IOL Master predicts lens power

You will likely 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. The only exceptions may be that selected patients receiving new multifocal or accommodating type implants may need glasses very little. 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.

Here are some general considerations:

"Perfect" vision without glasses after cataract surgery is NOT to be expected. Nonetheless, there are ways to try to make a closer match between your visual lifestyle and your uncorrected vision. IF DIMINISHED DEPENDENCY ON GLASSES AFTER SURGERY WOULD BE OF INTEREST TO YOU, THERE ARE OPTIONS TO CONSIDER: For some patients the "multifiocal"  lens or an "accommodating" technology lens may be appropriate, or "Monovision." (see below)

"Perfect" results of your implant power calculation are NOT 100% predictable. Laser refractive surgery (LASIK, for example) is more precise. 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; Karen has measured an estimated 10,000 eyes! 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 "Contact A-Scan."

To supplement the curvature measurements from our IOL Master, we use "Manual Keratometry" when indicated. We also use a new type of scanning laser to add to the tools we use to measure corneal curvature, the 3-D Wave. This instrument also measures optical aberrations and maps astigmatism. It is particularly useful when planning LRI astigmatism correction to be done in conjunction with selected cataract surgeries.

3-D Wave

Astigmatism: In general, cataract surgery has little effect on astigmatism. If you have significant astigmatism, glasses will certainly be helpful after surgery in all of your visual tasks. It is possible, however to reduce (not eliminate) astigmatism in many cases by adding a step to your surgery called "LRI," or Limbal Relaxing Incisions. This method often helps, sometimes gives no benefit, and rarely leads to annoying side effects due to shifting the astigmatism rather than reducing it. There are lens implants to correct astigmatism; they come in limited power options and in some cases need to be repositioned (in the operating room) in the early weeks after surgery to adjust their position. LASIK surgery is perhaps the most accurate, and most expensive, option to correct astigmatism. It is best done after the cataract surgery, once the eye is fully healed. While "LRI" for astigmatism correction is often a useful addition to cataract surgery, there are some additional out-of-pocket expenses that insurance generally will not cover for this elective procedure and the associated special testing.

Optical Aberration: some patients may benefit from use of a type of lens called "aspheric." The FDA permits the Tecnis® lens to claim that it may improve functional vision and driving safety over standard implants, although occasionally they may actually increase optical aberration or reduce depth of focus. There is no increased lens cost for the patient, but one special pre-operative test (corneal topography) may not be covered by insurance.

Another aspheric IOL, the Acrysof® IQ lens is based on similar optical principles. We have both of these lenses available at MarinEyes.

Near Sighted / Far Sighted: Patients with very little astigmatism can elect to have their uncorrected postoperative vision emphasize distance (swimmers like this), near (people accustomed to reading in bed at night without glasses) or in-between (social distance: conversation, playing cards). If you select near vision, your distance can be corrected with glasses. If you select distance vision, you will need glasses to read. Those selecting in-between will like progressive eyeglasses to sharpen both far and near. People who are FARSIGHTED before cataract surgery are likely to find that they see better without glasses after surgery than they did before at ALL distances, but generally need reading glasses.

Combined Near and Far Vision

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. These are the standard type of implant for cataract surgery. The effect is obtained by using a different power lens for each eye.

Multifocal lens implants: The "multifocal lens" has been available for a number of years. In our experience, rarely do they 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 some tolerance of the glare problem. Some of these lenses emphasize far and intermediate vision (ReZoom), while others far and very close vision (ReStor). While distance vision is usually quite good, they don't always succeed for near vision, and some patients will still need to use glasses. However, many of the patients do achieve excellent "social" vision: far, intermediate and a look at their watch. About 75% of patients will be spectacle free with these lenses. We are currently using ReZoom, and soon the ReStor as well, for selected patients.

There will be “out-of-pocket” expenses not covered by insurance for patients electing to have these types of lens due to the cost of the lens, the special precautions in measurement, surgery and follow-up. The best candidates for these lenses will have little astigmatism and otherwise healthy eyes.

Accommodating lens implants: Another lens is the "Accommodating" type. It accomplishes the same ends using a different technology. Presently the only lens in this class is the CrystaLens®. There will be “out-of-pocket” expenses not covered by insurance for patients electing to have these types of lens due to the cost of the lens, the special precautions in measurement, surgery and follow-up. The best candidates for these lenses will have little astigmatism and otherwise healthy eyes. We are not currently using this lens at MarinEyes.

Medicare Policy on Upgrading Your Lens Implant

Medicare has recently approved the option for MediCare patients undergoing cataract surgery to upgrade, at additional patient expense, to new types of lens implants including the CrystaLens® , Restor® and ReZoom®.

There will be “out-of-pocket” expenses not covered by insurance for patients electing to have these types of lens due to the cost of the lens, the special precautions in measurement, surgery and follow-up. The best candidates for these lenses will have little astigmatism and otherwise healthy eyes.

Unusual Special Circumstances

Clear Lens Extraction: As a totally cosmetic, elective surgery some patients may elect to have their NORMAL clear lens removed and replaced with an implant. These patients basically simply want vision correction surgery usually for farsightedness or extreme nearsightedness for whom LASIK is not advised. Some may wish to have this done in order to receive a multifocal or accommodating implant hoping to rid themselves of reading glasses.

Planned combination cataract surgery with implant and later LASIK: Patients with high astigmatism may be best served by having cataract surgery with LRI, with the expectation of a "touch-up" LASIK surgery to remove remaining refractive error after cataract surgery. Occasionally patients who want refractive surgery but who are too nearsighted may elect to have "clear lens" extraction with a lend implant to reduce their refractive error as much as possible, followed if necessary by LASIK to treat the remaining refractive error.

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 who have had prior refractive surgery We use a combination of methods to make the best estimate. Refractive "surprises" can still happen, leading to a second surgery. Options are to either replace the lens implant, "piggyback" a corrective implant over the original or undergo a LASIK procedure. Sometimes a contact lens is best.

Questions you should consider relating to lens implant selection

Questionnaire in PDF for download

Current Glasses Use:

Current Contact Lenses:      Do you wear monovision contacts?  Yes   No

How much do you wear contacts for these activities:

After cataract surgery, I expect my activities to be:

If possible, I would NOT like to wear glasses for:________________________________

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