The goal of this program is to provide patients with Limbal Stem Cell Deficiency access to the BRM421 eye drops.

Participants will:

• Use BRM421 two times a day for at least 12 weeks
• Visit the clinic monthly for checkups and tests

Inclusion Criteria:

• Adult patients with mild to moderate LSCD who unsatisfied with the standard of care treatments and who seek the treatment with BRM421 Ophthalmic Solution. Patients scheduled for LSC transplant may be included, but treatment with BRM421 should begin only after the surgery.
• Be able to sign the informed consent and follow with investigator instructions.
• If a female is of childbearing potential, they must: use an acceptable means of birth control (acceptable methods of contraception include: hormonal oral, implantable, injectable, or transdermal contraceptives, mechanical spermicide in conjunction with a barrier such as a diaphragm or condom, IUD, or surgical sterilization of partner) and have a negative urine pregnancy test at the time of consent.

Exclusion Criteria:

• The patients eligible for the BRIM clinical trial(s).
• The patients diagnosed with primary LSCD which is the genetic mutations that lead to LSC dysfunction or destruction.
• Have a condition or a situation in which the investigator feels the patients is not suitable and may put the patient at significant risk.
• Be a female who is pregnant, nursing, or planning a pregnancy at the time of consent. Be a woman of childbearing potential who is not using an acceptable means of birth control; acceptable methods of contraception include: hormonal oral, implantable, injectable, or transdermal contraceptives; mechanical spermicide in conjunction with a barrier such as a diaphragm or condom; IUD; or surgical sterilization of partner. The risks of BRM421 among pregnant patients are not known.