Experimental transconjunctival diode laser retinal photocoagulation through silicone scleral exoplants.
OBJECTIVE
To study the feasibility of inducing a chorioretinal lesion under a previously placed scleral buckle by experimental transconjunctival diode laser photocoagulation.


METHODS
We performed transconjunctival diode laser photocoagulation in the peripheral retinas of seven pigmented rabbit eyes with a silicone exoplant (No. 42 band or No. 276 tire) and seven eyes without an exoplant. Each eye received burns with an intensity of grades 1 to 3 in different quadrants at varying power levels, with a 0.5-second duration and 650-micron spot size. Eyes were enucleated for histopathologic studies 1 day and 1 week after treatment.


RESULTS
Although the irradiance emitted through the No. 42 band and the No. 276 tire was attenuated by 17% and 23%, respectively, the range of threshold powers needed to produce grades 1 to 3 burns was similar between eyes with and without a silicone exoplant. At 1 day, full-thickness coagulative necrosis was observed in all lesions, except that the ganglion cell layer and inner nuclear layer were preserved in two of four grade 1 burns and the ganglion cell layer was intact in one of six grade 2 burns. Inner scleral changes were noted acutely in three of five grade 3 lesions. At 1 week, burns of all intensity grades showed a full-thickness atrophic chorioretinal lesion with inner scleral changes.


CONCLUSIONS
Experimental transconjunctival diode laser photocoagulation through hard silicone elements reproducibly created a chorioretinal lesion with histopathologic findings similar to those of lesions obtained without these elements. Although retinal photocoagulative effects were prominent, inner scleral abnormalities were also observed histologically.
Nanda
S K
SK
Department of Ophthalmology, Eye Institute, Medical College of Wisconsin, Milwaukee, USA.
Han
D P
DP
D000818:Animals; D001284:Atrophy; D002829:Choroid / Q000473:pathology / Q000601:surgery; D003228:Conjunctiva; D005240:Feasibility Studies; D005654:Fundus Oculi; D017075:Laser Coagulation / Q000379:methods*; D009336:Necrosis; D011817:Rabbits; D012160:Retina / Q000473:pathology / Q000601:surgery*; D012165:Retinal Ganglion Cells / Q000473:pathology; D012591:Scleral Buckling; D012826:Silicone Elastomers
D012826:Silicone Elastomers