Cataracts and Glaucoma
Chat Highlights
December 5, 2001

Norma Devine, Editor

On Wednesday, December 5, 2001, Dr. Elliot Werner, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Cataracts and Glaucoma."

Moderator:  Our topic tonight is "Cataracts and Glaucoma."  Doctor Werner, how would you describe a cataract? 

Dr. Elliot Werner:  A cataract is an opacity in, or clouding of, the natural lens of the eye that interferes with vision.

Moderator:  What is a nuclear cataract?  

Dr. Elliot Werner:  A nuclear cataract is an opacity in the central portion of the lens called the nucleus.  Nuclear cataracts can develop at any age, but rarely before ages 45 to 50.  They are the most common type in older people and usually affect distance vision more than reading. 

Moderator:  Is it true that about one-third of trabeculectomy patients develop cataracts within five years?  

Dr. Elliot Werner:  Most recent studies have shown closer to 40% of trabeculectomy patients will need cataract surgery at some time.  

P:  Does that vary according to age or gender or type of trabeculectomy performed?

Dr. Elliot Werner:  No.

P:  What is the percentage of cataract surgery for patients who have had peripheral iridectomy?

Dr. Elliot Werner:  Peripheral iridectomy does not seem to be associated with cataract development, but angle-closure glaucoma is, so sometimes it is hard to separate the causes.   

P:  Can an iridectomy contribute to hypotony following trabeculectomy?

Dr. Elliot Werner:  Probably not.  Hypotony usually results from over filtration or injury of the ciliary body.  

P:  Doctors say that I have a sector iridectomy.   What relationship does that have to my glaucoma?

Dr. Elliot Werner:  A sector iridectomy just means a large part of your iris was removed, probably because your pupil was very small at the time of your surgery.  It has no effect on your glaucoma.

P:  Is an iridectomy always performed during a trabeculectomy? 

Dr. Elliot Werner:  Generally, yes.  But now some surgeons don't.  It is done to prevent the iris from plugging the trabeculectomy opening. 

P:  Is late onset open-angle glaucoma secondary to cataract surgery usually due to increased aqueous production, decreased drainage, or both?

Dr. Elliot Werner:  I don't believe there is such an entity as late onset open-angle glaucoma as a primary disease following cataract surgery.  Unless the glaucoma is a complication of the cataract surgery, the co-existence of the two conditions is probably a coincidence. 

P:  Let me rephrase my question then:  Are aphakic people more likely to develop open-angle glaucoma, and if so, why?

Dr. Elliot Werner:  I don't know of any evidence that is true.

P:  Just to clarify, are you saying that people who are aphakic (or psuedophakic) are at no higher risk of developing elevated intraocular pressures than the general population?

Dr. Elliot Werner:  As far as I know, they are not more likely to develop open-angle glaucoma.  There are other complications of cataract surgery that can cause a variety of secondary glaucomas.

P:  Could you mention a few?

Dr. Elliot Werner:  You can get glaucoma secondary to uveitis, angle closure, malignant glaucoma, retained lens material, vitreous in the anterior chamber, etc.

P:  Wouldn't an aphakic patient have vitreous in the anterior chamber?

Dr. Elliot Werner:  The patient might if the lens capsule is not intact.

P:  In old-style cataract surgery, in which the lens was removed through the pupil, could damage to the ciliary body cause an increase in its production of aqueous humor -- through an iridectomy, that is. 

Dr. Elliot Werner:  Not as far as I know.  Glaucoma due to increased aqueous production is extremely rare, if it occurs at all.

P:  What percentage of cataract surgeries these days leave the patient aphakic?  Why does that happen? 

Dr. Elliot Werner:  That's very rare, in my experience.  The usual reason is either a very bad intraoperative complication or a very myopic patient to begin with.  I, personally, haven't left a patient aphakic in years.

P:  What does "aphakic" mean?  Can a person see out of an aphakic eye?  

Dr. Elliot Werner:  Aphakic means not having a lens in the eye.  If the natural lens is removed and no implant is used, the eye is aphakic.  If an implant is used, the eye is said to be pseudophakic.  In order to see from an aphakic eye, you need those very thick cataract glasses people used to wear in the pre-implant days or a very heavy contact lens.

P:  What effect does cataract surgery have on a trabeculectomy?  

Dr. Elliot Werner:  About 30 to 50% of trabeculectomies fail after cataract surgery.

P:  Why is cataract formation so prevalent after trabeculectomies?  

