Glaucoma Surgery in Turkey: SLT Laser, MIGS and Trabeculectomy in Istanbul

Glaucoma is a group of eye diseases that damage the optic nerve, the cable that carries what your eye sees to your brain. In most cases the damage is linked to pressure building up inside the eye. The front of the eye is filled with a clear fluid (aqueous humour) that is made all the time and drains out through a tiny sieve-like channel called the trabecular meshwork. When that drainage works poorly, fluid builds up, the pressure rises, and over time the pressure damages the nerve.

The most common form, open-angle glaucoma, develops slowly and usually has no symptoms in the early stages, according to the US National Eye Institute (NEI). Side (peripheral) vision is lost first, so many people do not notice until the damage is advanced. The American Academy of Ophthalmology (AAO) is clear that glaucoma damage is permanent and cannot be reversed, but that blindness from glaucoma can often be prevented with early treatment. Worldwide, the World Health Organization (WHO) estimates that glaucoma accounted for 7.7 million of the cases of vision impairment in 2020 that could have been prevented or have yet to be addressed.

Every glaucoma treatment, from eye drops to surgery, works in the same way: it lowers eye pressure, either by helping fluid drain out or by reducing how much fluid the eye makes. Lowering the pressure is the only proven way to slow glaucoma. Glaucoma surgery is not a cure, and it does not improve vision; its job is to protect the sight you still have. That is why the right moment for glaucoma surgery depends on how fast your glaucoma is changing, not only on a single pressure number.

High eye pressure means the fluid pressure inside your eye is above the normal range, because fluid is not draining out as well as it should. When the pressure is high but your optic nerve and visual field are still healthy, doctors call it ocular hypertension. It is not glaucoma yet, but it raises your risk of developing it. When high pressure has already damaged the optic nerve, it is glaucoma.

Pressure in the eyes is measured in millimetres of mercury (mmHg), the same unit used for blood pressure, but the two are unrelated: high blood pressure does not mean high eye pressure. High pressure in the eyes usually causes no pain and no symptoms you can feel, which is why it is normally found at a routine eye test. Tonometry (eye pressure measurement) →

Does high eye pressure always need treatment? Not always. In the large Ocular Hypertension Treatment Study (OHTS), 9.5% of people with high eye pressure who were only observed developed glaucoma within five years, compared with 4.4% of those treated with eye drops: treatment cut the risk by more than half. Most people with ocular hypertension never develop glaucoma, so the decision depends on your pressure, corneal thickness, optic nerve, age and family history.

The normal eye pressure range in the population is about 10 to 21 mmHg, with an average of around 15 mmHg in healthy adults, according to a 2023 review in Cureus. The AAO gives the typical range as about 10 to 20 mmHg. Your pressure is not a fixed number:

• it varies by about 3–5 mmHg over a normal day, usually highest in the early morning;
• in people with glaucoma, it can vary by 10 mmHg or more over 24 hours, and about two-thirds of glaucoma patients have their highest readings outside normal clinic hours (EyeWiki, AAO);
• the reading depends on your cornea: the standard Goldmann tonometer is calibrated for an average corneal thickness of about 520 microns, so a thicker or thinner cornea can push the reading away from the true pressure. Laser eye surgery thins the cornea and can make readings look falsely low (Royal College of Ophthalmologists, RCOphth).

This is why your doctor measures corneal thickness (pachymetry) and looks at your optic nerve and visual field, not just one pressure reading.

Ranges: Noya-Padin et al., Cureus 2023; AAO. Thresholds: NICE guideline NG81. A reading is always interpreted together with the optic nerve, visual field and corneal thickness.

Yes. An eye pressure of 17 mmHg is within the normal range of about 10–21 mmHg. On its own it is not a sign of glaucoma. Some people develop normal-tension glaucoma, in which the optic nerve is damaged despite normal pressure (AAO), so if you have a family history of glaucoma or your optician has seen changes in your optic nerve, keep having regular checks.

