Most of my patients think that astigmatism is a disease; it is not and it’s time to clear the air.  Astigmatism is a normal condition effecting 80 percent of the population.  Astigmatism is caused by an irregular shape of the cornea; the clear window on the front of the eye is the cornea.  In a non-astigmatic eye it has a round curve in all directions, like a basketball.  In the case of astigmatism, it is shaped like a spoon.  In one direction there is a steep curve and in the other there is a gentle curve.  This is called “regular astigmatism.”  When light passes into the eye it must pass through the cornea.  When there is no astigmatism the light comes to a perfect focus on the retina and the vision is excellent.  When light passes through an astigmatic cornea light from different directions is focused differently and there is a blurry image projected onto the retina.

Regular astigmatism is easily corrected with eyeglasses or contact lenses.  If you hold your glasses out in front  of you and look at a picture on the wall while rotating the glasses you might see some changing distortion; this is the lens correcting your astigmatism.  Rigid gas permeable (hard) contacts are excellent at correcting astigmatism while soft lenses are less effective.

There are excellent surgical techniques for the correction of astigmatism.  The oldest method that I began using in 1982 is astigmatic keratotomy.  Here small straight incisions are made on the cornea across the steeper curve (meridian).  This tends to flatten that meridian and steepen the flatter meridian, ultimately making the cornea more spherical.  Along came LASIK where after several years there emerged an algorithm for the correction of astigmatism along with nearsightedness and eventually along with farsightedness.  Very substantial amounts of astigmatism can be corrected with LASIK.  More recently, we have added a variation of astigmatic keratotomy (AK), known as limbal relaxing incision (LRI).  Here the corneal incision is moved to the outer edge of the cornea and is curved rather than straight.  It is more predictable than AK. 

When patients come for cataract surgery we always evaluate their astigmatism.  This is done so that we can calculate the power of the lens to be implanted at surgery and also to be in the position to offer them an opportunity to have the astigmatism corrected with LRI at the same time.  The purpose is to enable patients to achieve excellent vision without glasses when the cataract surgery is done.  We usually reserve the LRI for small amounts of astigmatism because there now is available the toric lens.  This is an intraocular lens with optics designed to neutralize the astigmatism along with the correction of myopia or hyperopia.  This lens is implanted just as any lens might be then it is rotated into a position to match the steep meridian on the cornea, thus neutralizing the astigmatism.

So don’t be concerned when you learn that you have astigmatism; it could be a lot worse.

Now that you have a visually significant cataract, that is, a cataract that is interfering with activities that you enjoy doing or those that you must do, the choice is no longer “should you do the surgery,” rather “how should the surgery be done.”  Needless to say, this decision must be made during a consultation with an ophthalmologist with whom you feel  comfortable.  Keep in mind that this is the last and best opportunity to not only remove your cataract but to correct other problems such as nearsightedness, farsightedness presbyopia and astigmatism.

To help with the discussion, the lens options fall into several classes; MONOFOCAL LENSES will deliver good vision at a single point in space, ie, distance or near.  A modern variation on this lens is the ASPHERIC LENS which has a curvature which neutralizes the curvature of the cornea and thus reduces glare and other types of distortion.  A TORIC LENS will correct astigmatism at the same time that it corrects nearsightedness or farsightedness and it has recently been manufactured in an aspheric form.  Then there are the MULTIFOCAL LENSES which are in many instances, aspheric as well.  These lenses correct for distance and near vision.  There is the Restor lens from Alcon Labs, the ReZoom lens and more recently the Tecnis lens from AMO.  In addition, the Crystalens from Bausch and Lomb which is somewhat different from the other lenses but ultimately yields a similar outcome.

The issue is that there are numerous lenses to place in the eye at the time of surgery. The lens must be matched to the patient’s visual needs, not the other way around; one lens does not fit all.  On the one hand, an 80 year old with macular degeneration and cataracts who does not mind wearing reading glasses would fair best with a lens that provides only distance vision and perhaps it should be an ASPHERIC LENS which minimizes glare and maximizes distant vision.  The opposite situation might occur in a 50 year old who needs distance vision, computer vision and reading vision and would be willing to wear reading glasses occassionally.  The latter case would call for a MULTIFOCAL LENS of which there are several. 

It must be said that every style of lens has different advantages and disadvantages and these must be reconciled with the patient; that is my job.  I must find out what you expect and want from the procedure.  What are the tasks that you want to do without glasses and which are you willing to occassionally put the glasses on in order to perform. 

Remember that cataracts come with having birthdays and perhaps this year’s present might be good vision and possibly no glasses to achieve that end.