On imaging and localizing untethered intraocular devices with a stationary camera

Untethered microrobotic devices have been proposed for use in ophthalmic surgeries, and localization information is required for their control. The environment of the human eye is externally observable, and images can be used to localize intraocular agents. There is currently no quantitative description of the effects of the human eye optics on imaging and localizing intraocular objects. In this paper, the common methods of ophthalmoscopy assuming a stationary imaging system are examined and compared with respect to their imaging and localizing properties on a schematic model of the human eye. A mechatronic device that can image intraocular objects with increased field-of-view, spatial resolution, and depth sensitivity is proposed. 3D localization using a depth-from-focus approach is discussed, and the validity and limitations of a method based on paraxial approximations is demonstrated by experiments in a model eye.