Lens replacement implants are small “intraocular lenses” (IOLs) implanted inside your eye to restore focus after cataract surgery.
When the natural lens inside your eye turns cloudy with age, it is called a cataract. After your cataract is removed, your ophthalmologist will implant a replacement lens often called a cataract lens.
Many patients will tell me at first that they don’t want a cataract lens placed after their natural lens is removed. The natural lens in your eye performs an important part of the focusing for your eye. If the natural lens is removed and a cataract lens implant is not placed, then coke bottle thick glasses would be required to try to make up for the loss of your natural lens. The cataract lens implants give a much higher level of optical quality and lifestyle convenience than the thick glasses so we always implant an intraocular lens at the time of cataract surgery if it is safe to do so.
History of the Intraocular Lens (IOL)
During WWII, Sir Harold Ridley, was caring for a pilot with a small piece of a plane’s PMMA plastic windshield forced inside his eye.
He noticed that it was well tolerated and realized that plastic lens implants of the same material could be formed for eye lens replacement after cataract surgery.
What are Intraocular lenses made of?
The original IOLs where made of rigid PMMA (plastic). They have been largely replaced by acrylic and silicone IOLs which are soft and will fold.
These “foldable” IOLs allow your ophthalmologist to roll the lens implant up like a taco and insert it into your eye through a very small incision. Once inside the eye, the intraocular lens opens up to its full size.
Most of the lens implants have 100% ultraviolet (UV) protection built in to protect the retina from damaging rays from the sun. Some IOLs even have high-energy blue protection that further shields the retina and decreases night glare.
How long will my Intraocular Lens last?
The materials used are inert plastics that tend to out last us by a hundred years.
Types of Intraocular Lenses for after Cataract Surgery
There are four basic types of intraocular lenses (IOLs) that can be used after cataract surgery. No man made lens is perfect, so you will want to choose the one the best fits your lifestyle.
- single vision
There are three distinct areas of focus that matter to humans, distance vision (driving, TV), intermediate vision (computer, cans on the shelf), and near vision (reading, crafting). What distance or distances matter most to you? You will want to choose an IOL that best helps you with your individual visual needs.
Single Vision Lens Implant
A single vision intraocular lens focuses for a single distance. If you choose a single vision IOL set for distance, you would be likely be able to drive and watch TV without glasses, but would need glasses to focus for intermediate and near tasks.
If you value your distance vision the most and don’t mind readers, then this would be a great choice. 90% of my single vision intraocular lens patients choose this approach.
Another option would be to choose a single vision lens set for near. With this option, you would be able to read without glasses, but would put on glasses for distance and computer tasks. 10% of my single vision IOL patients choose this option. If you read novels all day with your glasses off, then this might be the right choice for you.
The downside to the single vision intraocular lenses is that you will still need glasses for a large portion of your visual needs, but your optical quality tends to be very good.
What is Monovision?
In this option, a single vision intraocular lens is set for distance in one eye and for near in the other eye. Most prefer to have both eyes set for the same distance. However, if you have had success with monovision in the past with contact lenses, then this could be a great option for you if you desire more independence from glasses.
50% of us can stand monovision and it drives the other 50% crazy to have their eyes different. Of the 50% that can stand it, a much smaller percentage choose it.
The toric lens is a special form of a single vision cataract lens that has astigmatism correction built right into the lens implant. Astigmatism means that your eye is shaped more like and egg than a round ball. This irregular shape causes blurry vision. If you like the idea of a single vision intraocular lens and have astigmatism, then a toric lens would be a great choice for you. A toric lens that corrects your astigmatism inside the eye does a better job of correcting your vision than a pair of glasses that sit out away from your face.
There are four different toric intraocular lenses that are FDA approved, the Acrysoft Toric, Technis Toric, enVista Toric, and the Tulign Crystalens.
Crystalens Accommodating IOL
The Crystalens flexes as you use the focusing muscles inside your eye. This flexing and focusing mechanism is call “accommodating.”
Some individuals can flex the lens freely, some just a bit, and some not at all. In my hands, 90% of patients get distance and intermediate vision. Half of my crystalens patients get not just distance and intermediate, but also near vision. However, 10% of patients can’t flex the lens at all so they end up with a single vision lens.
I tend to recommend this IOL if you desire distance and intermediate vision, but would be OK with reading glasses.
With the FDA approval of the Trulign Crystalens, we now have an accommodating lens (the crystalens) that can correct astigmatism at the same time.
A multiple focus intraocular lens gives focus to more than one of the important areas of vision. If want your eyes do the focusing rather than glasses then a multifocus may be right for you. Around 80% of those with a multifocus lens implant never wear glasses again and around 94% don’t need reading glasses.
The Technis Multifocal and the ReSTOR 4.0 give distance and strong reading but are weaker at intermediate vision. The ReSTOR 3.0 gives distance and good reading with pretty good intermediate vision. The ReSTOR 2.5 (not FDA approved yet) gives distance and good intermediate with pretty good reading vision.
The multifocus lens gives the highest chance for freedom from glasses. They do cause some extra haloing around headlights compared to single focus lens implants and they slightly decrease contrast and optical quality.
Patients focused on freedom from glasses often choose a multifocal intraocular lens while those with an above average need for optical quality often choose a single vision lens.
How to choose and Intraocular Lens
You will only have cataract surgery once. That is your opportunity to achieve the kind of vision you want for the rest of your life. You don’t have to choose your intraocular lens by yourself. Your eye surgeon should examine the health of your eyes, consider your goals and lifestyle needs, and then recommend the ideal lens implant for you.
I have worked extensively with the caaract lenses discussed in this blog and was involved in the FDA trials for many of them. If I can help you with your decision, please let me know.
Gary Foster, M.D.
Cataract and Laser Eye Surgeon
Board Certified Ophthalmologist
Fort Collins, Colorado 80525