Many patients who get lens implant surgery to correct vision problems may develop cataracts or elevated pressure around the eyes within 10 years after the procedures, a Swiss study suggests.
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.
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."
