Summit Eye Center Blog
Cataracts...Now my Doctor Discussed Lens Options? Help!
Glare around streetlights and headlights is making driving at night difficult and your overall vision just doesn’t seem to be as good it once was...your eye doctor tells you that cataracts are causing your problems.
Cataract surgery is recommended. Your doctor explains that a cataract is a natural change to the crystalline lens within your eye. The same aging changes that got you into reading glasses or bifocals in you mid-40s have simply progressed to a clouding of the crystalline lens that leads to an increased scattering of light and decline in vision quality. The generalities of the surgery to remove your natural lens and replace it with a lens implant are discussed. You are following along nicely at this point. Then, the doctor begins to discuss that you have options as to what type of lens is placed in your eye and it is your choice as to what type of lens is used. Now you head starts to spin as details of these different lens choices are discussed. How do you put all of this information together?
Summit Eye Center is here to help make this process more manageable. This blog is going to breakdown the various intraocular lens, IOL, options in a way we can all understand.
First, lens options can be broken down into 3 basic varieties:
• Monofocal IOLs that correct for one focal point, most commonly distance vision, and do not treat astigmatism
• Toric IOLs that correct for one focal point, most commonly distance vision, and also correct a patient’s astigmatism to provide optimal vision at that focal point
• Presybyopia-correcting IOLs that correct for multiple focal points...distance as well and near and/or intermediate vision as well astigmatism if needed
Monofocal IOLs come in two varieties: spherical and aspheric lenses. Spherical lenses front surface have a uniform curvature from center of the lens to its edge. This allows for easier manufacturing of the lens, but does not match our natural lens that varies in curvature from the center to the edge. This variance in curvature is called being aspheric, not spherical. Aspheric IOLs are designed in a manner that mimics that natural lens’ asphericity to provide sharper vision, especially in low light settings and in people with large pupils.
These lenses allow the correction of a person’s nearsightedness or farsightedness for one focal point, but do not address any astigmatism that may be present. Most patients choose to have their distance vision maximized so that they can potentially see well for tasks such as driving or watching television without glasses. If significant astigmatism is present, glasses or contact lenses may still be needed to see well in the distance without glasses. Some patients who have always had a low level of nearsightedness that has provided them with the ability to read well at a comfortable working distance without glasses choose to stay that way due to being used this vision for their lifetime. Giving up their ability to read without glasses is not acceptable to them. They will then need glasses for distance tasks like driving.
Toric IOLs are lenses that correct a patient’s astigmatism as well as nearsightedness or farsightedness. Like with monofocal IOLs, most patients who have a toric IOL implanted during cataract surgery choose to have their vision targeted for maximum distance vision without glasses. For near tasks such as reading or working on a computer, they would then use glasses, possibly just over-the-counter readers, to help maximize the quality of their vision.
Presbyopia-correcting IOLs come in 3 varieties: Extended Depth of Focus (EDOF), Accommodating, and Multifocal.
Extended Depth of Focus (EDOF) IOLs are designed to give a range of clear vision from distance to intermediate. They also provide improved near vision when compared to monofocal IOLs. For near tasks such as reading small print, you will likely need some reading glasses. These lenses elongate one’s focus allowing one to have a full range of continuous, clear vision.
Accommodating IOLs are designed to mimic the natural lens, using the eye muscle to flex and accommodate in order to focus at different distances. This allows many to decrease their dependence on glasses after cataract surgery. For near tasks such as reading small print, you will likely need some reading glasses.
Multifocal IOLs are designed in a manner that splits the light entering the eye between distance, intermediate and near focal points. This allows many patients to decrease their dependence on glasses for many tasks. These lenses come in different designs that allow for different near working distances depending on a person’s occupation or hobbies. By splitting the light between different focus points, there is some sacrifice in vision quality when compared to EDOF and accommodating IOLS.
Several factors play a role in determining which lens implant is best for you. First, your doctor will do a thorough evaluation of the health of your eyes. If you have dry eye, your doctor will want to make sure it is being managed sufficiently. The doctor will also look for any irregularities of the cornea, optic nerve or retina that may dictate which type of lens implant will provide you with the best vision. You and your doctor will also have a discussion of what your goals for your vision are based on your occupation and hobbies.