Glaucoma

Glaucoma is a leading cause of irreversible blindness worldwide, affecting more than 2.7 million individuals age 40 or older in the United States alone. 

Glaucoma is an eye condition that, if left untreated, can cause damage to the optic nerve causing vision loss and even blindness.  The optic nerve is responsible for transmitting the images we see to the brain for processing.  Vision loss from glaucoma is due to damage of the cells that make up the optic nerve (ganglion cells).  When these cells within the optic nerve become damaged, the message that is sent to the brain is therefore impaired, which is reflected in our vision.  This vision loss usually starts peripherally and then involves more central vision later.  This process occurs when the pressure inside of our eye(s) becomes too high for too long. 

Our eye(s) are continuously producing a fluid called aqueous humor.  In cases where this fluid cannot drain through the eyes drainage channel at the rate of production, the pressure within the eye can build up over time.  This increase in pressure is almost never able to be felt or noticed by the patient.  Likewise, the patient is also unlikely to notice any changes within their vision in the early stages of glaucoma because damage from glaucoma results with a loss of peripheral vision or a patients visual field (what we see off to the sides while looking straight forward).  This is typically a slow and progressive process, but can certainly lead to blindness if not treated properly, making glaucoma the sneaky thief of sight.

Glaucoma Suspect:  A patient may be diagnosed as being a glaucoma suspect at their eye exam because of the pressure in their eye or the way the optic nerve looks.  Glaucoma suspects have no damage to their optic nerve and there is no visual field loss.  Periodic exams are necessary to ensure the findings do not progress into a true glaucoma.

Ocular Hypertension (OHTN):  Essentially this is the same as being a glaucoma suspect.  Patients with ocular hypertension have very normal appearing optic nerves, but higher than average eye pressures.  However, these pressures do not cause damage to the  optic nerve.  Again, patients meeting this diagnostic criteria have no damage to their optic nerve and there is no visual field loss.  Periodic exams are necessary to ensure the findings do not progress into a true glaucoma.

Open Angle Glaucoma:  This is by far, the most common form of glaucoma.  With open angle glaucoma, the drainage channel (or angle) that drains the aqueous fluid within the eye is wide open for adequate drainage.  However, the rate of production of aqueous is greater than the rate it is drained at causing a gradual build-up of pressure.  The patient can almost never feel the pressure increasing in their eye with open angle glaucoma.  This pressure build-up results in thinning or damage to the optic nerve, which results in a loss in the patients peripheral vision. 

Low Tension Glaucoma (LTG):  Like open angle glaucoma, the drainage channel is wide open for adequate drainage and their eye pressure is within a normal range.  However, even though the pressure is normal, thinning or damage to the optic nerve is observed and a visual field loss is present.  The patient can never feel this process occurring within their eye.  Patients with LTG often have some of the most severe damage to their vision.

Narrow Angle Glaucoma:  The angle of the drainage channel for the aqueous fluid to drain is not wide open for adequate drainage causing the pressure inside of the eye to rise.  Slowly but surely, the nerve will thin or become damaged while visual field defects become apparent. 

In rare cases, there is the potential for complete angle closure, and the fluid cannot drain at all.  In the event of angle closure, the pressure rises rapidly within 24 hours and patients may notice an aching sensation within the eye, followed changes in their vision while the eye becomes red or bloodshot.  The affected eye may have a difference in pupil size and react differently to light.  Patients may or may not experience a headache and nausea.  Damage from angle closure occurs rapidly (in less than 24 hours) and requires urgent treatment.  If the patient unable to get in to their eye doctor right away, they should go to the emergency room and not “ride it out” because damage from angle closure is irreversible—the longer the angle remains closed, the worse the damage inside of the eye becomes.

Other Forms of Glaucoma:  There are other clinical forms of glaucoma which behave just as any of the forms of glaucoma previously reviewed.  Your eye doctor will advise you on what type of glaucoma you have if you do in fact have glaucoma, and review precise signs and symptoms to watch for as well as treatment options.

