For your eyes only
Simple yogic exercises can keep your eyes free from impaired vision and ugly spectacles.india Updated: Jul 04, 2006 12:53 IST
The human eye is nature's most sophisticated camera. And sight is the result of an intricate mechanism within this camera. To understand problems of sight, it is necessary to peek within the eye and see this mechanism at work.
Our eyeball comprises three layers—sclerotic or the outer layer, choroid or the middle layer and retina or the inner layer. The sclerotic layer is white and opalescent, with a transparent center called the cornea.
Light is transmitted to the eye through the cornea. The choroid layer is called the iris, with the pupil in its center. Directly behind the iris lies the crystalline lens, which focuses light passing through it upon the retina. Around this lens lie the ciliary muscles that control its contraction and expansion. The retina or the inner layer is like a screen that receives the projected images of external objects.
|Ten causes of bad vision:|
Faulty reading posture
Reading against the light
Recurring cough and cold Blocked sinuses
Stiff neck and shoulder muscles
Reading under strain
You see something when the pupil lets light pass through the cornea onto the crystalline lens. Brightness is controlled by the pupil through contraction or dilation. These rays converge upon the retina via the convex crystalline lens, forming an inverse image. The optic nerve then transmits this image to the brain, producing the final sense of vision.
Sight can be adversely affected by various things, ranging from malnutrition to a recurring cough and cold. Perhaps the three most common defects of eyesight are myopia (short-sightedness), hypermetropia (long-sightedness) and presbyopia (failing eyesight due to age). While in myopia, the image is formed short of the retina, in hypermetropia or presbyopia the image is formed beyond the retina. These conditions are the result of faulty eye muscle action or imperfect accommodation.
(This article has been taken from Life Positive, September 1998 issue. For more log o towww.lifepositive.com)