April 2010

 

OPHTHALMOLOGY NEWS

 

Teen eyes still in flux


by Maxine Lipner Senior EyeWorld Contributing Editor 

 

 

Eye growth continues in the second decade

When examining teen patients, practitioners should keep in mind that eye growth can continue during these years Source: National Eye Institute

For those considering fitting teenage patients with multifocal lenses, it is important to keep in mind that axial length continues to grow in the second decade of life, according to M. Edward Wilson, M.D., Jenkins professor, chairman of the Department of Ophthalmology, and director, Storm Eye Institute, Medical University of South Carolina, Charleston. In a recent article published in the December 2009 issue of Transactions of the American Ophthalmological Society, investigators led by Dr. Wilson reported on axial length growth in teenagers and the implications of this in multifocal lens use.

“The use of multifocal lenses is of interest in all populations, and when something becomes popular in adults there’s a natural tendency to see if it’s applicable in kids as well,” Dr. Wilson said. “If you look at it on the surface, these lenses might be even more applicable in kids because in the adult population when people have cataracts they’re already of an age where they’re wearing bifocals. In a child we take away accommodation.” After the surgery the child is introduced to bifocals for the first time.

Outmoded thinking

Some practitioners have looked to multifocal lenses to help ease this tradeoff and potentially allow less reliance on spectacles. The thinking is that by the second decade of life, the size of the eye is pretty much set. “In my communications with cataract surgeons I have heard that they believe there is little if any eye growth in the second decade of life,” Dr. Wilson said. “I have heard for years that eye growth is early; there is a lot of growth when kids are young and then it slows down or stops. Because of that, once kids are old enough, maybe around age 10, it’s probably OK to talk to them about getting a multifocal lens so they won’t have to wear glasses.”

However, in Dr. Wilson’s experience he has seen many kids continuing to change their need for glasses after lens implantation, even into their early 20s. “We do see our own teenage children or teenage patients getting more nearsighted,” he said. “Even college kids’ glasses are still changing.”

Variable growth

To determine if the eye continues to grow in teenagers, Dr. Wilson looked at 98 of his own cataract patients who he routinely monitors for eye growth. “I pulled out of my database all of the second decade-aged children who had had two or more axial length measurements over time,” he said. “Then I took those 98 children and plotted all of them together to get an idea of how much growth there is in the second decade of life.”

Investigators took the data and combined it to make a theoretical patient. “If you take every data point that we had, then the change from age 10 to age 20 was about 1.4 mm,” Dr. Wilson said. “If we calculated an intraocular lens power difference, the power that we would need at age 10 versus the power that we would need at age 20 to leave that child with emmetropia was a 4 D change. That’s huge.” However, when Dr. Wilson looked specifically at individual patients, the data was not as clear cut. For some patients he found that there was a lot of eye growth while for others it was minimal. “There’s a lot of variability,” he said.

Such variable eye growth may put a hitch in multifocal lens use since this tends to work best in emmetropic eyes. “Multifocal technology works well if the patient is emmetropic and even works pretty well if the patient is a tiny bit on the farsighted side,” Dr. Wilson said. “But it doesn’t work well when the eye becomes myopic because then you have multiple images, none of which fall on the retina.”

Ironically, those who receive a monofocal lens may be happier. “I have seen anecdotally that a child who becomes a low myope with a monofocal implant is happy and doesn’t tend to wear glasses very often,” Dr. Wilson said. “But when a multifocal implant teenager becomes myopic, anecdotally I’ve noted that he or she is more spectacle dependent than the monofocal patients.”

Dr. Wilson hopes that the study will bring to light an awareness of the issue. “The whole point of the paper is to urge surgeons to be cautious,” he said. “This will cause some surgeons not to offer multifocal lenses until age 20 or beyond; others may offer these but change their informed consent.” He foresees some practitioners talking to their teen patients less about spectacle independence with multifocal lenses and more about reducing the need for bifocals following the procedure.

“You can certainly say up front, ‘Your eyes may be complete in their growth but if they’re not, don’t be too disappointed if you’re wearing glasses again,’” Dr. Wilson said. “Then you can tell them, ‘At age 20 we can take care of that nearsightedness with the laser or with an IOL exchange if they grow too much.’ That’s a more realistic informed consent.”

Editors’ note: Dr. Wilson has financial interests with Alcon (Fort Worth, Texas) and Bausch & Lomb (Rochester, N.Y.).

Contact information

Wilson: 843-792-7622, wilsonme@musc.edu

Teen eyes still in flux Teen eyes still in flux
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