Patient Management
IOL Implantation: Avoiding Complications
Four surgeons share strategies they've developed to help ensure the best possible surgical outcome.
Compiled by Christopher Kent, Senior Associate Editor

ADVANCES IN MEDICAL TECHNOLOGY--and the promise of an increasing supply of cataract patients in the years ahead--offer plenty of opportunity for surgeons to streamline technique and improve outcomes. Here, we've asked four experienced ophthalmologists to share some of what they've learned during years of successfully implanting IOLs.

Make incisions as close to watertight as possible without impeding flow entirely. Thanks in large part to Dr. Richard Mackool and his Mackool sleeve, everyone is aware that the main incision must fit the phaco tip. However, not everyone is aware of how critical the paracentesis incision is. Anything over 0.5 mm will result in up to a 22 cc/minute loss of BSS out of the paracentesis, leading to increased turbulence and surge and decreased efficiency and safety.

The same closed-system principle applies to irrigation and aspiration. Always use a silicone sleeve, never a metal sleeve. A metal sleeve won't plug the incision made to fit the phaco tip. This can cause collapse of the bag fornix and increased incidence of capsule rupture during this phase of the operation.

Use the pupil margin as a guide for capsulorhexis shape, but not size. As the excellent research of Dr. David Apple demonstrated, an intact circle covering all edges of the implant optic is the gold standard for implantation. However, both the dilation size and corneal diameter will vary from case to case.

You'll increase your percentage of on-target outcomes if you get a feel for how much volume of tissue should be removed from the capsule. Use the radius of the tear and the surface area of the torn capsule as the constant. As with a nomogram, you'll eventually reduce your margin for error by observing how a given volume affects the size of capsulorhexis after implantation, and then adjusting it accordingly the next time. (I've also designed capsulorhexis forceps with laser marks in millimeters that provide a visual guide for measuring the radius of curvature as the tear is being made. They are available through ASICO.)

If the tear goes awry, act quickly. At the first sign that the tear is going in an unpredictable direction, regrasp the tissue and redeepen the anterior chamber with viscoelastic to flatten any convexity of the lens capsule. Also, to maintain good visualization while correcting the vector, stop within the first millimeter of outward run before the tear reaches the iris edge.

Be aware of the state of the zonules from the first touch of the capsule with the cystotome. We depend on the zonular complex for uncomplicated surgery and post-op results. Signs that all is not well with the zonules include:

• the capsule tents instead of puncturing easily
• you have to use a more centripetal vector for the tear than you expected to create an adequate size capsulorhexis
• after hydrodissection, the nucleus springs back into position when rotated.

Hopefully all surgeons will soon have access to endocapsular tension rings. In the meantime, if the zonules are problematic, try using:

• multidirectional hydrodissection
• lower flow phaco parameters
• phaco chop or another zonule-friendly, nonsculpting phaco technique
• small sector cortical stripping
• secondary capsulorhexis enlargement (if appropriate).

Don't use a dialing technique to place the implant when these conditions exist.

Maintain a good viscoelastic barrier under the cornea. Phacoing is like using a microscopic jackhammer between two delicate membranes. To address this, Dr. Steven Arshinoff gave us the wonderful technique of "soft shell" using a dispersive viscoelastic under the cornea, ironed into place by a cohesive viscoelastic posterior to it.

In longer, denser cases, you can take this one step further and re-instill dispersive viscoelastic through the paracentesis with the phaco tip held steady in foot position zero. The goal is to fill the anterior chamber completely with the Viscoat or Vitrax so it fills into itself, eliminating any visibility issues. (Be sure to establish flow before engaging foot position three.)

If you maintain a barrier, the cornea will be clear the next day -- even if you're dealing with 5+ brunescent lenses.

Clean the bag meticulously. The more completely you clean the bag, the lower your posterior capsule opacity rate will be and the less post-op inflammation the eye will suffer. I recommend that you:

• Always remove cortex from anterior to posterior to avoid missing wisps and strands that are time-consuming and frustrating to remove.
• If your technique makes use of cortical hydrocleaving (a la Dr. Howard Fine), consider an 0.2 mm port size rather than the standard 0.3-mm port size. This causes these strands to occlude the port more effectively, allowing vacuum to build in a peristaltic pump machine.
• Use the capsule vacuum modality (which is available on all machines) to clean the fornices and vacuum the anterior flaps of cells.

Avoid stretching the incision. Solid wound closure is your best defense against endophthalmitis -- and a stretched incision won't close as readily. For that reason, err on the side of making the wound a little too large, rather than too small. If the internal Descemet's line is straight, attached, and there's no fish-mouthing from stretch, the incision will close without hydration. (I don't use stromal hydration routinely; I only irrigate the tunnel to remove any invisible material and permit internal valve closure.)

