Abstract
Glaucoma is a chronic neuropathy of an optic nerve characterized by a progressive loss of retinal ganglion cells and their axons, by topographic changes of optic nerve disc together with a visual field loss. As the changes caused by an occurrence of glaucoma are irreversible and the prognosis of keeping good visual function of a patient is significantly better if the treatment is started at early stages of the disease, it is necessary to diagnose it as soon as possible.
To examine the perimeter i.e. a visual field test is a standard diagnostic glaucoma method. However, it is known that glaucomatous visual field defects do not appear until the loss of retinal nerve fibers is at least 30%.
That is why our current glaucoma diagnostics focuses on a detection of the disease already in so called pre-perimetric stage i.e. before an occurrence of visual field defects using an analysis of the optic nerve disc, a nerve fibre layer and their changes in time. The Heildelberg retinal tomograph is a device which helps significantly to diagnose the glaucoma disease in its early stage in its current version 3.
It is a confocal laser scanner, which obtains and analyses three dimensional images of a posterior segment of the eye. Its source is a diode laser with wavelength 670 nm.
It enables a representation and aquantitative description of the optic nerve disc and to observe possible changes in time.