Pari Talks

  Pupil. P.K.Ghatak,MD No.60 The central aperture of the iris is the pupil. People who like talk and write British English call students as pupils. The pupils, by varying their sizes, control the amount of light that can enter the eye for us to see clearly. Pupil also serves as a passage for the aqueous humor to circulate from the posterior compartment to anterior compartment. At the periphery of the iris (No.5 in the diagram below) the aqueous humor is absorbed and goes back to the blood, Thus this process maintains the pressure of the eye ball and prevents damage to delicate structures of the retina. Aqueous humor supplies nutrients to the cornea and oxygen and nutrients to the lens. [ cristalino = lens. cuerpo ciliar = ciliary body. Canal de Schlemm = Schlemm canal, point where aqueous humor is drained from the eye back to the blood.] When light is shone in one eye, both pupils contact. This reflex action is known as direct contraction for the eye receiving the light and co...

Iris P.K.Ghatak, MD No.59 In a conversation, the word Iris generally refers to Irish, the people from Ireland. If the talk is around flowers, then Iris means a lovely delicate Iris flower. In biology the Iris is a part of the eyeball, a very delicate screen like structure which regulates the amount of light rays can enter through the center aperture, Pupil to the retina for vision. This screen is like the diaphragm of a single lens reflex camera; and both have many common features. In fact, the design of a camera is based on the eyes. Anatomical structure of human iris: The iris is thinnest at the periphery where it is attached to the ciliary muscles, and thick in the middle because the circular and radial muscle layers criss-cross in the middle of the iris The central aperture of the iris is the pupil of the eye. Contraction of circular muscles narrows the pupil and radial muscles enlarges size. Histology of iris. Structerally the iris consists oftwo distinct parts, anterior and poste...