Glaucoma eye disease » Basic facts and role of eye pressure in glaucoma

Glaucoma is a chronical eye disease of the ocular nerve, that in the case of a late diagnosis and inadequate treatment leads to severe eye damage and blindness. In the world, there is more than 70 milions of people suffering from glaucoma. More than a half of them begin a treatment late and on the other hand, based on the latest knowledge about this disease, it apears that many people are treated uselessly. Eye glaucoma is the most often cause of blindness in developed countries.

The cause of glaucoma is not exactly known. We know it is genetically determined. We also know some risk factors. The most important is increased eye pressure. The risk is also increased by some diseases such as high blood pressure, sclerosis, diabetes. Recently, attention is given to relation of migraine and glaucoma.

The so-called primary eye glaucoma (which is not subject to any other eye disease) occurs in two basic forms. The first, most appearing form is insidious because a patient do not have to have any troubles. Sometimes just a feeling of pressure in the eyes, behind the eyes or headache. The disease is usually ascertained accidentally when prescribing eyeglasses or during preventive ophthalmologic examination. If there are problems such as dropout in a visual field and decrease of visual acuity caused by glaucoma, it is too late for an effective treatment.

There is also a paroxysmal form of glaucoma. This is not half as dangerous because a pain in the afflicted eye, sudden worsening of vision, vomiting and a general poor condition bring a patient quickly to a doctor.

What is the role of eye pressure in glaucoma?

Eye pressure is the pressure inside the eyeball and its value depends on the balance between production and outflow of intraocular fluid. It is measured by different types of tonometers, from the simplest mechanical to expensive electronic non-contact tonometers.

Normal values range from 10 to 22 mmHg. But this applies only if a patient has a standard thickness of the cornea. If the cornea is significantly thicker or thinner, these values are different. Eye pressure is one of the major risk factors for ocular nerve damage in glaucoma. However, it is not its condition. There is also a glaucoma with normal eye pressure.

Measuring of eye pressure is not enough to confirm or exclude the diagnosis of glaucoma. Examination of eyeground, computerized perimeter and examination of visual acuity is also necessary. Thus we can reliably diagnose only a fully developed glaucoma and a treatment may not be successful. Glaucoma at an early stage can not be reliably confirmed nor excluded by these standard examining methods. In other words, based on these methods we can not exactly distinguish glaucoma at an early stage from the state not requiring a treatment.

Therefore, recently in diagnostic, ophthalmology also starts to use highly technical and expensive imaging techniques, that can detect glaucoma changes earlier than their clinical manifestation.