Careful screening, measurement reduce ectasia incidence

Key Points

Cancún, Mexico-Risk factors for ectasia may exist, but if ophthalmologists carefully screen patients and carefully measure what they're doing, the incidence of this complication of LASIK will be reduced, said Perry S. Binder, MS, MD, here at the 27th Pan-American Congress of Ophthalmology.

He cited a paper (Amoils SP, Deist MB, Gous P, Amoils PM. Iatrogenic keratectasia after laser in situ keratomileusis for less than –4.0 to –7.0 diopters of myopia. J Cataract Refract Surg. 2000;26:967-977) that reported results of 13 eyes in 18 patients in which ectasia developed.

Three other studies

Subsequent to this publication, Dr. Binder said, three other studies have suggested that an increase in the likelihood of ectasia developing after LASIK surgery is associated with these risk factors: age less than 25 years, residual bed thickness less than 250 μm, corneal thickness less than 500 μm, high myopia, corneal curvatures greater than 47 D, enhancement surgery, and against-the-rule astigmatism.

"Everyone now is fearful: 'If I operate on a patient with these risk factors, I'm going to have a case of ectasia,' " Dr. Binder said. "But there are some perplexing issues in the literature: a case of LASIK in one eye and both eyes developing ectasia; LASIK in both eyes, with only one eye developing ectasia; LASIK in a patient with known keratoconus in both eyes, and only one eye develops ectasia; ectasia after radial keratotomy, after hyperopic automated lamellar keratoplasty, after a partial flap; ectasia able to be reversed by lowering the IOP. All of these things are telling us that something else is happening in these eyes that we don't know about, and there are many unproven theories as to why we develop ectasia."

When Dr. Binder examined cases in his own database, he found no incidences of ectasia under several different conditions: