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Screening for keratoconus can improve outcomes after refractive surgery
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NEW YORK — Effective screening for keratoconus using topography and pachymetry can help ophthalmologists predict risk factors and outcomes of refractive surgery.
Risk factors for ectasia after refractive surgery include abnormal topography, high myopia, reduced preoperative corneal thickness, reduced residual stromal bed after laser ablation and advanced age, Stephen D. Klyce, PhD, said at OSN New York 2009.
"The highest risk factor for the development of ectasia after refractive surgery is still abnormal corneal topography. Abnormal topography is something you need to be able to recognize using standardized procedures," he said.
By using axial power when screening, subtle changes arise that are consistent in keratoconus suspects. Using instantaneous scales can be confusing, Dr. Klyce said. "There's too much noise, and it's hard to differentiate what's a bad cornea from the other components in that display."
The truncated bow tie shape, shown on topography, is "one of the faces of keratoconus that you need to recognize," he said. Also, an asymmetrical "lazy eight" bow tie shape in which the radial axes are skewed is another sign of keratoconus.
For best outcomes, "evaluate thickness carefully, use a thick standard scale and axial diopters in screening, learn how to estimate the [inferior-superior] value in lieu of a screening program and learn the different features of keratoconus," Dr. Klyce said.
OSN New York 2010 will be held November 19-21, 2010 at the Sheraton New York Hotel & Towers in New York City. Learn more at OSNNY.com.