Post-cataract Surgery Issues for Glaucoma Patients
Chat Highlights
April 14, 2004

Norma Devine, Editor

On Wednesday, April 14, 2004, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Post-cataract Surgery Issues for Glaucoma Patients."

Moderator:  The topic tonight concerns complications after cataract surgery. 

Moderator:  What kind of doctor usually performs cataract surgery on glaucoma patients?  

Dr. Rick Wilson:  In most cases, it is the general ophthalmologist.  Problems arise when the patient has serious nerve damage or is on so much medication that the doctor can add little more if the IOP (intraocular pressure) increases after surgery.

P:  What are some complications glaucoma patients suffer after cataract surgery?  

Dr. Rick Wilson:  The main one is an increase in IOP, because there is no excess capacity in the glaucoma patient's drainage apparatus, as there is in the normal patient's.  If any debris or viscoelastic agent, a gel-like liquid that is used to protect the cornea, remains in the eye at the end of surgery, there can be a huge post-operative rise in IOP.  

P:  What can be done when removing a glaucoma patient's cataract to prevent the gel-like liquid from remaining in the eye?  

Dr. Rick Wilson:  All debris should be thoroughly removed and the front of the eye well should be washed out.  

P:  Is there an artificial vitreous that can fill the space left when the cataract is removed?   

Dr. Rick Wilson:  There is an artificial vitreous, but it is not long-lasting, so it does not continue to occupy the space vacated by the cataract.

P:  Can't the eye create more vitreous to replace the artificial vitreous used during surgery?

Dr. Rick Wilson:  No.

P:  Is it true that cataract surgery can cause a torn retina? 

Dr. Rick Wilson:  It used to be more common, but it happens less than 0.5% of the time now. The retina tears when the volume of the lens that is removed (cataract) is much greater than the volume of the thin plastic intraocular lens that replaces it.  The jelly that fills the back of the eye moves forward to replace some of the volume vacated by the cataract and tugs on the retina.  If there is a thin area, the pull of the jelly (vitreous) can tear the retina.

Moderator:  Does that happen more often in glaucoma patients? 

Dr. Rick Wilson:  No.  

P:  Are you saying that a torn retina is one of the complications of cataract surgery?  If so, how often does that happen, and is it manageable?  Doctor, you're making me very reluctant to undergo cataract surgery!

Dr. Rick Wilson:  It happens in less than one patient in 200, or .5% of cases.  Often the tear is recognized and easily treated with laser.

P:  How common is an injured cornea after cataract surgery?

Dr. Rick Wilson:  The injured cornea is inversely related to the skill of the surgeon, so each surgeon would have different numbers.  But the numbers should be small; that is, less than about 2%.  (I'm just guessing here.)

P:  What are the main causes of severe visual loss after cataract surgery?

Dr. Rick Wilson:  A common cause is swelling of the center part of the retina, the macula.  We don't know why that happens, but the swelling can reduce the vision dramatically.  Besides the torn retina, the cornea could be injured during the surgery, and swelling of the cornea will also cause blurred vision.  Infections and hemorrhages are not common (about 1 in 1,500 to 1,800).

P:  After cataract surgery, what effect does the use of corticosteroids have on IOP?  

Dr. Rick Wilson:  If used over several weeks, corticosteroids can cause an elevated eye pressure.  Only 5% of the general population has a rise in IOP greater than 15 mm Hg when using steroids for six weeks, but 95% of glaucoma patients do.

P:  Is it true that certain medications like Xalatan are not recommended for glaucoma patients after cataract surgery?

Dr. Rick Wilson:  Xalatan, Travatan, Lumigan, and perhaps Rescula can cause macular edema (swelling).  Since that can happen after cataract surgery without medication, it is thought that taking those medications may be additive to the risk of macular edema.

P:  Is that macular edema temporary?  

Dr. Rick Wilson:  Yes, it occurs just before and during the first few weeks.

P:  When Xalatan first came out of clinical trials, it was said that the risk of macular edema was only to patients with certain risk factors, such as lens surgery or other pre-existing or predisposing conditions.  Has that been borne out?

Dr. Rick Wilson:  Yes.  Macular edema is not seen without risk factors being present.  Unfortunately, cataract surgery is one of those risk factors.

P:  When problems arise after a trabeculectomy, sometimes a revision or another type of surgery is performed.  Does cataract surgery ever need to be revised?

Dr. Rick Wilson:  Yes.  The most common problem is fibrosis (scarring) of the capsule that enclosed the cataract and is used to hold the intraocular lens.  That problem is called a secondary cataract and can usually be corrected with a laser.  The lens could also become displaced and need to be repositioned in the eye.

P:  How would a patient know if the lens was becoming displaced? 

Dr. Rick Wilson:  Vision would be distorted and there could be multiple images.

