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This gonioscopic view reveals haptic fixation onto the ciliary body

There is a significant amount of literature discussing the decreased rate of posterior capsular opacification seen with heparin-coated and acrylic lOLs, but there are no definitive data on which specific group of lenses provides the best results. Many factors contribute to posterior capsular opacification making it difficult to isolate one variable without injecting material, surgeon and/or technique bias. Standardized, randomized prospective studies would be helpful in further clarifying the issue.

Symptomatic posterior capsular opacification is generally easily treated with Nd:YAG capsulotomy, though even this procedure can be problematic, especially for certain IOL types. Complications include severe IOL iatrogenic damage, significant IOL subluxation or dislocation, retinal detachment and secondary glaucoma. We have seen several cases of platetype, foldable silicone lenses migrate deep into the vitreous cavity following Nd:Yag capsulotomy.

Although uncommon, anterior capsulotomy phymosis syndrome can be another IOL-related headache. This occurs when a small diameter capsulorhexis (usually under 6 mm) in an otherwise perfect cataract/intraocular-lens-implantation case has organized fibrotic activity at its border. This fibrosis slowly constricts the anterior capsule margin, creating tension on the whole capsular bag that may unpredictably decenter the intraocular lens. In my experience, this complication is more common with silicone intraocular lenses and very small anterior capsulorhexes (5-mm diameter or less). The catch-22 here is that smaller capsulorhexes may be associated with less PCO. Often this problem can be managed, if it is noticed early, within several weeks postoperatively, with Nd:YAG laser treatment of the anterior capsulotomy's border to release the traction. Great care must be taken to avoid damaging the anterior surface of the intraocular lens.

Anterior chamber lOLs bring their share of side effects, and occasionally may cause significant postoperative problems including pseudophacodonesis resulting in cornea endothelial injury, secondary glaucomas from trabecular meshwork outflow compromise, anterior uveitis, and recurrent hyphemas.

Other postoperative problems associated with PC foldable intraocular lens implantations are IOL subluxations. This is known as the "sunrise" or "sunset syndrome," depending on the direction of the subluxation. This may be secondary to haptic damage during implantation, which creates an imbalance between the two haptics that ultimately decenters the IOL optic. The lens decenters toward the damaged haptic.

Highly myopic eyes may be at greater risk for a decentered IOL because the capsular diameter may be too large for the IOL that is implanted. Exercising caution in highly myopic patients or patients who have larger than normal corneal diameters can help to prevent such postoperative surprises. In these eyes, consider a foldable intraocular lens with a maximal total diameter (13.5 mm or larger) or the implantation of a rigid intraocular lens with a large total diameter.

Intraocular lens subluxation usually results from zonular dehiscence, either not clinically present at surgery or overlooked at the time of the surgery. If it is a mild subluxation due to a small arc of zonular dehiscence, and does not cause visual problems for the patient, it need not be treated. If subluxation causes the optic's edge to present within the visual axis, symptoms of glare or monocular diplopia, it probably is time to intervene.

There are several viable options to manage this complication, including recentering the IOL or explanting it and inserting another. Placement of a capsular expansion ring to .return the capsular bag to a more centered position and re-centering the intraocular lens may resolve the problem. Other options are sulcus fixation or fixation of one or two haptics to the sclera to obtain centration.

High postoperative spherical refractive error can be another unpleasant surprise. This is more common in high myopes and hyperopes, and in patients who have had refractive surgery or cornea transplantation procedures. The options for these eyes include exchanging the intraocular lens, piggybacking an IOL or performing a refractive procedure.

LASIK may also be a reasonable option for patients with stable refractions and good capsular support and intraocular lens centration.

Dr. Kanellopoulos practices with Ophthalmic Consultants of Connecticut. He is a clinical consultant for several international eye centers, including the Orasis Hellenic Eye Center, Athens, Greece, and the El-Maghraby Eye Hospital, Jedda, Saudi Arabia.