Glaucoma & High Eye Pressure

Glaucoma is a group of conditions that damage the optic nerve — the bundle of over a million nerve fibres connecting the retina to the brain — and is a leading cause of preventable vision loss. It typically has no symptoms in its early stages, affecting side (peripheral) vision first, which is why regular eye examinations matter even before any change in vision is noticed. With early detection and appropriate treatment, further vision loss can often be prevented or significantly slowed. Dr Zoran Aleksic diagnoses, monitors, and treats glaucoma at his rooms in Sea Point, Cape Town, and Vredenburg on the West Coast.

How Glaucoma Damages the Optic Nerve

A clear fluid called aqueous is constantly produced inside the eye and drains out through a spongy meshwork located where the cornea and iris meet, known as the drainage angle. If this fluid doesn't drain properly, pressure builds up inside the eye, which can progressively damage the optic nerve over time. In some people, the optic nerve can be damaged even when eye pressure is within the normal range, which is why a full assessment — not just a pressure check — is needed to properly diagnose and monitor glaucoma.

Open-Angle vs. Angle-Closure Glaucoma

Open-angle glaucoma is the most common form. The drainage angle remains open, but for reasons not fully understood, fluid passes through the drainage meshwork too slowly, allowing pressure to build gradually, usually without any noticeable symptoms until vision is already affected.

Angle-closure glaucoma accounts for roughly a third of glaucoma cases and occurs when the iris blocks the drainage angle, preventing fluid from draining properly. This can develop gradually over months to years, or suddenly over minutes to hours. A sudden (acute) episode is an ocular emergency, with symptoms including severe pain in and around the eye, seeing halos or rainbow-coloured rings around lights, reduced vision, nausea and vomiting, and eye redness — if you experience these symptoms, seek urgent care immediately rather than waiting for a routine appointment.

Risk Factors

You're at higher risk of glaucoma if you're over 40, have a family history of the condition, are of African, Hispanic, or Asian heritage, have high eye pressure, are short- or long-sighted, have had an eye injury, use long-term steroid medication, have thin corneas, or have conditions such as diabetes, migraines, high blood pressure, or poor circulation. For angle-closure glaucoma specifically, being over 60, female (women are about three times more likely to be affected than men), long-sighted, or having a strong family history all raise your risk. Having more than one risk factor increases your overall risk further, and is worth discussing directly with your surgeon so an appropriate monitoring or treatment plan can be set.

Diagnosis and Monitoring

Glaucoma can't be reliably diagnosed by an eye pressure check alone — a complete eye examination is needed, and typically takes around 30 minutes. This generally includes measuring eye pressure, inspecting the drainage angle, examining the optic nerve for damage, testing peripheral vision (a visual field test, or perimetry), photographing or scanning the optic nerve for future comparison, measuring corneal thickness, and assessing the thickness of the nerve fibre layer using optical coherence tomography (OCT).

Visual field testing (perimetry) measures your field of vision by showing small lights of varying brightness while you focus on a central point, building a map of any areas where sensitivity has been lost — an important test both for diagnosing glaucoma and tracking whether it's progressing over time.

Optic disc photography captures the appearance of the optic nerve itself, allowing your surgeon to compare its appearance over the years and detect signs such as thinning of the nerve tissue or small bleeding spots (disc haemorrhages).

OCT (computerised imaging) uses light to measure the thickness of the nerve fibre layer at the back of the eye in fine detail, helping detect early damage and monitor whether it's stable or progressing, alongside your other test results.

How often you'll need a full eye exam depends on your individual situation: if your eye pressure, optic nerve, and visual field are stable, testing every four months to a year is generally advised; if your glaucoma is progressing despite treatment, more frequent checks — around every four months — are usually needed until things stabilise.

Treatment Options

Glaucoma treatment generally starts with the least invasive option and escalates only if needed: eye drops first, then laser treatment, then surgery — with the goal of lowering eye pressure to protect the optic nerve from further damage, rather than restoring vision already lost. Which combination is right for you depends on the type and severity of your glaucoma, and your surgeon will discuss this with you after your assessment.

Laser treatment: SLT and LPI

Selective laser trabeculoplasty (SLT) is a quick, non-invasive laser treatment for open-angle glaucoma that helps improve natural drainage from the eye, lowering eye pressure. It's performed at Peninsula Eye Clinic (PEC) in Claremont and doesn't require hospital admission.

Drops are used beforehand to numb the eye and constrict the pupil, and the laser itself takes about five minutes, with your full visit taking around two hours, including a wait afterwards to recheck your eye pressure. It's generally painless, though you shouldn't drive yourself home afterwards due to the eye drops and bright light used. Effects can take up to six weeks to become apparent, and continuing your usual glaucoma drops as normal (including on treatment day, unless told otherwise) is important throughout. SLT doesn't damage the drainage tissue of the eye, so it can be repeated if needed, though it isn't suitable or effective for every type of glaucoma or every patient.

Laser peripheral iridotomy (LPI) creates a small opening in the iris to help fluid drain more freely, and can help prevent angle-closure glaucoma in some high-risk patients, or treat an acute angle-closure episode.

