Selecta
PBL200051, Rev J
102 Professional Use Instructions
SLT Clinical Procedure and Parameters
Selective Laser Trabeculoplasty (SLT)—532nm Nd:YAG
Prior to treatment, a topical anesthetic is administered to the eye to be treated.
A standard gonioscopy lens without magnifying optics is placed on the eye to
be treated. The pigmented trabecular meshwork is brought into focus using
the slit lamp.
Treatment consists of delivering 50 (±10) single, non-overlapping laser pulses
of a determined optimum energy level to 180 degrees of the trabecular
meshwork. The optimum energy level for treatment is defined as the
maximum energy that can be delivered without causing photodisruption/
optical breakdown of the trabecular meshwork. The optimum energy level for
treatment will vary from patient to patient because the threshold for thermal
injury, evidenced by bubble formation, is determined primarily by the level of
pigmentation in cells of the trabecular meshwork.
To determine the optimum energy level for treatment, the laser energy should
initially be set to 0.8 mJ. The aiming beam can be used to target the area to be
treated. Pulse delivery is controlled by means of a footswitch or activation
button on the slit lamp joystick. A single laser pulse is delivered to either the
six o’clock or twelve o’clock position of the trabecular meshwork. The energy
level should be increased or decreased by 0.1 mJ until bubble formation is
observed; the energy level at which bubble formation occurs is known as the
“threshold energy”. After the threshold energy has been identified, the laser
energy level should be decreased by 0.1 mJ; this lower energy level is known as
the “treatment energy”. Treatment should continue at the treatment energy
level until 50 (±10) single, non-overlapping laser spots have been created
along 180° of either the nasal or temporal segment of the trabecular
meshwork.
SLT Mechanism of Action
The mechanism of action of the Lumenis Selecta 532nm frequency-doubled,
Q-Switched Nd:YAG ophthalmic laser is the selective targeting of pigmented
trabecular meshwork cells. The Selecta achieves its intended effect through the
use of single laser pulses of short duration and low fluence (energy/area). The
short duration of the laser pulses minimizes the amount of heat that is
dissipated from pigmented cells and absorbed by surrounding, non-
pigmented tissues. When the Selecta is operated within a defined energy
range, the fluence of the resulting laser pulses is below the level where optical
breakdown occurs. Higher energy levels may cause photoacoustic and/or
photomechanical damage to adjacent non-pigmented cells or the trabecular
support architecture.
To Next Page
Loading...
