SLT laser settings are built around one idea: deliver the lowest pulse energy that still produces a visible, selective effect on pigmented trabecular meshwork cells. This guide walks ophthalmologists and laser technicians through the usual parameters of a 532 nm SLT laser, how energy is titrated, what to record, and which device features make the routine easier to repeat from patient to patient.
How an SLT laser works and which laser type is used
Selective laser trabeculoplasty uses a Q-switched, frequency-doubled Nd:YAG laser at 532 nm. The pulses are very short, so energy is absorbed by pigmented trabecular cells without the heat spreading into neighbouring tissue. That selectivity is the answer to the common question of how an SLT laser works, and it is why the technique is considered repeatable compared with older thermal trabeculoplasty.
The slit-lamp platform matters as much as the laser head. The CITO 532 is a Q-switched, frequency-doubled Nd:YAG built on diode-pumped µ-Chip technology, with coaxial slit illumination, laser and observation optics and a fixed 400 µm spot. The manufacturer quotes pulse energy from 0.2 to 2.0 mJ and a power deviation below 2%, which is relevant because stable output makes titration meaningful.
SLT laser energy: typical starting values and titration
Published protocols commonly start in the region of 0.8 mJ for a moderately pigmented angle and use lower values for heavily pigmented angles. The surgeon then raises or lowers the setting until the faintest tiny bubbles appear at the treated meshwork. If bubbles are large or the patient reports discomfort, energy is reduced; if no effect is seen, it is increased in small steps.
These figures are orientation only. The treating ophthalmologist sets energy according to the clinic protocol, angle pigmentation, prior treatment and the manufacturer instructions for the specific device. A 0.2–2.0 mJ adjustable range, as on the CITO 532, gives enough headroom for both lightly and heavily pigmented eyes.
Spot size, number of spots and repetition rate
The spot size on SLT devices is fixed and relatively large, about 400 µm, so it covers the meshwork width without precise focusing on individual cells. Treatment is applied through a gonioscopy lens, with the aiming beam placed on the pigmented band. Many protocols treat either 180 or 360 degrees, with adjacent but not overlapping spots, and the choice is a clinical decision.
Repetition rate affects chair time and ergonomics rather than outcome. The CITO 532 offers Quick-Repetition at about 10 Hz, which shortens a 360-degree session, but the surgeon still controls each pulse. When comparing machines, ask how the footswitch or pulse sequence behaves and whether a stable beam profile is maintained at higher rates.
Documentation, safety and room set-up
Good records make later retreatment decisions easier. Note laser model, energy used, number of spots and degrees treated, lens, pre-treatment and follow-up intraocular pressure, and any medication changes. A touchscreen that keeps the selected energy in view, as on the 7-inch display of the CITO 532, reduces transcription errors.
The CITO 532 is listed as laser class 3B and includes a permanent physician protection filter, but the room still needs local laser-safety rules: door signage, controlled access, and a designated laser safety officer. See our guides on medical laser safety and laser classes for room-level requirements.
What to ask a supplier before equipping an SLT room
Compare energy range and stability, spot size, repetition rate, optics quality, the slit lamp it sits on, and the table height range for wheelchair users. Ask about the service route in the UAE, training for technicians and the registration status of the device with the relevant authority.
If your clinic also performs capsulotomy, consider a combined workstation; see SLT versus YAG lasers for how the two compare. To discuss configuration and delivery, contact Beckfinity and our specialists will prepare a proposal for your clinic.
Frequently asked questions
What energy is normally used for SLT?
Many published protocols begin around 0.8 mJ and titrate up or down until minimal bubble formation is seen. The exact value depends on pigmentation and the clinical protocol, so it must be decided by the treating ophthalmologist.
Is the SLT spot size adjustable?
On most SLT devices the spot is fixed. The CITO 532 uses a 400 µm spot, which is designed to cover the trabecular meshwork without fine focusing.
How is an SLT laser different from a YAG laser?
SLT works at 532 nm with low-energy nanosecond pulses for the trabecular meshwork. Nd:YAG at 1064 nm is used for capsulotomy and iridotomy. Some workstations combine both.
Does the clinic need laser goggles for SLT?
The physician looks through a built-in protection filter, but anyone else in the room should follow the facility laser-safety policy, including eyewear rated for 532 nm where required.
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