Iridex IQ 577 - Page 6

2 IRIDEX IQ 577
®
/IQ 532
®
Laser Systems Operator Manual 15510-EN Rev G
MicroPulse (Optional)
MicroPulse (μP) is a laser delivery consisting of a group of microsecond bursts.
Duty Cycle% =
μP Duration
× 100
μP
Duration
+
μP
Interval
MicroPulse is typically used to administer subvisible threshold laser treatments to macular
and perimacular targets. When used here, the terms “subvisible”, “subvisible threshold”
or “subthreshold” denote that the desired endpoint is one in which treated tissue offers no
ophthalmoscopicallyobservablelasereffects.Nevertheless,577nmand810nmstudieshave
confirmed that subvisible laser treatment strategies can be clinically effective while inducing no
changes discernible by slit lamp observation, fluorescein angiography (FA), fundus autofluorescence
(FAF), or at any time postoperatively.
1,2
Tissues receiving subvisible MicroPulse laser treatment show no such changes because:
• MicroPulselaserdeliveryisbeingusedinsteadofCW,and
• Thetotallaserenergyofsuchdosesisonlyapercentage(oftenchosenbyclinicianstobe20-70%)
of that energy needed to produce a visible endpoint.
Energy (J) is equal to [Laser Power (W)] ×[ExposureDuration(s)]×[DutyFactor(%/100)].DutyFactor
isoften5%to15%whenusingMicroPulsemode,andis100%whenusingCWmode.Clinicianshave
reported various strategies to adjust these parameters relative to suprathreshold burns in order to
achieve clinically effective subvisible endpoints.
1-4
Additional parameters to consider in any laser treatment protocol, and particularly during
MicroPulse, is spacing between laser treatment spots, and the total number of treatment spots
administered.DuetothelimitedthermalspreadofMicroPulseexposures,subvisibletreatmentsoften
call for the administration of a greater number of treatment spots with denser spacing than that used
for threshold laser grid treatments.
4
MicroPulse
μP
Interval
μP
Duration
Pulse Envelope
Duration
Pulse Envelope
Interval
Time (ms)
Power (W)