An eye pressure of 24 mmHg is above the normal range. It is the threshold the UK's National Institute for Health and Care Excellence (NICE) uses: if the pressure is 24 mmHg or more on Goldmann-type tonometry, NICE recommends referral to an eye specialist (ideally after a repeat measurement), and below 24 mmHg it advises continuing regular visits with your optician. If you have ocular hypertension of 24 mmHg or more and are at risk of visual impairment in your lifetime, NICE recommends treatment, with 360° SLT laser as the first option offered. A reading of 24 does not mean you have glaucoma; it means your eyes need a proper specialist assessment.

When people search "pressure behind my right eye", they usually mean a feeling of fullness or ache, not a measured eye pressure. Raised eye pressure from open-angle glaucoma almost never causes that feeling. The AAO notes that eye diseases are one of the least common causes of headaches; a pressure feeling behind one eye more often comes from sinus congestion, tension-type headache, migraine or eye strain from long periods of near work.

The important exception is acute angle-closure glaucoma. Here, fluid is suddenly blocked from draining and the pressure rises quickly. Warning signs, according to the AAO and NHS, include severe eye pain, headache, a red eye, blurred vision, rainbow-coloured halos around lights, and nausea or vomiting. This is a medical emergency: go to an emergency department or eye casualty straight away, because sight can be lost permanently if it is not treated quickly.

There is no safe way to reduce eye pressure instantly at home. Real, measurable eye pressure is lowered by prescribed eye drops, laser or surgery. If you have a sudden painful red eye with blurred vision or halos, do not try home remedies: get emergency care.

What the evidence does support, according to the AAO:

• Use your prescribed drops exactly as directed. Missing doses is one of the commonest reasons pressure stays high.
• Exercise regularly. Brisk walking and moderate exercise can lower eye pressure in some people with open-angle glaucoma.
• Avoid long head-down positions (inversion tables, some yoga poses), which can raise eye pressure considerably.
• Do not rely on supplements. Many herbal remedies are advertised for glaucoma, but none has been proven effective, and they should never replace prescribed treatment.
• Protect your eyes with safety glasses during sport and DIY, because eye injury is a glaucoma risk factor.

If what you feel is sinus or tension-related pressure behind the eye, the usual remedies for those conditions apply, and a pharmacist or GP can advise. If you are unsure, an eye test that includes a pressure check will tell you whether your eye pressure is actually high.

Prescription eye drops are the most common glaucoma treatment (NEI). Some reduce the amount of fluid the eye makes; others help it drain. In the UK, NICE recommends a generic prostaglandin analogue (such as latanoprost) as the usual first drop. Drops work well when used every day, but the AAO lists possible side effects including stinging, red eyes, eyelash growth, darkening of the iris or eyelid skin, and, with some drops, effects on pulse and breathing. If drops cause problems, or if you find them hard to use, tell your doctor: there are preservative-free drops, other drug classes, and laser and surgical alternatives.

Selective laser trabeculoplasty (SLT) uses a gentle laser on the eye's drainage meshwork, which triggers the body's own repair processes so that fluid drains better and the pressure falls. It is done in the clinic with numbing drops, takes about 10 minutes per eye, and most people feel no pain, according to Glaucoma UK. SLT typically lowers eye pressure by 20–30% (EyeWiki).

The evidence for SLT as a first treatment is strong. In the UK LiGHT trial, published in Ophthalmology in 2023, 69.8% of eyes treated first with SLT were still at their target pressure without drops or surgery six years later. Fewer SLT eyes progressed than eyes started on drops (19.6% vs 26.8%), fewer needed trabeculectomy (13 vs 32 eyes) and fewer needed cataract surgery (57 vs 95 eyes), with no serious laser-related side effects. Since 2022, NICE has recommended offering 360° SLT as the first treatment for newly diagnosed open-angle glaucoma that is not advanced, and for ocular hypertension of 24 mmHg or more when treatment is needed.

