Cataracts and the Glaucoma Patient
Chat Highlights
December 3, 2008

On Wednesday, December 3, 2008, Dr. Michael Pro, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Cataracts and the Glaucoma Patient".

Moderator: Welcome everyone. Our topic this evening is Cataracts and the Glaucoma Patient.

Dr. Pro: Good topic! It should be an interesting discussion.

P: Do glaucoma medications cause cataracts?

Dr. Pro: There is some evidence that they can. Certainly older drops like pilocarpine can lead to pupillary constriction and eventual scarring to the anterior surface of the lens, which can hasten a cataract; there is less evidence that newer drops cause cataracts.

P: Why is a trabeculectomy a risk factor for cataracts? Can the skill level of the surgeon involved increase the risk?

Dr. Pro: Certainly a trab increases the risk for a cataract and this is seen in studies. In AGIS (Advanced Glaucoma Intervention Study) [See the chat highlights from October 1, 2008—ed.] patients who had a trab had a risk of developing a cataract of 78 percent. The trab is a risk factor for several reasons; probably the most important in an uncomplicated trab is post-op inflammation, which likely hastens the development of a cataract. But if there is a complication such as a flat anterior chamber, then the risk of developing a cataract is much greater because the surface of the lens touches the inside of the cornea.

P: What exactly is a cataract?

Dr. Pro: A cataract is opacification of the intraocular lens. When you are born your lens is very clear, but as you age the lens becomes increasingly yellowed and opaque. It is called a cataract when the lens is noticeably opaque to an examiner and/or the patient has a diminution of corrected vision.

P: How successful is endocyclophotocoagulation (ECP) in treating cataracts and glaucoma, and what experience have Wills doctors had with this procedure?

Dr. Pro: ECP – endocyclophotocoagulation – is a probe that treats the gland that produces the aqueous and is used during cataract surgery. It can be effective in patients who require drops to maintain a controlled IOP. Many Wills doctors are skilled in the ECP (I should mention that it was invented by a Wills graduate). I perform ECP routinely in select patients.

P: ECP has been recommended to me by a local doctor. I am a monocular patient and wish to choose the best procedure. My cataract is affecting my life at this point.

Dr. Pro: It's a safe option in a person who needs cataract surgery, and avoids the risk of a trabeculectomy.

P: Dr., what is your opinion on having ECP for my plateau iris done at the time of cataract surgery? I am 48 and the vision in that eye is 20/25 with correction.

Dr. Pro: It is an option. I generally use the device in a patient with early glaucoma or ocular hypertension who requires cataract surgery, but may not need a trabeculectomy.

P: So is ECP useful if you already have a working trab but also need the cataract removed?

Dr. Pro: If the trab is working, I would not usually perform an ECP. An ECP causes slightly more inflammation than a cataract surgery alone, so doing the ECP may increase the risk of scarring the bleb.

P: Could you please describe ECP? I thought it was an end-of-the line treatment that could greatly decrease vision.

Dr. Pro: You are thinking of trans-scleral cyclophotocoagualtion. The ECP uses a probe. On a monitor the surgeon treats the ciliary processes (which make the aqueous fluid) with a laser. The treatment causes shrinkage of the ciliary processes. It is relatively safe and does not cause worsening of vision in most cases.

P: Do all eye surgeries cause cataracts or just trabs?

Dr. Pro: Yes, any intraocular eye surgery can lead to a cataract. In terms of glaucoma procedures, the non-penetrating glaucoma procedures would probably be less likely to cause a cataract.

P: How does shunt surgery effect cataracts?

Dr. Pro: The same or maybe worse than a trab. With a tube shut there is a greater chance of touching the surface of the lens, which can hasten a cataract formation.

P: If a patient does not suffer from hypotony after a trabeculectomy is the risk of a cataract lessened?

Dr. Pro: It depends on the severity of hypotony. If the IOP is low, but the anterior chamber is formed with minimal inflammation, then the risk of a cataract should not be higher than in an uncomplicated trab, but if the IOP is low and the anterior chamber is flat, or there is a lot of inflammation, then the risk of a cataract is much higher.

P: Is cataract surgery more difficult for those with advanced glaucoma, or particular types of glaucoma?

Dr. Pro: Cataract surgery can be more difficult in many types of glaucoma. Drops like pilocarpine can cause a constricted pupil, which can affect the ease of surgery.
Pseudoexfoliation syndrome deserves special mention. This condition causes lens laxity during surgery and increases the risk of a lens dislocation into the vitreous cavity.

P: For what it's worth to others, my cataract surgery was easy and successful in spite of my eye having been damaged by trauma, and it led to a pressure drop that kept me off drops for three years. How common is that, Dr. Pro?

Dr. Pro: It is quite common. There are many case series that report this and the magnitude of the IOP drop is related to the pre-op IOP level. So a person with an average IOP of 28 pre-op may see a greater IOP drop than someone whose pre-op IOP was 18. But this effect is unpredictable and thus one cannot consider cataract surgery as primary treatment of glaucoma.

P: What is the likelihood of a bleb failure after cataract surgery if the bleb was functioning effectively prior to the cataract surgery?

Dr. Pro: I don't know an exact percentage, but I would place the risk of bleb failure after surgery at about five to 10 percent.

P: Is the recuperation time post cataract surgery the same for those with glaucoma as for those without?

Dr. Pro: Yes, as long as a glaucoma procedure is not performed at the same time.

P: Is there ever a circumstance when cataract surgery should not be performed?

Dr. Pro: Sure, such as a patient who is monocular with a very dense cataract, bad glaucoma and corneal disease. That would be a high risk patient (not to say that surgery should never be performed). There are always circumstances where any surgery can be risky.

P: If one is seeing fairly well with a cataract but a shunt is needed at this time, why would the cataract be removed at the same time of shunt surgery?

Dr. Pro: Well, sometimes cataract surgery is done because the surgeon knows that the patient is likely to develop a significant cataract sooner after the shunt. With that in mind doing both surgeries saves the patient the stress of two trips to the operating room.

P: Dr. Pro, I thought cataracts had to be at a certain stage before they were safe to be removed! Is that correct? Or it does not matter what stage it is at?

Dr. Pro: Cataracts are removed at all degrees of opacification. It really depends on the perception of the patient. Some patients see 20/20 but have disabling glare and go for surgery; some patients see 20/50 and are content with their vision.

P: Can a pupil that has been scarred closed be repaired during ECP and cataract surgery?

Dr. Pro: Yes, it can be stretched open.

P: I noticed a lighter color change in my eyes after cataract surgery; they used to be a green but now are a blue green.

Dr. Pro: There can be loss of pigment on the iris which could lead to a color change.

Moderator: Dr it is now 9:30 pm. Thank you again for joining us in the chat room and for a very educational chat.

Dr. Pro: You're welcome. It's always a pleasure. Have a great two weeks until we meet again.

On December 17, Dr. Pro discussed "Migraines and Glaucoma" in the Chat room. Click here for highlights of that meeting.

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