Laser photocoagulation has traditionally been utilized to treat a variety of retinal diseases. However, continuous wave cyclophotocoagulation works by essentially destroying the ciliary body, often with collateral damage of the surrounding tissue. As such, there are high risks for adverse reactions.
Conversely, MicroPulse laser treatment (Iridex) is an effective alternative procedure with a much higher safety profile that is not marred by thermal damage. Instead, treatment results in the stimulation of the retinal pigment epithelium (RPE), inducing heat shock protein expression in the cells. Biologic activity is not possible in RPE cells that have been destroyed by laser. Therefore, a gentler treatment is necessary in order to create stimulation.
With MicroPulse, this stimulation is possible as the thermal energy of the laser is broken into smaller bursts instead of a continuous wave as in the past. This decreases the duty cycle of the laser, allowing retinal tissues to more effectively disperse the heat and avoid collateral tissue damage. Wavelength, power strength, pulse duration and spot size can all be altered as necessary to customize the level of thermal energy being applied. It does not take much. Short pulses of laser energy generally vary from 100 µs to 300 µs with rest periods between each pulse of 1,700 µs to 1,900 µs. Changes in the RPE have been shown with MicroPulse power settings as low as 10% of threshold power.
I liken this treatment to intense pulsed light treatments or even the fractional CO2 laser I use for facial rejuvenation. Fibroblasts can be stimulated with light, heat and energy, and true rejuvenation of the system is possible, no matter what system you are addressing, be it the skin or the trabecular meshwork.
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Wilson AS, et al. Invest Ophthalmol Vis Sci. 2003;doi:10.1167/iovs.02-0622.
Disclosure: Toyos reports she is a speaker and consultant for Valeant and Sun; conducts research for Lumenis, Magellan and Kala; is a speaker and consultant and does research for Shire, Mallinckrodt and MixtoLasering; is a consultant and does research for DigiSight; does research for Novaliq; and is a consultant for Iridex.