Spectral transmittance of the ocular media of the thirteen-lined ground squirrel (Spermophilus tridecemlineatus)

Abstract

Direct spectral transmittance data over the wave band 200–2500 nm were obtained for the ocular media of the thirteen-lined ground squirrel (Spermophilus tridecemlineatus) using a Zeiss (Oberkochen) DMR-21 dual-beam recording spectrophotometer. These data were used to calculate cumulative transmittance curves for each of the interfaces between optical media in the ground squirrel eye. Although radiation in the wave band 300–2500 nm can penetrate the cornea, our data show that the yellow pigment of the crystalline lens absorbs all wavelengths below 410 nm, while the vitreous humour absorbs most radiation longer than 1400 nm. The ground squirrel retina is, therefore, effectively protected from both near ultraviolet and infrared radiation, both of which are known to have deleterious effects on retinal photoreceptors.