Patient (right) being screened for glaucoma using the laser scanner. - Carlington Wilmot /Freelance Photographer Using a laser scanner, the medical specialist can now diagnose the eye disease, glaucoma, as early as four years
before the usual clinical signs appear.
SMALLER, MORE subtle changes in the eye's optic nerve can be detected using a laser scanner. This improvement in the ability of the medical specialist to examine the optic nerve is making it possible to diagnose, much earlier, the very common eye disease, glaucoma. The painless, non-invasive testing plus the printing of a computer-generated report, takes about five minutes.
Dr. Albert Lockhart, ophthalmologist -- one-half of the well-known West-and-Lockhart team who invented the glaucoma treatment, Canasol -- says, in fact that using his laser scanner, he can pick up glaucoma or damage to the eye from glaucoma from as early as four years before the usual clinical signs occur.
He explained that the laser scanner takes pictures in two planes of the optic nerves and in the nerve fibres of the retina. It takes about six million views in a matter of seconds and compares the patient's eye with about 100,000 other people of the same age and with comparable demographic statistics. The laser scanner then produces a picture of the optic nerve and the retina nerve fibre layer, which the specialist can read as normal or abnormal and then decide on the treatment plan.
"There are several types of glaucoma but the one that we are concerned about most, is known as chronic, simple glaucoma or chronic glaucoma or open-angle glaucoma because it is symptomless until it is well advanced. When the patient starts to see blurred visions that means that he has already lost nerve tissue or function in the optic nerves," Dr. Lockhart said.
The database of glaucoma information, to which the examined eye is compared, he said, is developed from world-wide data. He said the information in the database is gathered from all the major studies on the topic -- from United States, United Kingdom and other major research centres and also includes a Barbados study.
"Now each patient that goes in becomes part of the database. So that after the patient's third test, their eye is no longer compared only with the international database but with their own eye and then other people's eyes are compared with their eye as they become part of the general database," Dr. Lockhart said.
He said that it was the theory behind the ganja-derived drug, Canasol, that engendered this new technology. Canasol's treatment of glaucoma was based not only on the build-up of pressure in the eye but also on the protection of the optic nerve.
Using other instruments (the ophthalmoscope) the medical specialist diagnoses glaucoma by the raised pressure in the eyes or loss of visual field or changes in the appearance of the optic nerves. The glaucoma laser scanner measures pressure build-up and also what's happening in the optic nerve and the nerve fibre in the retina.
"This machine reads and interprets what is happening to the optic nerve -- it might say that the nerve fibre layer is getting thinner. So even if the doctor says the pressure is normal, we can say yes, the pressure is normal but based on what is happening in the retina and in the optic nerve, that pressure needs to be lowered because in your eye, your normal pressure is too high for your optic nerve," Dr. Lockhart explained.
