Multifocal Lens Implants Several multifocal lens implants are now available for use by surgeons in the US. These lenses work in a fashion similar to a multifocal lens in a pair of eyeglasses, in that they contain regions or "zones" for distance viewing, zones for intermediate viewing, and zones for near viewing. These include the ReStor lens (made by Alcon Surgical), and the ReZoom and Array lenses (made by AMO - Advanced Medical Optics). The ReStor Lens
 The ReStor Lens © All Rights Reserved. | The ReStor lens has an overall design very similar to other single-focus lenses. The optical surface has concentric rings of differing focus as shown in the higher-magnification image at right, below. Sharp distance vision is afforded by the more peripheral portion of the lens (like the upper part of a bifocal lens in a pair of glasses), while sharp near vision is provided by focal properties of the more central portion of the lens (like the reading portion of a bifocal lens). The multiple concentric rings of different focus in this lens effect a much broader range of focus than a single-focus lens implant, through both refractive and diffractive optics. This lens received FDA approval in April '05, after review of 3-year safety and efficacy data in clinical studies (see below).
 Optic of the ReStor Lens © All Rights Reserved. | A multifocal lens implant like ReStor, ReZoom or Array (see below) should be distinguished from other lens implant designs that enable focus at multiple distance ranges. Other methods of adjusting focus include: - Change of focus by effecting a position change within the eye with focusing effort, as with the CrystaLens , and
- Change in focus through shape change of the lens itself, as with the eye's natural lens.
One challenge with multifocal lenses, as anyone who has worn bifocals will acknowledge, is that the "near" portion of the lens can cause blur when viewing objects at distance, and vice versa. Another concern with older diffractive implant lenses is that the ridges on the lens can cause some 'edge effects' including glare, halo, and reduced contrast sensitivity under certain viewing conditions. The precise engineering and fabrication of the ReStor lens (referred to as an "apodized diffractive optic") has overcome many of these concerns. Restor Clinical Data Data from clinical trials presented to the US FDA is reviewed below. These studies represent data from patients followed for 3 years after implantation of the ReStor lens. In addition to the data presented below, there were no cases of lens-related complications, and no cases of lens removal for undesirable optical consequences or effects.
Fig. 1: Glasses Use After Surgery: ReStor vs. Control |
Percentage of patients wearing eyeglasses after lens implantation. In the ReStor group (orange) 80% never wore glasses after implantation of this lens in both eyes , compared to 5% of patients that had monofocal (traditional or standard) lens implantation. |
| Fig. 2: Near Vision After ReStor Implantation |
Breakdown of near vision results in the ReStor group (both eyes having Restor lens implantation) compared to a control group (both eyes having monofocal lens implantation). Near vision acuity scores were significantly better in the ReStor group (orange), compared to the control group (yellow). |
Fig. 3: Distance Vision After ReStor Implantation |
Comparison of distance vision in the ReStor group (ReStor lenses in both eyes) compared to control group (monofocal lenses in both eyes). Distance vision scores were comparable in both groups, suggesting that the multifocal lens design of ReStor does not contribute to any decrease in distance vision . | The Array and ReZoom Lens
| The ReZoom Lens © All Rights Reserved. |
| The Array lens © All Rights Reserved. | The Array and ReZoom lenses are similar in design to ReStor, but there are differences. These are analogous to the differences between blended , progressive and Varilux multifocal (spectacle) lenses. Shown at left is an image of the Array lens and at right of the ReZoom lens, both made by Advanced Medical Optics ("AMO"). The Array lens is an older design which did not gain wide acceptance or popularity among surgeons when it was introduced in about 1997. There are very subtle differences in the ratio of near-, intermediate- and distance-focusing proportions of these lenses and in their edge design. The ReZoom lens apparently causes less light scattering, less glare and less halo than the Array. Any multifocal lens will cause some light scattering and glare due to the zones of different focus; this is unavoidable.
Most surgeons develop a familiarity with one of these three multifocal lenses and will therefore recommend it in preference to the other two products currently available. From a practical standpoint, it is not it is not possible for any single surgeon (or practice) to be expert with every conceivable brand and model of lens implant, so surgeon judgment and individual preferences will influence surgeon opinion here. |