27
Clinical & Safety
13102C-EN
Power density and spot size
Tissue response to laser light is primarily determined by power density
.
Power density (Watts/cm
2
) is laser power (Watts) divided by the area (cm
2
)
of the illuminated spot; therefore, you can increase power density either
by increasing the laser power or by decreasing the spot size.
It is important to remember that changing the aspheric lens affects spot
size, power density, and the field of view.
Choosing anesthesia
Topical anesthesia is most commonly used and has advantages over
general anesthesia. Topical anesthesia decreases the blink reflex. The
patient is not sedated and maintains the ability to change positions if
necessary during treatment.
Retrobulbar anesthesia may be desirable when treating the anterior half of
the eye. It is often more painful treating anteriorly compared to treating
the posterior retina. The disadvantage; however , is the removal of the
patient’s ability to move the eye is various directions. Scleral depression is
vital in manipulating the eye during
TruFocus LIO+ treatment with
retrobulbar anesthesia.
NOTE
The relationship between
spot size and resultant
power density is not linear.
Halving the spot size
quadruples the power
density. The physician
must understand the
relationship between spot
size, laser power, power
density, and laser/tissue
interaction before using a
console and the
TruFocus LIO+.
