I've heard that glaucoma is caused by high eye pressure, and that left untreated glaucoma can cause blindness. At what pressure will I go blind?

Glaucoma is a multi-factorial, complex eye disease with specific characteristics such as optic nerve damage and visual field loss. While increased pressure inside the eye (called intraocular pressure or IOP) is usually present, even patients with normal range IOP can develop glaucoma.

There is no specific level of elevated eye pressure that definitely leads to glaucoma; conversely, there is no lower level of IOP that will absolutely eliminate a person’s risk of developing glaucoma. That is why early diagnosis and treatment of glaucoma is the key to preventing vision loss.

Measuring Eye Pressure

Eye pressure is measured in millimeters of mercury (mm Hg). Normal eye pressure ranges from 12-22 mm Hg, and eye pressure of greater than 22 mm Hg is considered higher than normal. When the IOP is higher than normal but the person does not show signs of glaucoma, this is referred to as ocular hypertension.

High eye pressure alone does not cause glaucoma. However, it is a significant risk factor. Individuals diagnosed with high eye pressure should have regular comprehensive eye examinations by an eyecare professional to check for signs of the onset of glaucoma.

Elevated IOP

In the past, eye care professionals sometimes referred to a person with an elevated IOP as a glaucoma suspect, because of the concern that the elevated eye pressure might lead to glaucoma. However, the term glaucoma suspect is usually reserved today to describe anyone who has a finding that could potentially now or in the future indicate glaucoma. For example, elevated intraocular pressure or a suspicious optic nerve, or even a strong family history, could put someone in the category of a glaucoma suspect.

In the majority of cases, vision loss usually occurs when the eye pressure is too high for the specific individual and damages the optic nerve. Any resultant damage cannot be reversed. In eyes with glaucoma, peripheral (side) vision is affected first. The changes in vision may be so gradual that they are not noticed until a lot of vision loss has already occurred.

In time, if the glaucoma is not treated, central vision will also be decreased and then lost; this is how blindness from glaucoma is most often noticed. The good news is that glaucoma can be managed if detected early, and with medical and/or surgical treatment, most people with glaucoma will not lose their sight.

If You Are at Higher Risk

If you are at higher risk for glaucoma, you should have a thorough eye exam every one or two years after age 35. If you are diagnosed with glaucoma, it is important to work with your eye doctor and carefully follow your prescribed treatment. Glaucoma medications will only work if they are taken exactly as advised by your doctor, so it is important to follow your medication regimen carefully.

Glaucoma Eye Drops: Suggestions on Use

Eye drops for glaucoma contain medications. Bottle shapes and sizes vary as do the type of containers.

Most commercially made eye drops deliver a drop that is bigger than the eye can hold. Because of this, it is normal for a small proportion of the drop to roll over onto your cheek. Also, different bottle types may last varying amounts of time as each may have a distinctive eye drop size.

It is difficult to squeeze just one drop from a bottle at a time. It is therefore normal for a bottle not to last as long as your pharmacy provider may think it should. If that happens, make sure you remind your pharmacy that CMS (Medicare) and many states have mandated that you are allowed extra eye drop refills.

Eye drops can be challenging to instill. Here are some tips you may find helpful.

• Before instilling drops, make sure to wash your hands. Dirty hands can result in eye infections which may be serious.

• Often, when beginning to use drops, it is hard to tell if the drop actually went in the eye or not. You might want to refrigerate your eye drop bottle - when you put the drop in, you will feel the cold drop on your eye and know that you are successful (this is not necessary to preserve the drop, but useful to help you discover if the drop actually touches your eye).

Open eye with your non-dominant hand.

• Almost 20% of people are unable to put drops onto their own eyes for various reasons and are reliant upon others. They may have tremors, poor vision, poor coordination, or just fear. Don’t feel badly if this is you. Depending upon your situation, make sure you find a friend or family member to help you.

• If your doctor has prescribed more than one type of eye drop, wait five minutes before putting the next drop in your eye.

There are many methods for instilling drops; the following suggested method works well for many people.

Instilling the eye drop.

1. Make sure that your eye is open. Use any finger to open your eye - most people prefer to use the first finger of their non-dominant hand (your left hand if you are right-handed).
2. Make sure the bottle is aiming downwards. (Let gravity help you). Also, have your eye perpendicular to the bottle by having your head parallel with the floor. The easiest way to do this is to lie down or sit back in a chair. In this way, the drop will go straight down onto your eye, rather than fall on your lid or your cheek.
3. Finally, brace the thumb of your dominant hand (right hand if you are right-handed) on the first finger of the non-dominant hand. By doing this you will be able to accurately aim a drop onto your eye.

Make sure that you have a friend or your doctor watch you instill the drop in your eye. If you are having problems, ask your doctor or your doctor’s technician for help.