Glaucoma is a term applied to a group of eye diseases that cause a characteristic and recognisable deterioration of the optic nerve. The optic nerve carries visual information between the eye and the brain, much like the cable between a computer screen and the computer. In the brain, this information is assembled into a visual image that we recognise as sight (Figure1).
When the optic nerve is damaged or injured, the transmission of visual information is altered and, hence, the visual image is impaired. Since patients with glaucoma may be unaware of any change in their vision until late in the course of the disease, they may not seek medical attention until there is substantial permanent damage. Fortunately for patients who do have regular examinations, ophthalmologists can usually detect glaucomatous optic nerve damage before there is noticeable visual loss by examining the back of the eye. Sometimes, damage to the nerve can be observed even before specialised tests detect a change of vision.
When the optic nerve is damaged or injured, the transmission of visual information is altered and, hence, the visual image is impaired. Since patients with glaucoma may be unaware of any change in their vision until late in the course of the disease, they may not seek medical attention until there is substantial permanent damage. Fortunately for patients who do have regular examinations, ophthalmologists can usually detect glaucomatous optic nerve damage before there is noticeable visual loss by examining the back of the eye. Sometimes, damage to the nerve can be observed even before specialised tests detect a change of vision.
