Please select the eligibility criteria that correspond to the clinical trial below.
Title: Phase III Study of Corneal Collagen Cross-linking Using Two Different Techniques.
Brief Summary: The corneal collagen cross-linking treatment has been used with increasing success to treat corneal dystrophies such as "keratoconus." Recent advances have allowed different techniques for performing this cross-linking treatment. This study investigates the effects of corneal cross-linking using different surgical techniques.


Options:
A: Inclusion Criteria:

1. 10 years of age or older
2. Having documented ectasia on topography or tomography after previous refractive surgery OR progressive keratoconus defined as one or more of the following changes over a period of 36 months or less before randomization:

   1. An increase of ≥ 1.00 D in the steepest keratometry value (or sim K)
   2. An increase of ≥ 1.00 D in regular astigmatism evaluated by subjective manifest refraction
   3. A myopic shift (decrease in the spherical equivalent) of ≥ 0.50 D on subjective manifest refraction
   4. Documented decrease in visual acuity associated with irregular astigmatism and topographic features of ectasia.
3. Subjects with keratoconus diagnosis only:

   a. Axial topography consistent with keratoconus b. Presence of central or inferior steepening on the Pentacam map. c. Presence of one or more slit lamp findings associated with keratoconus, such as: i. Fleischer ring ii. Vogt striae iii. Corneal thinning iv. Corneal scarring
4. Contact Lens Wearers Only: Removal of contact lenses for the required period of time prior to the screening refraction:

   Contact Lens Type Minimum Discontinuation Time Soft 3 Days Soft Extended Wear 1 Week Soft Toric 2 Weeks Rigid gas permeable 2 Weeks
5. Signed written informed consent

Exclusion Criteria:

* 1. Any keratoconus patient over 21 years of age without evidence of progression of his corneal deformity.

  2. Patients with excessively thin corneas. 3. Previous ocular condition in the eyes 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, recurrent erosion syndrome, corneal melt, corneal dystrophy, etc.) b. Clinically significant corneal scarring in the proposed treatment zone 4. A history of chemical injury or delayed epithelial healing in the eye(s) to be treated.

  5. A known sensitivity to treatment medications. 6. Patients with a current condition that, in the treating physician's opinion, would interfere with or prolong epithelial healing.

  7. Pregnancy (including plan to become pregnant) or lactation during the course of the study
B: Inclusion Criteria:

* Documented keratoconus progression in both eyes during the last 12 months before the treatment - decrease in best spectacle-corrected visual acuity (BSCVA) and/or increase in cornea curvature or asymmetry
* Corneal thickness ≥400μm at the thinnest point
* Age range from 18 to 40
* Amsler-Krumeich classification graded stage I to III

Exclusion Criteria:

* Corneal thickness \<400μm at the thinnest point
* History of viral keratitis
* Severe dry eye
* Concurrent corneal infections
* Previous ocular surgery
* Hard contact lens wear for ≤4 weeks before baseline examination
C: Inclusion Criteria:

* Age 10-70, willing to participate, diagnosis of corneal ectasia disorder

Exclusion Criteria:

* Unwilling or unable to participate in trial
D: Inclusion Criteria:

* Age between 16-40 years
* axial topography consistent with keratoconus
* minimum corneal thickness more than 400 µm and a progression of keratoconus in past 12 months

Exclusion Criteria:

* history of ocular herpes or non-healing corneal ulcers
* subjects with current ocular infection
* severe preoperative corneal haze or scar
* severe ocular surface disease
* autoimmune diseases
* pregnant women

Answer: C