Final answer:
An emmetropic patient typically does not need corrective lenses for distance vision but might require reading glasses for presbyopia, which often starts at around age 40. Depending on their individual needs, they might also choose bifocals, trifocals, or progressive lenses.
Step-by-step explanation:
Given that the patient is emmetropic, which means they have no refractive error and their vision is considered normal or 20/20, they would not generally require corrective lenses for distance vision. The type of spectacles an emmetropic patient might need would depend on their specific visual requirements. If the patient has presbyopia, which typically starts around the age of 40 and is caused by the natural loss of flexibility in the eye's lens, then they might be prescribed reading glasses to improve near vision. However, if they need correction for multiple distances, they could opt for bifocals (which provide two optical powers), trifocals (three optical powers), or progressive lenses, which offer a gradual change in lens power for a natural visual transition from distance to near vision without visible lines on the lenses.
For individuals with myopia, glasses with diverging lenses are worn to correct their vision, as it over converges light rays. Hyperopia is corrected with converging lenses. People with astigmatism would need glasses with a cylindrical correction. To determine the power of spectacle lenses needed, one must know the patient's far point, the greatest distance at which they can see clearly. The spectacle lens produces an image of the object at a distance where the individual can see it clearly, compensating for their specific refractive error.