Glaucoma and Disorders of the Lens
Chat Highlights
September 10, 2003

Norma Devine, Editor

On Wednesday, Septebmer 10, 2003, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Glaucoma and Disorders of the Lens."

Moderator:  Dr. Wilson, are there disorders of the lens that can cause glaucoma?

Dr. Rick Wilson:  What a wide-open beginning!  There are many ways that a lens can cause glaucoma or be associated with glaucoma.

Moderator:  Well, how about starting with cataracts?  

Dr. Rick Wilson:  If a lens becomes a cataract, it can grow so large it can push the iris up against the trabecular meshwork (the drain), causing angle closure.  If the cataract becomes so mature that it is white, it can actually split the capsule and let the lens material into the eye.  That causes a great amount of inflammation and blocks the trabecular meshwork.  The lens can also leak proteins when it becomes too cataractous.  These proteins and the white cell reaction that occurs can also clog the drain.  

P:  Do cataracts increase the size of the lens?

Dr. Rick Wilson:  Yes.  The lens in the eye grows throughout life.  Since there is not much room in the eye, the lens material becomes compacted.  In most cases it grows to a small extent, but in a few cases it can grow too much.  As the lens material becomes compacted, it becomes more greenish-brown and then white.

P:  Does that hold true for all types of cataracts?

Dr. Rick Wilson:  Yes, although there are many kinds of cataracts.  Some are white; some are dark brown.  

P:  If a cataract causes the angle to close, can the cataract be removed? 

Dr. Rick Wilson:  Yes, if it is caught in time.  Once the iris has been in contact with the trabecular meshwork for some time, the iris will be stuck in the drain and would have to be surgically removed.  

P:  Does removing the cataract correct the problem?

Dr. Rick Wilson:  Removing the cataract regains plenty of space on the inside of the eye.  If, however, the iris remains against the trabecular meshwork (the drain) too long, the drain will remain clogged with iris.

P:  Will you please elaborate on your statement that there are many kinds of cataracts?

Dr. Rick Wilson:  The normal type of cataract is usually a darkening green color that matures into brown.  In the end, it turns white.  Cataracts, however, can start as white spots in the lens, especially in patients who are diabetic or have been on steroids.  The white spots may enlarge to fill the entire lens.

P:  An overly mature white cataract that splits sounds serious. How is that treated?  Is it common?

Dr. Rick Wilson:  In America, hypermature cataracts are uncommon.  To correct the situation after the cataract has split, as much of the material as possible must be removed.  Hypermature cataracts that leak protein are also uncommon in America.

P:  Why is that?

Dr. Rick Wilson:  Mostly because Americans get medical care, and the cataracts are removed before they become white and leak protein or burst.

P:  Can cataracts cause increased cupping?

Dr. Rick Wilson:  Cataracts are not a cause of glaucoma, but glaucoma can cause cataracts.

P:  What causes lens-related glaucoma?

Dr. Rick Wilson:  The most common cause for lens-related glaucoma is pseudoexfoliation.  

P:  What are the symptoms?

Dr. Rick Wilson:  White flakes form on the surface of the lens, and other parts of the eye.  These flakes then rub off the lens as the pupil moves back and forth.  The flakes float into the drain.  The blockage causes the intraocular pressure to rise.  Pseudoexfoliation is much more prevalent in the older population.  It is rare in patients under age 60, but becomes increasingly common as the patients age.

P:  Waiting until cataract surgery is positively needed is recommended after trabeculectomy.   Is it difficult to gauge when that time has arrived, before the lens can do damage?

Dr. Rick Wilson:  No, it's easy to see if the lens is becoming too cataractous.

P:  I was told I have the beginning of a cataract, a slight yellowing of the lens. The doctors don't seem to be concerned.  When should they be concerned?  

Dr. Rick Wilson:  We used to have to wait until a cataract was mature.  With the technology now available, even very dense lenses can be removed safely.  Therefore, there is no reason to remove a cataract unless it is causing enough visual symptoms that the patient wishes to take the small risk involved in cataract surgery.

