Dr. Miguel Boncquet Vieira

Ophthalmologist

Glaucoma:
New laser treatments SLT and MP-TLT

HPA Magazine 24 // 2025

What is glaucoma? 
Glaucoma is a chronic degenerative eye disease of the optic nerve that causes progressive and irreversible vision loss. In its early stages, it is asymptomatic (often called the "silent thief of sight"), gradually stealing peripheral vision. It is the leading cause of irreversible blindness worldwide, affecting around 80 million people. In Portugal, it is estimated that approximately 150,000 individuals suffer from glaucoma. Early screening and diagnosis are therefore crucial to initiate timely treatment and prevent severe vision loss. 
Glaucoma is generally associated with elevated intraocular pressure (IOP), which damages the optic nerve fibres over time. Among the identified risk factors for the development and progression of glaucoma, elevated IOP is the only modifiable factor, underscoring the importance of adequate control. 
There are several subtypes of glaucoma, with primary open-angle glaucoma being the most common. In all cases, the goal of treatment is to reduce IOP to halt disease progression and preserve the patient's remaining vision.

Conventional treatments and limitations 
Currently, the primary treatment for glaucoma involves hypotensive eye drops that lower IOP. Although effective, these medications can cause ocular and systemic side effects and face adherence challenges over time. When eye drops are insufficient to control the disease, surgery (such as trabeculectomy) may be necessary. 
While surgery effectively reduces IOP, it is invasive, carries significant risks, and requires a lengthy recovery. 
In recent years, innovative laser treatment options have emerged, aiming to overcome some of the limitations of eye drops and traditional surgery. Two of these therapies are selective laser trabeculoplasty (SLT) and micropulse transscleral laser therapy (MP-TLT), offering effective and safe solutions to halt disease progression at different stages.

SLT – Selective Laser Trabeculoplasty 
SLT is a minimally invasive laser treatment applied to the anterior segment of the eye, specifically the trabecular meshwork. Unlike surgery, it involves no cuts or tissue removal. 
It is performed with the patient awake, under topical anaesthesia, using a special contact lens to direct the laser at the trabecular meshwork. The laser stimulates the meshwork to enhance the drainage of intraocular fluid, leading to a reduction in IOP. The procedure is quick and painless, performed on an outpatient basis. After the laser treatment, IOP does not drop immediately but decreases progressively over several weeks. 
In terms of efficacy, SLT achieves an average IOP reduction of 20 to 30%. Clinical studies show that approximately 74% of patients treated with SLT maintained controlled IOP without eye drops over three years. SLT is primarily indicated for open-angle glaucomas. It can be used as initial therapy, avoiding or delaying the need for drops, or as an adjunct to medications. One major advantage of SLT is that it can be safely repeated if needed. Additionally, it is a cost-effective option, reducing the long-term need for continuous treatments. Regarding safety, SLT has an excellent profile. Adverse effects are generally mild and transient, such as slight ocular inflammation or temporary elevation of IOP, which are easily managed.

MP-TLT – Micropulse Transscleral Laser Therapy 
MP-TLT uses a diode laser applied through the sclera to target the ciliary body, reducing the production of aqueous humour and consequently lowering IOP. Unlike traditional continuous-wave cyclophotocoagulation, the MicroPulse technique delivers energy in short pulses with rest intervals, minimizing collateral tissue damage. The procedure is usually performed in the operating room under local anaesthesia, without incisions, on an outpatient basis. 
Studies demonstrate that this laser effectively reduces IOP (by an average of around 30%) and shows high success rates (over 70% of cases controlled) after one year. Thanks to its improved safety profile, MP-TLT can be used not only in refractory glaucoma cases but also in patients with moderate glaucoma and good visual acuity. Notably, by preserving ocular anatomy, MP-TLT keeps future treatment options open if necessary. Recovery is rapid, and ocular discomfort is generally mild and short-lived.

Advantages over conventional treatments 
Laser treatments SLT and MP-TLT offer several advantages compared to conventional therapies:
• Effective reduction of IOP (20–30% or more); 
• Minimally invasive and painless procedures; 
• Rapid recovery, with a return to daily activities within a few days; 
• Reduced long-term dependence on eye drops; 
• Very favourable safety profile, with rare serious complications; 
• Preservation of future surgical options, especially with MP-TLT.

Conclusion 
The availability of selective laser trabeculoplasty (SLT) and micropulse transscleral laser therapy (MP-TLT) at the Hospital Particular do Algarve represents a major advancement in glaucoma management. These technologies allow effective control of intraocular pressure with minimal impact on patients' daily routines, offering a safe, effective, and personalized alternative. SLT and MP-TLT personalize treatment for each patient, from early to advanced stages, improving quality of life and preserving vision. HPA thus reinforces its commitment to providing excellent healthcare, offering patients the most innovative and effective technologies to prevent glaucoma-induced blindness.