Dr. Elliot Werner:  I do not know.  It's probably due to surgical trauma to the lens,  or interference with normal lens nutrition due to alteration of aqueous flow.

P:  Why is angle closure such a high risk?

Dr. Elliot Werner:  That's probably because the aqueous interferes with the normal nutrition of the lens.  Remember that the aqueous is the blood for the transparent structures of the eye.  Oxygen and nutrition come from the aqueous.  Anything that interferes with the normal aqueous flow may damage the lens and cornea.

P:  Can that also be associated with glaucoma medications? 

Dr. Elliot Werner:  Yes, but some, such as pilocarpine, are more likely to cause it. 

P:  If glaucoma due to increased aqueous production is rare, why are medications used to decrease aqueous production?  

Dr. Elliot Werner:  Reducing aqueous production below normal levels will reduce the intraocular pressure, but at the cost of decreasing the nutrition of the anterior segment of the eye.

P:  If cataract surgery causes a trabeculectomy to fail, what can be done?  

Dr. Elliot Werner:  If necessary, another trabeculectomy or a tube shunt.  Glaucoma isn't easy and it isn't kind. 

P:  After cataract surgery, what is the risk of a detached retina?  

Dr. Elliot Werner:  If the capsule is intact, less than two percent.  If the capsule is not intact, it's probably about five to ten percent. 

P:  Why can cataract surgery cause detachment of the retina?  

Dr. Elliot Werner:  Because the surgery alters the normal relationship between the structures and fluids of the eye and can cause the vitreous to move in abnormal ways and tug on the retina.

P:  Do glaucoma or retina problems pose more problems for cataract surgery?  

Dr. Elliot Werner:  Glaucoma usually is more of a problem for cataract surgery.  The retina is remote from the site of the cataract operation.  

Moderator:  If someone has large pupils, can more light getting into the eye increase the chance of cataract?

Dr. Elliot Werner:  I have never heard anything about pupil size.  There is an association with long-term exposure to sunlight and ultra violet light and cataract.  People with light-colored eyes are at greater risk.  

P:  If the pupil in an eye that has had a trabeculectomy stays large all the time, is there any harm in that?  

Dr. Elliot Werner:  I don't know.  I  have never seen any studies on that.

P:  What causes intraocular pressure to rise after a laser capsulotomy?

Dr. Elliot Werner:  Probably inflammation. 

P:  After a capsulotomy, is there much chance of losing the low pressure needed to control the glaucoma? 

Dr. Elliot Werner:  Not much.  The pressure rise is usually very temporary.  I have never seen a long-term adverse effect on intraocular pressure after a capsulotomy.

Moderator:  If the lens becomes stuck to the iris because of chronic-angle closure, can the cataract still be removed?  

Dr. Elliot Werner:  Yes, those adhesions can be broken fairly easily during the operation, but the patient is left with a distorted pupil.  

Moderator:  During cataract surgery, why would a lens not be put in place?  

Dr. Elliot Werner:  It is.  It's called an implant.  We couldn't use them before they were invented, of course.  Practical and safe lens implants were introduced in the late 1970's and became very popular by the mid-1980's. 

P:  Would someone who had the old-style cataract surgery -- say, 30 years ago -- be a candidate for an implant now?

P:  Can an eye that has been aphakic for some years receive an implant? 

Dr. Elliot Werner:  Yes, secondary implants are commonly done if the eye is otherwise intact and not too damaged. 

Moderator:  Does a cataract cause a person's vision to become more yellow? 

Dr. Elliot Werner:  Yes, most cataracts are yellow, and cause the world to look yellow.  After cataract surgery, people often remark that things look very white or even blue, for that reason.  They often can see the yellow tinge with the unoperated eye.

Moderator:  What is the relationship between juvenile glaucoma and cataracts?  

Dr. Elliot Werner:  Children with congenital cataract often develop a severe open-angle glaucoma as young adults.  Surgical treatment of juvenile open-angle glaucoma; can cause cataracts.

Moderator:  Thanks for coming tonight, Dr. Werner.  We look forward to your next visit.  

Dr. Elliot Werner:  You're welcome.  I will be back on December 26th.  For those of you in the Philadelphia area, I will be leading the Glaucoma patients' support group this Sunday at 1:30 p.m. at Wills.  The topic is "Communicating with Your Doctor."  Goodnight everyone. 

End of highlights for December 5, 2001.

On December 12, Dr. Wilson discussed "ICE Syndrome, Sturge-Weber Syndrome, Inflammatory & Traumatic Glaucomas" in the Chat room. Click here for highlights of that meeting.

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