Glaucoma is an Eye Affliction Caused by Disturbance of Fluid Balance in Eyeball.

Glaucoma is an eye affliction caused by a disturbance of the fluid balance with the eyeball and a consequent increase of pressure inside the eye. If allowed to persist, glaucoma may damage vision by pressing against the optic nerve. One of the main symptoms of glaucoma is a tunnel vision. Well, in other words, an increasingly restricted field of vision, even though you can still focus perfectly well. Other warning signs and symptoms which may or may not be present are headaches and seeing auras or haloes around bright objects. Because glaucoma is an age associated defect it is rarely seen in people under 35 and because it ca be absolutely symptomless in the  early stages by the time it is diagnosed medially, the process has often gone so far that the sufferer can be classified as blind for health insurance purposes. You should have an eye test at about the age of 45 to check that you have not got it. This is particularly important if there is a history of it in your family. Once detected glaucoma can never be cured but it can be controlled in one of three ways; medically through prescription of certain drugs, surgically, in order to release pressure inside the eye, or through the use of prescription eye drops which use a drug called pilocarpine to constrict the pupil, so making the wearing of glasses unnecessary.  Source: Charismatic Planet