From observation of the temporal development of photocoagulation lesions generated by a quasicontinuous ruby laser source described earlier, it was concluded that lesions less densely distributed would still result in satisfactory welding of the retina. Biomicroscopic follow up of more than 200 cases has shown that this conjecture is essentially correct. Indeed, lesions of very low pulse energy lead to strong stimulation and proliferation of pigment epithelium. Among the cases only one, that is, 0.5%, developed postcoagulative maculopathy (puckering syndrome); whereas, of a comparable number treated with the Zeiss xenon photocoagulator, 3.1% were afflicted with this disease. This result is ascribed to the large difference in light energy between the xenon arc and the Siemens ruby laser apparatus required to cover comparable areas of the retina with coagulates.
Fankhauser F, Lotmar W, Roulier A. Photocoagulation Through the Goldmann Contact GlassV. Further Experience With a Quasi-continuous Ruby Laser Source: Long-Term Observations of Clinical Efficiency. Arch Ophthalmol. 1971;85(2):154-162. doi:10.1001/archopht.1971.00990050156007