In ophthalmic surgery, following removal of the lens of the eye, it is well known to implant an intra-ocular lens to take the place of the removed natural cataractous lens.  Various types of lenses are in use, and several are described in Fechner and Alper, "Fechner's Intra-Ocular Lenses," published by Thieme, Inc., New York (1986), incorporated herein by reference in its entirety.  Many lenses are also the subject of patents, including (as an illustrative sample only): Shearing, U.S. Pat.  No.  4,159,546; Feaster, U.S. Pat.  No.  4,418,431; Kelman, U.S. Pat.  Nos.  4,174,543 and 4,370,760; Anis, U.S. Pat.  No.  4,251,887; Ong, U.S. Pat.  No.  4,365,360, and; Sheets, U.S. Pat.  No.  4,328,595. 
Intra-ocular lenses may be implanted at various locations within the eye, such as in the iris plane, or within the posterior chamber or within the anterior chamber.  Lenses designed to be placed in the posterior chamber may be positioned in either the ciliary sulcus or the capsular bag of the eye.  Many lenses, known as optics, are supported in the posterior chamber by two or more flexible filaments, known as haptics, which are secured to the optic, and which lodge against some adjacent portion of the eye.  The haptics serve to position and retain the optic in its proper location.  The haptics may also serve to position the lens implant in the anterior chamber by lodging in a groove formed by the scleral spur and the iris. 
Unfortunately, subsequent post-implantation injuries or other conditions in which the implant is dislodged and the anterior, posterior or both chambers fill with blood or some other clouded medium, are known to occur.  In these cases of traumatic dislocation, it becomes difficult for the surgeon to visually locate the intra-ocular lens implant.  In many situations, location of the intra-ocular implant is impossible without the aid of time-consuming and highly sophisticated imaging techniques such as ultrasonic imaging or CT scanning.  However, ultrasonic imaging is contraindicated in a ruptured globe, and CT scanning is expensive and delays surgery.  Simple radiologic examination and diagnosis, such as by routine X-ray, is not helpful, as the materials used to fabricate presently known intra-ocular implants are substantially radiolucent. 
An intra-ocular lens implant which could be accurately located by ordinary, quick and simple X-ray diagnostic techniques would be a major advance in the field of ophthalmic medicine, and would help solve a difficult and common problem faced by ophthalmic surgeons.