choice of lens

[bigapopka]

I am 79 years old and going in for first time cataract surgery on right eye, left eye has 20/25 vision. The person in charge of going through the details had me view a screen showing the difference between a spherical lens and an aspherical lens when driving at night. The difference was there but the price is five times higher. I found literature on the difference that indicates pro and con on both types as follows...
Thanks

The cornea is not spherical, it is aspherical (or "prolate"), meaning it has a steep curvature centrally that flattens out toward the edge.  Asphericity causes spherical aberrations, which can cause distorted vision if not neutralized.  If a spherical intra-ocular lens is implanted after cataract surgery, then additional spherical aberrations can occur, possibly resulting in decreased contrast sensitivity and reduced visual acuity.  
Aspheric IOLs are now being made to counteract spherical aberrations.  The AcrySof (Alcon) and Tecnis (AMO Inc.) IOLs have "negative" spherical aberrations, meaning they can neutralize the "positive" spherical aberrations of the cornea.  However, there seems to be an optical "trade-off" when eliminating positive spherical aberration; that is the depth-of-focus gets shallower.  The SofPort AO (Bausch & Lomb) aspheric IOL is "aberration free" and is not a "negative" lens in terms of spherical aberration.  This means that this lens would not add to any spherical aberrations, but the eye's "natural" aberration could be maintained and depth-of-focus would not be reduced.
It is also possible that the pre-operative spherical aberrations of the cornea could be "negative", perhaps after hyperopic laser surgery, or Conductive Keratoplasty.  In this case, the eye may benefit from the "positive" spherical aberrations produced by the standard spherical IOL.
As you see, this business can get very complicated.  A corneal topography measurement can be performed to arrive at a measure of corneal asphericity (the "Q value").  With this information,  and with advanced formulas, the doctor can theoretically choose an intra-ocular lens with a design that will optimize the patient's vision.  This is one step closer to being able to design a "custom" intra-ocular lens for each eye.
Aside from the depth-of-focus issue, there are some other potential negatives with an aspheric lens design:
• The lenses have to be placed without significant tilt and must be well centered to work effectively.
• There is significant potential for glare and halos around point sources of light at night.  This seems to be reduced if the lenses are implanted in both eyes, and over time.
• These lenses may be most beneficial to younger patients because changes in the aging retina may reduce any benefit from the increased visual contrast provided by the aspheric design

[John C Hagan III, MD, FACS, FAAO]

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[JodieJ]

I did some research on this issue before I had cataract surgery myself.  There are some people (e.g., those who have had previous hyperopic laser surgery) who should not get aspheric IOLs.  For the rest of us, the potential benefits of aspheric IOLs are very subtle.  In independent studies comparing aspheric vs. spheric lenses, most of the people who had been implanted with one of each could not see (literally) the difference.

Since there is no additional charge for an aspheric monofocal lens (as Dr. Hagan points out above), why not go for the possibility of enhanced night vision?  It's probably best to leave the choice of brand to the surgeon.  

[John C Hagan III, MD, FACS, FAAO]

You are mistaken if you live in the USA.  Aspheric monofocal IOLs are not "premium" lens and Medicare and almost all insurance companies do not allow extra payment for asphericity.

Multifocal IOLs whether aspheric or spheric are much more expensive than monofocal IOLs and require a substantial out of pocket payment.

JCH MD

[starman6600]

Very good information.  Thank you for posting this.  Seemingly, everyone considering a lens implant should read this and discuss it with the physician.  I plan to  do this.
Starman