July 1997

Interaction Between Infrared Radiation and Vitreous Substitutes

Author Affiliations

From the Department of Ophthalmology and Visual Sciences (Drs Azzolini, Brancato, and Patelli) and Laser Medicine Research (Drs Gobbi and Brancato), Scientific Institute H S. Raffaele, University of Milan, Milan, Italy, and the Department of Physics and Istituto Nazionale Fisica della Materia, Polytechnic of Milan (Drs Bosi, Gallo, and Zelada).

Arch Ophthalmol. 1997;115(7):899-903. doi:10.1001/archopht.1997.01100160069011

Objective:  To characterize the interaction between midinfrared radiation of cutting lasers used or proposed for vitreoretinal surgery and fluid vitreous substitutes commonly used in vitreoretinal surgery.

Methods:  Optical transmittance of vitreous substitutes was measured with a double-beam spectrophotometer. Measurements were performed in a wide spectral range of infrared radiation, including the 2120-nm wavelength of the holmium-YAG laser and the water absorption peaks at 1440, 1930, and 2940 nm.

Results:  The wavelengths considered have a penetration depth varying from 410 to 1 μm in Ringer's solution, balanced salt citrate-buffered solution, balanced salt bicarbonated-buffered solution, hyaluronate sodium, and hydroxypropyl methylcellulose ophthalmic solution, from 2000 to 13 mm in perfluorocarbon liquid, and from 52 to 2.5 mm in silicone and fluorosilicone oils.

Conclusions:  Midinfrared optical radiation exhibits dramatic differences of penetration depth in different vitreous substitutes. High-absorbing liquids should be used mainly with contact laser procedures and could provide a shield for remote structures. Low-absorption vitreous substitutes allow noncontact laser surgical procedures, but they also may cause direct optical damage to remote tissues. The knowledge of wavelength transmittance of vitreous substitutes is necessary to evaluate and optimize the efficacy and safety of cutting laser sources.