LASER VS XENON ARC PHOTOCOAGULATION
Because the light source from laser is coherent and monochromatic, it offered many practical advantages over the gas discharge lamp’s electric light. Although the landmark Diabetic Retinopathy Study (DRS) of the 1970s is commonly cited for photocoagulation’s ability to reduce severe visual loss in diabetic retinopathy, the study also compared the argon blue-green laser to Dr. Meyer-Schwickerath’s xenon arc photocoagulator.
Argon laser and xenon arc photocoagulation were both found to decrease the likelihood of severe vision loss in proliferative DR. When the argon laser-treated eyes were compared to the xenon arc-treated eyes, the former had less early vision loss, peripheral vision loss, and progression of pre-existing tractional retinal detachments.
The DRS results, in addition to the relatively awkward inefficiency of the xenon arc photocoagulator, paved the way for the development of lasers for retinal photocoagulation, including the ruby, argon, and krypton lasers.
The physical design of these latter lasers included coupling them to a slit lamp with rotating mirrors and a mobile joystick, which allowed them to project a single aimed beam onto the retinal surface.