The nictitating membrane is a transparent or translucent third eyelid present in some animals that can be drawn across the eye from the medial canthus for protection and to moisten it while maintaining vision. Some reptiles, birds, and sharks have full nictitating membranes; in many mammals, a small, vestigial portion of the membrane remains in the corner of the eye. Some mammals, such as camels, polar bears, seals and aardvarks, have full nictitating membranes. Often called a third eyelid or haw, it may be referred to in scientific terminology as the plica semilunaris, membrana nictitans, or palpebra tertia.
Eye surgery, also known as ocular surgery, is surgery performed on the eye or its adnexa, typically by an ophthalmologist. The eye is a very fragile organ, and requires extreme care before, during, and after a surgical procedure to minimise or prevent further damage. An expert eye surgeon is responsible for selecting the appropriate surgical procedure for the patient, and for taking the necessary safety precautions. Mentions of eye surgery can be found in several ancient texts dating back as early as 1800 BC, with cataract treatment starting in the fifth century BC. Today it continues to be a widely practiced type of surgery, having developed various techniques for treating eye problems.
Electrooculography (EOG) is a technique for measuring the corneo-retinal standing potential that exists between the front and the back of the human eye. The resulting signal is called the electrooculogram. Primary applications are in ophthalmological diagnosis and in recording eye movements. Unlike the electroretinogram, the EOG does not measure response to individual visual stimuli.
The orbicularis oculi is a muscle in the face that closes the eyelids. It arises from the nasal part of the frontal bone, from the frontal process of the maxilla in front of the lacrimal groove, and from the anterior surface and borders of a short fibrous band, the medial palpebral ligament.
Pseudostrabismus is the false appearance of crossed eyes. When the eyes are actually crossed or not completely aligned with one another it is called strabismus. Pseudostrabismus generally occurs in infants and toddlers whose facial features are not fully developed. The bridge of their nose is wide and flat, creating telecanthus. With age, the bridge will narrow and the epicanthic folds in the corner of the eyes will go away. This will cause the eyes to appear wider, and thus not have the appearance of strabismus. To detect the difference between strabismus and pseudostrabismus use a flashlight to shine into the child's eyes. When the child is looking at the light a reflection can be seen on the front surface of the pupil. If the eyes are aligned with one another then the reflection from the light will be in the same spot of each eye. If strabismus is present then the reflection from the light will not be in the same spot of each eye.
The lacrimal lake is the pool of tears in the lower conjunctival cul-de-sac, which drains into the opening of the tear drainage system. The volume of the lacrimal lake has been estimated to be between 7 and 10 µL.
Indirana beddomii, Beddome's leaping frog, Beddome's Indian frog, or simply Beddome's frog, is a species of frog found in the Western Ghats. They are usually detected by their long leaps as they flush from the ground when disturbed. The species is named after the naturalist Richard Henry Beddome.
The plica semilunaris is a small fold of bulbar conjunctiva on the medial canthus of the eye. It functions during movement of the eye, to help maintain tear drainage via the lacrimal lake, and to permit greater rotation of the globe, for without the plica the conjunctiva would attach directly to the eyeball, restricting movement. It is the vestigial remnant of the nictitating membrane which is drawn across the eye for protection, and is present in other animals such as birds, reptiles, and fish, but is rare in mammals, mainly found in monotremes and marsupials. Its associated muscles are also vestigial. It is loose, thus eye movements are not restricted by it. Only one species of primate, the Calabar angwantibo, is known to have a functioning nictitating membrane.
Oculoplastics, or oculoplastic surgery, includes a wide variety of surgical procedures that deal with the orbit, eyelids, tear ducts, and the face. It also deals with the reconstruction of the eye and associated structures.
Indirana leptodactyla is a species of frog endemic to the southern Western Ghats in Kerala and Tamil Nadu states of South India. Precise reports are from Anaimalai hills, Palni hills, Meghamalai, Travancore hills and Agasthyamalai, It is a terrestrial to semi-aquatic frog associated with the leaf-litter of high-elevation evergreen montane forest; it is not known from modified habitats. It is uncommon and believed to be declining in abundance.
The lacrimal caruncle, or caruncula lacrimalis, is the small, pink, globular nodule at the inner corner of the eye. It is made of skin covering sebaceous and sweat glands.
Leptopelis karissimbensis is a species of frog in the family Arthroleptidae. It is found in the highlands of western Rwanda and southwestern Uganda and in the adjacent eastern Democratic Republic of the Congo. It is very similar to Leptopelis kivuensis and has been confused with that species. Common names Karissimbi forest treefrog and Karissimbi tree frog have been coined for it.
Leptopelis kivuensis is a species of frog in the family Arthroleptidae. It is found in the highlands of western Burundi, Rwanda, and Uganda, and in the extreme eastern Democratic Republic of the Congo. It has been considered synonym of Leptopelis karissimbensis, and has been confused with that species. Common names Kisenyi forest treefrog and Kivu tree frog have been coined for it.
Telecanthus refers to increased distance between the medial canthi of the eyes, while the inter-pupillary distance is normal. This is in contrast to hypertelorism, where the inter-pupillary distance is increased.
Moraxella lacunata is a rod-shaped, Gram-negative, nonmotile bacterium, generally present as diploid pairs. It causes one of the commonest forms of catarrhal conjunctivitis.
Orbitomeatal line is a positioning line used in radiography of the skull. It passes through the outer canthus of the eye and the center of the external auditory meatus. It is used for positioning the patient for different radiographic views including Water's view, Perorbital view, Lateral view, and others.
Mongoloid refers to populations that share certain phenotypic traits common in most of Asia, the Arctic, the Americas and most of the Pacific Islands.
