Astigmatism is an irregular shape to the cornea. The cornea is the clear front part of the eye you look through. If a normal cornea is shaped round like a basketball, a cornea with astigmatism is shaped more like a football. This football shape to the cornea bends light as it passes through causing vision to be blurry. Blurry vision caused by astigmatism is separate and independent from the blurry vision caused by nearsightedness (myopia) and farsightedness (hyperopia). Regular astigmatism can be lessened and/or corrected as below.
There are several options to treat regular astigmatism during Cataract Surgery:
- Wearing Glasses: you may choose a standard Monofocal lens implant (IOL) for near or distance vision and wear glasses or contacts to correct your astigmatism
- Toric Lens Implant: you may choose to have a Toric intraocular lens implant placed in your eye to reduce and/or correct your astigmatism
- Refractive: LASIK or PRK: you may choose to have refractive surgery called LASIK or PRK to reduce and/or correct your astigmatism
- Limbal Relaxing Incision (LRI): you may choose to have a procedure called an LRI in which a small incision is made in the cornea to make the cornea rounder and reduce and/or correct your astigmatism. More than one incision may be needed. These incisions may be made by hand (typically with a diamond blade) or by using a Femtosecond Laser.
If you would like a Toric Lens, Refractive surgery, or LRIs you will need to pay extra. Medicare and Private Insurance do not pay for astigmatism correction.
Presbyopia is a condition that makes it hard for the eye to focus on near items, especially for reading. Distance vision may unaffected by this change. Presbyopia happens to most people as they age. It can also happen to people of any age after they have cataract surgery, especially if they choose a Monofocal or single vision lens implant for distance vision. People with presbyopia might hold a book or menu at arm’s length to see it more clearly and they often need bifocals or separate reading glasses to see clearly up close.
Your eye surgeon can reduce and/or correct presbyopia during cataract surgery. The goal of treating presbyopia is to reduce your need to wear eyeglasses. There are two options for correcting presbyopia during cataract surgery. This may be one of the most important decisions you need to make about your cataract surgery, so please take the time to review your options and ask questions. If you have underlying eye conditions, you may not be a candidate for presbyopia correction at the time of cataract surgery.
MONOVISION: custom use of two different Monofocal (single focus) IOLs.
Monofocal lens implants focus light in one place (for distance, intermediate, or near vision). They offer high-quality vision but do not provide a range of vision. To treat presbyopia and achieve a blended range of vision with both eyes open, you can choose to have one Monofocal lens implant set for near vision in one eye and one Monofocal lens set for distance vision in the other eye. The goal is to improve both near and distance vision by having these two IOLs work together, with both eyes open. Some patients do not like having one eye for distance and one eye for near. To see if you will like this kind of vision, you can do a trial with two different monofocal contact lenses before your surgery.
MORE INFORMATION ABOUT MONOVISION
In order to have good depth perception, your eyes need to be corrected for any refractive problems such as nearsightedness or farsightedness, and “balanced” for distance. Eye care professionals refer to this as binocular vision. Monovision or “blended” vision can impair depth perception because the eyes are not focused together at the same distance. It is important to choose which eye you will use for distance vision. Eye surgeons generally believe that one eye is the dominant one, preferred for viewing. This is similar to people being right- or left-handed. Several tests can be performed to determine which eye is dominant in a particular person. With monovision, the dominant eye is usually corrected for distance, and the non-dominant eye corrected for near. However, a very small percentage of persons may be co-dominant (this is similar to being ambidextrous). In rare circumstances, a person may actually prefer using the dominant eye for near viewing. Your doctor will discuss and try to demonstrate monovision with glasses or contact lenses to simulate the type of vision you will have after cataract surgery. Because your vision is decreased by the cataract, it is not possible to show you exactly what your postoperative vision will be like. If you would prefer not to have to wear glasses for quick tasks like looking at your cell phone, a menu, a computer, or an invoice, then you might be interested in monovision. Many monovision patients will often be more comfortable wearing glasses to balance their vision for prolonged reading tasks or for driving (especially at night), or for sports like tennis or golf. If you have been wearing contact lenses or had refractive surgery for monovision, you will most likely be happy with this option after cataract surgery. Although many patients will adjust well to monovision, some may find it uncomfortable. For those patients, the monovision may be reversed by refractive laser vision correction, but this surgery will not be covered by your medical insurance.
