Glaucoma is a serious disorder that causes damage to the eyes and therefore impairs vision. Through regular testing of the eyes, you can get keep your vision and your eyes healthy. Usually once you are about forty years old, a complete eye test every 1-2 years can be beneficial. However, if someone in your family has had glaucoma, it is best to increase the frequency of this testing.
There are four regular diagnostic check ups done for glaucoma. They are tonometry, ophthalmoscopy, perimetry, and gonioscopy.
The tonometry tests are done to check the pressure inside the eyes. This test is conducted using a special device which can check for pressure inside the eyes. In the ophthalmoscopy tests, the pressure on the optic nerve is examined. The shape and the color of the optic nerve can be seen using a special instrument called an ophthalmoscope.
After these two tests are performed, if there is any deviation from the normal results, two other tests are performed. The perimetry test basically tests the distance of the visual field. A light is moved in the peripheral vision and you will be asked to respond when this light is moved around. In gonioscopy however, the eyes are checked to see the angle at which the iris and the cornea meet. The position of the angle and whether the angle is open or closed, can indicate the presence of glaucoma.
In each of these eye tests for glaucoma, there are several small tests involved. To check for the ocular pressure, several different instruments may be used. There are different types of tonometers that help register the intra ocular pressure. The Schiotz tonometer, air puff tonometer, Pneumotonometer and the Perkins tonometer are some the commonly used instruments.
To check for the vision field, automated field analyzers, like the Humphrey or the Octopus perimeters are used. The glaucoma hemifield test is also performed to check the variations between the two hemispheres.
Of late, techniques like the optical coherence tomography, scanning laser polarimetry and confocal laser ophthalmoscopy are being used. These systems are automated and therefore accuracy and precision are warranted. Ocular hypertension can also be examined by checking the corneal thickness. Corneal thickness is directly related to the accuracy of the pressure reading taken in the tonometry procedure. Abnormal corneal thickness can affect the test results. If the corneal thickness is not taken into account, a person may end up receiving treatment for glaucoma without really suffering from the disorder.