Choosing An Intraocular Lens Implant For Cataract Surgery
Choosing an Intraocular Lens Implant
This article, the second in a series on cataract surgery, is designed to help you make an important decision - which intraocular lens implant (IOL) you wish to have implanted in your eye. This decision is secondary only to choosing a surgeon to perform the implant.
While your particular eye will partially dictate which lens is right for you, and only your doctor and a thorough eye exam can help here, it will be very useful to understand what is available today and which lens might be of particular interest to you.
Past corrective actions such as Lasik surgery will play a part as will the presence of astigmatism. Any physical damage will have to be considered as well as your general and especially your eye health. Be prepared at your first ophthalmologist visit to keep an open mind and listen carefully to your doctor - after your eye exam he will have more information that you can possibly collect on your own.
If you are just beginning to gather information about cataracts in general, a good start might be the first in this series, covering the subjects of "What is a cataract" and what the symptoms of cataracts might be.
In very general terms there are two types of IOL's available; the standard implant and "premium" implants. The premium implants can add as much as $3,000 to the cost, per eye, of your surgeries, however. Few insurance companies will cover the cost of a premium implant and neither will medicare nor medicaid. What you are likely to find, however, is that you can choose a premium implant and your insurance (plus medicare and medicaid) will usually cover the cost of implanting a standard lens while you pick up the extra cost.
Whatever you choose, please, please do not make the determination and choice based solely on cost. With or without insurance there are programs and loans that can help pay for the procedure, that can help out and soften the blow somewhat. Ask your doctor for help; most have an association with credit companies and some may cut their cost some. In the final analysis it is your eyes, your vision and your quality of life - do not compromise it unless absolutely necessary.
The standard intraocular lens
The standard lens is implanted in an overwhelming number of people and performs very well. It has been around for decades and has an excellent record of success.
So why not choose this cheaper option that works satisfactorily? Perhaps because "satisfactory" isn't "good" or "excellent". The standard lens has problems. It has a single focal length and will give good vision at only one distance - generally far away. Reading glasses will almost certainly be necessary, and most likely a different set for intermediate distance such as computer use. Most recipients will still have the effects, if not the actual disease, of presbyopia (an age related hardening of the natural lens with the result it cannot focus on near or intermediate items).
One possible solution is to have different lenses implanted; a distance focus in one eye and a near vision IOL in the other. Some people do well with this (although depth perception suffers) but many do not.
Another problem is night vision; standard lenses are rather poor here. In addition, many recipients report "halos" around light sources such as oncoming headlights. Glare from lights is often objectionable. In both of these matters the standard IOL is often considered superior to the premium lenses, but is still objectionable.
Premium Multi-Focal Lenses
There are several possible choices in this area, but they all operate on the same basic principle. "Rings" of different focal length are built into the lens and your brain must be trained as to which ring to use. That process is automatic and the large majority of people accomplish it in just a few weeks or months, but for a very few it just doesn't seem to work.
I might add here that when I looked at these lenses I was not impressed. I have worn bifocals for years now and always had great trouble adjusting to the "lined" variety - I was very concerned that the multifocal intraocular lenses would be the same and I would not be able to adjust to them. My doctor, however, has assured me that there is no comparison; the implants do not act as "bifocals" in any sense. That put the multifocal lenses back onto my list of acceptable possibilities.
The Acrysof ReSTOR lenses are manufactured by Alcom Laboratories and have been in use for many years. Alcon claims that 80% of recipients do not need glasses after surgery and that 94% of patients would use the same lens again. Some 25 million Acrysof lenses have been implanted over the years. These are impressive statistics and the lenses are certainly worth a closer look. As with all multifocal lenses, both near and distance vision is usually excellent.
Some possible negatives here are that night driving may be difficult; some patients report haloes around lights at night. Dim light often presents problems as only a small portion of the lens is actually used at any one time. Intermediate distance (think computer usage) is problematical at best; this is the weak point in all multi-focal lenses.
Abbott Medical Optics makes the Tecnis line of IOL's. Similar to ReSTOR, Tecnis claims that 90% of people won't need glasses and that 94% are satisfied with their surgery and would do it again. Not much difference here, but the claims are from the company benefiting from those claims.
