Technique Makes LASIK Possible for Estimated 10-12 Million Americans with High Degrees of Nearsightedness and/or Thin Corneas

A study published in the Journal Clinical & Surgical Ophthalmology reports that LASIK performed with a "thin flap" 130-micron microkeratome head is safe and effective for patients with high degrees of nearsightedness (myopia) and/or thin corneas. The journal is the official publication of the Canadian Society of Cataract and Refractive Surgery.

Previously considered poor candidates for LASIK surgery, an estimated 10 to 12 million Americans suffer from high degrees of nearsightedness (typically more than -6 diopters) and/or thin corneas (typically less than 550 microns).

"The results of this study demonstrate that surgeons can consistently perform safe and effective LASIK on patients who until now have been forced to pursue other vision correction options," said study author Paul Dougherty, M.D., medical director of Dougherty Laser Vision Institute (Los Angeles and Camarillo, Calif.) and a clinical instructor at UCLA's Jules Stein Eye Institute. ”Thin flap' LASIK using a 130 micron head can treat a broad range of patients with high degrees of nearsightedness and/or thin corneas."

The published study, titled “Thin Flap LASIK” (Clinical & Surgical Ophthalmology 1/21:8, 2003), compared results from 155 eyes of 80 patients in the 130-micron group to 279 eyes of 148 in the 160-micron group. The results for both groups were found to be similar in terms of vision improvement and flap complications. No flap complications were noted in the "thin flap" group. The study site was Dougherty Laser Vision Institute. Results were achieved using the BD K-3000 Microkeratome manufactured by BD Ophthalmic Systems (Franklin Lakes, New Jersey).

While surgery performed with a 130-micron microkeratome is especially advantageous for the roughly 10 percent of patients with high degrees of nearsightedness and/or thin corneas, it also holds benefits for many typical LASIK patients by preserving more eye tissue after the laser treatment to ensure long-term stability of the results. Dr. Dougherty currently treats up to 70 percent of his LASIK patients using the thin flap approach.

During LASIK surgery, a thin flap of corneal tissue is cut and peeled back to allow a laser to reshape the cornea underneath. The cutting is performed using a device called a microkeratome that creates a flap typically 160 to 180-microns thick -- a measure equal to the thickness of one or two human hairs. While this approach works well for the majority of patients, it is often ill suited for those with high degrees of nearsightedness and/or thin corneas, because their correction requires more tissue to be removed with the laser and/or they have less initial cornea tissue available. With "thin flap" LASIK,
surgeons peel back a thinner 130-micron flap, thus retaining more of the patient's corneal tissue with which to work.

Despite the very encouraging study results, Dr. Dougherty warns that the "thin flap" technique has its limits. "Even with the success of the 130-micron microkeratome head, I strongly advise against performing LASIK on any patient whose cornea is thinner than
500-microns," he said.