What is the eye condition, glaucoma?

Glaucoma stands for a collection of eye conditions that affect the health of the optic nerve. Damage to the optic nerve arises from high intraocular pressure. Eye pressure rises due to the build-up of a fluid called “aqueous humour,” a natural watery discharge that surrounds and bathes the eye. Usually, fluid drains from tissue (trabecular meshwork), a point where the cornea and iris reach.
You may not be aware you have glaucoma until signs of this begin to develop in time. For example, the first signs of poor eyesight, such as loss of peripheral (side) vision, seeing halos, and a sudden decline in vision, start to occur.

Why does glaucoma occur?

The trabecular meshwork remains partially or completely blocked. As a result, aqueous humour may not drain adequately. The iris may also protrude unnaturally and obstruct the drainage angle where the cornea and iris touch. Therefore, fluid is unable to circulate, and eye pressure rises.

What does glaucoma screening consist of?

Usually, eye doctors can confirm glaucoma by conducting a comprehensive eye exam. However, just checking the eye's pressure will not suffice because various types of glaucoma arise due to structural defects, damage to the trabecular meshwork or its inefficiency.
Eye screening consists of a gonioscopy to explore the angle of the eye, an examination of the optic disc and retina through eye dilation and automated perimetry to check for defects affecting your visual field, as well as an OCT to look for any structural damage to the retinal nerve fiber layer.

How do you manage glaucoma?

A less intrusive surgery called minimally invasive glaucoma surgery (MIGS) utilises microscopic instruments to create small incisions and reduce eye pressure.

Doctors can lower eye pressure through the following surgical techniques:


An iStent is most probably the smallest device that can be implanted into the body, more especially the eyes. This tiny titanium stent is implanted in two different positions in the front of the eye. By creating a bypass, more fluid can pass through the eye’s drainage system.

XEN gel implants

XEN gel implants are made to reduce eye pressure in patients with open-angle glaucoma, a procedure known as aqueous shunt surgery. This particular implant works by opening up a channel for fluid to drain through.

High-Frequency Deep Sclerotomy (HFDS)

High-frequency deep sclerotomy is a minimally invasive microscopic procedure that involves immediate access to the Schlemm’s canal from the anterior chamber. The Schlemm’s canal is a structure designed to drain aqueous humour into the eye’s drainage system.

Trabeculectomy surgery

Trabeculectomy surgery aims to create a new channel for the liquid to flow to relieve optic nerve compression. Trabeculectomy is a procedure that entails creating a new pathway for aqueous to filter. This procedure works by making an ostium from the anterior chamber.

Glaucoma drainage devices:

Baerveldt tube

Baerveldt tube is a glaucoma drainage device inserted in the eye to reduce the build-up of intraocular, aqueous fluid. As a result, aqueous humour flows out from the inner eye to a tiny capsule, also known as a bleb, just outside the eye.

Ahmed valve

Aqueous shunt procedures to treat glaucoma boast high success rates within five years of between 60-80 per cent. An Ahmed valve is just one way to redirect the aqueous build-up. After implantation of an Ahmed valve, most patients discontinue the use of eye drops or administer them at a low dose.

Paul Glaucoma implant

A Paul glaucoma implant named after the creator, Professor Paul Chew in Singapore, is a silicone-made, medical-grade device used to reduce pressure from the accumulation of intraocular fluid.

Further laser operative procedures include:

SLT laser (Selective laser trabeculoplasty)

SLT is performed in the comfort of the eye doctor’s office. Unlike the above procedures that rely on shunt devices to reduce high eye pressure, a laser is used to promote intraocular fluid's outflow. SLT utilises short wavelengths of low light to target pigment in the affected eye cells. In response, the body reacts by producing a healing response to assist the cells in recovering.


An Iridoplasty (Gonioplasty) uses low-level energy beams, which the doctor applies to the peripheral iris. This helps dilate the anterior chamber angle or eliminate synechiae (adhesions).

YAG peripheral iridotomy

A small puncture is made in the outer region of the iris, the part that provides colour to the eye, using a YAG laser. This procedure aims to increase space in the angle to expose the trabecular meshwork, increasing the outflow of aqueous.

Micropulse laser

A micropulse laser is a tissue-sparing procedure. Short, low-dose laser beams are applied with brief rest periods in between treatments to give the tissue (trabecular meshwork) time to cool down.

Cyclodiode laser

A Cyclodiode laser is a handheld device used to remedy refractory glaucoma for patients with painful eyes. A Cyclodiode laser terminates tissue (ciliary body), producing aqueous humour. The ciliary body rests just after the iris, the part of the eye that gives the eye colour.


Glaucoma eye drops

Glaucoma eye drops reduce pressure built up from the rise of aqueous humour. After waiting three to four hours, you will notice the difference as the fluid drains. Eye drops must be taken regularly, every day, as prescribed by your eye doctor.



What are some of the symptoms that signal open angle glaucoma

Symptoms include:

  1. Elevated intraocular pressure
  2. Changes/abnormalities of the optic disc
  3. Blind spots
  4. Tunnel vision
  5. Loss of peripheral vision

Is glaucoma a painful condition?

Generally, glaucoma is not recognised as a painful condition, but it can lead to blindness when not treated early enough. However, glaucoma can lead to severe eye pain. Some people describe the pain as the worst pain they have ever experienced. The condition only becomes painful when eye pressure rises significantly. This is often seen in patients with neovascular glaucoma, whereby new blood vessels form on the iris and obstruct the drainage angle.

How can you stop glaucoma pain?

Topical eye antihypertensive medication is usually prescribed to treat glaucoma pain. Your eye doctor may also prescribe secondary medications (b-blockers, carbonic anhydrase inhibitors, etc.) at a set frequency.

Dr Philip and Dr Precious Phatudi
are skilled ophthalmologists based in Sandton