Sir,

Modern optic nerve head (ONH) analysers can now give detailed information about the structure of the ONH. However, stereoscopic optic disc pictures (SODP) are still important in glaucoma management.1 At present, these are viewed either through special viewers for slides or computer monitors, or by special monitors with out a viewer.2 The principle is to simultaneously present slightly disparate images to the corresponding eyes.

Hobbyists use animated images (AIs) in which the two images in the stereo-pair are presented alternately in rapid succession, which creates an illusion of simultaneous presentation, and provide some information about the depth of different structures. The principal of the AI was adapted to view the digital SODP. Sequential stereo-images of the ONH were taken by a Canon CF-60S retinal camera fitted with an Olympus E-330 digital SLR camera body. The images were cropped to highlight the ONH and were used to construct graphics interchange format (gif) AIs, the outline of the ONH from the two images being kept on the same position. The interval between the alternating images was kept at 0.15 s. The resulting animated or ‘ wiggling’ images, although looked unfamiliar at first, and were not as natural as by the conventional methods, were able to provide nearly the same information about the contour of the optic disc as the conventional side-by-side pair as seen through a stereo-viewer.

Proper studies are needed to determine how favourably the AIs compare with the side-by-side SODP seen through a stereo-viewer, as these images can be viewed without any special viewer, from any position or distance, and are convenient to use in electronic medical records and tele-ophthalmology. Furthermore, the depth can be perceived by individuals with abnormal stereoscopic vision. The AIs can easily be created with most graphic software. As in other methods, the better the original images and stereo-separation, the better will be the stereoscopic effect. AIs can be used for a quick glance, and kept in record along with the conventional methods.

A PowerPoint slide show is available as supplementary information at the journal website (file name: animated_stereo.pps).