Iris claw lenses in aphakia

Aphakia is defined by the absence of the natural crystalline lens in the eye. It is most often encountered in patients who have undergone cataract extraction.

In the Western world, with the advent of modern cataract surgery (extracapsular cataract extraction (ECCE) and phacoemulsification) combined with systematic intraocular lens (IOL) implantation in the capsular bag, aphakia has become less common over the years. It can still be encountered after complicated cataract surgery (post-traumatic dislocation of the crystalline lens as well as capsular loss during cataract extraction) leaving insufficient capsular support for the IOL implantation in the sulcus. In addition, the surgical treatment of Ectopia Lentis in congenital conditions such as Marfan syndrome, homocystinuria, Weill–Marchesani syndrome, hyperlysinaemia, sulfite oxidase deficiency and Ehlers–Danlos syndrome often leaves the patients aphakic.

In the developing world, many patients are still left aphakic after intracapsular cataract extraction (ICCE), which is still performed for several reasons, one of which is the advantage of avoiding posterior capsule opacification and the need for YAG laser capsulotomy.

Spectacle correction of bilateral aphakia is far from ideal, and unilateral aphakic even more so. It is responsible for reduced peripheral vision, a ring scotoma from prismatic effect of the edge of the lens and the so-called “Jack in the box” phenomenon (if an object is in the periphery of the patients visual field, it appears blurred. When the patient moves their head towards the object in order to see it clearly, it disappears. Then, as they turns their head further so that the object comes to lie in front of the spectacle it reappears again clear at that time. Due to a magnification of 20 to 35% of the image in the aphakic eye, a good binocular vision is difficult to achieve with spectacles. The tolerance for anisoeikonia is limited between 5 and …