Advanced Glaucoma Surgery
What is Glaucoma?
Glaucoma is a complicated disease in which damage to the optic nerve leads to progressive, irreversible vision loss. Glaucoma is the second leading cause of blindness. Glaucoma damage may be caused by raised eye pressure or a weakness in the optic nerve. Your eye needs a certain amount of pressure to keep the eyeball in shape so that it works properly. The eye contains a clear watery fluid that circulates within the eye and gets drained away through drainage channels known as the ‘trabecular meshwork’. In the normal eye, the amount of fluid produced and the amount being drained is equally balanced. However, in glaucoma this balance is upset and causes the intraocular pressure to rise. It is this rise in pressure that damages the optic nerves. The amount of damage there is depends on how high the pressure is and how long it lasts, and whether there is a poor blood supply or other weakness of the optic nerve.
Types of glaucoma
The different types of glaucoma include:
- Open Angle Glaucoma: in this type of glaucoma, the angle between the iris and cornea is wide and open. As a result, the eye’s drainage system (trabecular meshwork) remains free of obstruction although increased resistance to fluid leaving the eye may still occur. This type of glaucoma may either be primary or secondary to other conditions such as pigment dispersion syndrome or pseudo exfoliation syndrome.
- Primary Open Angle Glaucoma:
Primary open angle glaucoma (POAG) or chronic glaucoma is the most common type of glaucoma. As a chronic condition its effects occur slowly over time.
In Primary Open Angle Glaucoma, the drainage of the aqueous fluid from your eye doesn’t happen as well as it should and this causes the pressure to increase. Your eye may seem perfectly normal and your eyesight will seem to be unchanged – because when the pressure starts to build up it doesn’t cause you any pain – but your vision will still be getting damaged.
Your peripheral vision, which is the vision you have around the edge of what you are looking directly at, gradually gets worse. This type of glaucoma becomes more common over the age of 40, so you should have your eyes tested every two years.
- Angle Closure Glaucoma: in this type of glaucoma, the angle between the iris and the cornea comes into contact resulting in a blocked trabecular meshwork. This may happen either quickly (acute) or slowly (chronic) and can be either primary or secondary to other conditions such as uveitis, neovascularisation or iridocorneal endothelial syndrome (ICE).
- Congenital Glaucoma: This type of glaucoma occurs before the age of 2 years and often runs in families. It is caused by improper development of eye’s drainage channels before birth.
Risk factors for Glaucoma:
Awareness and early detection of glaucoma are extremely important because this disease can be successfully treated when diagnosed early. While everyone is at risk for glaucoma, certain people are at a much higher risk and need to be checked more frequently by their ophthalmologist. The major risk factors for glaucoma include:
- Age over 45 years
- Family history of glaucoma
- Black racial ancestry
- History of elevated intraocular pressure
- Nearsightedness (high degree of myopia), which is the inability to see distant objects clearly
- History of injury to the eye
- Use of cortisone (steroids), either in the eye or systemically (orally or injected)
- Farsightedness (hyperopia), which is seeing distant objects better than close ones.
The goal of glaucoma treatment is to decrease the pressure in the eyes. This is achieved using special eye-drops or medications. Surgery is recommended if medications don’t yield the desired result, or with an aim to prevent further vision loss or blindness.
Depending on your particular situation, surgical options include:
- YAG Laser: A YAG targets specific cells in the trabecular meshwork by using a powerful beam of light directed into your eye. This treatment eases the outflow of fluid from the eye, thereby reducing the pressure inside the eye.
- Peripheral Iridotomy: This procedure is used for a relatively less common type of glaucoma called closed angle glaucoma that causes a sudden buildup of pressure in the eyes, which can lead to an irreversible loss of side and central vision. During iridotomy, the laser creates a small hole in the outer region of the iris (colored part of the eye). This allows free circulation of fluid in the eye, thereby lowering the eye pressure.
- SLT (Selective Laser Trabeculoplasty): SLT is employed in the most common type of glaucoma called open-angle glaucoma that develops slowly over time. During SLT, the frequency of the laser beam is varied to target specific cells of the trabecular meshwork. This procedure opens up the clogged areas in the mesh work, making it easier for the fluid to flow out of the eye.
- Trabeculectomy with or without antimetabolic agents with releasable sutures: Trabeculectomy is a commonly employed surgical procedure that relieves pressure in the eye caused due to glaucoma. It involves creation of a new drainage channel that allows the fluid to drain out of the eye leading to the formation of a bleb covered by a white outer covering (conjunctiva) of the eye. The drainage site may scar over time leading to its closure. This scar formation can be prevented with the help of antimetabolites, which act by inhibiting the multiplication of cells forming the scar tissue.
- Express Shunt: This is a simplified version of trabeculectomy. This procedure uses an extremely small tube to divert the fluid to outside of the eye. As only controlled and precise amounts of fluid are let out, the internal pressure of the eye stands maintained at a healthy level.