CONTACT: JENNIFER CRONIN
2130 Medical Laboratories
Iowa City IA 52242
(319) 335-6660; fax (319) 335-9917
UI study shows correlation between amoeba levels, onset of eye problems
IOWA CITY, Iowa -- There are pesky, microscopic organisms lurking in
lakes and ponds, just waiting for unsuspecting individuals on which to
latch. As a result, it should come as no surprise that a University of
Iowa study showed the higher the concentration of amoebas in surface water,
the more likely one might be to develop an eye infection.
However, the correlation does not necessarily mean that the individuals
will catch the infection by coming into contact with contaminated water.
Only 17 percent of the UI study patients noted exposure to such water.
The precise link between the amoeba levels in surface water and the onset
of amoeba infections remains obscure.
"We have a lot of questions about this that need to be answered,"
said Dr. William Mathers, UI professor of ophthalmology and principal
investigator of the study. "But these findings strengthen our understanding
of the relationship between our environment and amoeba-like disease."
From January 1993 through December 1996, UI researchers diagnosed 137
cases of amoeba-like keratitis, or inflammation of the cornea, in Iowa.
Over the four years, the researchers found the onset of infection symptoms
varied significantly from month to month. The infections peaked in June
with an average of 4.25 cases and November when the average reached five
cases. These times closely correspond to the periods each year when amoeba
levels in surface water are highest. The lowest infection rate occurred
in February with a reported average of 0.75 cases.
Mathers said researchers do not know why amoebas on the eye result in
frequent infections. Amoebas are found elsewhere on the human body and
do not cause problems.
Of the 137 diagnosed cases, 52 patients (39 percent) reported contact
lens use. Mathers speculated that the large number might be due to the
fact that contact lens wearers touch their eyes more frequently and, thus,
are more likely to contaminate their eyes. Mathers estimates that one in
10,000 contact lens wearers has an amoeba-like infection each year.
Most of the eye infections are minor -- not blinding, but bothersome.
Patients complain of discomfort, irritation or blurred vision. Very few
individuals end up with vision loss or scarring, but it is possible if
left untreated, Mathers said. Treatment usually involves the use of special
eye drops that patients take for at least several months.
Mathers' research into amoeba-like eye problems is included in the October
issue of the British Journal of Ophthalmology. He and other UI researchers
plan to continue to investigate amoebas and how they affect the eye.
"This research is important," Mathers said. "It is a
significant public health issue. Amoeba-like infections are treatable problems,
and better detection will result in improved eye health."
Until recently, researchers did not know the extent to which amoebas
infected the eye. Most had attributed patients' complaints to bacterial
infections. Prior to 1993 UI ophthalmologists diagnosed only about two
cases of amoeba-caused infections annually. It was not because they were
not occurring, but because there was no real way to detect them. For the
past five years, UI researchers have used a confocal microscope to identify
amoebas. As a result, researchers have been able to diagnose many more
types of previously unknown amoeba infections. Now UI researchers confirm
50 amoeba problems each year, placing the pathogen as one of the most common
causes for eye infections.
Mathers became interested in the water amoeba-eye infection correlation
following the great Midwestern floods of 1993. It was then that he began
noticing problems in patients from counties with the highest levels of
ground water contamination. Through those patients and the confocal microscope,
UI ophthalmologists learned what to look for in amoeba eye infections.
Individuals can take precautionary measures to guard against infection.
Mathers recommends that contact lens users wear and clean contacts as directed
and that everyone practice good eye care.