Our good friend Dr. Kenneth Fong wrapped up the discussion with a dive into subliminal laser therapy for macular diseases.
He focused on the technical side of the procedure, so if you’re looking for numbers this is where your ears should perk up.
The duty cycle — mentioned earlier in this article — represents the difference between the on time and off time of a laser pulse.
For example, if a laser pulses for 100 µs and is off for 1900 µs, the duty cycle is 5%.
Allowing for time between pulses allows energy to remain concentrated in the tissue that should be targeted rather than diffusing out into adjacent tissue and causing collateral damage. ลาวสามัคคี วีไอพี
Dr. Fong pointed out that SubLiminal laser therapy offers a similar efficacy to classic laser photocoagulation while preserving the retinal tissue.
This same therapy is known to have a durable effect and can be combined with intravitreal therapies like injections of implants.
The limits come with visibility and managing treatment settings. Fortunately, the latter is what Dr. Fong is here to guide us with.
He suggested that a 577 nm wavelength has the ideal absorption characteristics of a uniform thermal effect, good penetration through opacities, and low xanthophyll absorption.
It also allows users to titrate power levels directly in the µpulse mode,
letting doctors reach a visible endpoint.
Additionally, since there is no intended thermal injury using SubLiminal, large, 160 µm spot sizes can be used to increase the treatment area and ensure a dense delivery of the laser impacts.
Doing so also minimizes the gaps between spots and maximizes the treated area. With a spot size of 160 µm and a duty cycle of 5%, Dr. Fong recommends an exposure time of 0.2 seconds.
The laser lens he uses is the Volk Area Centralis (0.94x) from Volk Optical (Ohio, USA).
Step one of the treatment involves power level titration.
First, a line pattern is used to determine the thermal threshold of each patient.
The power dose is evaluated in a healthy area of the macular periphery. Once the starting power has been selected, the laser spots of the pattern will automatically deliver increasing power.
The thermal threshold power level is obtained when a barely visible threshold burn is observed.
Then, reduce the power to 50% of the threshold power level for treatment.
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