Keeping track of changes in the IOL marketplace has become an important part of providing the best care for cataract patients. As surgeons, we need to be aware of new developments so that the appropriate IOL can be matched with each patient's unique physiology, anatomy and lifestyle.

Here, I'll review the most important recent changes among those IOLs that are FDA-approved and available for use.

The Health Care Financing Administration (HCFA) recently reviewed six applications for "New Technology" IOL status, with the intention of authorizing an additional $50 reimbursement when such lenses are implanted in an ambulatory surgery center (ASC). The HCFA determined that two of the IOLs it reviewed are worthy of "New Tech" status because of proven, substantial clinical advantages over existing IOLs. The two IOLs are the Toric IOL from STAAR Surgical and the AMO Array multifocal IOL from Allergan.

Let's begin by discussing what sets these two "New Tech" IOLs apart from the rest.

Controlling astigmatism has become a critical factor in the quest for post-op emmetropia. Strategies have included limbal relaxing incisions, astigmatic keratectomy, operating at the steep axis and tight-vs.-loose scleral sutures. Unfortunately, all of these methods share a common disadvantage: Wound healing can vary from eye to eye.

Now, the Toric IOL from STAAR Surgical has opened the door to predictable astigmatic correction. Surgeons no longer have to worry about the healing phase changing the astigmatic result. The entire astigmatic correction is included in the Toric IOL, just as it would be in a pair of glasses.

The Toric IOL is currently available in a silicone, plate-haptic design with two toric powers: +2.0D (to correct 1.4D of keratometric cylinder) and +3.5D (to correct 2.4D of corneal astigmatism). The disparity between the toric powers of the IOL and the cornea is a result of the difference in vertex distance between the cornea and the capsular bag.

The Toric IOL is placed through a 2.7- to 3.0-mm incision using a cartridge system. It's aligned at the same axis intraoperatively as a plus-cylinder spectacle correction (at the steep K-reading), and reduces residual refractive cylinder.

Results with the Toric IOL have been predictable, reliable and stable. Post-op corneal astigmatism is unchanged -- but the residual refractive cylinder is minimal.

The most common complication that occurs with a Toric IOL is off-axis rotation in the early post-op period. However, the frequency of significant rotation (more than 20�) is reported to be less than 5%, and recent changes to the Toric IOL design, including greater overall length, have caused the number of off-axis rotations to drop. (Leaving the eye normotensive at the conclusion of surgery also reduces the problem.)

In cases where Toric IOL rotation off-axis produces symptoms of reduced visual acuity, monocular diplopia or patient dissatisfaction, the IOL can be rotated back on-axis. Such intervention is best at the 1- to- 3-week post-op interval. (Earlier intervention may lead to a second rotation; later intervention is more difficult because of capsular fibrosis.)

Future improvements to the Toric IOL will include the new Collamer material that will further minimize rotation.

The second "New Technology" IOL designated by HCFA is the AMO Array multifocal lens from Allergan. As you know, correcting presbyopia is our next frontier. The Array represents an important step in that direction.

The Array employs a second-generation silicone 6.0-mm optic with alternating distance- and near-focusing concentric rings and blue PMMA haptics. When the pupil exceeds 2 mm, it provides excellent near vision without spectacles. It can be implanted through a 3.2- to 3.4-mm incision using the Unfolder, a reliable cartridge system produced by Allergan.

Patient selection is critical for success with the Array, for several reasons:

• The lens design creates halos around lights under scotopic conditions or when the pupil is dilated. This may be a serious issue for some patients.
• As with any multifocal lens that focuses some light rays for near and others for distance, there is slight loss of contrast sensitivity (more significant in the lower contrast range). Patients who demand crisp, high contrast vision aren't good candidates for this lens.
• Uncorrected near acuity shouldn't be expected if the pupil is unable to dilate larger than 2 mm, if there is significant (uncorrectable) astigmatism, or if the final expected acuity is reduced because of other factors such as macular degeneration.

Many surgeons are using the Array for clear lens extractions in patients who want refractive surgery and demand minimal spectacle wear, yet aren't good candidates for monovision. The Array isn't FDA approved for such use, but its high predictability and proven track record in appropriate patients make it a reasonable choice. However, a positive outcome will depend on several key factors:

• excellent pre-op biometry
• atraumatic surgery
• perfect centration of the lens
• an undisturbed, round and fully reactive pupil (so that all the near-dominant regions can be used to their fullest).

