It is generally necessary to distinguish the type of refraction to determine how many degrees the eye 0.5 is, the most common type of is myopia, if for myopia the vision is only 0.5, it may exist in about 150-200 degrees of myopia. Also if it is a refraction that is farsighted after optometry, 0.5 vision may usually be around 400-500 degrees of farsightedness before the vision drops to around 0.5. If the vision is astigmatism 0.5, it usually takes about 200-300 degrees of astigmatism to bring the vision down to about 0.5. So generally 0.5 vision usually requires an optometry to be able to determine the type of refraction and the degree of refraction. But in the end, if you need to improve your 0.5 vision, you will need glasses or surgery to correct it and improve your vision.