MiSight contacts look like normal soft lenses. They are packaged as a daily disposable, meaning you open a new lens each day. They are worn during the day and removed (thrown away) at night. Generally they are worn every day although occasionally a day without the lenses will not adversely affect the treatment. The lens are worn as long as myopia progression is considered a risk.
MiSight contact lenses do not currently have any published journal articles that describe their success. Promotional literature is available online. The reason they apparently work is not that they reduce the reading effort, which they do, but rather that they create a ring of increased power surrounding central vision that the eye interprets as a "stop signal" for further growth. When eyes grow longer, they become more myopic. The signals for this growth are in the peripheral retina. You can read about it in the different sections of the Definitions menu. Here's a link to the hyperopic defocus section.
The greatest risk of any contact lens wear is abrasion and infection. Radial Refractice Gradient (RRG) contact lenses, such as MiSight, used to slow myopic progression are no different, no better or worse, than regular contact lenses worn by millions of people. The risk is greatly reduced by following instructions on lens care, handling, wearing time and follow-up visits with your doctor who can often identify small problems before they become more severe.
RRG lenses are generally a bit more difficult to get used to than regular single vision lenses. Adaptation, if necessary at all, usually occurs within a few weeks. There are always some people who are too sensitive, whether psychologically ("squeamish") or physically (dry eyes, difficult to fit eyes, etc.) but these can usually be overcome with either time or proper treatment.
Children, even young children, can make excellent contact lens patients. They need a certain level of maturity and they need more parental supervision, but they often can be trained how to apply and remove their lenses more quickly than adults can be trained.
Risks specific to MiSight contact lenses used as a treatment for myopia progression are essentially the risk that it won't work. There can be no guarantee of how the eye will respond but the data is very encouraging. Some eyes may do better.
MiSight contact lenses are the brand name of a lens currently (2010) marketed in Hong Kong by CooperVision, a major world-wide contact lens company. MiSight contact lenses are prescription devices that are worn on the eye to change the eye's focus. If the eye is nearsighted (shortsighted or myopic) for example, the lens is normally designed to give clear distance vision. A MiSight lens has two powers which can be located at different locations on the lens, usually designed as a ring of power change, similar to a "bull's eye" target. This allows the lens to rotate on the eye without changing how it performs optically. These are called concentric ring designs.
MiSight lenses are marketed specifically as a treatment to slow myopic progression in children. There is no other reason to wear them. The design appears to be similar to other CooperVision bifocal lenses.