Study objective is to evaluate the outcomes of placing gamma-irradiated corneal tissue (VisionGraft, CorneaGen, USA) within the cornea of patients with keratoconus, a procedure called Corneal Tissue Addition for Keratoconus (CTAK).

Using E gamma irradiated sterilized preserved corneal tissue, shaped corneal tissue inlays are placed in a keratoconic cornea. Preserved corneal tissue is currently available commercially from CorneaGen (VisionGraft,1200 6th Ave., STe.300, Seattle, WA 98101). Such tissue is currently used in a number of eye surgical procedures. It is considered suitable for corneal surgical procedures that do not require viable corneal endothelium, as is the case for a tissue enhancement procedure in keratoconus. The goal of the current protocol to evaluate the outcomes of placing gamma-irradiated preserved tissue within the keratoconic cornea in order to enhance corneal thickness, stability, and optical conformation.

Inclusion Criteria:

• At least 18 years of age, male or female, of any race

• Provide written consent and sign a HIPAA form

• Willingness and ability to follow all instructions and comply with schedule for follow-up visits

• For females: must not be pregnant

• Having topographic evidence of keratoconus which is graded as moderate or severe keratoconus defined as the following:

  • Moderate Keratoconus: Axial topography consistent with keratoconus, Maximum keratometry on Pentacam greater than or equal to 51.01 D
  • Severe Keratoconus: Axial topography consistent with keratoconus with marked areas of steepening, Maximum keratometry on Pentacam greater than or equal to 56.01 D

• Presence of central or inferior steepening on the Pentacam map

• BSCVA less than or equal to 20/25

• Contact lens wearers only: remove contact lenses one week prior to the screening refraction

Exclusion Criteria:

• Contraindications, sensitivity or known allergy to the use of the test article(s) or their components

• If female, be pregnant

• Eyes classified as either normal, atypical normal, keratoconus suspect or mild keratoconus on the severity grading scheme

• Previous ocular condition (other than refractive error) in the eye to be treated that may predispose the eye for future complications. For example:

  a) History of corneal disease (e.g., herpes simplex, herpes zoster keratitis, corneal melt, corneal dystrophy, etc.)

• A history of delayed epithelial healing in the eye to be treated

• Have used an investigational drug or device within 30 days of the study or be concurrently enrolled in another investigational drug or device study within 30 days of the study