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  • Cornea/External Disease

    Review of: Corneal tissue addition keratoplasty: New intrastromal inlay procedure for keratoconus using femtosecond laser-shaped preserved corneal tissue

    Greenstein S, Yu A, Gelles J, et al. Journal of Cataract & Refractive Surgery, July 2023

    Corneal Tissue Addition Keratoplasty (CTAK) is a femtosecond laser–assisted intrastromal inlay treatment option for managing corneal ectasia. This prospective clinical trial saw favorable visual acuity and corneal topography outcomes after CTAK, supporting the recent commercial launch of CTAK and the potential for this procedure to be an alternative treatment option for patients with keratoconus.

    Study Design

    This was a prospective, single-center, open-label clinical trial investigating the outcomes of CTAK in 21 eyes (18 patients) with keratoconus. Using femtosecond laser, an inlay of preserved corneal tissue was cut to patient-customized size and inserted into a laser-created channel in the host cornea. Primary outcomes included postoperative uncorrected and corrected distance visual acuity (UDVA, CDVA), topographic mean keratometry (Kmean), and maximum keratometry (Kmax).


    Six months after CTAK, mean UDVA improved from 1.21 logMAR to 0.61 logMAR, with 20 eyes (95.2%) gaining >2 lines of UDVA and 10 eyes (47.6%) gaining >6 lines; no eyes experienced a UDVA decline. Mean CDVA also improved from 0.62 logMAR to 0.34 logMAR. Kmean flattened by −8.44 D, while average Kmax flattened by −6.91 D.


    The main limitation of this study is the small sample size, though it was also limited by a lack of observer masking.

    Clinical Significance

    Traditionally, patients with corneal ectasia were offered vision correction with specialized contact lenses, artificial instrastromal ring segments, or penetrating or lamellar keratoplasty. The development of corneal allogenic intrastromal ring segments (CAIRS) by Dr. Soosan Jacob1 offered an alternative to artificial inlays, and the current study introduces the use of femtosecond laser–cut preserved corneal tissue, CTAK, as a further option. This study’s positive outcomes support the recent launch of CTAK for commercial use and may help facilitate wider adoption of allogenic ring segments in the United States.

    Financial Disclosures: Dr. Daniel Choi discloses financial relationships with Glaukos (Lecture Fees/Speakers Bureau) and Kala Pharmaceuticals (Consultant/Advisor).


    1 Jacob S et al. J Refract Surg. 2018;34:296–303