Glaucoma Screening & Surgery
Glaucoma is considered an illness of the nerve conveying images from the eye to the brain. This is often, but not always associated with an increase in eye fluid pressure. The eyeball is “pumped” to a certain normal pressure by fluid production within the eye. In normal eyes, this pressure is often between 10-21 mm of mercury (mmHg).
Pressure in the eye that is above this range may damage the nerve by affecting the blood flow to the nerve, or may directly damage the nerve itself. Sometimes, the nerve itself is unusually susceptible to damage even at a normal level of eye pressure. Most treatments for glaucoma therefore aim to reduce the eye pressure to slow down or stop damage to the optic nerve. People who have a family history of glaucoma are at higher risk for glaucoma, and should be screened by the eye specialist for a raised eye pressure or other signs of glaucoma.
The initial treatment for glaucoma is usually with eyedrops to reduce the eye pressure. Many of these eyedrops now come with convenient once or twice a day dosing, and work for a large number of patients. Sometimes, 2 or 3 eyedrops may need to be combined to achieve a low enough eye pressure.
Unfortunately, some patients will need laser or glaucoma surgery to control their eye pressure when even multiple eyedrops provide unsatisfactory control. Laser treatment for glaucoma usually involves enhancing the drainage of fluid from the eye, or reducing the production of fluid, resulting in a drop in eye pressure. This can be done in the doctor’s office.
Glaucoma surgery is usually quick and effective, and is done as day-case surgery. With adequate anesthesia, surgery is painless. Certain chemicals may be used at the time of glaucoma surgery to reduce the amount of scarring at the surgical site, and improve the success rates of surgery. Following surgery or laser treatment, eyedrops are prescribed to reduce inflammation and infection and will need to be instilled usually for a few weeks to months.
During the assessment and follow-up of the glaucoma, the eye specialist will need to assess several parameters to determine whether the glaucoma is progressing. These include a visual field assessment, the eye pressure, and the size of the optic nerve hollowing (or cup-disc ratio).
A visual field assessment is a common investigation used to determine glaucoma progression. An automated machine projects a light in the patient’s field of vision, and the patient responds by pressing a button if the light is seen. The machine then goes on to map the area of functional vision by assessing which parts can and cannot see the light. This process takes about 5-10 minutes each eye, and gives the doctor an idea of the function of the eye and its optic nerve, and how much vision has been damaged by glaucoma. At EyeWise Vision Clinic, we use the Humphrey Visual Field system, which is the gold standard in glaucoma assessment.
If you have a family history of glaucoma or blindness in the family, especially in immediate family members then it is best for a thorough eye screening to rule out glaucoma. During its early stages, glaucoma has NO symptoms and no pain. Because of this, it has often been labeled “the silent thief of sight”.
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