Glaucoma is an eye condition that slowly robs a patient of their vision.  What makes this possible is the fact that glaucoma very rarely presents with symptoms that the patient is able to identify.  A 2002 Prevent Blindness America Survey found that the majority of people believed that they could tell if they had glaucoma due to symptoms.  In its early stages, glaucoma has no obvious symptoms and the patient will not recognize that their vision diminishing.  This is why everyone should have their eyes dilated at least every other year, no matter what the age or current vision appears to be.   The following describes some of the signs and symptoms of glaucoma, and risk factors for developing glaucoma.

GLAUCOMA WITH OPEN ANGLES:

• Vision loss, beginning with peripheral or side vision. A patient may compensate for this unconsciously by turning your head to the side, and may not notice anything until significant vision is lost.
• If you have a parent or sibling with glaucoma, you are at an increased risk for developing glaucoma as well.
• African Americans are nearly 4 times more likely to develop glaucoma.
• Hispanics are also at an increased risk of developing glaucoma, especially Hispanic males over the age of 60.
• If you use steroid eye drops, such as patients that have had a corneal transplant and are using these drops to prevent tissue rejection.
• Trauma to the eye can also increase your risk of developing glaucoma.

ANGLE CLOSURE GLAUCOMA:

• severe pain in the eye or forehead
• redness of the eye
• decreased vision or blurred vision
• seeing rainbows or halos
• headache
• nausea
• vomiting
• Patients of Asian and Indian descent are at an increased risk of angle closure.
• Females are at a greater risk for angle closure.
• Patients with very thick or dense cataracts can be at an increased risk of angle closure as well.

When glaucoma is caught early and treatment has begun, many patients may never experience any vision loss.  However; glaucoma behaves differently in every patient, so some patients may begin treatment early on, and still end up with damage to the optic nerve and some vision loss—fortunately, there is a low incidence of this occurring.

EYE DROPS:  When glaucoma is first diagnosed, the first line of defense is a prescription eye drop to help decrease the production of the aqueous (fluid) inside of your eye, reducing the pressure.  There are many drops available on the market and they each work a little differently.  If one drop isn’t doing the trick, your eye doctor may switch you to a different drop to see how you respond.  Likewise, some patients may require a combination of different drops to control the pressure.

LASER PROCEDURES:  If glaucoma drops prove to be ineffective, patient compliance becomes an issue, or the patient is responding adversely with the drops (e.g. sensitivity, red eye, irritation), laser treatment may be considered and performed by an ophthalmologist.  Laser works by energy being applied to the drainage tissue of the eye. This starts a chemical and biological change in the tissue that results in better drainage of fluid through the drain and out of the eye.  When successful, will eventually results in a lower eye pressure.  It may take 1-3 months for the results to appear and may be combined with eye drop therapy.

With angle closure or narrow angle glaucoma, laser is used to create a small opening through the iris (the colored part of the eye) and allows for the aqueous fluid to drain through this opening.

ORAL MEDICATION:   An oral medication is available to help reduce the eye pressure, and is essentially a stronger diuretic that is strong enough to effect the fluid outflow inside of the eye.  Oral medication is typically only used short term, as the side effects of its long term use are less than favorable (e.g. kidney stones).  Oral medication is often used in conjunction with eye drop therapy.

FILTERING SURGERY:  For more severe, uncontrolled, or advanced glaucoma cases, surgery may be an option for some patients.  This surgery works by draining the excess aqueous (fluid inside of the eye) through the trap-door to a small reservoir or bleb just under the eye surface, hidden by the eyelid.  Eye drop therapy may or may not be necessary after this procedure.

COMBINED SURGERY:  For glaucoma patients that also have cataracts that are at the point of needing surgery, a possible option is to have the cataract removed and while the surgeon is in this area of the eye, they are able to insert a very tiny, almost microscopic, drainage stent (iStent) into the angle of the eye to promote a more effective outflow of the aqueous.  Removing a cataract often can result with a slightly lower eye pressure for glaucoma patients, and when combined with the iStent, the pressure often goes down to an even safer range.  Eye drop therapy may or may not be necessary after this procedure.