ADVANCED GLAUCOMA

Ophthalmologist Carolina Valdivia, MD discusses advanced glaucoma and the risks associated with surgery.

Hi Dr. Valdivia. I have advanced glaucoma and have been under treatment for a year and a half. The specific type I have is open-angle glaucoma. Some of the vision in my left eye is gone. My right eye is a lot better but it is also affected. My most recent intraocular pressure reading was 18 in the left eye and 14 in my right eye. My doctor says I should get surgery for my left eye. However, another eye doctor told me that if I get operated on at this stage, I might become blind in that eye because of the effect of the glaucoma surgery. She mentioned that fibers of the optic nerve usually get destroyed in the eye surgery and that I may lose the small amount of fibers that I have left. Please help me to make a decision. It is very important to me.



Thank you for your interest in glaucoma-eye-info.com.

I am sorry that you are in such a difficult situation. From the details that you provided in your question, your left optic nerve appears to be severely damaged due to advanced glaucoma, but still contains a few remaining viable nerve fibers that are allowing you to have some vision in that eye. Your question pertains to whether or not glaucoma surgery might damage the remaining nerve fibers in your left eye and cause blindness.

All surgical procedures have risks, some more than others. Make sure that you understand the specific risks associated with the procedure that your ophthalmologist has recommended, so that you can make an informed decision about how to proceed.

For patients with advanced glaucoma that is the open-angle type, it typically is not the surgery itself that carries the greatest risk to optic nerve damage, but rather that intraocular pressure increases both during the procedure and throughout the recovery period after it.

Your doctor probably has told you that a normal eye pressure range is between 10-20 mmHg. However, this represents a population statistic. This means that it is based upon average intraocular pressure levels observed in large groups of people that show now evidence of eye disease. However, a normal eye pressure range is better defined as one that does not cause damage to YOUR optic nerve.

An ophthalmologist establishes your personal normal eye pressure range. He or she first starts with the population values (10-20 mmHg), but then must refine this to establish a pressure range that effectively controls further optic nerve damage in your eye. For this reason, although your level at 18 mmHg, assisted with medication, falls within the population statistical range for normal eye pressure, it still may be insufficient to control damage to the optic nerve and progression of your advanced glaucoma. This likely is why your ophthalmologist has recommended glaucoma surgery.

Researcher Tor Odberg [1] conducted a longitudinal study in patients with advanced glaucoma of the open-angle type. A longitudinal clinical research study is one in which patients are followed over time, usually 5-10 years or longer. Odberg found that patients who had intraocular pressures in ranges equal to or greater than 15 mmHg, and that were treated only with medication (eye drops), showed progressive worsening of optic nerve damage in 84% of the cases. Progressive worsening was 100% in those with ocular hypertension (more than 20 mmHg). However, in patients whose pressure was maintained below 16 mmHg, worsening was limited to 33%.

In other studies, Dr. Paul Palmberg [2, 3] found that this pattern changes dramatically in cases where glaucoma surgery has been used to lower ocular hypertension. Progressive worsening of optic nerve damage was only 8% in eyes that maintained an intraocular pressure below 15 mmHg over a period spanning 4 years.

Without examining you and knowing your complete history, it neither is possible for me to ascertain how many functioning optic nerve fibers remain in this eye and the rate at which optic nerve damage has occurred, nor can I give you an idea of how much time you might have before vision in this eye is compromised completely, even with the use of eye drops. It could range from a few months to a few years.

So, let us return to your original question. Does surgery for your advanced glaucoma have risks?

Yes, it does.

In fact, glaucoma surgery carries a risk for a total loss of vision in your left eye. This is because surgery causes inflammation, and inflammation can cause ocular hypertension. If it cannot be controlled, then the few functioning optic nerve fibers that remain could be lost. Nevertheless, despite the potential risks, it is glaucoma surgery that offers you the best opportunity to bring your ocular hypertension down and preserve vision in your left eye for a much longer period of time.

I do not know all the details of your case, so I cannot offer you definitive advice. But I have tried to provide you with key information that might help to give you clarity and facilitate your decision. Several other factors must also be taken into account when making a decision that is this important. Among these are risk factors, such as the degree of optic nerve damage that caused the advanced glaucoma, intraocular pressure values that have been responsible for the progressive optic nerve damage, in combination with the speed with which the disease has progressed, your age, family history, race, and any associated systemic diseases, such as hypertension and diabetes.

I recommend that you speak with your ophthalmologist again about your specific case. Be an active patient, not a passive one. Ask questions and make sure that you understand the answers that are given to you. It is important that you be clear about what the future holds for your eyesight if you elect not to have glaucoma surgery and then contrast that with the probability of you loosing sight in this eye, or having it worsened, if you choose to have it. Much of this will depend upon the factors that I have discussed here, in particular the confidence that your ophthalmologist has in being able to control ocular hypertension during surgery and throughout the recovery period after it.

As I said at the beginning of this response, you are in a difficult situation.

BUT

It is not an impossible situation. There is hope. Your ophthalmologist can help you to work through this decision, so that you can make it based upon the best evidence and information available. I wish you peace and courage as you embark upon the decision-making process.

Carolina Valdivia, MD

REFERENCES:

[1] Odberg T (1987). Visual field prognosis in advanced glaucoma. Acta Ophthalmol. 65, Suppl. 182, 27-29.

[2] Palmberg, P (2002). How clinical trial results are changing our thinking about target pressures. Curr Opin Ophthalmol. 13(2):85-8.

[3] Palmberg P (2004). Evidence-based target pressures: how to choose and achieve them. Int Ophthalmol Clin. 44(2):1-14.

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