Influence of a yellow-tinted intraocular lens on laser beam transmittance

Abstract

Purpose: To compare the transmittance of laser beams that are used for photocoagulation through a yellow-tinted intraocular lens (IOL) and a clear IOL.

Methods: The transmittance of laser beams of different wavelengths (488 + 514, 514, 521, 568 and 647 nm) through yellow-tinted and clear IOLs of varying dioptric powers [+10, +20 and +30 dioptres (D)] was measured using a laser power meter. The transmittance ratio was defined as the ratio of the transmittance thorough a tinted IOL to that through a clear IOL, assuming that the transmittance value of the latter is 1; this ratio was calculated for each IOL and each wavelength of the laser beam.

Results: There were no apparent differences in the transmittance values between the tinted and clear IOLs when the 521, 568 and 647 nm wavelengths were used. In contrast, the transmittance ratio decreased for the tinted IOL when the short wavelengths - 488 + 514 and 514 nm - were used, especially when an IOL of a higher dioptric power was used. This ratio was found to be 91.9% for a +10 D, 86.7% for a +20 D and 82.2% for a +30 D lens when a 488 + 514 nm wavelength beam was used.

Conclusion: When treating patients using photocoagulation, we must bear in mind the decreased transmittance ratio of short-wavelength laser beams when passed through tinted IOLs and increase the setting power of the beam accordingly.