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In general, we tell our cataract patients: "You will need to wear glasses
after the cataract extraction procedure for either distance or reading vision or
both in order to get the best possible vision. You should carefully discuss with
your doctor any questions you have about how your vision will be with and
without glasses. You and your doctor make a plan together to best fit your
needs."
In an attempt, however, to improve the
uncorrected vision at near, far and intermediate distances, two new categories
of lens implants are available for use in conjunction with cataract surgery:
Multifocal
IOLs and an "accommodating" IOL called Crystalens®.
Normally, lens implants have a fixed focus distance (see
Refractive Goals). Multifocal IOLs have elements for near and far, while the Crystalens®
is said to actually mechanically shift focus between near and far. The patients who are suitable
for this implant must have little or no astigmatism pre-operatively, and no
other eye disease, in order to increase the chances of success with this lens
implant. The surgery must go perfectly, and the pre-operative measurements must
give precise results in order to achieve this result.
Vaulting: Occasional patients may
experience a situation where the Crystalens®
becomes fixed at near vision. This usually occurs relatively soon after surgery,
and sometimes requires an additional procedure to correct. This does not happen
with MultiFocal lens implants.
Medicare has recently approved the option for MediCare
patients undergoing cataract surgery to upgrade to these multiple-focus implants
(Crystalens, ReZoom and ReStor). The best candidates for this lens will have
cataract, little astigmatism and otherwise healthy eyes. MarinEyes currently is
using ReZoom and soon ReStor. We are not currently planning to use the
Crystalens®.
There are other options available to
compensate for presbyopia:
Eyeglasses: Bifocals, progressive
lenses and trifocals are the most common correction, and allow for correcting
astigmatism as well as near- or far-sighted results. They are safe, effective
and highly reliable.
Monovision: People who have worn "monovision" contacts,
or who naturally have one distance eye and one focused for near are good
candidates to have one eye corrected far and one for near in the selection of
the implant for their cataract surgery. Glasses may still be helpful for such
activities as night driving and prolonged reading.
Multifocal lens implants:
While the "multifocal
lens" has been available for a number of years, there are two recently
approved improved implants available in this category. In our experience, rarely do
these lenses cause problems (although some glare from headlights
is expected with these lenses, so people who want to do much night driving are
poor candidates). They work best on patients who are highly motivated to go
without glasses after cataract surgery, have little astigmatism, appropriate
expectations and tolerance of the glare problem. They don't always succeed
for near vision, and a substantial number of patients use glasses for reading.
However, many of the patients do achieve excellent "social" vision: far,
intermediate and a look at their watch. Some studies report up to 75% of
patients don't need glasses for daily activities.
There are potential known and unknown
risks with any new technology. You must discuss this with your surgeon:
Any and all of the usual
potential problems
after cataract surgery can be encountered.
"Perfect" results of your implant power calculation are NOT
100% predictable. Laser refractive surgery (LASIK, for example) is more
predictable. Nonetheless, there are some ways to try to get more consistently
CLOSER to the exact power prediction for your lens implant. At MarinEyes, our
technicians are thoroughly trained and very careful. The measuring devices we
use include the IOL Master, a laser scanning device to measure the length and
curvature of your eye. We also use a method called "Immersion A-Scan" on some of
our patients. These methods are more accurate than the more commonly used
"Contact A-Scan." To supplement the curvature measurements from our IOL Master,
we use "Manual Keratometry" when indicated. Our new 3-D Wave scanning laser ("Wavefront technology") adds to the tools we use to measure corneal
curvature and analysis of optical aberrations in the eye. In instances where the
refraction results are not ideal, LASIK may be helpful in
adjusting for the unexpected result. Another option is a thin "piggyback" lens
implant.
Astigmatism: Astigmatism will
diminish the effectiveness of Crystalens, and the best candidates have little or
no astigmatism. Should astigmatism appear after the surgery, additional laser
treatment (LASIK) may be an option to correct this.
Cataract Surgery after LASIK is a special problem: The
instruments and IOL power calculation formulas available today DO NOT give
uniform accuracy in selecting the correct implant power for patients undergoing
cataract surgery. We use a combination of methods to make the best estimate,
including use of old records, careful measurements and special implant power
calculation formulas. Refractive "surprises" can still happen, making
patients who have had refractive surgery worse candidates for the Crystalens®.
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