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Article
November 1991

Energy Levels and Probe Placement in Contact Transscleral Semiconductor Diode Laser Cyclophotocoagulation in Human Cadaver Eyes

Author Affiliations

From the Morse Laser Center, Howe Laboratory of Ophthalmology, Department of Ophthalmology, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston (Drs Schuman, Noecker, Puliafito, Jacobson, Shepps, and Wang), and New England Eye Center of New England Medical Center Hospitals, Tufts University School of Medicine, Boston (Drs Schuman and Puliafito).

Arch Ophthalmol. 1991;109(11):1534-1538. doi:10.1001/archopht.1991.01080110070037
Abstract

• We investigated the effects of semiconductor diode laser contact transscleral cyclophotocoagulation in human cadaver eyes by gross examination, light microscopy, and scanning electron microscopy to determine optimum clinical treatment parameters. Irradiation was performed using a continuous-wave semiconductor diode laser with a fiber-optic probe. At 1.0 to 1.25 mm posterior to the limbus, spots were centered on the pars plicata by gross examination. Exposures of less than 2 J produced no visible damage. A 2- to 3-J exposure produced mild whitening of the ciliary processes, while 4- to 5-J exposures created more intense whitening of the pars plicata. Energies higher than 5 J frequently produced explosive tissue damage. Light microscopy of tissue treated with 1.8 to 6 J at 1.0 to 1.25 mm posterior to the limbus revealed coagulation necrosis of the nonpigmented and pigmented epithelium, with evidence of thermal coagulation of the ciliary stroma and stromal vasculature. Coagulation necrosis was more intense with longer exposure times. We found the optimum parameters for contact transscleral diode laser cyclophotocoagulation in cadaver eyes to be 3 to 4.5 J of energy delivered with the anterior edge of the probe 1.0 to 1.25 mm posterior to the limbus.

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