Here is the design of a clinical trial:

Official Title: Efficacy of Customized Corneal Cross-linking Versus Standard Corneal Cross-linking in Patients With Progressive Keratoconus

Included conditions:
- Keratoconus

Study Armgroups:
- {'label': 'Customized crosslinking', 'type': 'ACTIVE_COMPARATOR', 'description': "In the customized corneal cross-linking protocol (cCXL) a patient-specific treatment pattern, based on the patient's Pentacam images, will be used to treat the cornea. The CXL pattern exists out of 3 concentric circles and is centered on the cone. To estimate the cone location a combination of the thinnest corneal point, maximum anterior elevation and maximum posterior elevation is used. The epithelium is debrided with alcohol within the marked zone. After the application of riboflavin each circle receives a different amount of energy, which gradually decreases with increasing circle size.\n\nThe procedure is done with the Avedro Mosaic CXL device (Avedro, Inc. Waltham, Massachusetts, United States).", 'interventionNames': ['Procedure: Customized crosslinking']}
- {'label': 'Standard crosslinking', 'type': 'ACTIVE_COMPARATOR', 'description': 'In the standard corneal cross-linking protocol (sCXL) the epithelium is debrided with alcohol over a region with a diameter of 9.0 mm. After the application of riboflavin the cornea is irradiated with UVA with a fluence of 10 mW/cm2 during 9 minutes with a diameter of 9.0 mm, resulting in a total energy of 5.4 J/cm2.\n\nThe procedure is done with the Avedro Mosaic CXL device (Avedro, Inc. Waltham, Massachusetts, United States).', 'interventionNames': ['Procedure: Standard crosslinking']}

Interventions:
- {'type': 'PROCEDURE', 'name': 'Customized crosslinking', 'description': "In the customized corneal cross-linking protocol (cCXL) a patient-specific treatment pattern, based on the patient's Pentacam images, will be used to treat the cornea. The CXL pattern exists out of 3 concentric circles and is centered on the cone. To estimate the cone location a combination of the thinnest corneal point, maximum anterior elevation and maximum posterior elevation is used. The epithelium is debrided with alcohol within the marked zone. After the application of riboflavin each circle receives a different amount of energy, which gradually decreases with increasing circle size.\n\nThe procedure is done with the Avedro Mosaic CXL device (Avedro, Inc. Waltham, Massachusetts, United States).", 'armGroupLabels': ['Customized crosslinking']}
- {'type': 'PROCEDURE', 'name': 'Standard crosslinking', 'description': 'In the standard corneal cross-linking protocol (sCXL) the epithelium is debrided with alcohol over a region with a diameter of 9.0 mm. After the application of riboflavin the cornea is irradiated with UVA with a fluence of 10 mW/cm2 during 9 minutes with a diameter of 9.0 mm, resulting in a total energy of 5.4 J/cm2.\n\nThe procedure is done with the Avedro Mosaic CXL device (Avedro, Inc. Waltham, Massachusetts, United States).', 'armGroupLabels': ['Standard crosslinking']}

Primary Outcomes:
- {'measure': 'Change in maximum keratometry (Kmax)', 'description': 'Kmax is measured with Scheimpflug photography (Pentacam® HR, OCULUS Optikgeraete GmbH, Wetzlar, Germany)', 'timeFrame': '12 months postoperatively'}

Please estimate the sample size based on the assumption: 
Within-group standard deviation (SD) of 1.72 D, 90% power, one-sided significance level alpha of 0.025, and 10% loss-to-follow-up.
Sample size calculation
        For non-inferiority, we assume that the intervention group should have an average decrease in Kmax of 1.0 D, based on clinical experience and recent evidence. The non-inferiority margin is equal to -0.3 D (i.e., the mean difference between cCXL and sCXL should be greater than -0.3 to achieve statistical significance). Assuming this non-inferiority margin and a within-group standard deviation (SD) of 1.72 D, we need to include 55 patients per group to detect non-inferiority with 90% power and a one-sided significance level alpha of 0.025. The sample size was calculated using an online calculator for the comparison of two means (www.powerandsamplesize.com). Accounting for 10% loss-to-follow-up, we need to include 62 patients per group, i.e., 124 patients in total.