Elevated Intraocular pressure is the greatest known risk factor for Glaucoma. Now the question; what is Intraocular pressure and what is Glaucoma?
Just as the body has what is known as Blood Pressure, the eye has its own pressure called the Intraocular pressure and an increase in the pressure that is not controlled can lead to Glaucoma.
Glaucoma on the other hand, is a condition that results from the damage of the Optic Nerve that connects the eye to the brain. Here, increased pressure that is left uncontrolled leads to death of the nerves and when this happens, information (in the form of light) is not passed to the brain for interpretation and this leads to Blindness.
Intraocular pressure is the fluid pressure inside the eye that is determined by the production and drainage of Aqueous Humour- A transparent water-like fluid that provides nutrition to some of the structures in the eye amongst other functions. The production i.e. inflow of this fluid (Aqueous Humour) should equal outflow but in cases where the inflow outweighs the outflow, there’s a build-up of pressure that begins to affect the Optic nerve and this could lead to blindness if not controlled. But in the absence of nerve damage, this increased ocular pressure is called Ocular Hypertension.
Intraocular pressure could vary during the night and day (Highest in the morning upon waking up in the morning and lowest during the afternoon) and could be affected by other factors such as exercises, drugs- Alcohol and marijuana decrease the Intraocular pressure while Marijuana causes an increase; these effects are transient, only lasting for a short while and in the case of blunt trauma to the eye there could be an increase in pressure that should be considered an ocular emergency.
Intraocular pressure has to be measured by an Eye Doctor with an equipment known as a Tonometer by the process known as Tonometry. The eye Doctor could either use a Non-Contact tonometer that puffs air into the eye to take the pressure reading or use an instrument known as Applanation Tonometer where it’s been placed directly on the surface of the eye called the Cornea and the pressure reading recorded. The latter is considered the most reliable instrument for an accurate measurement but due to technology advancement and preference of Eye Doctor as well as some patients who would rather not have a direct contact with an equipment, the Non-Contact Tonometer is more widely used today.
There are a range of numbers considered safe after tonometry has been done and these numbers considered to be Normal lies within 10-21 (mmHg). mmHg is the unit of measure of IOP recorded beside the figure as well as the time the procedure was conducted. In cases where the pressure is high, series to tests are conducted amongst which is Gonioscopy that examines the drainage channel. These channels may be open, closed or narrow and in cases where they are narrow or closed, the fluid called Aqueous Humour cannot drain properly so this causes a build-up.
Make it a duty to check your eyes regularly.
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