Study of the MEL 80 Excimer Laser Using LASIK in the Treatment of Mixed Astigmatism

Inclusion Criteria: * Naturally occurring mixed astigmatism when the magnitude of cylinder (up to 6.0 D) is greater than the magnitude of sphere, and the cylinder and sphere have opposite signs, at the spectacle plane; * Have a stable refraction for at least the past twelve months, as demonstrated by a change of less than or equal to 0.50 D preoperative spherical equivalent shift over twelve months prior to surgery; * Discontinue use of contact lenses at least 2 weeks for hard contacts and 3 days for soft lenses prior to the preoperative examination; * Hard contact lens wearers must have two central keratometry readings and two manifest refractions taken at least one week apart that do not differ by more than 0.50 D * Have visual acuity correctable to at least 20/40 in both eyes * Have no more than 0.75 D of latent hyperopia as determined by the difference between the preoperative manifest refractive spherical equivalent (MRSE) and cycloplegic refractive spherical equivalent (CRSE); * Be at least 18 years of age * Corneal topography should be normal; * The operative eye must be targeted for emmetropia; * Be willing and able to return for scheduled follow-up examinations for twelve months after surgery; * and provide written informed consent. Exclusion Criteria: * History of anterior segment pathology, including cataracts (in the operative eye); * Clinically significant dry eye syndrome unresolved by treatment; * Residual, recurrent, active ocular or uncontrolled eyelid dis…