The sight test, also known as the eye examination, is more than just a test of your vision. A comprehensive sight test will include a test of vision, known as the 'refraction', and a thorough examination of the front and back of the eye for any health problems. You may have certain tests – such as ‘auto-refraction’ (to provide the optician with a rough estimate of any spectacle prescription), and ‘tonometry’ (a measurement of the pressure inside the eye) before entering the consulting room.  The optician will ask questions about any problems you are having with your eyes or may have had in the past. They will also ask about any family history of eye problems as some eye problems are hereditary.  The refraction includes the use of a letter chart and different lenses are placed in front of the eye while the optician uses further techniques to fine-tune the prescription. The prescription is the power of lens for the right and left eye which will correct the patient's vision. During the eye health check the optician checks the condition of the various structures of the eye using an ophthalmoscope and a number of other instruments which may include the slit-lamp and a visual field analyser.