Please select the eligibility criteria that correspond to the clinical trial below.
Title: Standard Versus Transepithelial Corneal Crosslinking for Treatment of Progressive Keratoconus
Brief Summary: The gold standard corneal crosslinking (CXL) technique involves the initial step of epithelial removal, in order to achieve a sufficient treatment effect (meaning: stabilisation of progressive keratoconus (KC). Our aim is to evaluate the effects of transepithelial CXL (TE-CXL), whereby the epithelium is left intact and the cornea is instead treated by a solution composed of 0.1% riboflavin, combined with enhancers, after which standard CXL is performed. This solution seems to facilitate riboflavin penetration into the corneal stroma through the intact epithelium. The investigators expect to achieve a similar effect of TE-CXL with the advantage of a faster healing time and less risk of infections.


Options:
A: Inclusion Criteria:

* Documented progressive KC (by Pentacam and/or corneal topography imaging).
* A clear central cornea.
* A minimal corneal thickness of ≥ 400 µm at the thinnest corneal location (Pentacam imaging).
* Minimal Snellen corrected distance visual acuity of ≥ 0.4.
* Patient age of ≥ 18 years.

For this research study, the inclusion parameters will be the same as mentioned above, with the following additional inclusion criteria:

* Documented progression of KC, as demonstrated by anterior segment imaging and/or corneal topography:

  o Defined an increase in maximal keratometry, steepest keratometry, mean keratometry or topographic cylinder value by ≥ 0.5 D over the previous 6 months and/or a decrease in thinnest pachymetry
* Documented progression of KC defined by increase in refractive cylinder of ≥ 0.5 D over the previous 6 months

Exclusion Criteria:

* Presence of corneal scars.
* History of epithelial healing problems.
* Presence of previous ocular infection (such as herpes keratitis).
* Patients who are pregnant and/or breastfeeding.
B: Inclusion Criteria:

* diagnosis of infectious keratitis

Exclusion Criteria:

* corneal ulcer that has perforated
* corneal ulcer that has produced a descemetocele
* women who are pregnant or breastfeeding
* patients who are immunocompromised or unwilling or unable to comply with a medication regimen
C: Inclusion criteria:

* Corneal ulcer that is smear positive for either bacteria or filamentous fungus
* Pinhole visual acuity worse than 20/70 in the affected eye
* Not treated already with antimicrobial medications at presentation
* Age over 18 years
* Basic understanding of the study as determined by the physician
* Commitment to return for follow up visits

Exclusion criteria:

* Evidence of concomitant infection on exam or gram stain (i.e. herpes, both bacteria and acanthamoeba on gram stain)
* Impending or frank perforation at recruitment
* Involvement of sclera at presentation
* Non-infectious or autoimmune keratitis
* History of corneal transplantation or recent intraocular surgery
* No light perception in the affected eye
* Pinhole visual acuity worse than 20/200 in the unaffected eye
* Participants who are decisionally and/or cognitively impaired
D: Inclusion Criteria:

* Willing and able to provide written informed consent
* Willing and able to comply with study assessments for the full duration of the study
* Age ≥ 18 years
* Candidate for a Boston Keratoprosthesis / Cornea transplant
* In generally good stable overall health
* Patients with an eye at risk for a cornea sterile ulcer which includes:

  * Autoimmune diseases (mucus membrane pemphigoid, Stevens-Johnson syndrome, systemic lupus erythematosis, rheumatoid arthritis, or other autoimmune diseases); OR
  * History of previous sterile cornea ulceration requiring a cornea transplant

Exclusion Criteria:

* Age \< 18 years
* Inability to provide written informed consent and comply with study assessments for the full duration of the study
* No or minimal tear production with evidence of keratinization of the bulbar conjunctiva
* Corneal or ocular surface infection within 30 days prior to study entry
* Ocular or periocular malignancy
* Inability to wear a contact lens due to lid abnormalities or shortened fornix
* Signs of current infection, including fever and current treatment with antibiotics
* Pregnancy (positive pregnancy test) or lactating
* Participation in another simultaneous interventional medical investigation or trial

Answer: A