P:  Are any physical symptoms associated with a cataract at any stage of its development?  

Dr. Rick Wilson:  Cataracts cause no symptoms except problems with vision. 

P:  Are cataracts one of the leading causes of blindness in the world?

Dr. Rick Wilson:  Cataracts are the number one cause of blindness in the world, followed by glaucoma, and then trachoma.

P:  What is trachoma?

Dr. Rick Wilson:  It's an infectious disease of the conjunctiva that scars the lids, rotating the lashes against the cornea.  The constant rubbing of the lashes on the cornea is painful and leads to white, scarred corneas and blindness.  In 1979, I operated on a woman with severe trachoma in Kenya.   She had not seen a doctor in 17 years.  After the surgery, she had some tearing, but could see again.  It was really heartwarming.

P:  How does glaucoma cause cataracts?

Dr. Rick Wilson:  We are not sure.  It is certainly possible that the elevated pressure injures the lens, causing a cataract.

P:  Do most surgeons not use stitches in cataract surgery?

Dr. Rick Wilson:  Yes, most surgeons do not use stitches.  

P:  If stitches are not used, how is the incision closed?  

Dr. Rick Wilson:  The incision in cataract surgery is approximately three millimeters long and three millimeters wide. If the wound has not been stretched too much, it should be watertight, and held together by the pressure on the inside of the eye.  

P:  Does all cataract surgery involve lens implants?

Dr. Rick Wilson:  More than 99% of the surgery does. 

P:  Are there other ways besides the three you mentioned that the lens can cause glaucoma?

Dr. Rick Wilson:  If the lens is knocked loose from trauma, it can push the iris forward into the trabecular meshwork and cause the pressure to rise.  Another entity is called spherophakia.  The lens in this condition is like a sphere, rather than being flattened on the front and back.  The spherical lens then can get stuck in the pupil and block the flow of fluid from the back of the eye to the front. That also pushes the iris forward and blocks the drain, causing quite high pressure. 

P:  Are there inherited entities?

Dr. Rick Wilson:  Yes, several have lenses that are not in a good position in the middle of the eye behind the pupil. The lenses can become dislocated.  In such cases, the people are subject to glaucoma that may be related to other causes besides the lens.

P:  What does "the lens is clear" mean?  A lack of opacity, a lack of discoloration, or both?  

Dr. Rick Wilson:  A clear lens means there is no opacity and no color.

P:  Is there a particular reason some cataracts grow faster than others? 

Dr. Rick Wilson:  As I mentioned earlier, cataracts in patients with diabetes, or in those on steroids, may progress much faster than normal.  Most cataracts take many years to grow to the point that they need to be removed.  My grandmother had cataracts for 25 years before I deemed they required cataract surgery.

P:  Can glaucoma medications cause cataracts?

Dr. Rick Wilson:  The very strong miotics like phospholine iodide, which are rarely used anymore, were said to encourage faster cataract growth.

P:  Do the preservatives in the various glaucoma medications induce the formation of cataracts?

Dr. Rick Wilson:  No, I have never heard that.  The preservatives do cause inflammatory changes in the conjunctiva and may also cause allergy.

P:  I have read that smoking and diabetes may contribute to cataract formation.  I've also read that the National Eye Institute, for one, is researching drugs to control cataracts, as well as evaluating the roles of vitamins and minerals in the control and prevention of cataracts.  Can you bring us up to date on some of this research?

Dr. Rick Wilson:  We mentioned earlier the close association of diabetes with cataracts.  Smoking is also a proven risk factor for cataracts.  I have not read much about vitamins and cataracts, but it stands to reason that the antioxidants would be at least slightly helpful in preventing cataracts, as are good sunglasses if you spend a lot of time in the sun. 

End of highlights for September 10, 2003.

On September 17, Dr. Spaeth discussed "Genetics and Genetic Testing" in the Chat room. Click here for highlights of that meeting.

Click here for the most recent glaucoma chat highlights and links to the chat archives.

Click here for upcoming glaucoma chat events.