The Pathologic Effects of Photodynamic Therapy on the Larynx: Experimental Study

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Abstract
• Using an argon pump dye laser at a wavelength of 630 nm, varying amounts of energy (10 to 170 J/cm2) were delivered to the presensitized (hematoporphyrin derivative) canine larynx. There appear to be four energy zones that result in progressive degrees of tissue response. Between 10 and 40 J/cm2 the larynx appears normal, with only mild erythema noted at 60 J/cm2. Above 100 J/cm2 moderate to severe erythema and edema were seen, with two upper-airway deaths observed. Transmission pattern analysis revealed that by either increasing the total energy applied and/or positioning the cylindrical diffuser tip at different levels of the larynx, the entire structure including the undersurface of the vocal cord and subglottic region could be exposed to red light. (Arch Otolaryngol Head Neck Surg 1988;114:33-39)