Clinical Guide
Smart532
™
A-8 UM-1151440EN, Rev. C, May 2016
Media opacities such as a non-transparent cornea, a dense cataract or a
vitreal hemorrhage can obstruct the delivery of laser energy through a slit
lamp or an LIO. A solution is to circumvent these media opacities by
delivering the laser energy via an endoprobe (a disposable fiber optic). In
addition, laser delivery via an endoprobe is often employed in the
operation room, as an adjunct to vitreo-retinal surgery.
The endoprobe is inserted in the ocular globe via a scleral incision done at
the pars plana level. The size of the laser burn can be controlled by
changing the distance from the tip of the endoprobe to the target: the closer
the tip probe is from the retina, the smaller and more fluent (i.e., higher
energy density) is the spot of influence.
The following precautions should be taken when using laser energy in
ophthalmic procedures:
● Excessive power density (power/area) may cause unwanted target
tissue damage. Hence, caution must be exercised when reducing the
spot size, as the spot size is inversely related to the power density:
decreasing the spot diameter by 1/x multiplies the power density by x
2
.
For example, halving the spot diameter quadruples the power density.
● Approximate power settings are usually found by titration using a
continuous waveform at a peripheral location, starting from low values
and gradually increasing the power, until the desired endpoint (such as
blanching in posterior segment indications) is achieved. Once power
settings P
vis are identified through titration with a continuous
waveform, if the user desires to operate in SmartPulse Mode then the
power typically used is P
vis multiplied by a factor of 1.2 to 2.0 (see
Table A-2 for references)
● Increased pigment density can increase the absorption of laser energy,
thereby increasing the thermal effect. Physicians should take account
of this fact when intending to treat areas of increased pigmentation,
either by reducing the power setting, or by treating areas with less
pigmentation.
● Opacities in the ocular media may absorb the laser light and cause
inadvertent and undesirable thermal damage to the tissues in which the
opacities are located. Opacities in a patient’s ocular media include
makeup remnants in the corneal tear film, corneal lesions, pigment or
blood on the surfaces of the crystalline lens, and cataract formation.
Prior to laser therapy, debris should be removed from the patient’s tear
film.
● Direct treatment of vascular or vascularized structures can cause
intraocular bleeding that can impair a patient’s vision as well as the
physician’s ability to complete the laser procedure.
Vascular/vascularized structures should be treated with caution, using
treatment patterns and parameters appropriate for the specific
indication and conditions.
Precautions
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