Two honest points: it takes about two to three months to know how well SLT has worked, and the effect usually lasts a few years and can wear off, although SLT can usually be repeated (Glaucoma UK). SLT may be unsuitable for advanced glaucoma or angle-closure glaucoma.

In angle-closure glaucoma, the coloured part of the eye (iris) blocks the drain. In laser peripheral iridotomy, your ophthalmologist uses a laser to make a tiny hole in the iris so fluid can flow to the drainage angle (AAO). It is a short procedure under numbing drops. In some people with narrow angles, cataract surgery can also lower eye pressure by creating more space between the iris and the cornea (AAO), so your surgeon may discuss lens surgery instead of, or after, laser. Cataract surgery in Turkey / Istanbul →

MIGS (minimally or micro-invasive glaucoma surgery) is a group of procedures done from inside the eye through a tiny corneal incision, with less disruption to the eye than traditional surgery and a faster recovery. Examples include trabecular bypass stents (such as the iStent inject and the Hydrus microstent) and procedures that open or remove part of the blocked drain (goniotomy or ab-interno trabeculotomy, for example with the Kahook Dual Blade). According to EyeWiki, MIGS suits people with mild to moderate glaucoma, people who cannot tolerate drops, and people having cataract surgery who want to reduce their drops.

Combined with cataract surgery, results are good in suitable eyes: in the pivotal trials summarised by EyeWiki, 75.8% of iStent inject eyes and 77.3% of Hydrus eyes achieved at least a 20% pressure reduction at two years. The limitation is equally clear: MIGS usually lowers pressure less than trabeculectomy and is often not enough for advanced glaucoma that needs a very low target. An NHS patient leaflet gives about 20 minutes for an ab-interno trabeculotomy on its own and about 40 minutes when combined with cataract surgery.

Trabeculectomy creates a new, guarded drainage channel in the white of the eye, under the upper eyelid, so that fluid drains into a small blister called a bleb and is absorbed (AAO). It is usually done under local anaesthetic and takes about one to two hours (Glaucoma UK). Anti-scarring medicine, such as mitomycin C, is commonly applied during surgery to help the new channel stay open; NICE recommends glaucoma surgery with this type of augmentation for advanced open-angle glaucoma.

Trabeculectomy can achieve lower pressures than other options, which matters when glaucoma is advanced. One NHS trust reports that pressure fell by at least a third in 66% of patients at one year, and about one in three may still need some drops. It is also the most demanding option for recovery: several clinic visits in the first weeks, adjustment of stitches, and at least two weeks off work.

Trabeculotomy opens the eye's natural drainage canal (Schlemm's canal) by cutting through the trabecular meshwork, so fluid can reach the outflow channels more easily. Modern versions are done from inside the eye as a MIGS procedure (ab-interno trabeculotomy or goniotomy), while the traditional external operation is used mainly for glaucoma in babies and children. Your surgeon explains which version, if any, suits your eyes.

In tube or shunt surgery, a tiny silicone tube is placed into the eye and carries fluid to a plate that sits under the eye's surface, where it forms a bleb and is absorbed. Common devices include the Ahmed glaucoma valve and the Baerveldt, PAUL and Molteno implants (Glaucoma UK). Tubes are usually offered when glaucoma is advanced, when pressure stays high after other treatments, or after previous eye surgery. Five years after surgery, Glaucoma UK reports that shunts still work well for more than 7 in 10 people.

Which is better, tube or trabeculectomy? It depends on the eye. In eyes that had already had cataract or glaucoma surgery, the Tube Versus Trabeculectomy (TVT) study found a 29.8% probability of failure with tubes compared with 46.9% with trabeculectomy at five years. In eyes with no previous surgery, the Primary Tube Versus Trabeculectomy study (2022) found that trabeculectomy with mitomycin C failed less often, with similar pressure reduction, and tube patients needed more drops.

Cyclodiode laser (laser to the fluid-producing ciliary body) is a further option, usually when surgery has not controlled the pressure or is not suitable (NICE).