Gender and Glaucoma
Chat Highlights
December 15, 2004

On Wednesday, December 15, 2004, Dr. Rick Wilson, a glaucoma specialist at Wills, and the glaucoma chat group discussed "Gender and Glaucoma."

Moderator:  Tonight's topic is "Gender and Glaucoma."  Are there significant gender-based risk factors for glaucoma, as there are for age, race, and family history?

Dr. Rick Wilson:  Yes, females are much more prone to angle-closure glaucoma, because their eyes are smaller than men's.  With the added crowding of the anterior segment, the iris is closer to the trabecular meshwork and more likely to get sucked in, causing the angle closure.  Females are also more prone to normal-tension glaucoma (NTG), possibly related to a greater propensity for vasospastic diseases and low blood pressure.

P:  Why are women more prone to angle-closure, and why is the anterior segment more crowded? 

Dr. Rick Wilson:  Their eyes are smaller than men's eyes, just as their heads, hands, and so on, are also smaller.  Males are more prone to pigmentary glaucoma due to their larger eyes, which put the iris much closer to the ligaments (called zonules) holding the lens in place.  This contact with the zonules rubs pigment particles off the back of the iris, liberating them to float into the trabecular meshwork, and blocking it.  

P:  The size of glaucoma eyedrops used by men and women is the same.  Do women, because of their smaller eyes, get a stronger effect from the eyedrops?  

Dr. Rick Wilson:  No, not in their eyes.  Even the smallest drops contain over twice what the eye lids can hold when fully expanded, and four to five times what they normally hold.  The rest is excess and runs down the lacrimal duct into the nose, or over the top and down the cheek. The smaller blood volume in the average female compared to the average male will mean a higher blood concentration and more systemic side effects.

P:  Is there any indication that some medications are more effective for males than for females?   

Dr. Rick Wilson:  There is some evidence of differences in medical effectiveness by race.  I am not aware of gender differences.  A relatively new difference is the thickness of the cornea.  Patients with thin corneas usually respond better to topical medications, because more of the medicine can penetrate the thinner cornea.

P:  Is an attempt made in clinical trials of glaucoma medications to include an equal number of males and females?  

Dr. Rick Wilson:  Yes, but the main thing is to represent the genders accurately.  If there are two groups, an attempt is made to match them for age, sex, type of glaucoma, height of IOP (intraocular pressure), etc.

P:  You said that females are more prone to NTG, possibly owing to "a greater propensity to vasospastic diseases."  To what vasospastic diseases are you referring?  

Dr. Rick Wilson:  Migraines, Raynaud's, and vasospastic syndrome are disorders of autoregulation of the circulation in a particular area of the body.  When an organ such as the eye is more active, its metabolism increases.  The organ needs more oxygen and nutrients. The vessels going to the eye should expand and deliver more blood.  If they don't, that is a disorder of autoregulation.  Many patients with NTG are suspected of having this disorder of autoregulation. 

P:  Why are males more subject to congenital and infantile glaucoma?

Dr. Rick Wilson:  It would seem to be genetic, but we haven't found all the genes yet.

Moderator:  Was gender taken into account when the normative databases that visual field machines use to determine normal vision at a particular age were developed?

Dr. Rick Wilson:  I believe it was, but I am not sure.

P:  Are males or females more likely to get primary open-angle glaucoma (POAG)?

Dr. Rick Wilson:  I don't believe there is much of a gender bias in POAG.  More women than men have POAG,  but that is because women live longer than men.  The prevalence of glaucoma is directly related to age.

P:  Is either gender more prone to being a steroid responder (someone in whom steroids cause a significant rise in IOP)?

Dr. Rick Wilson:  It used to be thought that only 5% of the population would have a marked rise in IOP, but the original study with dexamethosone in St. Louis at Barnes (Barnes-Jewish Hospital,  St. Louis, Missouri) lasted only six weeks.  More recent data show that the real prevalence of steroid responders in the population is over 50%, if steroids are used for six months or more.  Since steroid response seems to be related to POAG, there is not a gender preference, that I know of.

Moderator:  Is there a gender difference in central corneal thickness?

Dr. Rick Wilson:  I don't think there is a difference.

P:  Wouldn't optic nerve damage from spasm of blood vessels be considered some form of ischemic optic neuropathy (stroke of the optic nerve) rather than glaucoma?

Dr. Rick Wilson:  Ischemic optic neuropathy is usually an acute effect, whereas the additional stress with decreased circulation to the optic nerve takes its toll over time.

P:  I understand the risk factors from glaucoma are not necessarily identical to the risk factors for progression.  Will you discuss this in relation to gender, please?

Dr. Rick Wilson:  That's a tough question to summarize for a lay audience.  The main risk factors of developing glaucoma are IOP level, vertical size of the disc cup, family history, race (African-American and Hispanic), and age.  Low systemic blood pressure is a definite risk factor.  Thin corneas are a risk factor.  Hypothyroidism has been debated, but a recent paper declared it a risk factor.  Diabetes seems to be a mild risk factor, as does myopia, but there still is debate about the last two.  Many of these risk factors are also prominent risk factors for progression -- especially thin corneas, low blood pressure, and higher IOPs.

P:  How about gender?

Dr. Rick Wilson:  Gender is only a weak risk factor for normal-tension glaucoma, and angle closure for females, and pigmentary glaucoma for males.  Males are also more subject to congenital and infantile glaucoma.  Usually only women get the iridocornealendothelial (ICE) syndrome.

P:  Do you note differences between the way men and women respond to glaucoma and its effect on their lives?

Dr. Rick Wilson:  Young men, as in other areas, are more likely, on average, to disregard the danger of glaucoma and resist treatment.

P:  Is there any connection between production of testosterone and glaucoma?  That would certainly correlate with the age factor.

Dr. Rick Wilson:  Good question, but I have not heard of a connection.

Moderator:  Thank you, Dr. Wilson.

Dr. Rick Wilson:  This will be the last chat until January 2005, so let me wish everyone a great holiday and a healthy and satisfying new year.

End of highlights for December 15, 2004.

On January 5, the glaucoma chat support group discussed "The Informed Patient" in the Chat room. Click here for highlights of that meeting.

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