When working with mature cataracts, use capsular staining. Staining before starting the anterior capsule tear makes it much easier to see. I recommend using either indocyanine green (ICG) or trypan blue (Vision Blue). (The latter isn't yet FDA approved, although it's available in Europe. It costs about one-tenth as much as ICG, and it stains better.)

If the patient has a small pupil, perform a bimanual pupil stretch. This is easily done using two instruments, instead of cutting the iris or using iris hooks, which can be very labor intensive. One stretch does the trick. It's so easy that some surgeons don't believe it will work!

If you expect problems, use a scleral tunnel. In traumatic cases, or whenever difficulty is expected, consider using a scleral tunnel incision rather than a clear cornea incision. This will allow you to enlarge the incision if you need to loop out lens fragments or switch to an anterior chamber lens. The scleral tunnel also reduces the risk of induced astigmatism.

When working with a posterior polar cataract, consider alternate techniques. Some of these patients will have a weak central place in the posterior capsule that can blow out under hydraulic pressure, deep-sixing the nucleus. In these cases, consider moving the lens to the anterior chamber and do the emulsification there. Also, consider using Dr. Robert Osher's slow motion phaco technique -- using low bottle height, low flow and vacuum, and proceeding in a very slow, controlled manner.

Try using the IOLMaster to measure axial length. For lens power calculation we've found the IOLMaster to be an order of magnitude more accurate than ultrasound, although other variables make the improvement in the final calculation less impressive. Basically, the IOLMaster either measures accurately or won't measure at all. Plus, Medicare now pays for using the IOLMaster, although reimbursement is still less than for ultrasound.

Avoid silicone and multifocal lenses if the patient may require a future vitrectomy. Some patients, such as those with diabetic retinopathy, may be candidates for vitrectomy at a later date. If the surgeon has to use air during the vitrectomy, it will cloud up the back of a silicone lens, obscuring the surgeon's view. If the surgeon uses silicone oil, it will adhere to the lens and bead up, clouding the patient's vision.

Similarly, multifocal lenses become problematic: The different zones in the lens can cause viewing problems for the vitrectomy surgeon. Some have described the tip of the instrument suddenly disappearing from view as they move behind a different segment of the lens.

The anterior or posterior capsule is torn. The IOL you choose in this situation makes a big difference. I recommend the Alcon SA60AT single-piece lenses because the haptics unfold very slowly and the lens can be inserted into the bag with a very small profile. This allows you to position the lens without any pressure against the equatorial capsule. (In contrast, a traditional style lens creates pressure on the capsule, which can cause a tear to extend.)

The SA60's haptics are so soft, and the lens unfolds so slowly, that you can perform all manipulations or maneuvers before the lens is fully open. Also, if the lens has to be moved after it's fully open, the soft, flexible haptics are extraordinarily easy to reposition.

Once the viscoelastic has been removed and the haptics fully expand, the lens has excellent centration. Also, the biocompatibility of the material allows a fribronectin adhesive to form between the optic and the capsule. Once the lens is in position, it's likely to stay there.

When the lens must go in the ciliary sulcus. In this situation, I'd choose an old-fashioned, single-piece lens with an overall length of 13.75 mm and an optic of at least 6 mm. This way you can be reasonably certain that the haptics will be supported not only by the capsule and zonule but by the pars plicata as well. My preference is the model 75 UV lens from Bausch & Lomb, which has cantilevered haptics. The larger optic also gives you an extra margin of safety, should there be a slight decentration.

The iris is dysfunctional from traumatic mydriasis. To avoid optical aberrations such as edge glare, I'd either use:

• some type of pupillary cerclage or pupilloplasty to cover the edge of the optics
• an artificial iris device attached or in addition to the IOL
• a larger optic such as the 6.5 mm Alcon MA50. With the larger optic, a moderate traumatic mydriasis will still allow the lens edge to be covered by the iris.

It's necessary to reposition the IOL. On rare occasions it's necessary to reposition the IOL once it's inside the eye. For example, a PC IOL may be placed in the ciliary sulcus -- or even in the anterior chamber -- if the surgeon is faced with severe positive pressure.

To reposition it into the capsular bag, I hold a curved Y-hook in my left hand and a straight Y-hook in my right hand. While I place the straight Y-hook in the optic-haptic junction and use it to rotate the lens clockwise, the curved Y-hook straddles the proximal haptic, compressing and depressing it into the proper position. This maneuver is both very safe and very reliable.

The lens is inadvertently placed backwards. In this situation, I fill the capsular bag and anterior and posterior chambers with Healon5 and use two hooks to somersault the lens.

If I have to cut the lens to remove it through a small incision, I use a technique developed by Shuichiro Eguchi, M.D., in Tokyo. A quadrant of the lens is excised by making two radial incisions 90° apart. (See photograph, left.) After the quadrant is removed, the remaining 3/4 of the lens can be maneuvered out through a small incision by rotating the lens.

