The influence of exposure duration in transscleral Nd:YAG laser cyclophotocoagulation.
Transscleral cyclophotocoagulation was performed in human autopsy eyes by using three Nd:YAG lasers with different durations of exposure: a pulsed, contact laser with a duration of 0.75 millisecond and a range of one to ten pulses per burst (GLase 106, Sunrise Technologies, Fremont, California); a pulsed, noncontact laser with a duration of 20 milliseconds (Microruptor 2, Lasag Medical Lasers, Thun, Switzerland); and a continuous-wave, contact laser with durations of 700 and 2,000 milliseconds (Microruptor 3, Lasag Medical Lasers, Thun, Switzerland). Tissue responses were observed with a high-magnification videographic recording technique to analyze the immediate, real-time laser effects, and by light microscopy to characterize the laser-induced lesions further. Videographically, both pulsed lasers were noted to cause mild whitening of the pigment epithelium with frequent vaporization and explosive tissue disintegration. Histologically, the 0.75-millisecond pulse typically produced the most marked epithelial disruption, referred to as an explosive-like lesion, whereas the 20-millisecond pulse more often caused moderate tissue disruption with elevation of the epithelial layers in a blister-like lesion. In contrast, the continuous-wave laser was observed videographically to produce prominent tissue whitening and puckering, seen histologically as convolution of the epithelium and coagulation of stroma, which was called a shrinkage-like lesion. Our study suggests that exposure duration influences in vitro tissue response to transscleral Nd:YAG cyclophotocoagulation, although in vivo studies and clinical trials are needed to determine which tissue response is optimum for clinical use.
Prum
B E
BE
Department of Ophthalmology, Duke University Eye Center, Durham, North Carolina 27710.
Shields
S R
SR
Simmons
R B
RB
Echelman
D A
DA
Shields
M B
MB
D002924:Ciliary Body / Q000473:pathology* / Q000601:surgery*; D006801:Humans; D017075:Laser Coagulation / Q000009:adverse effects*; D010857:Pigment Epithelium of Eye / Q000473:pathology; D012590:Sclera; D013997:Time Factors; D014741:Video Recording