The eye operate like a camera.
The cornea is transparent and provides the first objective lens of the eye. The lens is the zoom: adjusting focus to all distances.
The sclera is the visible white part of the eye that maintains its shape and protects it.
The pupil is the black hole at the centre of the eye which allows light to come through and is controlled by the iris.
The iris is the colored part of the eye that functions as a diaphragm. It automatically adjusts the amount of light that enters the eye.
The retina is the film which converts light rays into images.
The macula is the region of the retina that provides better vision. The brain transforms the received information into images, for a visual representation in 3 dimensions.
When this image is blurred or distorted, it reveals a problem of vision. This disorder may be related to:
a defect (myopia, hyperopia, astigmatism)
natural aging (presbyopia)
an excess of UV
Simple and quick tests can be done to detect visual problems. It will also help in identifying the solutions.
Regular visual checkup will enable you to benefit from a good vision and will also help in detecting any eye disease. It is recommended that an adult go for a checkup every two years and children and elderly every year.