TruScan 532 Single - Wavelength – Operators Manual Rev. No 02
Page 27 of 114
vitreous regions of the eye. If the patient’s eye does not allow for good transmission or
introduces some dispersion of the beam then the patient is not suitable for this type of
laser treatment. Increasing the laser power and pulse duration will generate more heat
and therefore the coagulative effect will be greater.
If the power or duration of exposure is too high then the surrounding tissue may
sustain some damage. Therefore, a careful selection of the power and pulse duration is
essential to a successful treatment.
Different Types of LDU
For the Slit lamp Delivery Units and LIO, the laser beam is delivered into the patient’s eye
as a focused spot that can be positioned accurately by the doctor to the treatment site.
When using the LIO the laser beam is delivered through a Contact Lens that is held by the
doctor and assists in positioning the laser beam on the site and setting the desired spot
size.
For the Slit lamp delivery unit the spot size at the treatment site is adjustable and set by
the doctor according to the type of treatment to be used. The spot size selector is
located on the delivery unit attached to the Slit lamp and can be set from 50µm to
1000µm in a continuous adjustment for the Integrated SL980 design.
TruScan system is integrated with SL980, the laser beam for LightLas Multi-Wavelength
Pattern Scanning System-TruScan 532 Single-Wavelength laser beam is delivered to the
patient’s eye by a high speed galvanometer scanner. The doctor has to select the
scanning pattern before treatment and spot size is adjustable from 50
m to 1000
m.
When using the Endoprobes, the doctor will use an Operating Microscope to view the
patient’s eye. These probes are inserted into the eye and used in very close proximity to
the treatment site (almost in contact). The Endoprobes are sterile devices intended for
direct patient contact and are a purchased item with a sterility guarantee.
For each LDU, a “Delivery Key” is used by the laser console as a means of determining
which type of LDU is connected. The Delivery Key is required because each type of LDU
has a different amount of loss through the optical elements and therefore the output
power factor calibration will be different for each. The Endoprobes have the least loss
of all the LDU’s because the only losses are through the fiber itself and in the coupling of
the laser beam into the fiber.
The LIO has more loss than the Endoprobes as it has a collimating system, mirror, and
focusing lens for the laser beam to be transmitted through and all of these have some
contributing losses. The least efficient of the LDU’s is the Slit lamp delivery unit. There
are many optics in this unit due to the spot size adjustment zoom system so the losses
are the greatest. Also when the small spot sizes are selected there may be some
aperture of the beam that contributes to the losses.
