Feasibility of iFS™ for Intrastromal Arcuate Keratotomy (ISAK) Procedures

Inclusion Criteria

• Male or female, of any race, and at least 21 years of age at the time of the pre-operative examination and signing the consent form
• Refractive error, no limitation on spherical refractive myopia or hyperopia and refractive astigmatism of 0.75 to 7.00 diopters (D) in the operative eye
• Best Spectacle Corrected Distance Visual Acuity (BSCVA)
• Group 1: Natural astigmatism, no cataract: BSCVA of 20/25 or better in both eyes
• Group 1: Pre cataract surgery, no BSCVA criteria in the operative eye
• Group 2: Post cataract surgery, BSCVA of 20/25 or better in both eyes
• Uncorrected Visual Acuity (UCVA) of 20/40 or worse in the operative eye
• Demonstration of agreement in the operative eye: Corneal astigmatism (as determined by keratometry) must be in agreement with refractive astigmatism (as determined by manifest refractions) as follows: Within ≤ 0.75 D in magnitude and within 15° axis when cylinder ≤ 1.5 D or 10° axis when cylinder > 1.5 D.
• Preoperative central and peripheral (in planned treatment area) pachymetry of ≥ 500 um in the operative eye
• Keratometry must be between 38.0 (flat) and 48.0 D (steep) in the operative eye
• Corneal power (diopters) difference at the 3mm point from topographic center shall be ≤ 1D at the steepest meridian, by topography measurements in the operative eye
• Intraocular pressure (IOP) of 12 to 21 mm Hg in the operative eye with no glaucomatous retinal changes
• Stable refractive error in the operative eye, based on an exam (or prescription) at least 6 months prior to the pre-operative examination, and as compared to the pre-operative manifest refraction, must be ≤ 0.75 D (sphere and cylinder) and axis within 15 degrees for eyes with cylinder > 0.5D.
• Subjects who have worn a contact lens in the operative eye within the past 30 days must remove the soft lens at least 2 weeks prior and a rigid or toric lens at least 3 weeks prior to baseline measurements. In addition, rigid or toric lens wearers must demonstrate stability in topography, keratometry and refraction before proceeding with surgery. Refractive stability is defined as a change of not more than 0.50 D in manifest sphere, cylinder, or keratometry (either axis) as compared to the unadjusted preoperative refraction in two visits at least one week apart.
• Willing and capable of returning for follow-up examinations for the duration of the study
• Subject must sign and be given a copy of the written Informed Consent Form

Exclusion Criteria

• Abnormal topography, including evidence of keratoconus or pellucid marginal degeneration, in either eye
• Irregular astigmatism in the operative eye
• Evidence of clinically significant corneal opacity/scar in the operative eye within an 8 mm diameter zone of the visual axis
• Women who are pregnant, breast-feeding, or intend to become pregnant over the course of the study, as determined by verbal inquiry
• Concurrent use of topical or systemic medications that may impair healing, including but not limited to: antimetabolites, isotretinoin (Accutane®) within 6 months of treatment, and amiodarone hydrochloride (Cordarone®) within 12 months of treatment
• History of any of the following medical conditions, or any other condition that could affect wound healing: collagen vascular disease, autoimmune disease, immunodeficiency diseases, ocular herpes zoster or herpes simplex, endocrine disorders (including, but not limited to unstable thyroid disorders and diabetes), lupus, and rheumatoid arthritis
• History of active ophthalmic disease or other non-refractive abnormality (including, but not limited to, corneal dystrophy, symptomatic blepharitis, recurrent corneal erosion, dry eye syndrome, neovascularization > 1mm from limbus), retinal detachment/repair, at risk for developing strabismus, or with evidence of glaucoma or propensity for narrow angle glaucoma NOTE: Subjects with open angle glaucoma, regardless of medication regimen or control, or an IOP gr