That puff of air in my eye at the optometrist's office still disturbs me, but I think I'm getting better about keeping my eye open long enough for a good reading of my intraocular pressure. It's part of the screening for glaucoma, and I'm impressed with the technology. The older method involves pressing a force meter on the surface of the anesthetized cornea, in the technique known as applanation tonometry and introduced in 1954. Passing the test does not guarantee that you're free of glaucoma; the doctor still has to examine the retina because some forms of glaucoma damage the optic nerve without elevation of the fluid pressure in the eye. But if you fail the air puff test, this is a strong sign that you need treatment.
Eye drops provide sufficient treatment for many cases. There are several types, used to reduce the production of aqueous humor or increase its outflow. If these are not successful, surgical options may be appropriate.
A procedure called trabeculectomy is called the “gold standard” for glaucoma surgery. It is the most effective at lowering intraocular pressure, and is relatively inexpensive. However, it has relatively high rates of complications. Up to six percent of eyes undergoing this surgery may have severe loss of central vision. For this reason, other techniques have been developed.
The Trabectome surgical device was approved by the U.S. Food and Drug Administration in 2004 for glaucoma treatment. Canaloplasty is another advanced surgical treatment. Both of these require expensive equipment, and are not available everywhere. A recent article in the medical literature reported that these are reasonable options for some patients, based on published data. Other techniques include iStent and gold suprachoroidal shunt, but there are limited data available on how well they work.
There are currently 116 studies on glaucoma surgery listed at http://clinicaltrials.gov. Glaucoma can affect children, but it is mostly a disease of older adults since the prevalence rises with age. Thus, as the population ages, eye surgery research will become more and more important.
Risk factors for glaucoma include:
1. Near-sightedness
2. Family history
3. Thin cornea
4. Other eye disease
5. Elevated or fluctuating intraocular pressure. The risk of glaucoma rises by 12 percent for each 1 mm Hg rise in eye pressure.
References:
Dietlein TS et al, “The Medical and Surgical Treatment of Glaucoma”, Dtsch Arztebl Int 2009; 106(3): 597-605.
Mosaed S et al, “Comparative Outcomes between Newer and Older Surgeries for Glaucoma”, Trans Am ophthalmol Soc. 2009; 107: 127-135.
Linda Fugate is a scientist and writer in Austin, Texas. She has a Ph.D. in Physics and an M.S. in Macromolecular Science and Engineering. Her background includes academic and industrial research in materials science. She currently writes song lyrics and health articles.