Viscoelastic must be removed despite extreme positive pressure. A good technique for preventing chamber collapse and lens contact with the corneal endothelium is to place a 30-guage cannula on a 3-cc syringe filled with BSS solution. Insert the cannula through the second stab incision and lay it across the optic while inserting the I&A tip; use it to hold back the optic after the viscoelastic has been removed. (See photograph, above.) After withdrawing the I&A tip, inject the BSS through the cannula. This will deepen the chamber and prevent IOL-corneal contact.

Dr. Osher is a consultant for Alcon and Pharmacia. For additional information or videotaped demonstrations of these techniques, contact Gay Earlywine at the Video Journal of Cataract and Refractive Surgery by sending a fax to (513) 936-4881 or an e-mail to gearlywine@cincinnatieye.com.

Use visco to position the bag for easy lens insertion. I prefer to use a highly cohesive viscoelastic such as Healon5 or GV for this task. First, I fill the capsular bag to fully expand it, allowing more room for easier insertion of the IOL. Then, I inflate the anterior chamber to allow room for the IOL to traverse it, but not so deep that I have to reach posteriorly to insert the IOL.

At this point I inflate the capsular bag differentially so that the distal bag is fully inflated but the proximal part of the bag is only partially inflated. I then flatten the proximal anterior capsule, displacing it slightly posteriorly. Once this is done, the IOL can be projected straight across into the open jaw of the fully inflated distal side of the bag, while easily traversing the proximal side of the bag.

Use a cartridge-type injector for most lens insertions. This prevents contamination from the lashes and ocular surface and reduces instrument-induced trauma to the IOL. However, use only a moderate amount of viscoelastic to lubricate the cartridge. Too much viscoelastic may cause the inserter rod to override the lens, which can cause the lens to jam or tear. Conversely, too little lubrication may cause the lens to become jammed in the inserter.

Also, be sure to position the IOL in the cartridge exactly as recommended by the manufacturer to avoid optic trauma or kinking or breaking the haptic.

Don't use too small an incision. A common error in IOL insertion is using too small an incision, which will likely lead to irregular tearing of the tissue with resulting tissue gape and the need for suturing. Open the incision just enough so that the tip of the cartridge can be inserted with a modest amount of pressure and a gentle rotation of the cartridge shaft until it's inside the eye.

I make my primary incision 2.8 mm wide with a Langerman Hinge and use a parallel-sided blade to enter the anterior chamber. With the Allergan SI40 or SA40N (Array) lens I don't usually need to extend this during lens insertion. However, with acrylic lenses a small amount of extension is needed. I try to widen only the internal aspect of the incision, forming a trapezoid, leaving the external opening at its original size. This allows enough room to insert the IOL but keeps the incision small enough to obviate induced astigmatism and to be self-sealing.

Be sure to remove ALL viscoelastic. Removal of residual viscoelastic is essential for two reasons: It may cause elevated IOP, and if it's sequestered behind the IOL it can cause capsular block syndrome, leading to progressive myopic shift.

Healon5 has become my preferred viscoelastic for this reason; it's extremely cohesive with good followability, which promotes its removal en bloc from the eye. Also, it's easily visible at the aspiration tip during removal so I can visually confirm that all of it has been evacuated.

I like to insert the IOL so that it ends up in a slightly nasally displaced position. (Because Healon5 "stops motion," the IOL stays where I place it during insertion.) Then, with the lens slightly off-center I remove the viscoelastic by inserting the Koch bimanual I/A, sweeping its tip easily beneath the IOL. Under high vacuum and flow, I place the aspiration port against the IOL, which protects the posterior capsule from being captured by the I/A tip. Then the mass of Healon5 aspirates easily. Once this is accomplished, the IOL springs into centration, signaling that the viscoelastic is gone. Finally, I sweep behind the iris and into the anterior chamber to remove any residual viscoelastic.

If you need a capsular ring but don't have one, use the haptic to compensate. Before inserting the IOL, I evaluate the stability of the capsule and the zonules. If the capsule appears unstable or I find frank sectorial zonular dehiscence, I insert a capsular tension ring to stabilize the capsule bag. (Although these rings aren't currently available for general use in the United States, we're participating in a multicenter FDA clinical trial to evaluate the efficacy of a capsular tension ring manufactured by Ophtec USA.) If no capsular ring is available to you, you can place the IOL into the capsular bag and orient the haptic so that it's coincident with the zonular tear. This helps to support the tear and increases IOL stability.

Size the capsulorhexis properly. If the rhexis is too large, the IOL may tend to bow anteriorly causing papillary capture or decentration out of the bag. Later, more aggressive posterior capsular opacification may occur because of the lack of any barrier effect that would result from pressure of the IOL against the posterior capsule. Too large a rhexis may also result in edge glare because the capsule doesn't overlap over the IOL.

If the rhexis is too small, it may be difficult to insert the IOL, and the progressive capsular contraction may ultimately interfere with the IOL centration and stability. Furthermore, a small rhexis in the presence of an Array lens may reduce its multifocality.