Review of surgical devices using small aperture optics

Small aperture optics work by blocking unfocused peripheral light rays while allowing central light rays to focus on the retina. This pinhole effect creates an extended depth of focus and has been used in presbyopia correction, improving intermediate and near vision without markedly affecting distance vision. Another beneficial effect of small aperture optics is reducing aberrations caused by irregular corneas or irregular pupils. The first small aperture surgical device was the Kamra corneal inlay used on the nondominant eyes of presbyopic emmetropes. The pinhole concept was also adapted into the IC-8 intraocular lens (IOL) for presbyopia correction during cataract surgery and by the XtraFocus piggyback device to lessen unwanted aberrations in eyes with irregular corneas or pupils. The IC-8 IOL can be placed monocularly or binocularly with mini-monovision for further near vision improvement. The XtraFocus piggyback device can be placed either in the sulcus or capsular bag. The aim of this literature review is to synthesize evidence on the efficacy, safety, and patient-reported outcomes on surgical devices utilizing small aperture optics. A comprehensive search on PubMed was conducted with the keywords "small aperture optics," "small aperture corneal inlay," "small aperture IOL," "Kamra corneal inlay," "IC-8 IOL," and "XtraFocus." In this review, we describe the progression of small aperture surgical devices, patient criteria, visual outcomes, complications, satisfaction, and recommendations for surgical success.