When the natural lens of the eye becomes clouded from cataracts, surgery is performed in order to
remove the clouded lens. During cataract surgery, the natural lens is replaced with
an artificial one to provide clear vision and improve color contrast. Vision correction can
also be accomplished through the use of such an intraocular lens or IOL implant.
There are 4 main types of lens implants: monofocal,
multifocal, extended depth of focus, and toric.
Monofocal intraocular lens is the default choice for most standard cataract surgeries. This
lens type allows for a single vision correction which can correct either
near vision or far distance vision, but not both.
As such, although visual clarity is improved, one will still need to wear eyeglasses after
surgery to address either near or far vision depending on what focal length option was picked.
Here is what normal vision would look like, followed by cataract development.
After monofocal lens placement correcting far vision, clarity of the road and city is great,
but the dashboard and phone representing intermediate and near vision is poor.
Another monofocal lens option which is less common is called monovision.
In monovision a lens is placed for far vision in the dominant eye and a lens
for reading in the non dominant eye. This is one way to decrease dependence on eyeglasses,
but is less common due to compromised depth perception and intermediate vision given
the dominant eye is focused for distance and the non-dominant eye is focused for near vision only.
Multifocal lens, as the name implies, offers more than one lens power to correct both near and far
vision. However, although eyeglasses often are not needed after surgery, some patients may still
require eyeglasses if there is difficulty seeing at a certain intermediate distance
in between the corrected near and far focal lengths. Also, some patients may develop glares,
halos, and starbursts around lights after dark as well as suffer reduced nighttime vision ability.
Here is what normal vision would look like, followed by cataract development.
After multifocal lens placement correcting near and far vision,
clarity of the distant road and city is great as well as the near vision clarity of the phone,
but the intermediate vision of the dashboard is not as good.
At night, normal vision clarity is shown followed by how things would
appear after multifocal lens placement. Night-vision is reduced overall followed
by appearance of glare, halos, or starbursts around points of light.
Such photic side effects do improve over time, but may persist.
Extended Depth of Focus (EDOF) lens, as the name implies, offers not only near and far vision,
but also focal lengths in between in order to improve range of vision.
There are many different types of technologies emerging but all work
by increasing the depth of focus and decreasing the need for eyeglasses.
This lens, just like the multifocal lens, may also create photic phenomenon such as glares,
halos, and starbursts surrounding lights after dark, as well as reduced nighttime vision ability.
Here is what normal vision would look like, followed by cataract development.
After extended depth of focus lens placement, visual acuity at all distances is very good.
At night, normal vision clarity is shown followed by how things would appear after lens replacement.
Night-vision is reduced overall followed by appearance of glare, halos, or starbursts
around points of light. Such photic side effects do improve over time, but may persist.
However, depending on the extended depth of focus lens type chosen,
such photic side effects can be minimized, but at the expense of decreased near vision clarity.
Finally, toric lens is an IOL implant that also corrects for
any underlying astigmatism. Astigmatism is when the eyeball is more egg shaped rather
than spherical which causes blurred vision due to the varying curvature.
Toric monofocal, multifocal, and extended depth of focus lenses are available.
Talk to your eye doctor regarding which intraocular lens would work best for you!