Topcon NW6S Digital Fundus Camera

A fundus camera or retinal camera is a specialized low power microscope with an attached camera designed to photograph the interior surface of the eye, including the retina, optic disc, macula, and posterior pole (i.e. the fundus).

A fundus camera provides an upright, magnified view of the fundus. The optics of a fundus camera is similar to that of an indirect in that the observation and illumination systems follow dissimilar paths. The observation light is focused via a series of lenses through a doughnut shaped aperture, which then passes through a central aperture to form an annulus, before passing through the camera objective lens and through the cornea onto the retina.

The light reflected from the retina passes through the un-illuminated hole in the doughnut formed by the illumination system. As the light paths of the two systems are independent, there are minimal reflections of the light source captured in the formed image. The image forming rays continue towards the low powered telescopic eyepiece.

When the button is pressed to take a picture, a mirror interrupts the path of the illumination system allow the light from the flash bulb to pass into the eye. Simultaneously, a mirror falls in front of the observation telescope, which redirects the light onto the capturing medium, whether it is film or a digital CCD. Because of the eye’s tendency to accommodate while looking though a telescope, it is imperative that the exiting vergence is parallel in order for an in focus image to be formed on the capturing medium.