Multi-Wavelength Pattern Scanning System - LightLas 532 / 670 – Operators Manual
Rev. No 01
Page 29 of 126
a source of energy to heat the tissue and thereby cause photocoagulation. The laser
beam is directly applied to the treated tissue and absorbed by the melanin pigment
within the retinal pigment epithelium and the choroid. This absorption converts the
light energy into heat energy which raises the temperature of the tissue being
treated producing thermal coagulation of the protein. The Green or UV laser beam is
readily transmitted through the cornea, lens, and 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 Multi-Wavelength
Pattern Scanning System - LightLas 532 / 670 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.
