What is MicroPulse Trans‑scleral Cyclophotocoagulation (MTCP) laser treatment?

MicroPulse Transscleral Cyclophotocoagulation (MTCP)

MTCP is a cyclodestructive laser procedure that delivers repetitive short bursts of diode laser energy with intervening rest periods to reduce aqueous humor production by targeting the ciliary body, representing a safer alternative to traditional continuous-wave cyclophotocoagulation for glaucoma management. 1

Mechanism of Action

• MTCP works by delivering pulsed diode laser energy in an "on-off" pattern rather than continuous energy, allowing tissue cooling between pulses to minimize collateral thermal damage to surrounding structures 1
• The procedure reduces intraocular pressure (IOP) by decreasing aqueous humor production through selective destruction of ciliary body tissue 1
• Unlike traditional continuous-wave cyclophotocoagulation, the micropulse delivery system theoretically preserves more tissue architecture and reduces inflammatory complications 1

Clinical Efficacy

IOP Reduction

• Success rates for cyclodestructive procedures range from 34% to 94%, with MTCP demonstrating IOP reductions of approximately 30-42% from baseline 1
• At 18 months, MTCP achieves mean IOP reductions of 41.82% (from 39.14 mmHg to 22.77 mmHg), with success rates of 70-91% depending on baseline IOP 2
• Long-term data shows sustained IOP reduction of 32.5% at 5 years, with mean IOP dropping from 23.4 mmHg preoperatively to 13.8 mmHg 3

Medication Burden

• MTCP significantly reduces the number of IOP-lowering medications, with decreases from a mean of 2.6-3.5 medications preoperatively to 1.8-2.7 medications postoperatively 2, 4, 3
• The procedure is particularly effective at eliminating oral acetazolamide use, reducing usage from 29% of eyes preoperatively to 9% at final follow-up 4

Clinical Indications

Primary Uses

• MTCP is traditionally used for refractory glaucomas that have failed medical management or previous surgical interventions 1
• The American Academy of Ophthalmology guidelines indicate transscleral cyclophotocoagulation is a good surgical option for eyes with limited visual potential or those who are poor candidates for incisional ocular surgery 1

Expanding Role

• Recent evidence suggests MTCP may be appropriate for earlier-stage glaucoma, not just end-stage disease 5, 6, 3
• The procedure can be considered for patients at high risk for incisional glaucoma surgery complications 6

Safety Profile and Complications

Advantages Over Traditional Cyclophotocoagulation

• MTCP causes less postoperative pain and inflammation compared to cyclocryotherapy and continuous-wave laser cyclophotocoagulation 1
• The micropulse approach avoids incisional surgery, requires reduced postoperative care, and offers technical ease 1

Potential Complications

• Common complications include postoperative inflammation (present in 46% at 3 months), pain, hypotony, cystoid macular edema, and IOP spikes 1
• Vision loss of at least one line occurs in approximately 41% of eyes at 3 months, though this may be attributable to cataract progression, retinal disease, or glaucoma progression rather than the procedure itself 6, 3
• Rare but serious complications include sympathetic ophthalmia, phthisis bulbi, fibrinous reactions, and choroidal detachment 1, 3
• The procedure frequently requires repeat treatment weeks or months later, with mean treatment sessions ranging from 1.26 to 1.3 2, 5

Reversible Complications

• Most complications are reversible with treatment, including cystic macular edema (n=3), fibrinous/uveitic reactions (n=1), and corneal graft rejection (n=2) in long-term studies 3

Treatment Algorithm

Patient Selection

1. Consider MTCP for patients with refractory glaucoma uncontrolled on maximum medical therapy 1, 2, 5
2. Prioritize MTCP for eyes with limited visual potential or high surgical risk 1
3. Evaluate for patients who have failed previous glaucoma surgeries (39.4% of patients in long-term studies had prior glaucoma surgery) 3

Procedure Details

• The procedure uses a diode laser (typically 810 nm) delivered through a contact probe applied to the sclera 5
• Treatment typically covers 270-360 degrees of the ciliary body 1
• Patients report moderate pain during the procedure 2

Follow-up Requirements

• Monitor IOP at 1 day, 1 week, 1 month, 3 months, 6 months, and then every 6-12 months 2, 5, 6
• Watch for persistent inflammation, which may be present in nearly half of eyes at 3 months 6
• Be prepared to perform repeat treatments, as single-session success is not universal 1, 2, 5

Evidence Quality and Limitations

A 2019 Cochrane Systematic Review found inconclusive evidence whether cyclodestructive procedures for refractory glaucoma result in better outcomes and fewer complications than other glaucoma treatments, or whether one cyclodestructive procedure is better than another 1

Key Caveats

• Most available evidence comes from retrospective case series and prospective cohort studies rather than randomized controlled trials 2, 5, 6, 4, 3
• The American Academy of Ophthalmology states that selection of cyclophotocoagulation over other procedures should be left to the discretion of the treating ophthalmologist in consultation with the individual patient 1
• Additional randomized clinical trials are needed to elucidate the merits of MTCP relative to other cyclophotocoagulation types and other glaucoma surgeries 1

Common Pitfalls to Avoid

• Do not underestimate the need for repeat treatments—mean treatment sessions exceed 1.2, and some patients require multiple interventions 2, 5
• Do not assume immediate medication reduction—while IOP drops significantly, medication burden may only decrease substantially in the first 6 months 4
• Do not overlook persistent inflammation—nearly half of eyes still show inflammation at 3 months, requiring ongoing monitoring and treatment 6
• Counsel patients preoperatively about the possibility of vision loss, need for repeat treatments, and that complete IOP control may not be achieved 1, 6