Tecnis lenses operate very much like ReSTOR lenses, with concentric rings of differing focal lengths. They also tend to have the same negatives; while use of glasses may decrease there is a tradeoff in less sharpness of vision, especially in low lighting or fog. There may be some visual effects such as halos and glare from lights at night. Intermediate distance vision is poor compared to distance or near vision. Again, all multifocal lenses seem to have these same problems, but for most people they are fairly minor.
The Tecnis lens is available in a aspherical configuration, just as the ReSTOR lens is. This design helps correct low light vision. Still not as good as your biological lenses, they are an improvement over was available in the past.
Manufactured by Alcon again, the Toric lens is specifically designed and constructed to correct astigmatism as well as provide good vision at varying distances. Depending on the severity and type of astigmatism present, it may well be possible to correct for it with this specialty lens at the same your cataracts are being corrected.
Accommodating Lenses - Crystalens
At this time there is only one implantable accommodating lens available in the US, although several are available in Europe. This is the Crystalens, made by Bausch + Lomb and is a radically different concept from the multi-focal lenses from other manufacturers.
The Crystalens is a slightly smaller lens but is designed to move and/or flex using the muscles of the eye that also move and focus the natural lens. It thus operates in the same manner as the biological lens that everyone is born with and can have significant advantages.
Vision at long distance is at least as good, normally, as that produced with any other lens. Near vision is probably not quite as good, but is in most cases acceptable; Baush + Lomb claim that 80% of patients can read without glasses at a J-3 level, or about that need for reading books or newspapers. Around 20% find that they can read at a J-1 level, or the small print on a prescription bottle, again without glasses. These results will vary, of course, with the patient and a small number of patients will still need glasses for near vision.
Vision at intermediate distance is generally very good and few patients will need reading glasses for use on a computer; it is here that the Crystalens excels over other implants. Vision at long distance is again very good, on par with other implants.
Negatives are a relatively long adjustment period; most people will need between 6 months and 1 year to gain full use of their new lenses. This is not to say that vision is poor - you can reasonably expect very good distance immediately and improvement at intermediate and near distances. It will take time, however, to strengthen the muscles of the eye and train them in exactly how much movement is necessary for proper focus at closer distances. A very small number of patients find the lenses to be unacceptable, never gaining the ability to truly focus well. Dim light vision is again poor when compared to biological lenses, although a recent increase in the size of the lens has helped, and the Crystalens is normally better in dim light than the multifocal lenses.
My Own Choice For New IOL's
With the development of my own cataracts it was necessary to choose a lens, just as millions of other people have. I liked the idea of returning my eyes to as nearly what they were as possible, but did not rule out the multifocals completely and the discussion with my doctor very definitely left them in the running.
I love to read, and in that respect a multifocal lens would probably be superior. I also spend several hours each day using a computer and have to keep a second pair of reading glasses on the table just for use there - it would surely be nice to be rid of that pair of readers.
I spend considerable time outdoors (camping, fishing, hiking, golf, etc.) and my work requires considerable variation in the distance involved. Some reading is necessary but a great deal of work is done at arms length, or the intermediate distance, and bifocals are a real hassle when working overhead.
My cataract evaluation (presurgery exam and consultation) convinced me that the Crystalens was the right choice for me; time will tell if I'm right as surgery is in about 10 days. The consultation and discussion with several doctors and other staff members was invaluable with a lifestyle evaluation as part of the process. As I suspected that large amount of time on a computer coupled with overhead work is the primary factor as it is there where the Crystalens outperforms other lenses. I expect to read a restaurant menu without glasses and hope to read books for hours at a time, but if I need readers for books I'll survive. I do fully expect to use a computer without assistance and my doctor assures me that that is a reasonable expectation.
This article is the second in a series dedicated to cataract surgery. The first article covered the subjects of cataracts in general and the symptoms of cataracts. The articles are the result of my own eyes developing cataracts and needing corrective surgery; each will have a report on my own experiences as well as the result of much research on the subject.
The next article will cover the surgery itself and immediate impressions and results from that surgery - it will be written in the next few weeks. Links are available below to the other articles and will be updated as they come available.
© 2012 Dan Harmon