Study: square-edge configuration of CeeOn Edge IOL inhibits PCO

Tight seal prevents fibroblastic and epithelial cells from reaching posterior capsule.

LOS ANGELES — One surgeon's experience with the new CeeOn Edge foldable IOL (Pharmacia Corp., Peapack, NJ) indicates that the IOL's unique square-edge configuration inhibits posterior capsule opacification (PCO).

---The barrier effect of the square edge configuration in a rabbit eye. The CeeOn Edge lens is effective in inhibiting the migration of cellular elements across the posterior capsule.
(COURTESY OF DAVID APPLE, MD)

D. Michael Colvard, MD, who is in private solo practice here, has 3-years of follow-up data on 35 CeeOn Edge implants. To date, not one single patient has shown signs of PCO. "The optic material of the CeeOn Edge lens is a UV-absorbing silicone with an index of refraction of 1.46," he said. But, more important, "the optic is a 6-mm biconvex lens with a square-edge configuration."

Dr. Colvard's clinical observations about PCO are supported by animal studies conducted by David Apple, MD, an ocular pathologist at the Storm Eye Institute in Charleston, S.C., and his colleagues. "Modifications made in the edge of this IOL may prove to have a significant effect in reducing capsule opacification," Dr. Colvard said.

Visual results in Dr. Colvard's patient group "are exactly the sort we would expect to find in an IOL," he said. None of the patients had significant preoperative pathology. "All the patients did well visually," he said. Every patient achieved a visual acuity of at least 20/40 at 2 weeks. "These patients have continued to maintain this level of vision over the 3-year follow-up period," said Dr. Colvard, who spoke at the American Society of Cataract and Refractive Surgery annual meeting.

Crystal clear capsules

---The square edge configuration of the CeeOn Edge lens allows the capsule to seal to the lens.

But what caught Dr. Colvard's attention "was the absolute absence of any capsule opacification in any of the patients. This was apparent very early in the postoperative course of these patients. The capsules were not just clear; they were all crystal clear. The posterior capsule appeared to be absolutely optically empty." Overall, "these lenses look different in the eye than other IOLs I have ever implanted."

After evaluating these same patients time and again and noting that the IOLs "look better than any silicone lens I have ever used," Dr. Colvard became curious and contacted the investigators at Pharmacia & Upjohn. "I asked them what they had done with this lens," he said. "You have to realize this was long before anyone was talking about the effect of a square-edge configuration on capsule opacification. I frankly was completely clueless as to why these patients had such clear posterior capsules."

It turned out that the difference between the CeeOn Edge and other IOLs that Dr. Colvard had implanted is the CeeOn's square-edge configuration. "The standard biconvex lens has a tapered edge," Dr. Colvard said. In contrast, "The CeeOn Edge has what David Apple calls the ‘barrier-edge design.' Dr. Apple and his colleagues have observed clinically and in experimental rabbit models that IOLs with tapered edges allow the migration of fibroblastic and epithelial cells under the edge of the IOL. This results in the fibrous encroachment in an annular pattern that we've all seen."

Shrink wrap effect

---The net result of the lens' "barrier-edge design" is an extraordinarily clear lens.
(COURTESY OF DR. W. SCHMACK)

On the other hand, the CeeOn's square edge "causes the capsule to almost shrink wrap and seal around the edge of the IOL and across the posterior surface of the IOL," Dr. Colvard said. "It is amazing to me that such a simple thing can have such a profound effect. This tight seal means that fibroblastic and epithelial cells simply cannot reach the posterior capsule in the area of the optic."

At the meeting, Dr. Colvard shared a slide of a rabbit capsule after the explantation of a CeeOn Edge lens. "This demonstrates the absolute barrier-edge effect of the IOL in this rabbit model," he said. "This also explains why these capsules appear so clear clinically."

Dr. Colvard, who is an associate clinical professor of ophthalmology at the University of Southern California School of Medicine, said he has experienced no lens complications with the CeeOn Edge, including glare or halo. Furthermore, the lens is easy to insert because "it has a high index of refraction. You can easily place it through a 3-mm incision." Dr. Colvard's positive experience with the CeeOn Edge lens "reflects the European experience, which has shown a capsule opacification rate of approximately 1% after 1 or 2 years with this particular lens."

In summary, the CeeOn Edge lens in this small series of patients "gave excellent visual results," Dr. Colvard said. However, "the most remarkable clinical observation about the lens, in my experience, is that the capsules are extraordinarily clear. This appears to be the result of the barrier-edge design, which seems to have a positive effect in inhibiting capsule opacification."

For Your Information:

• D. Michael Colvard, MD, can be reached at Colvard Eye Center, 5363 Balboa Blvd., Ste. 545, Encino, CA 91316; (818) 906-2929; fax: (818) 906-0567; e-mail: eyecolvard@aol.com. Dr. Colvard is a paid consultant of Pharmacia Corp.
• Pharmacia Corp. can be reached at 100 Route 206 North, Peapack, NJ 07977; (888) 768-5501; fax: (908) 901-1871.