A cataract forms when the eye’s natural lens becomes cloudy, causing decreased vision. During surgery the cataract is removed through a small incision and replaced with a clear artificial lens. Standard monofocal lenses have been used for many years and allow a patient’s vision to be set for distance or near, but not both. If vision is optimized for the distance, the patient will require reading glasses. If the vision is adjusted for reading, then patient will require distance glasses. Checkout article about the Evolution of Cataract Surgery here.
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Over the last decade, multifocal intraocular lenses have become widely available, allowing many patients to decrease their dependence on glasses for both near and distance. These lenses have concentric rings on their surface. Some of the rings focus the light for near and some focus light for distance.
Multifocal lenses have increased the quality of life for many patients, allowing them to be less dependent on glasses. However, they also have significant limitations, such as increased halos and glare at night. Most patients are able to adjust to this over time, though rarely, a patient may be bothered enough to request removal of the lens. For this reason, multifocal lenses may not be recommended for patients that do a lot of night driving. Patients also lose some contrast sensitivity, or crispness, of distance vision when they opt for multifocal lenses. For this reason, patients who desire the absolute clearest distance vision may choose a monofocal lens, knowing that they will need reading glasses after surgery.
Finally, patients with significant amounts of astigmatism are not candidates for multifocal lenses as these lenses are unable to correct astigmatism. A better option for these patients is a toric lens that corrects astigmatism so patients can see clearly in the distance without glasses, although they will still need readers for near work.
It’s been exciting to hear that a new lens has just been FDA approved that will help eye surgeons overcome many of these limitations, and help more cataract patients see well with less dependence on glasses. This new lens, called the Symfony lens, improves vision from the distance all the way up to about 18 inches from the patient. Patients treated with this lens have been shown to have excellent vision for distance activities, such as driving and sports as well as intermediate activities such as using a computer or tablet. Many patients also have the ability to perform some activities at a distance closer than 18 inches, although low power readers are needed for activities such as reading fine print and knitting. There are some impressive features that make the Symfony a large advancement compared to lenses previously available. One unique feature is that it is the first lens that corrects near and intermediate vision that can be used in patients with significant astigmatism as it also corrects mild to moderate astigmatism. The Symfony also has a much lower incidence of glare and halos compared to previous multifocal lenses. Finally, the contrast sensitivity, or crispness of the vision is excellent, similar to a monofocal lens.