Researchers focused on a procedure known as posterior phakic lens
implantation, which involves cutting in front of the eye outside the
cornea to insert a lens that floats behind the iris in front of the
eye's natural lens. The surgery can correct vision problems such as
myopia, or nearsightedness, and astigmatism, an imperfection in the
curvature of the cornea.
To assess long-term complications from the implants, researchers
followed 78 patients who had operations on a total of 133 eyes -
some people only got the operation in one eye.
After five years, two of every five patients had lens opacity, or
cataracts, and by 10 years 55 percent of them did, the study found.
After 10 years, 12 eyes developed what's known as ocular
hypertension – elevated pressure in the eye that can eventually lead
to glaucoma – and required eye drops to treat the condition, the
study also found.
"This was a surprise because we didn't have any information about
this point," said senior study author Dr. Francois Majo of the
University of Lausanne in Switzerland.
"Intra-ocular pressure has to be followed because the risk of
glaucoma in myopic eyes is a delicate end point," Majo added by
email.
Understanding the long-term effects of this surgery is important
because young people may get the procedures to improve their
eyesight and then have the lenses in their eyes for several decades.
The study included 34 men and 44 women who were 39 years old on
average at the start of the research. They all received surgery at
some point between 1998 and 2004 at Jules-Gonin Eye Hospital in
Lausanne.
After five years, a surgery known as phacoemulsification had been
done to treat cataracts in five eyes, and within 10 years after
surgery this procedure had been done on 18 eyes.
Eye pressure didn't change much in the years right after surgery,
but by 10 years 12 eyes had eye pressure increase enough to require
topical medication.
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One limitation of the study is that the implanted lenses have
changed a great deal since the late 1990s, so some patients who got
operations early in the study period may not have benefited from
improvements in technology in the intervening years.
Even so, the findings suggest that doctors should discuss cataracts
and eye pressure increases as potential long-term side effects, the
authors conclude in JAMA Ophthalmology.
Young patients in particular should consider these side effects
carefully because the complications may become more likely over
time, Dr. Stephen McLeod of the University of California, San
Francisco wrote in an editorial.
"The risk of cataract is not surprising: the space available inside
the eye if we don't remove the existing natural lens is very
limited, and so there is always the chance that this implant might
affect the health of the existing lens through trauma or through
compromise of nutrition," McLeod said by email.
"However, the ocular hypertension is surprising, since it isn't
obvious that this implant would affect fluid outflow."
SOURCE: http://bit.ly/24GCNUT JAMA Ophthalmology, online March 3,
2016.
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