Experimental use of semiconductor diode laser in contact transscleral cyclophotocoagulation in rabbits
J. S. Schuman, J. J. Jacobson, C. A. Puliafito, R. J. Noecker and W. T. Reidy
Howe Laboratory of Ophthalmology, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Boston 02114.
Acute and long-term effects of contact transscleral semiconductor diode
laser cyclophotocoagulation were studied in rabbits. Immediately following
cyclophotocoagulation, light microscopy revealed coagulation necrosis of
the ciliary pigmented and nonpigmented epithelia and stroma; destruction
increased in relation to power. There was architectural disruption with
higher energy levels. The findings with diode and continuous-wave contact
neodymium-YAG lasers were similar. In rabbits treated and followed up for 6
weeks there was a decrease in intraocular pressure during the observation
period (P less than .05, paired Student's t test). The gross and light
microscopic examination revealed focal atrophy and fibrosis of the ciliary
processes, with pigment-laden macrophages on the ciliary processes and in
the outflow pathways. Higher energy levels caused lens capsule damage and
vitritis. The diode laser produced ciliary destruction similar to the
continuous-wave contact neodymium-YAG laser in rabbits, with significant
intraocular pressure lowering during the 6-week follow-up.
