As you have seen on previous pages, when your natural lens becomes cloudy you have a cataract. When cataract surgery removes this cloudy lens, a new crystal-clear intraocular lens is almost always placed in order to refocus images.
Before discussing these replacement IOLs, you must learn about something called presbyopia. Presbyopia is a natural age-related part of life, and usually starts to affect people at about age 40-50. It results from the lens slowly losing its elasticity as the lens thickens over the years. When we are younger, we have a muscle inside of our eye that contracts when we attempt to focus on a close object like a book. After the muscle contracts, the lens “fattens” and increases its refractive power, which allows us to see the near object clearly. With the decrease in lens elasticity that occurs with increasing age, the eye has a hard time focusing on near objects. This is why you see people wearing reading glasses or “cheaters” while reading restaurant menus, threading a needle, or tying a fishing lure – they are suffering from presbyopia.
Standard IOLs have been used for over 30 years in cataract surgery. They can provide excellent distance vision (such as seeing street signs or watching a golf ball) for patients. You will still need glasses to help get intermediate (such as a computer screen) and near (such as reading the newspaper) objects in focus. Watch a video about Standard Monofocal IOLs.
Premium IOLs have been used for approximately 15 years. There have been several different designs over the years. The newest generation of premium IOLs have had excellent results, and their popularity is exploding. Another name for these lenses could be “presbyopia-correcting” IOLs because the goal is to give you more than just good distance vision. In addition to providing good distance vision, these IOLs also provide you good intermediate and near vision! Their goal is to reduce your dependency on reading glasses and bifocals – can you imagine being glasses free?
The ReSTOR IOL is a multifocal IOL – it incorporates both distance and near powered lenses into one IOL. The lower power zones bend light coming from distant objects to a clear focus on the retina. The higher power zones bend light from near objects to the same clear focus on the retina. Thus, different zones of lens power work together to provide the eye with near and distant vision! There are currently two different types of ReSTOR IOLs used, the ReSTOR 2.5 and the ReSTOR 3.0. They differ in the distance of the near focal point (approximately 21 inches for the 2.5 IOL, and 17 inches for the 3.0 IOL). This lens is usually implanted into both eyes after cataract surgery. Between 85-90 percent of patients do not wear glasses (for any distance) after the surgery!
Tecnis Multifocal IOL
The Tecnis Multifocal IOL is similar to the Restor IOL in design in that there are both distance and near powered lenses incorporated into a single IOL design. Just like the ReSTOR, there are different versions of the Tecnis Multifocal. The Tecnis platform actually has three different versions (+2.75, +3.25, and +4.00) that differ in the distance of the near focal point (approximately 20 inches, 16.5 inches, and 13 inches, respectively). Patients usually choose which type by matching up where they like to read, use the computer, or use their cellphone. There are minor differences that our eye surgeons will discuss with you based on your individual vision needs. Just like the Restor IOL, 85-90 percent of patients do not wear glasses after having this lens implanted into both eyes!
The Crystalens combats presbyopia with a completely different design than the multifocal IOLs. This lens attempts to use the eye muscle we previously discussed, and actually move forwards and backwards naturally in response to the brain’s desire to see at different distances. As the IOL moves, objects at different distances come into focus! This allows for continuous vision at both far and near. Crystalens is not used as commonly as it was 10-15 years ago, as many of the new multifocal IOLs provide a higher percentage of spectacle independence.
Tecnis Symfony IOL
The Symfony IOL is also designed to improve the range of vision provided with cataract surgery. Slightly different than a multifocal IOL, this lens uses small eschelettes to extend the depth (EDOF) or range of focus. Most studies show that EDOF lenses like a Symfony IOL have less glare than a traditional multifocal IOL, but also provide “slightly weaker” near vision than a traditional multifocal IOL as well, as it’s near focal point is at approximately 23 inches. The beauty of the Symfony lens is the excellent depth of focus provided.
Multifocal/EDOF Toric IOLs
For several years, people that have astigmatism could not choose a multifocal IOL, unless the astigmatism was mild and could be treated with laser corneal incisions. Now, however, many of the multifocal and EDOF IOLs also come in toric versions, which treat astigmatism at the same time!
If you are interested in premium IOLs, please notify Dr. Rhodes or Dr. Dang, and they will be happy to discuss your options with you during your clinic visit.
The newest multifocal approved for use in the United States is the PanOptix trifocal IOL. This IOL is designed to give clear vision at distance, intermediate (computer), and near (reading). The actual intermediate and near focal points are at approximately 16 and 23.5 inches away. Currently, the PanOptix is the only trifocal IOL used in the United States. Over 99 percent of patients implanted with this IOL in their approval study said that they would have the same lens implanted again!