Laser treatment for glaucoma

When may it be indicated?

SLT is an option for open-angle glaucoma and ocular hypertension requiring treatment. It may be the first treatment or complement eye drops, for example when application is difficult, medication is poorly tolerated or pressure control is insufficient. The trabecular meshwork must be visible on gonioscopy.

The laser acts on pigmented cells in the meshwork, triggering a biological response that helps aqueous humour leave through the natural pathway. It does not make a hole in the iris or act as mechanical cleaning.

Success and results

LiGHT studied previously untreated eyes with open-angle glaucoma or ocular hypertension. The protocol allowed repeat SLT: this result does not mean a single session controlled all these eyes for six years, nor does it predict individual results.

The effect develops over weeks and may take up to around eight weeks to assess. Some eyes respond little or not at all. Benefit may decline over time; repeat treatment is considered according to the previous response. Do not stop eye drops without advice.

What should be monitored?

Discomfort, blurred vision, inflammation or a temporary pressure rise may occur. The team determines pressure monitoring and follow-up appointments.

When may it be indicated?

It is used in angle closure involving pupillary block and, in selected cases, to prevent an episode in eyes at significant risk. A narrow angle alone does not mean every eye needs this procedure: the decision depends on individual assessment.

The laser creates a small opening in the peripheral iris, usually with Nd:YAG. This allows aqueous humour to pass from the posterior to the anterior chamber, equalising pressure on both sides of the iris. Relieving the block may allow the iris to move backwards and open access to the trabecular meshwork.

What results are expected?

The aim is to treat the pupillary block component and reduce the risk of acute closure related to this mechanism. The opening does not drain fluid directly out of the eye. A narrow angle may persist because of other mechanisms, such as plateau iris, or existing adhesions.

The opening must be checked for patency, and the angle and pressure reassessed. Some eyes need another application, eye drops, lens surgery or another treatment. Iridotomy is not a universal cure for glaucoma.

Possible side effects

Inflammation, minor bleeding, temporary pressure elevation and, in some patients, reflections or lines of light may occur. The opening may be incomplete or close again.

What is its role?

Iridoplasty may be considered when the peripheral iris remains close to the trabecular meshwork, for example in plateau iris with residual closure despite a patent iridotomy. Gonioscopy helps distinguish reversible contact from adhesions and select suitable cases.

Thermal laser applications, usually argon, cause local contraction of peripheral iris tissue. The resulting traction moves it away from the drainage area and may widen the angle. Unlike iridotomy, it is not intended to make a passage through the iris.

Results and limitations

Angle opening may improve in the short term. Pressure reduction, the need for eye drops and duration of benefit vary. Long-term plateau iris studies report differing results; no single success percentage applies to all patients.

The angle can narrow again, and longstanding adhesions may limit the effect. Monitoring remains necessary, and other treatments, including lens surgery, may be considered according to the situation.

What should be monitored?

Inflammation, raised pressure and temporarily blurred vision may occur. Corneal injury is possible. The team determines medication and follow-up.

When may it be needed?

In deep sclerectomy, a thin trabeculo-Descemet's membrane is preserved. Aqueous humour filters through it into a reservoir created in the sclera. If membrane resistance limits filtration and pressure stays above target, goniopuncture may improve the surgical result.

Using a gonioscopy lens, the Nd:YAG laser makes a small opening in this membrane. The target is neither the iris nor the implant. Afterwards, the anterior chamber communicates directly with the reservoir: the barrier originally preserved during surgery is no longer intact at the treated site.

What results are possible?

Pressure may decrease, but the result also depends on healing and the function of the remaining drainage pathways. Fibrosis and movement of the iris towards the window may reduce the benefit.

Why is monitoring important?

Excessively low pressure, inflammation or obstruction of the opening by the iris may occur. Pressure and the treated area need reassessment; eye drops or further procedures may be necessary. An indicated goniopuncture does not in itself mean the previous operation has failed: it may be part of follow-up care.