Glaucoma is a tricky group of diseases, as it commonly develops slowly, over several years, without showing any symptoms. In the beginning, you may not even notice something is wrong, as the condition usually starts with unnoticeable blind spots on the outer (peripheral) field of vision - typical for the most common form, open-angle glaucoma. Glaucoma has already advanced quite far by the time you notice any defects like your vision gradually failing. If this happens, please consult an ophthalmologist as soon as possible, as this condition can lead to blindness.
WHAT IS GLAUCOMA?
Glaucoma affects the optic nerve connecting the eye to the brain (back portion of the interior of the eyeball). Damage very often occurs when the intraocular pressure (IOP)- the main risk factor for glaucoma - is too high. This happens when the drainage of the aqueous humour, a watery fluid that fills the space between cornea and lens and amongst others maintains the normal pressure in the eye, is blocked.
While most kinds of glaucoma involve elevated eye pressure, there is a form of glaucoma called normal-tension glaucoma (NTG). It is defined as glaucoma without a clearly abnormal IOP, and depends on recognizing symptoms and signs associated with optic nerve vulnerability, in addition to absence of other explanations for disc abnormality and visual field loss.
High pressure in the eye (IOP): the pressure in your eye increases, because the outflow of the aqueous humor (which maintains the normal pressure in the eye) is impaired for some reason.
Eye pressure can vary hourly, daily and weekly and is dependent on many factors. A statistically normal pressure varies between 10 and 21 mmHg (millimeters of mercury, a scale for recording the eye pressure}. In general: the higher the pressure, the more risk to the optic nerve. However, the eye pressure of some glaucoma patients is below 21 mmHg. In other words, the pressure tolerance of the nerve tissue depends also on the individual.
Other risk factors are:
- Age: Glaucoma is most common in elderly people, but may also start in a younger age.
- Family history: If glaucoma occurs in your family, you are more likely to get glaucoma.
- Near or short-sightedness (myopia): If you have myopia of over -3 diopters, the risk of glaucoma is higher.
- Race: If you are of African or Afro-Caribbean origin you are about 5 to 6 times more likely to get glaucoma than Caucasians.
- Other certain diseases: Diabetes, artherosclerosis (hardening of the arteries), and hypertension (high blood pressure) may impair your blood flow in the eye and expose to glaucomatous defects.
Visit your doctor regularly from the age of 40 years old.
To detect glaucoma, your doctor will examine your eyes with a special microscope, the so-called slit lamp, providing a magnified, three-dimensional view of the structures within the eye. When used in combination with special lenses, in particular the back of your eye, where the optic nerve head is located, can be viewed (in someone with glaucoma, there are specific changes that can be seen in this area).
Your ophthalmologist will also measure the eye pressure as well as the thickness of your cornea, as this can affect your intraocular pressure reading. He will also test the angle where your iris meets the cornea via gonioscopy. In addition, your field of vision may also be examined using a test called perimetry.
If the diagnosis is glaucoma, a pressure-lowering treatment is usually started.
If the pressure is high, but there are no signs of glaucoma, it is either possible to observe the situation without starting treatment or start prophylactic treatment. In any case, the decision should always be taken individually by the ophthalmologist.
Treating glaucoma is based on lowering the intraocular pressure. The aim is to slow the progression of your disease. Unfortunately, vision already lost cannot be restored. The choices of treatment are usually in the following order:
- Medicines (eye drops)
The medicinal treatment of glaucoma normally lasts for the rest of your life. For long-term treatment you should consider not only efficacy but also adherence and safety. Preservative-free eye drops could ensure optimal tolerability of the medication.
Medications work either to reduce the amount of aqueous humour (e.g. beta-blockers) or increase the drainage of aqueous humour (e.g. prostaglandin analogue drops). It is essential that you use the medicine as advised by your doctor because it helps only if used properly.
As an alternative, laser treatment (laser trabeculoplasty) of the chamber angle aims at improving the outflow of the aqueous humor, in order to decrease the pressure - at least for a few years. If, despite medical or laser therapy, glaucoma progresses, surgical treatment may be used.
The most common form of glaucoma surgery is trabeculectomy. This is a procedure to relieve intraocular pressure by removing part of the eye's trabecular meshwork and adjacent structures. It allows drainage of aqueous humor from within the eye to underneath the conjunct iva, where it is absorbed.
Santen product approved and available in the Philippines
NOTE: Other Santen prescription medicines are available to treat glaucoma, please consult with your physician.