Altered fundus appearance resulting from autofluorescence imaging with the confocal scanning laser ophthalmoscope (cSLO) in cats

Purpose: This paper is to report that imaging the tapetal fundus of cats with the 488 nm laser of the Spectralis(®) HRA+OCT (Heidelberg Engineering Inc., Heidelberg, Germany) can result in a pale appearance of the imaged area.

Animals studied and procedures: Wild-type and Rdy kittens (CRX mutant heterozygotes-CRX(Rdy+/-) ) (8-20 weeks of age) and adult cats (1-4 years of age) were imaged by confocal scanning laser ophthalmoscope (cSLO) and spectral domain optical coherence tomography (SD-OCT) using the Spectralis(®) HRA+OCT. Color fundus photography (RetCam II(®) , Clarity Medical Systems, Inc., Pleasanton, CA) was performed after imaging using the Spectralis(®) HRA+OCT.

Results: Following retinal cSLO imaging using the 488 nm laser (autofluorescence imaging) in both wild-type kittens and adult cats, the imaged region appeared paler than the adjacent retina that had not been imaged. This change was probably due to retinal bleaching and was fully reversible. Imaging CRX(Rdy+/-) kittens or adults, which had very reduced levels of visual pigments, did not induce the altered fundus appearance.

Conclusions: Those using autofluorescence imaging by cSLO should be aware that it can induce a characteristic pale appearance of the tapetal fundus in the imaged area of normal cats.