Purpose. To evaluate the efficacy of microsecond pulsed diode laser for creation of a full-thickness fistula in cadaver scleral tissue dyed with Indocyanine Green (ICG). Methods. Human cadaver scleral tissue preserved in glycerine was rehydrated with BSS and cut into strips of 5mm by 10mm. The scleral strips were focally stained by injecting ICG with 30G needle. After washing off excess dye, scleral tissue was mounted on a styrofoam block and positioned with its episcleral surface facing the delivery system of the pulsed diode laser. The laser was focussed and fired in a pulsed mode. Pulse rate was varied from 2.5 to 10 Hz to optimize energy delivery to achieve sclerectomy while keeping pulse duration (600 μs) and spot size (200μ) constant. Subsequently the tissue was fixed in Karnovsky's solution and subjected to histopathological assessment for the size of the fistula and extent of collateral damage using a hemocytometer grid and an optical microscope. Results. Local injection of ICG effectively stained the sclera and enabled the pulsed diode laser to create a full-thickness fistula of the size varying 200-600μ. The total amount of energy delivered for successful sclerectomy ranged from 0.6-4.0 joules. The magnitude of collateral damage was proportional to the pulse rate and varied from no microscopic detectable damage to a maximum of 10 μm. Conclusion. Pulsed diode laser in conjunction with focally injected ICG is an effective method to perform sclerectomy due to enhanced optical absorption of the laser by ICG. An optimal scleral fistula with minimal surrounding thermal injury can be achieved by maintaining a pulse rate below 2.5 Hz.
|Original language||English (US)|
|Journal||Investigative Ophthalmology and Visual Science|
|State||Published - Feb 15 1996|
ASJC Scopus subject areas
- Sensory Systems
- Cellular and Molecular Neuroscience