The Glaucoma Suspect
Chat Highlights
July 27, 2005

On Wednesday, July 27, 2005, Dr. Rick Wilson a glaucoma specialist at Wills, and the glaucoma chat group discussed "The Glaucoma Suspect."

Moderator:  Dr. Wilson, tonight we have with us a glaucoma patient in London.

Dr. Rick Wilson:  Welcome.  Considering the time difference, that's an extraordinary effort.  

P:  Thanks.   I follow the highlights of these chats.   Wonderful service to the world.  

Moderator:  Dr. Wilson, will you please start our discussion tonight by defining what "glaucoma suspect" means?

Dr. Rick Wilson:  A glaucoma suspect is someone who has borderline signs or symptoms of glaucoma.  It could be on the basis of a suspicious-looking optic nerve or visual field or a borderline high IOP (intraocular pressure).

P:  Do suspects require treatment to prevent glaucoma?

Dr. Rick Wilson:  At this point we are only treating suspects if the chance of their having early pre-clinical glaucoma or getting glaucoma is serious.  Otherwise, we follow them for the first sign of change and then treat them.

P:  Please define "pre-clinical" glaucoma.

Dr. Rick Wilson:  By that I mean glaucoma where the patient has no symptoms and the damage cannot be detected yet with our present technology and knowledge.  We know from patients who have died at that stage and donated their eyes to science that they may have already lost 25 to 40% of their nerve fibers.

P:  What are the early signs of glaucoma?

Dr. Rick Wilson:  The first sign is usually an elevated IOP.  (There's a 50% chance of catching an elevation on one screening in someone with demonstrable early glaucoma.)  Or the first sign could be injury to the optic nerve or retinal fiber layer, with visual field changes coming later in the disease process.

P:  What percentage of suspects finally get glaucoma?

Dr. Rick Wilson:  That depends upon what the basis of the decision is.  A little over 10% of siblings of patients with glaucoma get glaucoma.

P:  Wouldn't it be better not to wait before treating?  I think waiting to see what develops could be too late.

Dr. Rick Wilson:  If you are confident in your ability to detect early glaucoma, then you can detect it before the glaucoma damage becomes symptomatic.  However, if there are several risk factors present, such as an African-American or Hispanic-American heritage with a strong family history and mildly elevated IOP at age 56, I will start those people on medication.

P:  My husband was told he was a suspect at age 19.  He was 36 years old before he needed to start on eye drops.  Before that, he was just monitored.

Dr. Rick Wilson:  Interesting. What caused him to be a glaucoma suspect? Was it IOP?  The appearance of the optic nerve?

P:  He had three minor car accidents within six months and realized he needed glasses.  We never asked why he was a suspect; we just took the specialist's word.  Our daughter had IOPs in the low 20's by age 21, so we figured her father might have been diagnosed as a suspect because of her IOPs.

Dr. Rick Wilson:  Your daughter should certainly be followed by someone who has checked her corneal thickness.  A thick cornea could explain her borderline IOP and ease any worries she may have.

P:  Do you see many glaucoma suspects in your practice?

Dr. Rick Wilson:  My practice is mostly advanced glaucoma patients who have exhausted most of their non-surgical options for treatment.  So I don't see that many glaucoma suspects, maybe four or five a week.

P:  How will the aging of our population affect the number of glaucoma suspects?

Dr. Rick Wilson:  Since glaucoma patients make up anywhere from 0.1 to 3 or 4% of the population, the frequency is increasing.

P:  Do you test the central corneal thickness (CCT) of glaucoma suspects?  If they are thin, do you watch them more closely?

Dr. Rick Wilson:  The answer to both questions is yes.

P:  Why am I hearing frequently about people with IOPs running in the 20 to 22 mm Hg range, who have no recordable field damage and no observable nerve damage, receiving treatment for lowering pressure?  In other words, glaucoma suspects are being treated as if they have glaucoma.

Dr. Rick Wilson:  Most glaucoma specialists do not treat IOPs of 20 to 22 mm Hg (top of normal) without some sign of injury or one or more strong risk factors.

P:  If only one of the parents has glaucoma, what are the chances of glaucoma being passed on to their child?

Dr. Rick Wilson:  A family history of glaucoma damage increases the risk four to nine times; absolute lifetime risk at age 89 is 10 times for relatives of glaucoma patients versus non-relatives.

P:  Didn't the Ocular Hypertension Treatment Study (OHTS), which showed the significance of central corneal thickness, show a significant benefit from treating ocular hypertensives?

Dr. Rick Wilson:  Yes. Treating patients who were at serious risk lowered the risk of progression to glaucoma by half. Many of those patients who had IOPs in the upper 20s and low 30s, I would have treated, as well.  In other words, many of the patients in the OHTS probably already had pre-clinical glaucoma, and at those pressures almost everyone would have treated many of the subjects.

[Editor's note:  The OHTS study found that "Topical ocular hypotensive medication was effective in delaying or preventing onset of POAG in individuals with elevated IOP.  Although this does not imply that all patients with borderline or elevated IOP should receive medication, clinicians should consider initiating treatment for individuals with ocular hypertension who are at moderate or high risk for developing POAG." http://www.nei.nih.gov/neitrials/viewStudyWeb.aspx?id=24]

P:  I have optic nerve damage and visual field loss in only one eye.  My IOPs are high-normal, and the damaged eye does not have an IOP higher than the good eye.  I am now being monitored without medication, and my vision has not grown any worse over several years.  Because of these factors, and because I believe I lost vision suddenly, it is now felt (though not with certainty) that there may have been an ischemic event.  So I am in the category of "glaucoma suspect."  If the problem really is glaucoma, how long does it generally take before the unaffected eye begins to show damage?  Three or five years?

Dr. Rick Wilson:  It is so variable that it is very difficult to speculate.  If neither nerve nor visual field has progressed in four or five years, that would suggest you don't have glaucoma now.  Unfortunately, by then your risk factors may have increased, for example, decreased circulation.  You will still need to be followed to be sure your resistance is not declining even while your IOPs remain constant.

P:  What are some examples of previous episodes of one-time insults to the optic nerve that eye doctors should consider before making a diagnosis of glaucoma suspect?

Dr. Rick Wilson:  Ischemic optic neuropathy, which could be from an autoimmune disease or not; embolus; too low a systemic blood pressure, causing a period when the nerve did not get adequate blood supply; vasospasm, as with a severe migraine.

P:  At age 18, my daughter suffered a fractured skull in an auto accident.  She is now in her thirties, and has perfect vision, according to her optometrist.  Would you recommend she get checked by an ophthalmologist, since she also has a family history of glaucoma? At what age do you usually start checking IOPs?

Dr. Rick Wilson:  I start at birth, because nobody sees me without at least the suspicion of glaucoma.  Usually, the eye pressure should be checked by the eighth grade and then every two to three years, unless there is increased suspicion.

Moderator:  Thank you, Dr. Wilson.

Dr. Rick Wilson:  Tomorrow's my early day in New Jersey, so I will call it a night.

On August 3, Dr. Wilson discussed "Side Effects of Glaucoma Eye Drops" in the Chat room. Click here for highlights of that meeting.

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