Glaucoma is often defined as “high pressure in the eye”. But it is not the cause of glaucoma. Increased eye pressure is merely an associating risk factor that affects the disease. Glaucoma is a neurodegenerative disease. Nerve cells in the retina start to die. Leading neurodegeneration and glaucoma expert.
Let's start the conversation with glaucoma. Dr. Anton Titov, MD. Glaucoma results in increased pressure in the eye. It is often a silent eye disease until patients go blind. But when patients with glaucoma develop blindness, it's a significant disability. What is responsible for causing blindness in glaucoma? When pressure in the eye is increased. Dr. Francesca Cordeiro, MD. So, the concept of high pressure being the cause of glaucoma has changed over the time. We now say that the pressure being elevated in the eyes is a risk factor. It's not a criteria for diagnosis of glaucoma. We think now that glaucoma is more of a neuropathy. It’s a nerve eye disease. The eye pressure can modulate how the patient is affected. What happens is this. The nerve cells of the eye are specialized. These nerve cells are called the retinal ganglion cells. These are the cells that die over time in glaucoma. That's what leads to vision loss that develops in glaucoma. Dr. Anton Titov, MD. How does blindness develop in glaucoma? What are the first symptoms that patients with glaucoma notice? What is the symptoms that patients notice, if they are having this increased pressure in the eye? Dr. Francesca Cordeiro, MD. The thing about glaucoma is there are no symptoms. That's why it's called "the silent thief of sight”. Because patients don't recognize they have glaucoma. Because there's no way of knowing you have it. Because your brain compensates. Special compensatory mechanisms are filling in that we know a lot more of nowadays. What that means is where you cannot see things the brain patches missing information. Brain fills up those patches of lost vision. So, as a patient you wouldn't know you have the eye disease. That's one of the reasons why there is increasing evidence for traffic accidents. Patients with glaucoma are involved in road traffic accidents more often. Dr. Francesca Cordeiro, MD. There's great research being done around the world. This shows quite clearly the fact. Because your brain is filling things in, you may miss a child running through a road. Sometimes it happens to be in one of the areas that your brain has filled in. But you have not actually been able to see. What has to be done when you're talking about an eye disease that is asymptomatic and that is silent. You have to find ways of picking it up for the patient. That is where screening for glaucoma comes in. So, in this country one of the things that is offered to patients is glaucoma screening. Because we know that if you have a family history of the eye disease, you are at much greater risk of glaucoma than if you didn't. Especially if you're a first-degree relative with glaucoma. So, those patients who have first degree relatives with glaucoma, those relatives are offered free sight tests. What the sight tests do more in addition to measuring pressure. Increased eye pressure is a risk factor for glaucoma. But it's not actually a diagnostic criteria. They look to see if there are nerve changes at the back of the eye. You may be familiar with this. When you're going to the optician or your optometrist, they look at the back of your eye. They use the ophthalmoscope. They go very close to your eye. What they are looking at there is the visible structures of the nerve. This optic nerve that supplies vision. Optometrist sees if there's any damage to the back of the eye. In addition to that, they will do some imaging. Dr. Francesca Cordeiro, MD. Physicians will look to see if the optic nerve fiber layer of your eye is thinned. But also ophthalmologists will do what is called a visual field test. The visual field test still is the gold standard function test for for glaucoma. It's a little bit like playing Space Invaders game. You're positioned in a globe and the machine lights up at different places around this globe, randomly. You rely on the patient pressing the button every time that they are aware of light. There is some light that's flashing or coming into their field of vision. So, those ways of screening for the eye disease is the way we try to detect glaucoma. But it is very difficult to detect glaucoma. Often this is the real issue that we have. Patients present, more than anything else, with a loss of vision. Dr. Francesca Cordeiro, MD. In other words, you're already a long way down this decline of your vision loss. Patients are much nearer to blindness than if you had a symptomatic eye disease. Dr. Anton Titov, MD. You should be presenting to your ophthalmologist much earlier. Then you will possibly have better chances of stopping blindness occurring in the first place.