Magnification RNIB recommends that you have a low vision assessment before purchasing any type of magnifier. These devices may be available to you on permanent loan through your local low vision provider funded by the NHS. It is important that the magnifier is the correct power and type for you. A low vision practitioner can help you find the best options. If you're not sure who provides this service in your area, call the RNIB Sight Loss Advice Service on 0303 123 9999 or search our Sight Line Directory.