BIFOCAL LENSES AND THEIR FUTURE

One Man’s Opinion

Maurice E. John, M.D.

On the Horizon

As many of you know, I have been involved with refractive surgery since my first RK in May of 1980.  It is fair to say that for at least a couple decades doctors have been trying to minimize the dependence on glasses by a variety of surgical techniques.  For over 20 years, Luis Ruiz in Bogotá, Columbia, and several doctors in Europe have been trying to create bifocal or multifocal corneal ablations with lasers.  While that process is ongoing, I don’t think they will ever create a true winner.  Optical revision with a laser has to be “perfectly centered” for each individual person which makes laser ablation extremely difficult.  For approximately 2-10% of the population, centration is not going to be accurate enough and the surgeon is going to have dissatisfied patients.  Ophthalmologists who have great success with other types of refractive surgery and cataract surgery simply do not have the tolerance to deal with this percentage of unhappy patients. 

Another approach to bifocal correction at the cornea is through corneal implants, either creating a flap and putting a piece of foreign material under the flap, or creating a tunnel and placing a piece of refractive material into the pupillary area.  One problem has been the creation of a material that is truly inert and allows proper nutrition of the surrounding cornea.  Another problem is centration,   “Perfect” centration.  Again, quality of their vision is going to be a potential complaint of the corneal implant solution.  The blend of laser and corneal implants may offer a solution but there is no immediate evidence to support the process.

Refractive Lens Exchange and Presbyopic Refractive Lens Exchange (PRELEX)

Refractive lens exchange, on the other hand, has some real promise. Hyperopes are even more prone to success than myopes.  The risk of retinal detachment with an experienced cataract surgeon, is minimal in the typical hyperope. Lens implant power calculation has been refined and the advent of multifocal implants has revolutionized the “clear lensectomy” and cataract procedure.  My favorite multifocal lens is the ReZoom, and I very confidently tell patients that what they see at about three weeks after their second eye is done, is what they are going to see 30 or 40 years later.  If the patient is prepared properly, this technology works well.  With that being said it is critical to emphasize the importance of patient preparation to maximize the success with any multifocal implant. 

I’m not going to get into a battle over the ReZoom and the ReStor lens.  My favorite is the ReZoom.  The ReZoom offers the intermediate distance to which we are all becoming slaves.  Also, even if a patient has a fair amount of corneal astigmatism, that can be decreased up at the time of surgery with limbal relaxing incisions or combining the toric IOL in the capsular bag with a multifocal lens in the ciliary sulcus. Laser refractive surgery can even be added later and the patient will have pretty outstanding vision.

I have much less enthusiasm for those lenses which are going to depend on the ciliary muscle and flexible capsular bag to maintain their efficacy.  These types of lens implants depend on the ciliary muscle to adjust the focal point of these very flexible lenses to recreate a situation similar to what an emmetrope would have when they are between 10 and 30 years of age. All capsular bags do not remain equally flaccid as they heal. Some capsular bags become a bit more rigid and less pliable as they heal after lens surgery.  But my main concern is the status of the ciliary muscle.  As a guy who has lifted weights all his life, my voluntary muscles or striated muscles certainly are not as strong at age 63 as they were at 23 or 33.  Also, somebody is buying those Depends Adult Diapers.  Flacidity of various sphincters do diminish over time..  The ciliary muscle is a muscle.  I simply do not see it functioning as well at 78 as it did at 58.  In the meantime, lenses like the ReStor and ReZoom, which do not depend on any muscular function, will just keep on working. 

Ethics of Elective, Medicalyl non-necessary, Refractive Lensectomy. 

I have no problem doing Refractive Lensectomy on hyperopes.  However, on myopes with long eyes, I personally tend to draw the line.  If you do clear lensectomy on myopes who are perhaps between -1.00 to -3.00 with minimal astigmatism, you are probably never going to be able to duplicate the near vision that they had before surgery.  This ultimately leads to frequently greater chair time as they voice their unhappiness.  Then you have the high myopes with eyes that are longer than 25 mm who read a few inches from their face.  They may be happy with the quality of their vision at normal reading distance, but depending on who you believe, you have probably at least increased their risk of retinal detachment in their lifetime one percentage point.  I personally would not take that risk, so I don’t do it for my patients.  If they have a cataract and it’s medically reasonable to do and if they meet insurance/Medicare guidelines, then I would certainly offer a myope a multifocal lens.  However, we should all be aware that multifocals in one eye only frequently lead to a patient whose expectations are not met.  When I am implanting a multifocal lens in a hyperope who I consider to be a good candidate I tell them to expect to be underwhelmed with the first eye.  Then, when they get the second eye done, near vision, driving, glare, everything will become dramatically better.  Under-promise, over-deliver.  So, if the patient has a cataract in one eye only, and they are a hyperope, I may discuss the multifocal in the cataract eye and then give them the opportunity to pay for the multifocal out of their pocket in the second eye.  On the other hand, if they are a myope with a cataract in one eye only, I may mention the multifocal in passing, but only to tell them that they are probably not a good candidate and go ahead and give them a single vision lens.  The latter could certainly be debated, but I am just presenting you with my own conservative bias. 

I hope this is not too confusing.  If you have any questions, give me a call at 812/258-3044.  If I’m sitting there I’ll pick it up. If not, it will go to voice mail. 

Maurice E. John, M.D.