Many eye conditions develop slowly. As we have two eyes, changes in one eye are masked by the normal vision of the other eye. A full range of tests for glaucoma are always included in all our eye examinations.
It is especially important to check the elasticity of the eye as eye pressure readings alone could be misleading. The latest addition to glaucoma detection tests, Packymetry, is a simple but effective way to assess the risk associated with your eye pressure.
With glaucoma the peripheral vision deteriorates starting in very small areas of the field of vision and with only vague changes at first. These are initially always masked by the overlapping field of vision of the other eye and the progress of the deterioration and ultimate loss of sight can take several years.
What Is Glaucoma?
Vision commences when light is focused on the innermost membrane of the eye, the retina. Very simply, glaucoma is the loss of retinal sensitivity due to a deficient blood supply which results in poor nourishment of this vital tissue.
What Causes Glaucoma?
In many cases of glaucoma the reduction in blood supply to the retina is caused by a raised pressure within the eye itself. In approximately 20% of cases however, the blood supply to the retina, especially at the optic nerve, can very gradually become impaired even without a raised eye pressure. Called ‘simple chronic glaucoma’ this develops over a number of years but, in the very early stages, changes in the appearance of the optic nerve and subtle changes in the sensitivity of the visual field may become evident to your optometrist during a routine eye examination.
Infrequently, the intra-ocular pressure can rise above the normal level over a very short period of time if there is a very narrow angle between the iris and cornea. This condition is called ‘acute glaucoma’ and is the only variation of glaucoma to cause pain and needs immediate treatment.
Currently the most advanced test for predicting the possibility of glaucoma involves analysing the blood flow in the retina (OBF analysis). An Ocular Blood Flow test along with visual field mapping and routine observation of the interior of the eye fulfill a comprehensive screening for glaucoma. All these tests are provided as part of our routine eye examination wherever necessary.
Treatment with eye drops to regulate the eye pressure and promote a balanced blood flow is very effective in preventing loss of vision in 'simple chronic glaucoma'. The earlier the treatment starts the greater the chance of success. Surgery is usually necessary to relieve acute glaucoma or, occasionally where a raised eye pressure fails to respond to eye drops.
The Vital Statistics
The majority of glaucomas are called ‘simple’ or ‘chronic’. They are normally age-related and occur in the over forties. Between 1% and 2% of the population get glaucoma and the chances of developing the condition are greater if close members of the family have it. ‘Acute glaucoma’ usually affects younger people and commences with discomfort and a red eye. However, mild symptoms of eyestrain or even difficulty with reading can sometimes be associated with glaucoma.
The easiest way to be sure that your sight is safe is to have your eyes examined regularly.