The macula is the part of the retina that is responsible for our fine central vision. This is the vision necessary for reading a book, watching television, or seeing distant road signs. The retina works like film in a camera, and the macula is the most sensitive part of the film, containing more rod and cone photoreceptors than elsewhere. Problems at the macula, such as diabetic retinopathy or macular degeneration, can cause severe visual changes (though the peripheral vision remains intact). The macula can be viewed through dilation. The macula can also be measured using OCT photographs to look for swelling or sub-retinal bleeding. When there are problems, such as wet macular degeneration, the circulation under and around the macula can be further imaged using fluorescein angiogram (though this type of testing is usually left to retinal specialists).