Premium or Advanced Technology Lens Option.
Another option to try to correct presbyopia and lessen your dependence on glasses is to choose a lens implant designed to provide a range of vision. These specialty lens implants are called premium IOLs or advanced technology lenses. Premium IOLs allow your eye to focus at more than one distance so that you do not have to wear glasses as much. Premium IOLs work best when placed in both eyes. There are different types of premium IOLs each with specific advantages and disadvantages. For example, some Premium IOLs offer better reading ability but can have side effects such as glare and halos, which may be worse at night. Your eye surgeon can decide which Premium IOL is best for you.
Medicare and Private Insurance do not pay for custom vision or premium IOLs.
INFORMATION ABOUT INTRAOCULAR LENSES (IOLs)
The information provided here is for an overview of IOLs. Please talk to your doctor for more information about which lens may be right for you.
Intraocular lenses are implanted in the eye during cataract surgery to replace the cloudy cataract lens inside the eye. There are many types of intraocular lenses available today and they each have different advantages and disadvantages. To better understand your lens implant options, first, start by thinking of your vision as having 3 different focusing needs. Your eyes need to be able to focus up close (reading distance), at an intermediate distance (computer distance), and far away (driving distance). Your eye naturally has the ability to adjust its focus at each of these distances to see clearly though you gradually lose that ability over time (see presbyopia).
Monofocal Lens: these lenses provide high-quality optics but only focus light in one place (distance, intermediate, or near). As such, if you elect to have a distance vision monofocal IOL you should expect to need glasses to see at the other 2 distances, intermediate and near. Basic Monofocal IOLs are typically covered by Medicare and Private Insurances companies. They also do NOT correct astigmatism. The chance of being dependent on glasses full time or to see clearly at all 3 distances is highest with a monofocal IOL.
Toric Monofocal Lens: The toric monofocal IOL functions the same as the monofocal IOL described above in only providing focus in one place (distance, intermediate or near). The difference is that if you have regular astigmatism, the Toric Monofocal IOL can reduce and/or correct that astigmatism. Therefore, a toric IOL may reduce your dependence on glasses to see clearly at a distance. Reading glasses are typically still needed with a toric lens.
ADVANCED TECHNOLOGY OR PREMIUM IOLs
These lenses try to provide an expanded range of vision for patients to reduce dependency on glasses. There are many different types of lenses in this category. Some of them also come with the option for toric or astigmatism correction as described above. Some of these lenses achieve the expanded range by splitting light which may reduce contrast sensitivity.
Trifocal Premium IOL: this IOL uses advanced technology to offer a range of vision spanning distance, intermediate, and near. These lenses may reduce contrast sensitivity and be associated with glare or halos but can offer a full range of vision for patients interested in being the most independent from glasses.
Multifocal Premium IOL: this IOL uses advanced technology to offer a range of vision spanning distance and intermediate or distance and near. These lenses may reduce contrast sensitivity and be associated with glare or halos. Especially when blended together these lenses can offer a range of vision for patients interested in being independent of glasses.
Extended Depth of Focus Premium IOL: this type of IOL uses advanced technology to offer a range of vision spanning distance and intermediate. These lenses may provide some near vision as well but you should expect to need reading glasses for fine print. Newer versions of these lenses may preserve contrast sensitivity and avoid the glare and halo side effects associated with multifocal lenses. These lenses offer an expanded range of vision for active patients interested glasses independence.
Accommodative Premium IOL: this IOL uses advanced technology to offer a range of vision spanning distance and intermediate. These lenses typically do not provide near vision and sometimes do not achieve the intermediate vision. These lenses are not associated with reduced contrast sensitivity or glare or halos.
RISKS of PRESBYOPIA CORRECTION
As with all surgery, complications and problems can happen. In addition to all the risks of cataract surgery, here are some common or serious risks for presbyopia correction:
- You may see halos and ghost images. Or you could have night glare, double vision, or blurry vision.
- You might have trouble with depth perception (seeing which of two objects is closer) or problems driving at night.
- Premium IOLs may not work well if you have certain eye problems or large pupils.
- You may need to wear glasses at all times or just for some activities after surgery, even with premium IOLs.