ALTERATION OF PULSE CONFIGURATION AFFECTS THE PAIN RESPONSE DURING DIODE-LASER PHOTOCOAGULATION

Background and Objective: The shape of the treatment pulse of the diod e laser (810 nm) can be easily altered electronically in contrast to i on laser photocoagulators. We investigated whether changes in laser pu lse shape influenced the subjective pain response in patients undergoi ng retinal photocoagulation when only topical anesthesia was used. Stu dy Design/Materials and Methods: Twenty consecutive patients required peripheral retinal photocoagulation for proliferative diabetic retinop athy or extensive retinal breaks. Three diode pulse waveforms includin g a square wave, shaped-wave, and an envelope of micropulses were comp ared to one another. Power was adjusted so that each waveform delivere d the same total energy. The patients subjectively ranked the intensit y of any pain they experienced for each group of lesions. Responses we re compared to one another using an analysis of variance. Results: 40% of patients found the standard square wave pulse to be significantly more painful (P < 0.05) than the shaped pulse mode and 30% found the s quare wave significantly more painful (P < 0.05) than the micropulse m ode. Conclusion: Modification of the laser pulse waveform may ameliora te pain induced by diode laser photocoagulation of the retinal periphe ry. (C) 1995 Wiley-Liss, Inc.