Glaucoma surgery

If drops and laser treatment aren't enough to control eye pressure, surgery may be recommended to create a new or improved drainage pathway. Several surgical approaches exist, and not all are suitable for every type of glaucoma:

Trabeculectomy creates a new drainage pathway for fluid to leave the eye, and is a well-established procedure, especially for open-angle glaucoma, typically used once medication and laser treatment haven't sufficiently controlled pressure.
Stent implant surgery combines trabeculectomy with the insertion of a tiny drainage stent, such as an iStent, XEN gel stent, or Preserflo device.
Tube-shunt surgery places a small tube and collection reservoir in the eye to drain fluid.
Deep sclerectomy removes part of the outer white layer of the eye (sclera) to create a thin membrane that fluid can pass through more easily, sometimes alongside an implant.
Viscocanalostomy widens the eye's natural drainage channels to improve outflow.

Trabeculectomy surgery is performed at Life Peninsula Eye Hospital, usually under general anaesthetic, though local anaesthetic with sedation may be suitable depending on your general health. The operation typically takes 45–75 minutes: a small flap and drainage opening are created in the white of the eye, allowing fluid to drain into a space under the eyelid, with small stitches placed in the flap. Anti-scarring medication is often applied to improve the long-term success of the procedure.

As with any surgery, trabeculectomy carries risks, which your surgeon will discuss with you in detail — these range from common, usually temporary effects such as mild bleeding, low or raised eye pressure in the days after surgery, and mild discomfort, to less common complications including infection, significant bleeding, the drainage opening becoming scarred and less effective over time (sometimes requiring further treatment), or developing a cataract over the longer term. Surgery aims to slow or stop further damage rather than restore vision already lost, and — as with all glaucoma treatments discussed here — no specific outcome can be guaranteed. Leaving glaucoma untreated typically leads to progressive, permanent vision loss, which surgery aims to prevent or delay.

Recovery After Trabeculectomy

You'll need a responsible adult to take you home and stay with you for at least 24 hours, and to avoid driving, operating machinery, drinking alcohol, or signing legal documents for at least 24 hours. Your eye will be padded for the first day and night; the pad is then removed and discarded the next morning. Post-operative eye drops are started the morning after surgery, and any glaucoma (pressure-lowering) drops you were using beforehand are usually stopped until your surgeon advises otherwise — please don't restart them without checking first. Mild scratchiness is normal, but the eye shouldn't feel painful; contact us immediately, rather than waiting for your next appointment, if you experience increasing pain, sudden vision changes, or feel unwell.

For the first 4–6 weeks, avoid swimming and dusty environments, and avoid heavy lifting or bending with your head below your waist until your surgeon has cleared you. Most people need around two weeks off work, though your surgeon will confirm timing based on your recovery. You'll be seen the day after surgery and several times over the following weeks, since minor adjustments — such as loosening a stitch to improve drainage — are sometimes needed as part of normal healing.

Because your surgeon will need to check your eye the day after surgery and see you several more times over the following weeks for follow-up and any minor adjustments, please plan to stay within the Cape Metro area for at least the first few weeks of your recovery.

Medical Aid and Cost

Glaucoma is a Prescribed Minimum Benefit (PMB) condition in South Africa, meaning medical aid schemes are required to cover its diagnosis and treatment, including monitoring visits, even if there are no other funds available on your plan — most schemes cover glaucoma monitoring around twice a year. Cover for specific surgical devices, such as stent implants, may not be included and can be an out-of-pocket cost — we recommend confirming your specific benefits with your scheme, and our rooms can provide the relevant clinical information for your enquiry.

Frequently Asked Questions

Can glaucoma be cured?

No. Glaucoma treatment aims to lower eye pressure and slow or stop further optic nerve damage, but it can't reverse vision already lost. This is why early detection and consistent monitoring matter — protecting the vision you still have is the main goal of treatment.

What happens if I don't treat glaucoma?

Without treatment, the optic nerve typically becomes increasingly damaged, and you're likely to experience progressive, permanent vision loss. Treatment won't restore lost vision, but can help prevent or delay further loss.

Is glaucoma surgery the first treatment option?

No. Treatment usually starts with eye drops, moving to laser treatment and then surgery only if these aren't enough to control eye pressure. Your surgeon will discuss which approach — or combination — is right for you based on your specific type and severity of glaucoma.

Is glaucoma monitoring covered by medical aid?

Yes. Glaucoma is a Prescribed Minimum Benefit condition in South Africa, so your medical aid is required to cover diagnosis and monitoring, typically around twice a year. Specific devices used in some surgical procedures may not be covered, so it's worth confirming the details with your scheme.

Is angle-closure glaucoma an emergency?

An acute angle-closure episode is an ocular emergency — symptoms include severe eye pain, halos around lights, nausea, vomiting, and reduced vision. Seek urgent medical attention immediately if this happens, rather than waiting for a scheduled appointment. Gradual angle-closure glaucoma, by contrast, usually causes no symptoms and is picked up through routine screening.

If you have risk factors for glaucoma, have been told you have high eye pressure, or would like a full glaucoma assessment, book a consultation with Dr Zoran Aleksic at The Eye Surgery in Sea Point or Vredenburg. You can also read patient reviews online.