Out-of-the-bag IOLs

In cataract cases where the eye has poor capsular support because of capsular rupture or ocular co-morbidities, there is a range of options available, though a vitreoretinal surgeon may need to be on hand for assistance, according to Marc de Smet MD, PhD, Lausanne, Switzerland.

'In the management of secondary IOL implants you need to judge the amount of capsular support that is left and the retinal integrity, particularly with regard to a patient's likelihood of developing a retinal detachment in the future, in which case you would want to have a good view of the periphery,' Prof de Smet told the 11th EURETINA Congress.

In some situations there may be inflammation, and as a result the corneal epithelium may lose some of its transparency during surgery. Scraping the cornea or applying other means such as hypertonic glycerol will restore the transparency and enable the surgeon to assess the intraocular situation and perform surgery.

In cases of well controlled uveitis, there are many reports in the literature stating that a standard IOL placed in the capsular bag will produce good results, Prof de Smet noted. However, in cases where there is any evidence of constant inflammation or hypotony the wiser course is to remove of the capsular material and use a different type of implant.

Implantation of an intraocular lens into the capsular bag is possible in some eyes with capsule tears and ruptures if there are two regions 180 degrees apart that remain intact, and 90 degrees away from regions where there is no capsule, he said. Otherwise, the best results will be obtained with a sulcus-fixated or anterior chamber IOL, Prof de Smet noted.

Sulcus-fixated approach

Many of the IOLs commonly used for implantation in the capsular bag are inappropriate for implantation in the sulcus, Prof de Smet noted. The haptic angulation and edge design of such IOLs means that they will tend to rub against the iris, potentially causing pigment dispersion and iris transillumination, or in some cases even glaucoma and cystoid macular oedema.

'The ESCRS recommended avoiding these as much as possible and to select instead a three-piece IOL with foldable optics and rounded anterior optic edges, as they don't irritate the iris. With posteriorly angulated haptics and larger implants, they fit securely in the sulcus. In this way you are able to avoid some of the potential complications of inappropriate lenses,' Prof de Smet said.

He noted that single-piece IOLs could increase the rates of posterior iris synechiae after phacovitrectomy particularly in eyes where longstanding tamponade is required, since it will tend to push the implant forward causing it to rub against the iris. Silicone oil can have a similar effect (Kim et al, Ophthalmologica. 2009; 223:222-227).

'In cases where there is a posterior capsular rupture but the anterior capsule remains intact, one technique that can be very useful to prevent contact between a sulcus fixated IOL and the iris is to try and push the optic posterior to anterior capsule, leaving the haptics in the sulcus anterior to the capsule. The way to do this is to put some pressure superiorly and inferiorly on the IOL, perpendicular to the axis plane, until the optic is well-positioned and the anterior capsule takes somewhat of an ovoid shape,' he said.

Capturing the optic in this way not only enhances the stability and centration of the IOL, but also provides a vitreoretinal surgeon with an added advantage, following an air exchange or silicone oil tamponade, there will be less tendency for leakage into the anterior chamber.

Dr de Smet noted that sulcus fixation is often associated with some problems or complications. They include tilt, anterior segment and vitreous haemorrhages and secondary glaucoma. Persistent ocular inflammation may also occur when the haptic is positioned elsewhere than in the sulcus. Under these circumstances, macular oedema is frequent, and ciliary erosion may appear two to three years later, he said. Correct positioning when in doubt can be confirmed or insured by use of an endoscope (Olsen et al., Am J Ophthalmol 2011;151: 287-296).

IOLs that have fallen into the vitreous cavity can best be repositioned through an intrascleral tunnel. 'At a follow-up of about seven months you can see the position of the haptic through the sclera but there is no overlying erosion of scleral tissue. Moreover, the visual results are good and complications are limited. With a UBM you can see that there is no inflammation being generated by the haptic itself when it's placed mid-sclera,' Prof de Smet added.

Iris claw lens

Using an Artisan IOL is another alternative for eyes without capsular support, Prof de Smet noted. He cited the findings of a study that showed that Artisan IOL implantation provided good visual results in aphakic vitrectomised eyes without capsular support after trauma (Riazi et al, Eye, 2008; 22:1419-24). The lens appears to cause few complications apart from a few giant cells precipitates on the IOL.

'When placed on the iris surface it will very seldom dislocate or separate itself from the iris surface and there is no problem with regard to repairing retinal detachments since you get a very good view of the peripheral retina,' Prof de Smet added.