PCLI OD Newsletter (Summer 2005)

As the population ages we will be faced with previous refractive surgery patients in need of cataract surgery. Rick’s article reviews potential pitfalls and the limitations of cataract surgery with these individuals—and the key to reaching our common goal of happy patients.

As always, enjoy!

Lori Youngman, OD
PCLI—Vancouver, WA

Introduction

Over the last decade, LASIK has become increasingly popular among baby boomers. As this segment of the population ages, we will see more people who have had LASIK develop cataracts. However, prior to cataract surgery, several challenges need to be addressed.

With LASIK, patients may have enjoyed years without distance correction. So their expectations may be higher than the average cataract patient. It’s important that they understand the refractive impact of cataract surgery and the limitations of lens implant technology.

Refractive impact of cataract surgery:

Accurate selection of lens implant power can reduce myopic or hyperopic correction
Toric lens implants can reduce effects of astigmatism
A degree of myopia can be targeted in one eye (monovision) or both eyes, to aide near tasks without glasses
Lens implants for presbyopia are becoming available

Limitations

Patients need to be aware that technology is not to the point where lens implants are custom made like contact lenses for particular refractive errors. Implants are currently available in 0.5 diopter steps and there may not be a power that will give perfect plano refraction. In fact, it’s more common that the “perfect” lens implant power will not be available. So there’s a good chance some residual refractive error may persist after cataract surgery. Other factors such as capsular contraction can also affect the implant’s position and cause small shifts in post-op refractive error.

Calculations

The two major readings used to calculate lens implant powers are axial length and curvature of the front surface of the cornea. Because the corneal surface has been altered by LASIK, getting an accurate measurement of the new curvature is difficult. Inaccuracies can result in missed targeted refractions—and unhappy patients.

There are several ways to measure or calculate corneal curvature after LASIK:

Manually—If pre and post-LASIK keratometry readings, refractive data, and LASIK surgical data are available, the actual change of corneal curvature can be calculated manually. Unfortunately, this data is not always available—making the process more tedious.
Rigid contact lens over-refraction—This is the most accurate way to measure new corneal curvature after LASIK, but it takes a lot of time and may be uncomfortable for patients.
Topography—This is quick, comfortable for patients, and provides a more accurate measure of corneal curvature than conventional keratometry.

However, variability exists even when the best calculation methods are used. And variability is increased after LASIK. So cataract patients who have had LASIK especially need to be prepared for the possibility of residual refractive error.

Residual Refractive Error

Residual refractive error following cataract surgery can be dealt with in several ways:

Corrective Lenses
Obviously glasses and contact lenses are an option, but post-LASIK patients are often not willing to return to traditional optical corrections.
Lens Implant Exchange
Because of additional surgery risks, lens exchange is usually only considered when there is 1.0 to 1.5 diopters or more of post-op refractive error. Before a lens can be exchanged, refractive error must be stable with any corneal edema resolved that may affect refraction. But, the longer lens implants remain in place, the more difficult they can be to remove and replace. Generally, 1 to 2 months after cataract surgery is a good window for lens implant exchange.
LASIK
If corneal thickness allows, smaller amounts of refractive error may be corrected with LASIK. If refractive stability is achieved, we will consider treatment about 3 months after cataract surgery. In addition to monitoring intraocular inflammation, usually seen following cataract surgery, it is important to pay extra attention to the corneal cap created during LASIK and the interface of this tissue. There is a small risk that post-cataract inflammation can cause diffuse lamellar keratitis (DLK). It is also important to monitor the cap for misalignment or striae that may have occurred as a result of cataract surgery. For patients who experienced dry eye problems after LASIK, watch for evidence of surface disruption as the eye heals.

Pre-op Communication

Before cataract surgery, communication between the optometric physician and the surgery center is important—in all cases. Any specific refractive targets (i.e. monovision, which eye for near and how much myopia is desired) should be discussed. This allows us to review refractive targets with your patients before surgery to ensure that we all agree on the same refractive goal.

Conclusion

LASIK has been a blessing to a large number of people by reducing their dependency on corrective eyewear. But as they age, we will be seeing more and more of these folks as cataract patients. A frank discussion of the limitations of surgery, and careful selection of lens implant powers, will help ensure that happy LASIK patient become happy cataract patients.

InfantSEE—An Opportunity

Consider joining the national team of doctors that is making InfantSEE possible. At first, it may seem risky to provide free one-time, comprehensive eye assessment to infants in their first year of life. But the opportunities of this program may far outweigh the risks.

In addition to catching disorders not detectable in normal pediatrician screenings, optometric physicians participating in InfantSEE have the opportunity to:

Take advantage of a high profile advertising campaign
Build important referral relationships with primary care physicians and pediatricians (Click to see sample MD letter)
See new patients in their practice
Establish trust and goodwill with new parents
Become the eye care provider for the entire family

Several weeks ago former President Jimmy Carter helped launch InfantSEE—a program made possible through a partnership of the American Optometric Association (AOA) and the Vision Care Institute of Johnson & Johnson Vision Care. As the national spokesman, Jimmy Carter is issuing a compelling call-to-action through public service announcements—urging parents to take advantage of the program.

President Carter has 2 grandchildren suffering eye problems that could have been corrected if diagnosed in their infancy. So he is a passionate spokesman! Think about taking advantage of this powerful message President Carter is sending millions of American parents.

To participate or learn more about InfantSEE, visit www.infantsee.org

6 Hours of Free CE