Glaucoma is a condition of high pressure in the eyeball and is one of the most common causes of preventable blindness in the world. This leads to a reduced visual field and loss of sight, and if not treated, may lead to blindness. When the small channels that drain the fluid (aqueous humour) from the eye become clogged or completely blocked, pressure builds up in the eye and this damages the optic nerve. The eye can also produce too much fluid which cannot drain fast enough through the channels. Doctors measure intraocular pressure with a test called tonometry. Normal intraocular pressure is 10-21mmHg.
What are the risk factors?
Glaucoma affects people of all races, ages and genders.
The following people are at higher risk:
- Over the age of 40
- Family history of glaucoma
- Abnormally high intraocular pressure
- African, Scandinavian, Celtic or Russian ancestry
- Long-term use of steroids
- Previous eye injury
- If you suffer from high blood pressure or migraine
What are the symptoms?
Many people do not know that they have glaucoma until they lose some of their eyesight. It is a painless condition that develops slowly over time. Patients experience a gradual worsening of their peripheral vision. Unfortunately, the loss of vision is permanent and can’t be reversed. There are differrent types of glaucoma depending on the cause and they are treated accordingly.
How is it treated?
The goal of treatment is to reduce the intraocular pressure. This is mainly accomplished by the use of drops, but occasionally surgery or laser treatment is needed. The drops work by either increasing the drainage of fluid through the drainage canals or by decreasing the amount of fluid (aqueous humour) production.
- Prostaglandin analogues
- Beta blockers
- Alpha agonists
- Carbonic anhydrase inhibitors
Two forms are available for open angle glaucoma; Argon laser trabeculoplasty (ALT or LTP) and selective laser trabeculoplasty (SLT). The ophthalmologist uses the laser to stimulate the drainage canals to drain more effectively.
If medical treatment and laser surgery do not work, incisional surgery may be indicated.
The ophthalmologist creates an entirely new drainage system for the eye. Trabeculectomy and the application of artificial valves (such as the Ahmed valve or Ex-Press valve) are examples of this kind of surgery.
Micro-invasive glaucoma surgery(MIGS)
MIGS is the latest advance in surgical treatment for glaucoma. MIGS comprises a group of surgical procedures which share common features. MIGS procedures involve a minimally invasive approach, often with small cuts or micro-incisions through the cornea that causes the least amount of trauma to surrounding scleral and conjunctival tissues. The techniques minimize tissue scarring, allowing for the possibility of traditional glaucoma procedures such as trabeculectomy or glaucoma valve implantation (also known as glaucoma drainage device) to be performed in the future if needed.
Traditional glaucoma surgery generally involves an external approach through the conjunctiva and sclera; however, MIGS procedures reach their surgical target from an internal route, typically through a self-sealing corneal incision. By performing the procedure from an internal approach, MIGS procedures often reduce discomfort and lead to more rapid recovery periods. While MIGS procedures offer fewer side effects, the procedures tend to result in less intraocular pressure (IOP) lower than with trabeculectomy or glaucoma tube shunt implantation.