The object of the present invention is to provide an annular device superior to a conventional annular device in the stability over an eyeball when being worn, which overcomes problems caused by wearing a conventional annular device. The above object is attained by preparing an annular device to be worn over the surface of the sclera, the annular device including an opening exposing the cornea and one or a plurality of approximately encircling grooves on an intermediate part between an inner rim part and an outer rim part. The annular device has a maximum thickness preferably in the intermediate part.
