How to check and see the inside of an eye ?
Digital retinal photography allows for a quick and safe way to view the light sensitive layer and other supporting structures at the back of the eye, where the retina is located.
Some Cameras use and enface system to image the retina, like a drone view of the landscape. Others use a cross section system, like slicing up a cake and seeing the separate layers inside.
Both systems are very useful and are a vast improvement over the older version e.g. a direct ophthalmoscope which is not able to take recorded images of the retina.
What is the reach of a digital retinal camera ?
A digital retinal photograph can provide an image of 200 degrees width and increase this to 220 degrees with the use of eye steering. These images can usually be taken without the use of eye drops.
The widest reach of a digital camera is provided by Optos. Optos uses a Red and a Green laser to take painless images of the retina. Below is an image of the California model, this is the latest version of the Optos wide view enface digital retinal camera:
Other digital retinal cameras:
Zeiss have manufactured a digital retinal camera called Clarus 500. This camera uses full colour to produce a more accurate representation of the coloration of the fundus as seen during clinical examination.
All True Colour images can be separated into red, green and blue channel images to help enhance the visual contrast of details in certain layers of the retina. Below is an image of the Zeiss Clarus 500 enface digital camera:
Below is a Montage ultra wide image of the retina taken by the latest Zeiss camera, note the size of the small white circle. This is the optic disc and gives an impression of the reach of Clarus:
Other digital retinal cameras, these use a cross section approach.
Spectralis from Heidelberg engineering is the most detailed way to take a cross section of the retina. This is helpful in the long term monitoring of glaucoma and detection of wet macular degeneration. Below is an image of a Spectralis digital rentinal camera: