Anterior Chamber Intraocular Lens Placement Technique: A Tutorial

P. Christi Carter, MD, Thomas A. Oetting, MS, MD
Submitted July 5, 2016

"Just-in-Case" Situations

As a cataract surgeon, there are a handful of skills which are infrequently encountered, but may be unexpectedly required during any case. Cataract surgeons should be prepared for these rare situations and prepare virtually or in the wet lab for "Just in Case" techniques (PLEASE NOTE: This is not an all-inclusive list):

• Anterior chamber intraocular lens (ACIOL) placement
• Sulcus intraocular lens placement 
• Removal of marred IOL
• Anterior vitrectomy 

In this tutorial, we will address how to place an ACIOL.

Indications

Placing an ACIOL is indicated when capsular support for placement of the intraocular lens (IOL) posterior to the iris is deficient (capsular tear or zonular damage), the iris is normal, and the chamber is deep.[1]

Many options exist for IOL placement in the setting of poor capsular support. These include ACIOL (as discussed in this text), iris-fixation of the IOL, scleral-sutured IOL, and procedures to tuck the haptic into the sclera with or without gluing:

http://cataractsurgeryforgreenhorns.blogspot.com/2015/11/glued-iol-technique-agarwal.html

In 2003, Michael Wagoner led an American Academy of Ophthalmology meta-analysis that found that ACIOL, iris-sutured IOL, and scleral-sutured IOL were equivalent.[2] Shortly thereafter, a study comparing ACIOLs with iris-fixated intraocular lenses in the setting of poor capsular support confirmed the findings of the AAO meta-analysis, stating that there were no significant differences in outcomes (specifically visual acuity and post-operative complications) between the two groups.[3]   However, a study conducted in response to these reports comparing primary scleral-fixated IOLs with primary anterior chamber IOLs in complicated cataract surgery found visual acuity to be significantly more favorable in the primary ACIOL group.[4]

Relative Contraindications

• Any corneal endothelial disease
• Iridocorneal angle damage such as peripheral synechiae
• Shallow chamber
• Lack of substantial iris tissue[5]

Potential Complications

The proximity of an ACIOL to the cornea and anterior chamber angle accounts for the majority of its potential complications, which include:

• Pseudophakic bullous keratopathy (endothelial decompensation)
• Glaucoma
• Peripheral anterior synechiae
• Uveitis – glaucoma – hyphema syndrome
• Cystoid macular edema[1,5]

Newer ACIOL models (i.e. open-loop) have shown decreased complication rates compared to those of the 1970s and 1980s.[3]

Additional Equipment Needed for AC IOL Placement:

• Bimanual vitrectomy handpiece
• Westcott scissors
• Bipolar electrocautery
• Beaver blade
• Acetylcholine ("Miochol")
• Calipers to measure limbal white to white distance
• ACIOL (come in several sizes)
• 10-0 Nylon suture
• 8-0 Vicryl suture

Step-By-Step Tutorial for Primary Placement on an Anterior Chamber Intraocular Lens (in complicated cataract surgery)

Video on ACIOL placement

If this video fails to load, use this link: https://vimeo.com/134846224

The goal of this surgery is to place the ACIOL into the iridocorneal angle with the lens footplates contacting the scleral spur without capturing any iris tissue between the two in the process.

1. Close clear corneal incision with single interrupted 10-0 nylon suture (or extend to 6 mm for AC IOL placement)
2. Perform bimanual anterior vitrectomy according to usual practice guidelines.
   (Tutorial: http://www.eyerounds.org/tutorials/anterior-vitrectomy/index.htm)
3. Choose location for the scleral tunnel: The scleral tunnel may be placed temporally (either just posterior to the original clear corneal incision or via extension of the original clear corneal incision) or superiorly 
   • A temporal incision carries the advantage that the cataract surgeon is typically most comfortable and familiar with operating temporally. Also you will relax the typical WTR astigmatism with the temporal incision. However, the proximity to the clear corneal incision can be tricky. Typically, you will extend the existing corneal wound to 6 mm but bring it more posterior on either end to create the 6 mm wound
   • The advantage with a superior scleral tunnel is that an entirely new wound is constructed under the lid. The surgeon may need to sit superiorly to create a superior wound
4. Choose the appropriate anterior chamber lens:
   • The AC IOL is more anterior and will require less power than the more posterior intracapsular IOL. The A constant for the AC IOL takes this into account, and so if the IOL print out includes an AC IOL, simply use that IOL power. Expect the power to be about 3 diopters less than the PC IOL.
   • Determine the AC IOL diameter:  Measure the limbal white to white (WTW) diameter on the axis of IOL placement. Add 1 mm to the WTW and use the AC IOL length closest to this result. For example, if the scleral tunnel will be placed temporally, measure the horizontal white-to-white corneal diameter. The AC IOL length should be 1 mm GREATER than the WTW diameter.[5]
5. Create a scleral tunnel:
   • Create a peritomy of about 7 mm.
   • Use calipers to mark 6 mm about 1 mm posterior to the limbus.
   • The incision shape may either be mildly frown-shaped (as in manual small incision extracapsular cataract surgery) or linear.[6]
6. Inject acetylcholine ("Miochol") into the anterior chamber to induce miosis.
7. Create a peripheral iridotomy (PI):  If you do not place iridotomy, you will likely have iris bombe. See Dr. Oetting's blog: http://cataractsurgeryforgreenhorns.blogspot.com/2009/01/blog-post.html
   • Create the iridotomy away from the haptics so that the haptic cannot easily work its way into the iridotomy or block the flow of aqueous fluid. Usually, the IOL haptics are at 3 and 9 o'clock and the PI is at 12 o'clock.
   • There are many ways to create a PI. The easiest and most elegant is to use the anterior vitrector with a low cut rate (e.g. 100). Use dispersive OVD to maintain anterior chamber depth, turn the cutter posteriorly, directly over peripheral iris and depress the pedal into position 3 with vacuum and cutter active. As soon as you see the iris wiggle, stop. Look under vitrector where you will discover a perfectly round PI. (OK to smile at this point in the surgery).
   • Of note, if you forget this step, you can place an LPI in the clinic the next morning. You will lose some style points.
8. Inject dispersive OVD over the pupil, over the PI, and into the angle across from the wound. Dispersive is preferred in this situation compared to cohesive because some of the OVD will be retained, and dispersive is less likely to cause an IOP spike.
9. Insert AC IOL:
   • A lens glide (e.g. Sheets glide) can be used to facilitate placement. The glide is placed across the pupil into the angle opposite the wound under dispersive OVD. Using a lens guide is not required, but helps reduce the risk of catching iris during insertion and inserting the AC IOL posteriorly through the pupil.
   • Forceps (such as Kelman-McPherson forceps) are used to grasp the lens (the trailing haptic and about a third of the optic) and insert it into the anterior chamber through the scleral tunnel.
   • Ensure that the leading haptic remains anterior to the iris plane throughout insertion.
   • After releasing the lens, the trailing haptic will remain outside the scleral tunnel wound. Tuck the trailing haptic into the angle under the wound with forceps or a Kuglen hook.
10. Close the scleral tunnel using 2 or three 10-0 Nylon sutures. The knots do not have to be buried, but the tails should be rotated to the posterior edge of the suture tract, so that they will be covered by conjunctiva at the end of the case.
11. Check the location of the haptics to ensure that no iris tissue is caught between the haptics and the iridocorneal angle.
    • Using a Sinskey or a Kuglen hook, lift one haptic centrally and anteriorly, and then release it. Perform the same maneuver with the other haptic.
    • An oval or peaked pupil is a sign that iris tissue (or vitreous) may be tucked between the footplates and the angle.[5,6]
12. Aspirate any remaining viscoelastic from the anterior chamber. Ensure the wounds are watertight. Add additional sutures or sealant if necessary.
13. Close the peritomy using buried 8-0 Vicryl sutures. The conjunctiva should close nicely over the scleral tunnel and its interrupted nylon suture tails.

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