Glaucoma is defined as a chronic progressive optic neuropathy. This first sentence may be a difficult one to understand, but we will make an attempt to make sense of it. Glaucoma is a disease that commonly over a period of time, month to years, cause damage to the optic nerve and cause loss of sight little by little, until all vision is completely lost. This does not mean there are no treatments to prevent this loss of vision.
First of all, many of you, who come to see us as your ophthalmologists, come for a number of reasons. You have been labeled as one of the following: “Glaucoma Suspect,” “Ocular Hypertensive,” or simply a patient with “Glaucoma.” It is very important to understand exact nature of why you see us.
Patients that are glaucoma suspects are ones that have a suspicious finding on physical exam that warrants further evaluation. This simply means that a firm diagnosis cannot yet be made, and treatment may be delayed until further details are explored. Many times these suspicions are based on appearance of the optic nerve, difference in appearance of the optic nerve, high pressures of the eyes, and/or history of glaucoma in the family.
When the pressure reading in the eye is high, it is cause for alarm. High pressures over time may cause damage to the optic nerve and result in glaucomatous loss of vision. So what is the normal range? Each person has to have an individualized scale. Statistically speaking 95% of patients with “normal” pressures fall in between 10 and 21, BUT, there are folks that a pressure of 10 is too high for them and there are others that a pressure of 25 is perfectly normal for them. The eye pressure has to be customized for each individual based on age, corneal thickness, health of the eye and the optic nerve. Some doctors tend to read pressures higher or lower relative to other doctors. Ophthalmologist who see a large number of glaucoma patients tend to be much better at gauging their personal pressure reading.
A patient with “ocular hypertension” is one in whom the pressure readings of the eye may be high, yet there has been no glaucoma damage to the optic nerve. In this case, ignoring the pressure for too long may lead to glaucoma damage.
There are a myriad of ways to classify glaucoma. Most ophthalmologists tend to grossly agree on 2 major classifications of the glaucoma based on appearance of the drainage angle of the eye, open-angle and narrow-angle.
Open Angle Glaucoma
Open-angle glaucoma is by far the most common variety in our patient population. In this type of glaucoma, the fluid inside the eye has open access to the drainage angle, yet, the drainage systems of the eye no longer drain well and has high resistance to fluid drainage. This causes a relative “back-up of fluid” inside the eye causing the pressure to rise.
Therapy for open angle glaucoma centers on either a) reducing fluid production or b) increasing fluid drainage. By far the vast majority of patients are able to bring their pressures under control by simply using medicated eye drops. It is essential for patients to understand that these therapies DO NOT improve the eye in anyway shape or form… They ONLY help PRESERVE the vision that still exists. Once vision is lost, there is no recovery. This is why it is essential that your doctor’s instructions are followed faithfully. In few patients, glaucoma drops may not be sufficient for lowering the pressure enough and we must resort to a surgical treatment that creates alternative pathways for fluid drainage. The most common glaucoma surgery is called trabeculectomy. Tube shunts and more sophisticated procedures also are part of any surgical consideration.
Narrow Angle and Closed Angle Glaucoma
Narrow-angle glaucoma is less common. In this type of glaucoma, the fluid inside the eye has poor access to the drainage angle. Fluid may accumulate behind the iris and push the iris forward to cause further compromise of the drainage angle leading to episodes of “angle closure glaucoma.” Sometimes, an angle-closure glaucoma attach can happen when too much fluid is build behind the iris and causes the iris to bow forward and completely block all the draining sites. During such attach, the pressure can rise to 50 or more and result in significant permanent loss of vision. In the vast majority of cases, patients have small recurring events where pressure raises some, causing minimal, yet cumulative, damage without the frank exaggerated angle-closure glaucoma attach.
Treatment for this type of glaucoma is centered on creating an alternative pathway for fluid to get around the iris, a laser iridotomy. Unfortunately, sometimes it is not sufficient to perform a laser, rather, the lens inside the eye (which when clouded is called cataract), must be “de-bulked” by removing it. In some eyes the cataract mechanically is too large (5–6 mm in thickness) and compromises the drainage angle. Removal of the cataract and replacing it with a thin 1 mm intraocular lens creates an enormous change in many patients.
Amin Ashrafzadeh, MD, is proud to offer patients a range of leading-edge treatments, including advanced glaucoma procedures, refractive laser eye surgery and cataract surgery.