Who Gets Glaucoma?

Glaucoma is the second most common cause of blindness in the USA, and is being diagnosed more often, now that visits to ophthalmologists have increased.  In glaucoma, slowing or blockage of the flow of fluid in the front chamber of the eye causes pressure to build up in the eye. This raised intraocular pressure (IOP) causes damage to the optic nerve.

The exact cause of the most common type, open-angle glaucoma, is unknown, but a frequent first step is accumulation of exfoliated material from damaged cells lining the front chamber – so-called exfoliation glaucoma.  Open-angle glaucoma tends to run in families; and people of African descent and Europeans are at particularly high risk.  More is now known about the likely risk of contracting glaucoma in the USA, thanks to a study from Boston ophthalmologists published in the journal Ophthalmology. 

The researchers used data from 78,000 women in the Nurses’ Health Study and 41,000 men in the Health Professionals Follow-up Study.  They were over 40 at baseline, and free of glaucoma at entry.  Place of residence at age 15 and throughout the study was recorded.  The duration of follow-up was at least 20 years.

The risk of developing exfoliative glaucoma was strongly age-related: subjects 75 or older had a 44-times greater risk than those aged 40 to 55.  A positive family history of glaucoma was associated with a more than doubling of risk.  And men were 68% less likely to develop glaucoma than women.  However, no increased risk was found to be associated with ancestry, particularly Scandinavian ancestry.     

Compared with those living in the northern tier of the USA, lifetime residence in the middle tier was associated with a 47% reduced incidence, and living in the southern tier with a 75% reduction in risk. 

This large study has confirmed a lot of what we knew about the risk of developing the most common type of glaucoma, and added a new possible factor - place of residence.  Living in the south was linked with a significantly reduced risk, with a lesser (but still significant) benefit for dwellers in the middle tier of the USA.  The investigators postulate that lower ambient temperatures in the north interact with increased solar exposure to increase the risk of exfoliative glaucoma.     

Whatever your apparent risk of glaucoma, make sure you have regular eye exams by a recognized specialist – it’s well worth it.