GLAUCOMA TREATMENT MADE SIMPLE
Among ophthalmologists, it is said that you have had to have practiced for many years to understand the nature of the disease. This is because in most cases it is a long, slow process. However, within that framework, it is the ophthalmologist’s job to identify those individuals who have a more aggressive form of the disease and are at greater risk of vision loss.
The eyeball must have an internal pressure in order to function properly just as a basketball needs the proper pressure to bounce correctly. The normal range of eye pressure is 12 to 21mmHg. If you press on a healthy eye it will indent only slightly. Please don’t do this at home. When the pressure raises above 21mmHg, there is an increased risk of damage to the optic nerve; glaucoma. There are factors which muddy the water. Some people have thin corneas and some have thicker corneas, this effects the ability to accurately measure pressure and it effects the eye’s susceptablity to glaucoma. Using a pachymeter, the cornea thickness can be measured and the normal pressure is adjusted for the individual. Another confounding issue is that some people with elevated pressure don’t get glaucoma (ocular hypertensives) and some with normal or low pressure do get glaucoma (normal tension glaucoma). Based on this observation, it is clear that there is more to glaucoma than just eyeball pressure. But medical science at this moment in time only knows that if you lower eye pressure, patients tend to retain their vision. Some time in the future we will be directing the treatment at some neural-based regulatory mechanism controlling the circulation in the optic nerve.
Once the diagnosis is made, the question becomes, “how low does this patient’s pressure need to be so as to stop the progression of the disease.” Not surprisingly, it is different for each individual so the approach is to attempt to lower the pressure by 20% as the initial strategy. Once the target pressure has been achieved the vision is monitored for further loss of peripheral vision (visual field testing) and the appearance of the optic nerve is checked (optic nerve tomography) for degeneration. If patients continue to lose perpheral vision and/or optic nerve damage is progressive, the pressure is lowered further.
Pressure control is achieved with one of a number of eye drops which work by reducing the production of fluid within the eye or enhancing the outflow or both. If one or a combination of drops is not effective then laser surgery might be the next option or possibly traditional glaucoma surgery in the operating room.
In my experience, the majority of patients with open angle glaucoma do quite well with a lifetime of eye drops. In those people where pressure control is not attainable with conservative means (drops or laser) one must not waste time moving forward with surgical intervention. This is particularly important in younger individuals with advanced disease.
Tags: Glaucoma, glaucoma surgerry, normal tension glaucoma, ocular hypertension, optic nerve, optic nerve tomography, pachymeter, target pressure, visual field testing
