Surgeon offers method to address vision problems after cataract surgery with presbyopia-correcting IOLs
February 4, 2009
Modern refractive cataract surgery using accommodating and multifocal intraocular lenses (IOLs) is helping many people enjoy freedom from prescription eyeglasses and reading glasses after surgery.
But in some cases, vision problems remain after cataract surgery with presbyopia-correcting IOLs. The key to successfully resolving these vision problems is to take a systematic approach, says Roger F. Steinert, MD, a specialist in cataract and refractive surgery at University of California, Irvine (Irvine, CA).
Dr. Steinert outlined his approach to solving post-operative vision problems in a recent issue of Refractive Eyecare.
Careful questioning and post-operative exam helps reveal true nature of vision problems after cataract surgery
When patients are unhappy with their vision after cataract surgery with presbyopia-correcting IOLs, Dr. Steinert conducts a careful patient interview and history to determine the exact nature of their visual complaints and problems. He then examines the patient before and after dilating their pupils to see if the problem is related to pupil size.
"One of the chief goals of the patient history and exam is to determine whether the patient's complaint is a lack of visual clarity or a visual side effect, such as halos or glare," says Dr. Steinert.
Once he has determined the true nature of the visual complaint or vision problem, Dr. Steinert then evaluates possible causes in a step-by-step manner, starting with those that are the most likely and most easily treatable.
When vision is poor at one distance after presbyopia-correcting cataract surgery
If vision at one distance is clear, but vision at another distance is poor, the determination of the problem is sometimes quite straightforward.
For example, if a patient has cataracts in both eyes and then sees quite well in the distance but poorly up close after surgery on the first eye with a presbyopia-correcting IOL, Dr. Steinert feels he can provide better near vision after the second surgery by modifying the power or design of the accommodating or multifocal IOL he uses for surgery on the other eye.
Or, in many cases, distance and intermediate vision with presbyopia-correcting IOLs might be acceptable, but the patient may still have some problems reading fine print. In these instances, simply prescribing reading glasses can solve the problem.
If vision is poor at all distances after presbyopia-correcting cataract surgery
If vision is not clear at any distance after cataract surgery with presbyopia-correcting IOLs, determining the cause of the problem can be more challenging.
All components of the visual system must be examined, including the ocular surface, the cornea, the macula and optic nerve, and the posterior capsule of the eye's natural lens (which is left intact in the eye, directly behind the IOL).
In these cases, Dr. Steinert recommends a logical, step-by-step process to evaluate each of these potential causes of post-operative vision problems:
- Ocular surface. The surface of the eye is examined to evaluate the quality and quantity of tears and the health of the superficial layer of the cornea, called the epithelium. If dry eye problems exist, artificial tears or other treatments may improve vision.
- Cornea. The shape of the cornea is evaluated with topography instruments to determine if irregular astigmatism or other aberrations are present. If these problems exist, gas permeable (GP) contact lenses or laser surgery, such as LASIK or PRK, may improve vision.
- Macula and optic nerve. An examination of the internal structures of the eye and other tests can determine if problems exist in the macula or optic nerve. In some cases, cataracts can mask underlying problems such as macular degeneration, which cataract surgery cannot correct.
- Posterior capsule. The posterior capsule of the eye's natural lens can become cloudy and interfere with vision after cataract surgery. If this is the problem, a special laser can be used to create an opening in the center of the capsule to restore clear vision.
Addressing refractive errors and visual side effects
If the vision problem is due to uncorrected or residual refractive errors (nearsightedness, farsightedness and/or astigmatism), a secondary procedure, such as LASIK or PRK, can be performed to fine-tune the visual result.
For patients who don't wish to undergo additional surgery (due to the cost of LASIK or other issues), glasses can be prescribed instead.
If the problem after presbyopia-correcting cataract surgery is visual side effects (halos and glare), there are a number of possible causes and solutions:
- If glare and halos are caused by the patient's pupils being too large, special eye drops (called miotic agents) can be prescribed to reduce the size of the pupil and eliminate or reduce vision disturbances.
- If the post-operative exam reveals that the IOL is not properly centered behind the pupil, the surgeon can performa a secondary procedure to re-position the IOL.
- If no other cause of visual side effects exist exist, the IOL itself may be defective. If so, it may be necessary for the surgeon to perform a second surgery to remove the IOL and replace it with a new one.
In general, the greater optical complexity of multifocal IOLs make them more likely to cause visual side effects than accommodating IOLs, says Dr. Steinert. But he adds that even patients with accommodating IOLs can sometimes experience glare.