The goal of this clinical trial is to investigate the safety and clinical performance of ABCcolla Collagen Ophthalmic Matrix used for anterior lamellar keratoplasty in patients suffering from corneal ulcer.

Participants will undergo keratoplasty using the investigational product and be followed up for 24-week observation (total of 10 times).

1. Inclusion criteria:

1. Male or female from 20 to 80 years old
2. Subject who has been diagnosed with corneal ulcer
3. The depth or the size of the ulcer increases or increased anterior chamber inflammation after treatment (clinic, hospitalization, or others…)
4. The corneal ulcer affects corneal stroma depth to 1/3 and infiltrates >2 mm diameter, detected by OCT
5. Best corrected vision acuity < 0.05
6. Subject who signs the informed consent form (ICF), and agrees to complete the treatment and follow-up

2. Exclusion criteria:

1. Accepted keratoplasty
2. Has a corneal perforation and expects to have vision
3. Has a severe dry eye
4. Experience s incomplete eyelid closure
5. H as liver function (ALT and AST) tests with the score as twofold or greater than that of the normal
6. Has renal function (Cr) levels greater than normal two folders
7. Has serum protein 10% low than normal
8. Has severe cardiovascular and cerebral vascular disease
9. Subject with uncontrolled diabetes
10. Subject with current malignancy
11. Known to be allergic to collagen
12. Has a systemic collagen connective tissue disease
13. Has a constitution prone to severe allergic reactions
14. Use s anticoagulants 5 days before studying keratoplasty
15. Use s injectable NSAID 3 days before studying keratoplasty
16. Cannot accept investigated material due to religious or cultural reason
17. Pregnant or breastfeeding women or childbearing-age women who plan to get pregnant
18. Participation in any drug or medical device clinical trial within 30 days prior to signing the informed consent form;
19. Not being considered suitable for this study by the investigator