Glaucoma, Its all About Pressure

Glaucoma is an insidious disease which robs people’s vision slowly, generally over decades, and the vision loss starts in the periphery and works its way in.  Because it is so slow and starts at the edge of vision most people with the disease will lose over 30% of their vision before they recognize there is a problem.   An eye doctor can detect changes in the eye before vision loss occurs and with treatment we can prevent it.  Sadly however we cannot restore vision after it is lost.

Anatomy:

To help the eye maintain its shape a fluid fills the eye called the aqueous humor.   This fluid is constantly being produced at the cilliary body, and drained from the angle.  For a moment think of a full bathtub with both the faucet turned on and the drain open.  The same amount of water is flowing in as is draining out keeping the bathtub full.  Now if something blocks the drain or if the faucet it turned up the tub will overflow.  The eye works similarly  if the cilliary body produces to much aqueous, or the angle gets blocks there will be too much aqueous.  The aqueous cannot overflow out of the eye (like a bathtub) instead the pressure builds and causes vision loss.

Pressure:

Most people’s least favorite part of visiting the eye doctor is the air puff, this checks the pressure within your eye.  Normal intraocular pressure can be anywhere between 11_mmhg and 21_mmhg.  A classic case of glaucoma will involve someone whose pressures are 25_mmhg.  As time passes the elevated pressure causes damage to structures within the eye, causing vision loss.  Given enough time with high enough pressure it will lead to blindness.

In recent years we have come to realize that the normal ranges don’t matter that much.  We have realized that glaucoma is a disease that is caused by pressure that is too high for a specific individual.  Many people with high pressures (above 21_mmhg) do not have glaucoma, this is called ocular hypertension.  Conversely there are people who have normal pressures who do have glaucoma this is called normal tension glaucoma.

Now most of you are probably asking “If pressure doesn’t matter why do I need to get the air puff?”

The simple answer is pressure does matter; the “normal ranges” don’t matter.  For instance people’s pressure tend to rise with age, by knowing what someone’s pressures have been previously we can determine if the pressure is increasing and if we should be more suspicious of glaucoma.

Treatment:

Once a person is diagnosed with glaucoma treatment varies.  It can be as simple as an eye drop in each eye at bedtime, or a laser procedure.  Should that not be enough we can add more drops or even perform surgery.

To Sum Up:

Pressure matters, and there is no way for you to know your pressure except to go see an eye doctor regularly and get the air puff.

“Dodge”

William Dodge Perry, OD