Glaucoma, symptoms and treatment

What is glaucoma? 
Glaucoma is a group of eye diseases that have as a common characteristic the destruction of the optic nerve. The optic nerve can be visualized functioning as a cable containing maybe more than 1 million nerve fibers conveying the image that we see to the brain. When the optic nerve is damaged in some way, then the vision is impaired and deteriorates slowly.

The majority of patients with glaucoma do not experience any symptoms until they have lost a significant part of their vision. Therefore patients should be examined regularly, once or twice a year, especially if their age is over forty years old. The eye specialist can detect glaucoma alterations before considerable damage occurs, by examining the fundus or with the help of special tests such as perimetry.

Why you should have your optic nerve examined?
The examination of the optic nerve is an important part of the examination for glaucoma. This enables the ophthalmologist to detect any damage of the optic nerve, or if there is expansion of an existing damage. By examining your optic nerve the ophthalmologist can diagnose the presence of glaucoma or monitor the course of the disease.

How is the optic nerve examined? 
The optic nerve is situated at the back of the eye, at the fundus. It consists of nerve fibers which end up inside the eye, in the retina cells. The retina is the light sensitive layer of our eye. When the doctor examines the patient (fundoscopy), can observe the optic nerve (optic disc) as well as the nerve fibers spreading out on the retina. Although the optic nerve may be affected by various diseases, the damage due to glaucoma has a characteristic appearance which allows the ophthalmologist to diagnose the ailment.

Other methods for the examination of the optic nerve that are commonly used and are useful tools for assessing the damage of the nerve and glaucoma development, are perimetry (examination of the visual field), HRT (Heidelberg Retina Tomograph), the OCT (Ocular Coherence Tomography) etc.

In glaucoma (where the optical fibers are destroyed), a larger cupping occurs (i.e., the yellow inner ring is bigger than normal). Especially when the size of the cupping is different between the two eyes of a patient, the ophthalmologist can diagnose glaucoma early using this detail.

What is the examination of the visual field (automated perimetry)?
Examination of the visual field is used for the examination of the optic nerve and to assess the development of glaucoma. The examination of the visual field measures the patient’s ability to recognize the light in each region of the retina (and thereby to estimate the rate of nerve fibers that have been damaged by glaucoma). The examination of the visual field is one of the most essential tests for the diagnosis of glaucoma. When glaucoma is already diagnosed this examination helps the ophthalmologist to assess the course of the disease (if it is stagnant or aggravated).

What is the HRT test for? 
In HRT examination the optic nerve head is scanned by an optical scanner and the thickness of the nerve fibers-among others- is calculated with very high accuracy. This examination helps the ophthalmologist diagnose and assess the progress of glaucoma. Similarly other tests (such as OCT, GDx etc.) are used to this effect.

What are the causes of glaucoma?
The causes of glaucoma are not known. In some cases, the optic nerve is damaged due to increased intraocular pressure. When we lower intraocular pressure, we can stop or delay the destruction of the optic nerve. For some patients, the optic nerve damage can be continued even if the intraocular pressure is maintained at low levels. Worldwide research is ongoing so as to understand the causes of glaucomatous damage in these patients and to develop new treatments to protect the optic nerve.

Many situations can cause high intraocular pressure. Therefore, high intraocular pressure might be a result of inflammation, bleeding, injury, tumor, congenital malformation, drug use, etc. However in most cases of glaucoma, no particular abnormality is detected. This condition is known as primary open-angle glaucoma. In other cases the eye may show abnormalities that cause closed-angle glaucoma. The closed-angle or narrow-angle glaucoma may be an acute condition and might need immediate treatment.

At least fifty mechanisms have been described that may increase the intraocular pressure, but all cause similar damage to the optic nerve. All methods of treatment for glaucoma today are aiming primarily to lower intraocular pressure to a level where we can prevent further damage of the optic nerve.

What is the purpose of the examination of corneal thickness? 
The Goldmann tonometer we usually measure the intraocular pressure with, gives reliable results, provided that a person has a central corneal thickness of about 545mm. Still it turned out that not all people have the same thickness of the cornea. So for those with thin corneas intraocular pressure is underestimated, while for those with thicker than average corneas intraocular pressure is overestimated. Corneal pachymetry is an ultrasonic (usually) mapping of the corneal thickness, which allows the ophthalmologist to calculate with high precision the intraocular pressure.

Types of glaucoma 
Glaucoma is generally divided into two types: Open-angle glaucoma and closed-angle glaucoma. In open-angle glaucoma, the doctor is able to see the drainage system of the eye with special tests, but is not possible to see where exactly the problem is. In closed-angle glaucoma, the eye drainage system is usually obstructed by the iris and the aqueous humor is unable to reach the trabecular meshwork and be drained. The most common type of glaucoma is open angle glaucoma.

Treatment of glaucoma
glaucomaThe most important goal in the treatment of glaucoma is to preserve vision by preventing the damage of the optic nerve. It is known that high intraocular pressure can cause damage to the optic nerve. Therefore we try to protect it by lowering intraocular pressure. All the treatments available today are targeted at lowering the intraocular pressure. It is generally acknowledged that by lowering the pressure, we slow down or stop the visual field loss in most patients. It is true that some patients continue to lose part of their vision even when the pressure is significantly lowered; nevertheless most of them are able to maintain it.

Treatment options for glaucoma
There are three basic options for the treatment of glaucoma:

a. medication (drops or tablets).

b. laser operation. There are different types of laser (eg. selective laser trabeculoplasty (SLT), endocyclophotocoagulation (ECP), YAG laser iridotomy, cyclophotocoagulation with diode laser, etc.) and are applied at different points of the eye.

c. surgery (trabeculectomy or similar fistuloplasty surgery).

The ophthalmologist takes into consideration many factors in order to determine the appropriate treatment for each patient individually.

In our clinic we provide all the necessary means (technical equipment and specialized staff) to make the correct diagnosis and apply the appropriate treatment chosen by the attending ophthalmologist.