalmia (inflammation of both eyes following trauma to one eye), Neisseria gonorrhoeae, gonococcal ophthalmia, trachoma or "Egyptian" ophthalmia, ophthalmia neonatorum (a conjunctivitis of the newborn due to either of the two previous pathogens), photophthalmi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Inflammation
Inflammation (from la, wikt:en:inflammatio#Latin, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or Irritation, irritants, and is a protective response involving immune cells, blood vessels, and molecular mediators. The function of inflammation is to eliminate the initial cause of cell injury, clear out necrotic cells and tissues damaged from the original insult and the inflammatory process, and initiate tissue repair. The five cardinal signs are heat, pain, redness, swelling, and Functio laesa, loss of function (Latin ''calor'', ''dolor'', ''rubor'', ''tumor'', and ''functio laesa''). Inflammation is a generic response, and therefore it is considered as a mechanism of innate immune system, innate immunity, as compared to adaptive immune system, adaptive immunity, which is specific for each pathogen. Too little inflammation could lead to progressive tissue destruction by the harmful stimulus (e.g. b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cornea
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. While the cornea contributes most of the eye's focusing power, its focus is fixed. Accommodation (the refocusing of light to better view near objects) is accomplished by changing the geometry of the lens. Medical terms related to the cornea often start with the prefix "'' kerat-''" from the Greek word κέρας, ''horn''. Structure The cornea has unmyelinated nerve endings sensitive to touch, temperature and chemicals; a touch of the cornea causes an involuntary reflex to close the eyelid. Because transparency is of prime importance, the healthy cornea does not have or need blood vessels with ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Conjunctiva
The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium and stratified cuboidal epithelium (depending on the zone). The conjunctiva is highly vascularised, with many microvessels easily accessible for imaging studies. Structure The conjunctiva is typically divided into three parts: Blood supply Blood to the bulbar conjunctiva is primarily derived from the ophthalmic artery. The blood supply to the palpebral conjunctiva (the eyelid) is derived from the external carotid artery. However, the circulations of the bulbar conjunctiva and palpebral conjunctiva are linked, so both bulbar conjunctival and palpebral conjunctival vessels are supplied by both the ophthalmic artery and the external carotid artery, to varying extents. Nerve supply Sensory innervation of the conjunctiva is divided into ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ultraviolet
Ultraviolet (UV) is a form of electromagnetic radiation with wavelength from 10 nanometer, nm (with a corresponding frequency around 30 Hertz, PHz) to 400 nm (750 Hertz, THz), shorter than that of visible light, but longer than X-rays. UV radiation is present in sunlight, and constitutes about 10% of the total electromagnetic radiation output from the Sun. It is also produced by electric arcs and specialized lights, such as mercury-vapor lamps, tanning lamps, and black lights. Although long-wavelength ultraviolet is not considered an ionizing radiation because its photons lack the energy to ionization, ionize atoms, it can cause chemical reactions and causes many substances to glow or fluorescence, fluoresce. Consequently, the chemical and biological effects of UV are greater than simple heating effects, and many practical applications of UV radiation derive from its interactions with organic molecules. Short-wave ultraviolet light damages DNA and sterilizes surf ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
