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What is a Glaucoma Suspect?

If you've been told you are a glaucoma suspect, you're in good company — there are several million glaucoma suspects in the USA.

Three million persons have both structural injury to the optic nerve head inside the eye and functional damage measured in their visual field test, and that qualifies them as having glaucoma.

Glaucoma suspects, on the other hand, have some risk of the disease, but no proven damage (yet). The majority of suspects will never become damaged. But, once vision is lost, we can’t restore it, so the key is to decide whom to treat among suspects.

There are 2 types of glaucoma, open-angle and angle-closure, and suspects for each are different. Open-angle suspects have one or more eye findings that suggest a higher risk of having or developing glaucoma than the average person. First, their measured eye pressure (IOP) can be higher than the average range.

Glaucoma damage happens when the IOP is too high for the continued health of the optic nerve. Each person has their own level at which damage can occur. While anyone is in danger at very high IOP, half of those with open-angle glaucoma are hurt by IOP within the average range. Previously, this was called “normal-tension” glaucoma, but we now know it’s quite common and simply means that a person can get glaucoma without high IOP.

Suspects with higher than average IOP, but no damage, are called ocular hypertensive. In some eyes, the real IOP is lower than what’s measured because the cornea (the clear front of the eye) is thicker than average.

Risk Calculation

A large clinical trial study found that ocular hypertensives develop true glaucoma at a rate of about 2% per year. The rate was only half as fast if eye drops to lower IOP were taken. So the risk is small, but it’s cut in half by IOP-lowering treatment. How do you and the doctor decide then whether to treat ocular hypertension? It depends on a risk calculation that includes life expectancy, IOP level and other reasons that you can be a suspect. These include:

  • having a blood relative with glaucoma damage
  • having optic nerve or visual field findings on the border between glaucoma and normal
  • African-American ethnicity
  • being myopic (near-sighted)
  • having a thin cornea
  • having conditions called exfoliation or pigment dispersion that increase the risk of developing high IOP

Neither the suspect who chooses treatment nor the one who stays off treatment is making a bad choice. It should be a shared decision between doctor and patient, depending on actual risk and individual risk tolerance.

If you are someone who accepts risk easily, no immediate treatment is fine if risk is average. But, some people would lose sleep over possible damage, and for them trying treatment is a good option. Others are more worried by possible side effects of treatment—for these, the low level of worsening in untreated eyes is not that scary and no treatment is the right choice. Life expectancy is part of the decision—if you have significant risk and are relatively young, your chance of becoming damaged during life is greater, and treatment makes more sense. Treatment or not, suspects need detailed monitoring of disc and field every year.

If glaucoma is caught when the signs are very early and treatment begun at that time, the risk of developing serious visual loss is quite small.


Article by Harry A. Quigley, MD — the A. Edward Maumenee Professor and Director of the Glaucoma Center of Excellence at the Wilmer Eye Institute at Johns Hopkins, in Baltimore, Maryland. Dr. Quigley has participated in glaucoma studies worldwide and published over 350 peer-reviewed articles. Originally published in September 2013 with the title "Round Up the Usual Suspects!"

Last reviewed on June 11, 2021

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