Glaucoma is Not Just Eye Pressure
By Dr. Latif Hamed, MD, FAAO, MBA
Former Tenured Professor of Ophthalmology, UF College of Medicine
Many people think of glaucoma as high eye pressure. This is only partially true. More accurately, glaucoma is a disease of the optic nerve that leads to gradual loss of its fibers; it is often, but not always, associated with high eye pressure. The eye, like a football or a tire, has a recommended healthy pressure that if exceeded may cause optic nerve damage. What is the recommended eye pressure? Well, that is where the plot thickens. It turns out that the optic nerve’s ability to withstand pressure differs from one person to another. A pressure that may be high and damaging to one person may be entirely safe for another. Like people, some optic nerves are rugged and strong and can withstand higher pressure than other weaker and structurally fragile nerves. Therefore, although on average an eye pressure in the mid-teens may be safe to most, it may be too high for some patients with particularly fragile nerves and lowering to single digits in such patients may be required. This is an area of active research: How can we make the nerve more resilient to damage by promoting or administering neuroprotective factors?
Like an electric wire with many filaments, the optic nerve is a bundle of about 1.2 million fibers that connect the eye to the brain. Glaucoma entails losing a few fibers at a time and therefore the disease is gradual and surreptitious (sneaky) in the sense that the typical patient is unaware of the problem until the disease is advanced. This is particularly so since we have a lot of spare, redundant nerve fibers. We like to detect and treat glaucoma before the patient loses any fibers, and certainly before losing all of the spare fibers because any further loss will diminish the visual function.
Up to this point, we have mentioned eye pressure and the optic nerve structural strength as the two important factors in the genesis of glaucoma. If only things were this simple! The plot thickens even further as you delve deeper into the potential systemic, genetic, and environmental factors. However, our approach to treatment thus far largely focuses on those two factors: eye pressure and nerve strength.
First and foremost are treatments that aim to lower the eye pressure by instilling eye drops or performing eye surgery. If you know someone with serious glaucoma, then you may know that they need to take multiple eye drops of different types on a daily basis. Why so many eye drops for glaucoma? To answer this, you should know that the eye has a fluid cycle: fresh fluid loaded with oxygen and nutrients is secreted into the eye and then the fluid drains out through a filter or a sink. Normally, a balance occurs whereby the amount of fluid going in is equal the amount going out under normal pressure. If more fluid goes in than can be normally filtered out, or if the filter is clogged, then the pressure rises.
Therefore, to reduce the eye pressure we either need to decrease the amount of fluid going in or increase the amount of fluid going out. This is the basis for glaucoma drops and surgery so far. We have two basic eye drops: the first reduces the amount of fluid secreted into the eye and the second increases the amount of fluid that drains out of the eye. Some patients can be managed with just one type or the other, while others require a combination of drops to get their eye pressure low and safe enough.
The surgical procedures aim to do the same as the drops: either reducing the amount of fluid going into the eye or, more commonly, increasing the fluid coming out by creating a new drain or sink or outlet for the trapped fluid to get out of the eye to bypass the natural drain that is not working properly. These surgical procedures range from relatively brief laser procedures, to synthetic tubes and drains that are either implanted within the eye or bridge the inside and outside of the eye, to more involved surgical procedures that portend to fashion a new outlet for the fluid inside the eye to bypass the clogged natural drain.
Our discussion thus far has centered on what the medical profession has devised to help patients with glaucoma. This brings up an issue that I am passionate about, no matter what the ailment: The first question we as doctors and patients need to address is whether there are behavior modifications we can undertake besides medications and surgeries than can improve or cure the ailment under consideration before you embark on the pharmaceutical or surgical options.
The treatments we have for glaucoma now are far from ideal. Patients are prescribed daily drops and sometimes multiple kinds and multiple daily drops. That is inconvenient. These drops also have side effects such as burning and stinging, redness, blurred vision, and sometimes serious complications if given to the wrong patient. For instance, patients with heart failure and asthma may develop severe problems if given eye drops that are of the beta blocker variety.
The medical approach to health so far focuses on drugs that treat various diseases that often show up as we age, including glaucoma, cataract, heart disease, cancer, and stroke. Please focus on these two points:
Behavior modification by optimizing diet, exercise, sleep, and emotional and spiritual wellbeing should be the foundation of any treatment. For instance, one of the risk factors for glaucoma is diabetes, and most patients with diabetes develop it due to being overweight and then are ensnared in a web of medications that may lead to further weight gain and need of more medications, an unfortunate circuitous route that I see so often. We know that diabetes and hypertension are risk factors of glaucoma and that both are better controlled with proper diet and exercise, so it is the duty of healthcare professionals to help spark patients’ interest along those lines, and it is the intelligent thing to do from the patients’ perspective to not solely rely on the medical and pharmaceutical industry to safeguard their health.
All of these age-related diseases stem from a common stream that alters our biology as we age. Therefore, science is just beginning to ask the question of what causes our cells to age, and the answers may help us and our children to avoid or delay the onset of these diseases.
Until a solution arrives that can prevent or delay the onset of age-related diseases, we have to settle for the more modest accessible goals of treatment of a disease after the fact. The field of glaucoma is undergoing a renaissance. Instead of drops, we now have tiny implantable drug reservoirs that eliminate the need for drops. We have combination drugs all in one bottle to optimize convenience and compliance. And instead of major surgical procedures, we have much less invasive laser and micro incisional procedures that are sprouting rapidly. Finally, please remember that glaucoma in its most common form is silent, so routine checkups are recommended. Until we learn how to regenerate lost nerve fibers, any nerve fiber loss is permanent so prevention is key.
Take the First Step Toward Protecting Your Vision
Glaucoma often develops silently — but early detection makes all the difference. At Florida Eye Specialist Institute, Drs. Latif and Nadine Hamed and their team use advanced technology and personalized care to help protect your sight for years to come.
Schedule your comprehensive eye exam today. Call (352) 237-0090 or request an appointment online to keep your eyes healthy and your vision clear.
Don’t wait until symptoms appear — prevention is the best treatment.
