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Previous refractive surgery can make IOL power calculation difficult
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SAN FRANCISCO — IOL power accuracy “is not always possible” in cataract surgery candidates who have had previous refractive surgery, according to an experienced refractive surgeon.
Warren E. Hill, MD, said that there are many “potential pitfalls that make accurate IOL power calculations difficult” in these patients.
Here at Cornea Day, jointly sponsored by the Cornea Society and the American Society of Cataract and Refractive Surgery, Dr. Hill said that keratometry will typically “overestimate the central power of the cornea” following all forms of myopic keratorefractive surgery.
He explained that effective lens position, where the lens is located in relation to the cornea, is difficult to determine in patients who have had keratorefractive surgery, such as radial keratotomy, photorefractive keratectomy and LASIK.
“Current IOL formulas don’t know what do with these eyes,” Dr. Hill said.
Dr. Hill said that in patients who have had RK, calculation formulas “often show variable amounts of transient hyperopia immediately following cataract surgery.”
He added that IOL power calculations should be targeted for between –0.75 D and –1 D.
“The refractive goal is generally to have the operative eye mildly myopic, so that 5 to 10 years later the refractive error does not drift into hyperopia,” he said.