“I had cataract surgery 6 months ago but I’m still having blurry vision.” I see patients here at Miami Eye Center who come to see me for a second opinion totally distraught over the issue and in many instances their degree of concern is unwarranted. This could be you, if so there are several things to consider. Firstly, what is the cause of the blurriness and secondly, can it be fixed?”
We can start analyzing the problem from the front of the eye (cornea) and working to the back (retina). Some of the issues are simple yet overlooked while others are complex. If you have had a multifocal lens implant there is no margin of error as these lenses are unforgiving. If your tear film is not good you could be losing vision. I have many patients complain of poor acuity only to find that by putting a drop of artificial tears on their eye they recover substantial vision. A long term program of tear film enhancement leads to continued excellent vision.
There could be residual nearsightedness, farsightedness and or astigmatism. If this is the case and you have had a multifocal lens implant it is incumbent upon the surgeon to correct this. If you have opted for a generic lens implant, eyeglasses is the answer. However, with multifocals you should be offered LASIK correction which has the potential to completely correct the blurry vision.
The intraocular lens is placed into the eye on a clear membrane (like Saran wrap) called the posterior capsule. On occassion this clear membrane becomes cloudy and impacts the vision potential. This is easily treated with a Nd:YAG laser procedure which vaporizes the membrane and thus clears the vision.
Moving to the back of the eye there is the retina. If there is a problem with the retina it is the same as taking a photograph with bad film in the camera. In a small percentage of surgeries there could be swelling of the retina known as cystoid macular edema. This has a profound effect in reducing the vision. Fortunately, it is self limited to several weeks to months and often responds to therapeutic eye drops.
While the point of this discussion is to inform the reader that all is not lost if at first glance the outcome of cataract surgery appears to be less than optimum, however, there are a number of complications which require extensive evaluation and complex repair. One must keep in mind that if you lump all of the possible complications of cataract surgery into one, the risk is about 3%, one of the safest major surgical procedures performed today.
Here at Miami Eye Center I am seeing a gradual trickle of RK alumni who had their surgery in the 80’s now coming back for cataract surgery. While the outcome from cataract surgery following prior RK can be excellent, there are a number of important issues that should be understood by the patient. The cornea is a very complex tissue that is perfectly designed to help focus light on the retina and the result of making radial incisions vastly alters the optical properties. Most importantly is that the cornea loses its stability. As the years have past since the RK, the cornea has flattened. In addition, within any given day the cornea shape changes from flat in the morning to steep in the evening. This often makes people farsighted in the morning and nearsighted later in the day. When we make the preoperative calculations for the intraocular lens we are in effect shooting at a moving target. When the calculation is off, the patient will be either nearsighted or farsighted following the surgery. In addition, the algorithms applied to normal corneas are impacted by the flatness of the RK cornea further making the calculations difficult. While I have a pathway of making the appropriate calculation adjustments I still warn patients about the above possibilities. Also that one can not be certain of the outcome until several months following the surgery as the cornea continues to flatten. If the power of the eye is not satisfactory there are several options for improving the outcome. Eyeglasses are easiest but perhaps not the first choice. Contact lenses might be worn. Lastly, it is possible to insert a second intraocular lens into the eye to add or subtract the power necessary to yield good vision without glasses. I have done this on a number of occasions at which time the calculation of the “piggyback lens” is straight forward. I would recommend against a multifocal lens implantation because the multifocals don’t perform well if there is any significant power error. A second reason is that there could be too much glare as a result of the optical properties of the RK cornea combining with the optics of the multifocal lens. In many instances the Toric Lens has been helpful in managing astigmatism that is often seen after RK surgery. It is important that the surgeon understand the type of astigmatism since the lens is not optimally effect in irregular astigmatism. My advice to any post-RK cataract surgery candidate is to be certain that their visual loss is due to cataract and not a cornea related issue and find a surgeon who has been there, done it and has a T-shirt.
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.
I have been seeing an increasing number of folks coming in for an opinion about their pterygium. Most don’t know that is the name of the fleshy-looking growth on the nasal side of the cornea. It has a triangular shape which looks somewhat like a wing, therefore the name “pterygium” which from the Greek means “wing.” The pterygium may first appear as a reddish area on the nasal side of the dark central part of the eye (the iris provides the color and the cornea is the clear window over it) only to grow onto the cornea as a fleshy membrane. If left untreated, it has the potential to grow across the center of the cornea and result in a severe loss of vision. It seems that the growth and development of pterrygia are related to sunlight so if you have noticed a small pterygium, get some good quality sunglasses.
There is no reason to treat small pterygia (as most don’t become large pterygia) unless they are irritating and/or growing. I don’t often see middle aged people with pterygium problems, usually it becomes symptomatic in people in their 20’s and 30’s. I have found that the pterygium become stationary later in life. Quite frequently patients will ask me to remove a pterygium which they have had for many years while I’m operating their cataracts; this is very possible. Many people ask to have the pterygium removed for cosmetic reasons, ie, they are tired of answering the question: “what is that growing on your eye?” But if the pterygium is growing, it is time to act and the only action is surgical removal.
The removal of a pterygium is low risk as the entire procedure is conducted on the outside of the eye. The main risk is that it will recur after removal. When I began doing this surgery early in my career, the recurrence rate was as high as twenty-five percent. Back then we used low dose radiation applications to the eye to prevent recurrence. This approach was inconvenient and didn’t do much good. The next advance was the use of conjunctival grafts, that is, after the pterygium was removed we took a piece of the white filmy cover of the eye (conjunctiva) from under the eyelid and moved it to the surgical site and sewed it into place. This helped reduce the recurrence rate but it made the surgery long and tedious. At the same time we began using a drug called Mitomycin which was developed in the 1950’s for chemotherapy. The Mitomycin was applied to the surgical area with sponges for several minutes to inhibit new scar formation and reduce the chances of regrowth.
All of this has evolved to the state of the art which is the use of an amniotic membrane graft http://www.osref.org/medical-education-materials.aspx made of human placenta (only the inner basement membrane which is very thin) which is glued into place with fibrin glue http://www.baxter.ca/htdocs/en/doctors/biosurgery/products_tisseel.html (a human byproduct). The placenta is first lab tested for contaminants then frozen and shipped to us. When placed on the eye it provides stemcells which reduce inflammation and a barrier to recurrence. It is readily absorbed onto the surface of the eye. This approach coupled with Mitomycin has made the surgery reasonably fast and effective in terms of reduction of the recurrence rate. Postoperative course consists of one night with a patch then several weeks of eyedrops; vision is good immediately and folks can resume their usual activities in a day or so.
This technique has its greatest benefit in patients who have had prior pterygium surgery with a poor outcome, that is, a recurrence. If a graft with fibrin glue and Mitomycin is not done in these people, a further recurrence is a good probability.
While this technique is not fullproof, it is currently the most effective treatment for pterygium.
