Thinking of the Eye like a camera

If you think of the eye like a film-based camera, it helps to understand how the eye works. Light travels through the cornea (clear front surface) and lens and is then focused on the retina. The cornea and lens provide the focusing power of the eye, just as a lens does for a camera. The retina receives the image, just as the film of a camera does. The iris modulates the amount of light entering the eye, as the aperture setting does on a camera. If the cornea isn’t perfectly clear (opacity, swelling, scratches), the lens is cloudy (cataract), or the retina is not perfectly flat (retinal detachment, diabetic swelling, or macular degeneration), then the image you see, or the picture, will be blurry. In any of these cases, glasses and/or contacts will not improve your vision, as the light will still have to travel through the damaged structures after passing through the glass or contact lens in front of your eye.