Changes in Spectral Acuity following Laser Irradiation

Abstract

Maximal visual acuity and normal color vision are closely associated with foveal receptor function. When the fovea is destroyed or altered by intense laser irradiation, severe and sometimes permanent losses in visual acuity ensue. In this paper we have shown that the threshold for long-term functional alterations in the fovea is determined not only by the wavelength and corneal exposure power of a laser flash but also by the types of performance criteria used to assess visual functioning. Chromatic acuity provides a much lower threshold for permanent alterations (Krypton — 6 mW; Argon — 3 mW) as opposed to achromatic targets (HeNe — 11 mW). Further, the use of chromatic acuity to assess post-exposure functioning can more accurately delineate the specific cone process most affected by the exposing source. The data from these studies also suggest that some relatively long-term (24 h) cumulative process within the retina is occurring which obviously will affect any threshold value determined.