P:  What causes the lens to become displaced after cataract surgery?

Dr. Rick Wilson:  Usually the support structure for the lens is weak, as it often is in pseudoexfoliation glaucoma, or it has been injured during the surgery.

P:  I had cataract surgery last October 20 (in my "bad," traumatized eye only), and I've been quite happy with the results.  I've been off timolol since December and will have a pressure check in two weeks.  During the past week or so, the vision in that eye has seemed a bit cloudy when I wake up in the morning.  I can't really tell if it's more cloudy during the day.  Perhaps the way the light is in the bedroom when I wake up may make the cloudy vision more noticeable then.  Any comments on a possible cause?

Dr. Rick Wilson:  If what you think you see is real, it could be that your IOP is significantly higher in the early morning.  (Jake Wilensky has a patient in Chicago whose IOP drops 18 mm Hg during the first 30 minutes the patient is up in the morning.)  Or it could be something as simple as sleeping with your eyes partially open, so the cornea dries out and needs to be rewetted.

P:  If a glaucoma patient is a candidate for both cataract surgery and ALT or SLT, in which order, and with how much time between,  should these be done?  Can one surgery complicate the other?

Dr. Rick Wilson:  A trabeculotomy (SLT or ALT) done too soon before a cataract surgery can result in a pressure rise that cannot be treated with medication.  I would probably do the SLT first and wait three months before the cataract surgery.  A cataract surgery combined with a trabeculectomy could be a possibility if your IOP is not quite good enough.

P:  How common are complications from anesthetics used in cataract surgery?

Dr. Rick Wilson:  Cataract surgery alone is now done just with drops, so the risks of it are minimal.  If glaucoma surgery is added, a shot above and below the eye to administer local anesthetic has minimal risk of dangerous bleeding.

P:  What is the name of the anesthetic that cataract patients like so much?

Dr. Rick Wilson:  It used to be valium, but that is not used any more because it lasts too long.  Versed is the shorter-acting valium that is used commonly now.  Propofol is a short-acting barbiturate that puts the patient to sleep for just a few minutes.  Fentanyl is a narcotic that can give a drunken high if enough is given. 

P:  Can swelling occur with other types of surgery?  How long does the swelling last?  

Dr. Rick Wilson:  Corneal swelling often gets better over the course of a few weeks to a month or two.  Retinal swelling may need steroids or non-steroidal medications to improve and may take months.

P:  How can retinal swelling be measured?  

Dr. Rick Wilson:  By Optical Coherence Tomography (OCT).  Aren't you glad you asked?

P:  Can cataract surgery put a trabeculectomy at risk?  Would the doctor make one or two incisions?

Dr. Rick Wilson:  Yes.  Cataract surgery is usually done with two incisions, whether the patient has glaucoma or not.

P:  My mother had cataract surgery.  I was in the room with her when the doctor took measurements of the curvature of her eye to determine the lens he would fit her with.  He said he was having trouble getting the measurement.  In the end, the lens she was given didn't give her vision as clear as expected.  The doctor apologized, but didn't offer to change the lens.  How common is it to have difficulty in prescribing the correct artificial lens?  Can a poor lens be changed, or is this a one-shot deal?

Dr. Rick Wilson:  Measuring for the intraocular lens (IOL) is not an exact science, so small errors are common.  The more near- or far-sighted a patient is, the more difficult it is to determine the right power for the IOL.  Since exchanging the lens requires another intraocular surgery, most doctors don't do it unless the patient is not managing with glasses.

P:  Shouldn't a patient undergo cataract surgery on only one eye at a time?    

Dr. Rick Wilson:  Yes, because of the remote but real threat of infection that could cost the patient both eyes if both eyes were done at the same time.

P:  How is corneal edema measured?  

Dr. Rick Wilson:  The doctor can usually see that the cornea is thickened and slightly cloudy, with tiny water bubbles on the surface of the cornea.

P:  How many follow-up visits with the doctor should a patient have after cataract surgery?  How long is the recovery period if all goes well?  

Dr. Rick Wilson:  In a patient with cataract surgery and no other problems, two postoperative checks are fairly routine.  If there is any concern, more are needed.

P:  I am concerned that, with the present focus on glaucoma care, my ophthalmologist might be overlooking various problems that can develop, especially as I grow older.  I'm especially concerned about macular degeneration and retinal detachment.  Does an ophthalmologist look for these things during eye examinations of glaucoma patients? 

Dr. Rick Wilson:  In an older patient, an ophthalmologist should check the macula and the rest of the retina every year, at least.

Moderator:  That was the last question, Dr. Wilson.  Thank you again. 

End of highlights for April 14, 2004.

On April 21, Dr. Wilson discussed "Glaucoma Research 2004" in the Chat room. Click here for highlights of that meeting.

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