An observational study in Keratoconus; Post-Refractive Ectasia, sponsored by Corneagen LLC. Completed at 5 sites in United States. Per ClinicalTrials.gov, last updated 2026-10-29.
Sponsored by Corneagen LLC · Observational
This retrospective, multi-center observational study evaluates clinical outcomes in patients with keratoconus or post-refractive ectasia who previously underwent Corneal Tissue Addition Keratoplasty (CTAK) as part of routine clinical care.
The primary objective is to evaluate changes in corneal curvature, measured by steep keratometry (K2), maximum keratometry (Kmax), and mean keratometry (Kmean), from preoperative baseline to six months following CTAK.
Secondary outcomes include changes in uncorrected and corrected distance visual acuity, refractive stability, documented postoperative complications, subsequent corneal transplantation, and exploratory analyses across payer categories.
The study uses existing medical records from up to eight participating clinical sites, targeting up to 100 treated eyes. No study-specific intervention, patient contact, or prospective clinical assessments will occur.
Corneal Tissue Addition Keratoplasty (CTAK) is a surgical procedure involving implantation of a customized, gamma-irradiated donor corneal tissue segment into a femtosecond laser-created intrastromal channel. The procedure is designed to reshape the cornea and improve visual function in patients with keratoconus or post-refractive ectasia.
This retrospective, multi-center observational chart review evaluates clinical outcomes in patients who previously underwent CTAK as part of routine clinical care. The study will review existing medical records from up to eight participating clinical sites, targeting up to 100 treated eyes.
The primary objective is to evaluate changes in corneal curvature, measured by steep keratometry (K2), maximum keratometry (Kmax), and mean keratometry (Kmean), from preoperative baseline to six months following CTAK.
Secondary outcomes include changes in uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA), refractive stability over time, documented postoperative complications and adverse events, and progression to corneal transplantation. Exploratory analyses will evaluate outcomes across payer categories and clinical settings.
Clinical data will be obtained from existing medical records, including corneal tomography and keratometry, visual acuity measurements where available, relevant prior ocular procedures, and documented postoperative outcomes. The primary assessment occurs at six months, with additional available observations at one, three, and twelve months.
The primary unit of analysis is the treated eye. Statistical methods will account for correlation between eyes when both eyes of an individual patient are included.
No study-specific intervention, patient contact, additional clinical visits, or prospective clinical assessments will occur. Clinical care was provided independently of this retrospective study.
The study received a Category 4 exemption determination from Sterling IRB on June 8, 2026, along with approval of a waiver of HIPAA authorization.
313 studies on the registry are indexed under Keratoconus; 56 are open to participants now.
This study's enrollment of 61 is below the median of 130 across 97 observational studies indexed under Keratoconus.
Browse Keratoconus studies →This is the only study on the registry with Corneagen LLC as lead sponsor.
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Patients with keratoconus or post-refractive ectasia who previously underwent CTAK as part of routine clinical care at participating clinical sites and have the required clinical records.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
Retrospective, multi-center observational cohort study using existing medical records of patients who previously underwent Corneal Tissue Addition Keratoplasty (CTAK) for keratoconus or post-refractive ectasia. Clinical outcomes are evaluated at baseline and available postoperative follow-up intervals, with a primary assessment at six months. No study-specific interventions or patient contact occur.
Procedure: Corneal Tissue Addition Keratoplasty (CTAK)
Corneal Tissue Addition Keratoplasty (CTAK) involves implantation of a customized, gamma-irradiated donor corneal tissue segment into a femtosecond laser-created intrastromal channel. All procedures were performed as part of routine clinical care before and independently of this retrospective study. No interventions are assigned or administered as part of the study.
Also known as: CTAK
Change in K2 (Steep Keratometry)
Change in steep corneal keratometry, measured in diopters, from preoperative baseline to six months after CTAK.
Time frame: Baseline to 6 months
Change in Maximum Keratometry (Kmax) from preoperative baseline to six months after CTAK
Maximum corneal keratometry is measured in diopters using corneal tomography.
Time frame: Baseline to 6 months
Change in Mean Keratometry (Kmean) from preoperative baseline to six months after CTAK
Mean corneal keratometry is measured in diopters using corneal tomography.
Time frame: Baseline to 6 months
Change in Uncorrected Distance Visual Acuity (UDVA) from baseline to 6 months
Measured using the site's Standard of Care practice for collecting visual acuity and recorded in Snellen notation.
Time frame: Baseline to 6 months
Change in Corrected Distance Visual Acuity (CDVA) from baseline to 6 months
Measured using the site's Standard of Care practice for collecting visual acuity and recorded in Snellen notation.
Time frame: Baseline to 6 months
Refractive Stability
Change in post-operative MRSE and astigmatism from baseline to 6-months, when available.
Time frame: Baseline through available follow-up
Number of Participants with CTAK-Related Adverse Events and Complications as Assessed by Protocol v2.0
Incidence of documented clinically significant procedure-related complications and secondary surgical interventions.
Time frame: From CTAK surgery through 6-months post-op
Progression to Corneal Transplantation
Number and Proportion of Study Eyes that Progressed to Undergoing a Corneal Transplant following CTAK.
Time frame: From CTAK surgery through 6-months post-op
Comparison of Change in Keratometry Measurements from Baseline to 6-months by Primary Payer Category
Exploratory comparison of changes in Maximum Keratometry (Kmax), Mean Keratometry (Kmean), and Steep Keratometry (K2) from baseline to the 6-month postoperative visit across payer categories.
Time frame: Baseline to 6 months
Plan to share: No — Individual participant data will not be made publicly available due to patient privacy and confidentiality considerations associated with retrospective medical record data. Aggregate study findings are expected to be published in a peer-reviewed journal.
No publications or documents are linked to this record.
From the registry record's own update history. This site started tracking changes on Sep 25, 2026; for anything earlier, see the record history on ClinicalTrials.gov ↗
This study is completed, as verified in Oct 2026. You cannot join it, but the record below documents what was studied.
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