When these conditions are met, results are excellent, and these are among my happiest patients.

Although the previous two IOLs were designated "New Tech" by HCFA, the other lenses that applied to the HCFA for this designation are also impressive.

• Alcon's Acrysof.
This is the most popular lens on the market today, in terms of number of implantations during the last year. Benefits include:
• its acrylic composition makes it more hydrophilic than silicone, with increased biocompatibility
• a squared edge helps reduce posterior capsular opacification (PCO).

Also, a new one-piece AcrySof is now available, with a 5.5-mm optic and continuous construction acrylic haptics that have excellent memory.

• Allergan's Sensar IOL.
This is a new acrylic IOL with a 6-mm optic that's reported to have less glare than AcrySof because of its rounded optic edge. The Sensar can be injected into the capsular bag through a 3.2-mm incision using the Unfolder cartridge system.
• Pharmacia Corporation's CeeOn IOL.
This is a silicone-based IOL with a 6.0-mm optic and "Cap C" haptics. It's designed to reduce PCO in two ways:
• the lens' truncated edge creates a barrier to migration of lens epithelial cells, reducing the rate of PCO.
• the haptics have 90� elbows to stabilize the IOL and further inhibit migrating lens cells.

Hopefully, the heparin surface modified (HSM) technology used by Pharmacia on its rigid IOL's can be adapted to the foldable CeeOn to increase biocompatibility even further.

• STAAR's Collamer IOL.
This is composed of a new material based on a collagen copolymer. It has a high water content, is strongly hydrophilic and is negatively charged, discouraging protein deposits from forming. Because of its high water content, a "ding" during YAG capsulotomy has been shown to disappear spontaneously. In addition, the IOL is coated with a monolayer of fibronectin after implantation, isolating it from the immune system and contributing to its high biocompatibility.
The Collamer IOL is available in a plate haptic design with a 6-mm optic; it can be injected through a 2.5- to 2.8-mm incision. Plans for three-piece and toric Collamer IOLs are underway.
• Hydrogel lenses.
Two companies have introduced highly hydrophilic hydrogel IOLs: the Hydroview IOL from Storz, with a water content of 38%, and the Memory Lens from CIBA, more of a hydrogel/acrylic hybrid, with a water content of 19%. These lenses are a significant alternative to hydrophobic silicone, and both are more hydrophilic than either PMMA or acrylic.
Recently, the Memory Lens was voluntarily recalled because of reports of post-op inflammation, apparently caused by aluminum oxide used to polish the IOL. CIBA plans to release the IOL again soon.
• Piggyback IOLs.
For the first time, minus-power foldable IOLs, along with low-power plus IOLs, can be purchased from STAAR (AQ2050). These lenses can be delivered through an astigmatically neutral incision. They can correct small refractive errors in psuedo- phakes, avoiding an IOL exchange.
These lenses are ideal for piggybacking over an existing IOL. Their 14-mm overall length and Elastimide haptics enable them to center well in the sulcus, despite being injected through a 2.5-mm incision. They're available from -4D to +10D in 1D steps, with plans to extend the range to -10D in 0.5D steps.

IOL technology is advancing rapidly, with obvious benefits for everyone. The increasing diversity of lens materials and designs is leading to safer surgery and improved outcomes -- and making it possible to tailor IOLs for each patient.

The prospects for generating satisfied patients have never been greater.

A 75-year-old male with visually significant cataracts and 1.5D of with-the-rule astigmatism has 20/50 best-corrected acuity. Topography shows 1.8D of corneal astigmatism at 90�.

• Operating on the steep axis over the brow through a scleral tunnel self-sealing incision would decrease post-op corneal astigmatism by about 1D in the first 6 weeks -- but then the healing response would increase the K's back toward pre-op levels.
• Operating temporally and suturing tightly might produce a flipping of the axis to against-the-rule astigmatism.
• Clear corneal surgery through an incision of less than 3.5 mm wouldn't significantly change the K's.
• Astigmatic keratectomy or limbal relaxing incisions are only moderately predictable and risk destabilizing the cornea.

• Clear lensectomy

• Minimizing future complications

• CORRECTING AN "IOL SURPRISE"

-- Stephen Bylsma, M.D.

Dr. Bylsma practices at the Shepard Eye Center in Santa Maria, Calif. He specializes in cataract, glaucoma and refractive surgery, staying on the cutting edge of eye care by participating in numerous FDA clinical trials and investigational studies. Dr. Bylsma is also a faculty member at UCLA.