Walleye are a very diverse group of eye diseases, linked by the presence of a chronic and progressive damage of the optic nerve, with characteristic changes in the appearance of the optic nerve head, retinal nerve fiber layer, even in the absence of other ocular diseases .
Diseases are important as they can cause injury not reversible. Glaucoma if not diagnosed in time and if not treated properly can cause serious eye damage and blindness in some cases.
The most common form of glaucoma (primary open-angle glaucoma) is mostly asymptomatic, with the slow but inexorable trend and is often detected during an eye examination performed for other reasons.
The mechanisms by which it develops glaucoma, are still largely unknown, but have been identified many risk factors that are associated with the disease, among which are, in particular: high intraocular pressure, age, race, family history, myopia, central corneal thickness, and vascular factors.
High pressure in the eye
It is the first among the risk factors that have been identified. There is a value of normal pressure absolute, and the pressure level at which damage can occur is variable in individuals. The maximum value of 21 mmHg is still considered the limit of statistical normality. Taking into consideration populations of subjects divided by values of pressure in the eye, the frequency of glaucoma increases progressively in groups of individuals with ocular pressure more. Who has a pressure in the eye always below 18 mmHg, has a low risk of developing glaucoma. However, there are walleye in low-medium pressure more difficult to control. Ocular pressure still remains one of the most important risk factors, and what can be corrected more effectively with therapies.
The frequency of the disease in the population increases significantly after 40 years of age and you do not feel a difference between sex and other things. It is strongly recommended to carry out an eye examination after age 40. First for subjects with a family history or other risk factors. It is thought that 50% of patients with glaucoma is not aware they have the disease.
Who has a first-degree relative with the disease, your risk from 4 to 10 times greater than express it. Were already identified some genes definitely related to the onset of glaucoma.
If the high pressure is not always justifies the diagnosis of glaucoma. There are in fact many cases of ocular hypertension harmless. The status of the optic nerve (optic nerve head) and the study of the visual field may show whether damage to the optic nerve and dissolve any doubt. There are also specific tests (GDX-OCT) to help diagnose the disease in the early stages, when the disease is certainly more controllable and manageable. Another important consideration is to highlight pachymetry corneal thickness. The "normal" thickness of the cornea at the center is slightly higher than half a millimeter (520-540 μ). Patients with thin cornea have an increased risk of development and progression of glaucoma, while those with a thick cornea would be more protected. All the above tests are non-invasive and does not cause any pain, only require a little cooperation.
The therapy can be: medicines to take in life, parasurgical (laser surgery) or surgery. The first is the most common, while the last two tend to be adopted only for the most serious cases. Usually the drug therapy is focused on the administration of special eye drops while the intervention consists of a trabeculectomy (literally "cut the trabecular meshwork," which is the channel of leakage of aqueous humor). The usefulness of parasurgical is limited to a few cases.
Since June 2009, is also available in Italian for open-angle glaucoma the first preservative-free eye drops, based on a substance called Tafluprost .
The areas of the visual field lost due to damage to the optic nerve can not be recovered with any of the three therapies. The function has only conservative therapy or preventive against a further damage of the vision and prevent blindness. All three therapies have the same purpose of facilitating the outflow of aqueous humor where he created an obstruction, removing it if there is, or at the points where it is cheaper to drain the excess production of aqueous humor.
Medical therapy is based primarily on the use of eye drops that have the function of reducing the production of aqueous humor or increase their elimination; the founder was pilocarpine, extracted from a tropical plant and known since 1870 for nearly a century has been the only defense is rarely used today but due to some annoying side effects. Currently the most Beta-blockers are used, carbonic anhydrase inhibitors, alpha stimulating and prostaglandins with the founder Latanoprost, in business since 1997 In some cases we have seen the reduction of intraocular pressure with marijuana and cocaine, drugs still illegal for this problem. The main pharmacological effect of cocaine at the local level is that of a mild anesthetic and vasoconstrictor, at the level of the central nervous system (CNS) is to block the recovery (reuptake) of dopamine in the presynaptic terminal once this has been released by terminal of the neuron in the synaptic cleft; the removal of dopamine from the synaptic terminal is performed by the so-called transport proteins that promote the absorption of the neurotransmitter from outside to inside of the neuron. Cocaine acts on the functionality of the transport proteins, preventing the reabsorption of dopamine inside the neuron becoming thc.
In primary glaucoma for yet unknown reasons the increase in IOP is caused by a production of aqueous humor than normal, or more easily by the obstruction of outflow pathways. In cases in which the glaucoma was caused instead by changes in eye diseases, trauma or prolonged therapy with cortisone we speak of secondary glaucoma.
There are several species of primitive glaucoma:
open-angle glaucoma filtration
chronic simple glaucoma
glaucoma by cortisone
closed-angle glaucoma filtration