Secondary toric intraocular lens implantation in pseudophakic eyes. The add-on IOL system

The last 2 years have seen the development of toric IOL especially designed for implantation in the ciliary sulcus for correction of corneal astigmatism in pseudophakic eyes. The term 'add-on IOL systems' is becoming more and more widely accepted for the lenses used in this procedure. The main indications for it are regular corneal astigmatism in pseudophakic eyes, for example following perforating keratoplasty, or when corneal scarring is present following trauma or infection. The implantation is a simple atraumatic procedure carried out under topical anaesthesia through a sclerocorneal incision. When the IOL is oriented along the steepest corneal meridian with the aid of corneal topographical monitoring, reliable and lasting correction of even extremely pronounced astigmatism is possible. Although this procedure has proved to be very efficient over a long follow-up period in small patient populations, reports of later adjustment of the rotation of toric add-on IOLs must be tested in further trials, especially in the case of simultaneous implantation of endocapsular IOLs in both eyes. Nonetheless, the possibility of later correction and reversibility of the intervention are further advantages of this lens system. As well as the correction of astigmatism in pseudophakic eyes the add-on IOL system also offers the option of treating pseudophakic eyes with sulcus-fixed multifocal lenses in the context of refractive interventions, e.g. as a secondary procedure.