Many years ago the only phakic IOL available in the USA for treatment of large degrees of myopia was a rigid, claw lens that was clipped to the iris and positioned in the anterior chamber. Implantation of this lens required a large incision of about 6 mm wide because its PMMA (polymethyl methacrylate) material is not foldable or injectable through smaller incisions. Now, years later, many of these patients are developing cataracts and sustaining progressive corneal endothelial cell loss. We can explant these iris claw phakic IOLs and perform cataract surgery to help these patients regain excellent vision.
This type of iris claw phakic IOL was marketed as the Verisyse, Artisan, or Wörst lens at various times and in different countries. While it is often used very successfully for the treatment of aphakia, those plus power IOLs are not available in the USA. For treatment of aphakia, the claw lens can be securely clipped to the back surface of the iris in order to keep it farther away from the delicate corneal endothelium. In the USA, we only had access to the minus power iris claw lenses which were designed to treat severe myopia as an anterior chamber phakic IOL.
These highly myopic patients often have significant with-the-rule corneal astigmatism so surgeons typically used a superior incision to help neutralize that and achieve a better refractive outcome. Scleral tunnel incisions would often be preferred, though some surgeons used a limbal incision with suture closure. In the case presented here, the patient previously had a large 6 mm superior corneo-limbal incision which, over the years, resulted in overcorrection of the corneal astigmatism. This patient presents to us with a significant degree of against-the-rule astigmatism, steep at about the 180 degree meridian.
To explant this lens and perform the cataract surgery, a temporal scleral tunnel incision was made. The challenge is that the incision needs to be 6 mm wide to remove the Verisyse lens but we want a smaller 2.8 mm incision for performing phacoemulsification. The smaller incision is important to maintain fluidic balance during phaco and achieve chamber stability to minimize the risk of posterior capsule damage. There are three main approaches for this case: (1) perform the phaco under the Verisyse lens and then once the new IOL is in the capsular bag, enlarge the incision to explant the phakic IOL; (2) use two separate incisions, one to explant the Verisyse lens and the other to perform phaco; or (3) explant the Verisyse through the larger incision, then partially suture it to perform phaco.
The first step is to release the claws from the iris stroma by holding the IOL with forceps and then using the specially-design enclavation needle or a simple Sinskey hook to free the iris. Once the 6 mm wide incision is made in the sclera, the Verisyse lens can be explanted from the eye (Figure 1). The incision is then partially closed with 10-0 nylon to allow the phaco tip to be passed between sutures to perform the cataract surgery (Figure 2). This allows for better, but not perfect chamber stability and fluidics. Once the nucleus is removed, bimanual irrigation and aspiration can be used for more stability during cortex removal. With the new IOL in the capsular bag, the incision can be fully sutured with 10-0 nylon sutures and then covered with conjunctiva (Figure 3).
This patient recovered very well from the surgery and achieved an excellent visual outcome. While ophthalmologists in the USA no longer routinely implant these iris claw phakic IOLs, we must still know how to deal with them and when the time comes, to explant them.