There are many ways to insert the MemoryLens® (CIBA Vision Corporation, Duluth, GA). The particular technique I like to use is a two-handed method that I feel is a little bit safer and less traumatic to the zonules than rotating the lens in place. In the method I use, you can hold the lens with whichever instrument you prefer; I use Kelman-McPherson tying forceps (produced by a few difference manufacturers). There are several forceps specially designed for the lens; I like the Piovella MemoryLens® Forceps (ASICO, Westmont, IL). I grasp the lens with the instrument, insert it through a 3.2-mm incision, and hold the eye through the side port with a spatula. Then I use the spatula to push the nose or the leading edge of the optic into the bag. With the Kelman-McPherson in my left hand (I'm a left-handed surgeon), I enter through the side port and push the nose of the lens down. When the lens is just in the bag, I rotate it clockwise with my left hand. After that loops in, I switch hands, push the tail of the lens down into the capsule, grab the trailing edge or the proximal loop with forceps, and place it directly into the capsular bag. It sounds complicated, but it's very easy. The entire procedure takes me between 10 and 15 minutes to complete.
A LOW-MAINTENANCE LENS
My staff and I have found that the MemoryLens® takes about 12 minutes to mostly unroll, and about 30 minutes to completely unroll. If you don't have time to wait for the lens to unroll, you can simply insert it in the correct location and it will be in the same position the next morning, completely unrolled. There have been many thousands of these lenses inserted, and there has never been a report of one not completely unrolling. My staff and I have inserted approximately 3,000 of the MemoryLens® lenses, of both the tighter roll and the previous model, and I haven't seen a single lens shift.
PERFORMANCE
About a third to a quarter of the lenses I use right now are MemoryLens® lenses. I have not yet begun the study I'm planning that will document visual acuity with the MemoryLens® at 1 month, 6 months, and 1 year, but just on sight, the eyes with those lenses look good; the patients see well, their eyes are quiet, and they have very little inflammation. For diabetics, people with retinal pathology, high myopes, and anybody with a history of vitreoretinal pathology, I prefer a larger optic lens, but most of my other patients receive the MemoryLens®.
PLUS POINTS
The MemoryLens® offers many advantages. It comes prerolled, so neither you nor your staff has to fold the lens before implantation. The fold is consistent every time, unlike other lenses that occasionally have to be refolded or inserted with the poor fold, which requires a little larger incision. In addition, a folder can quite easily scratch the lens. The other nice aspect of the MemoryLens®, particularly with the way it is rolled now, is that the outside diameter is the same with a low diopter lens as it is with a high diopter lens; a 10 D lens has the same outside diameter as a 30 D lens. With the previous model, the outside diameter became thicker as the lens got thicker. Another advantage of the lens is that because it does not unroll immediately within the eye, there is time to remove any viscoelastic material from behind the lens. Other lenses can trap viscoelastic material behind them, which increases intraocular pressure.
ONE LAST NOTE
The haptics of the MemoryLens® are made out of polypropolene instead of polymethylmethacolate (PMMA). Previous studies have indicated that bacteria adhere more readily to polypropolene than to PMMA. However, a study that was presented at the May 2000 American Society of Cataract and Refractive Surgeons meeting by Tom Paul, PhD, Head of Research Department of CIBA Vision Surgical, in Atlanta, GA, and Thomas Neuhann, MD, of the Alz Eye Clinic in Munich, Germany, showed that although dry polypropolene material does have higher bacterial adherence, wet polypropolene material actually has less bacteria adherence than PMMA. Instead of an increased risk of infection, there is probably less risk with the polypropolene, although the risk is very small for either material. n
