Earlier approaches for cornea reepithelization in patients with bilateral LSCD included allogeneic corneal limbus grafting from postmortem donor or livingrelated relatives with concomitant systemic immunosuppression (Cheung and Holland, 2017) and cultivated oral mucosal epithelial transplantation (COMET) (Nishida et al., 2004).

The novel surgical technique for corneal re-epithelization were described by Liu et al. (2011) and Choe et al. (2019). In both clinical studies, the autologous labial mucosal epithelium graft was transplanted as a surrogate corneal limbus for purpose of treatment the LSCD. Authors reported positive outcomes in terms of anatomical success and corneal status improvement.

The purpose of the study is to evaluate the feasibility of the novel surgical intervention in clinical use.

Earlier approaches for cornea reepithelization in patients with bilateral LSCD included allogeneic corneal limbus grafting from postmortem donor or livingrelated relatives with concomitant systemic immunosuppression (Cheung and Holland, 2017) and cultivated oral mucosal epithelial transplantation (COMET) (Nishida et al., 2004).

The novel surgical technique for corneal re-epithelization were described by Liu et al. (2011) and Choe et al. (2019). In both clinical studies, the autologous labial mucosal epithelium graft was transplanted as a surrogate corneal limbus for purpose of treatment the LSCD. Authors reported positive outcomes in terms of anatomical success and corneal status improvement.

Lip oral mucosa is a promising autologous source of epithelial cell for the trial because it has similar histological characteristic as the normal corneal. In particular, lip oral mucosal epithelium is stratified squamous and nonkeratinized.

The indicated histological and molecular features of the lip oral mucosal epithelium predetermined the use of labial mucosal epithelial graft for treatment patients with bilateral LSCD.

The purpose of the study is to confirm the validity of the hypothesis about the possibility of re-epithelialization diseased cornea using labial mucosal epithelium graft as a surrogate limbus in patients with bilateral LSCD.

Inclusion Criteria:

• Man or woman 18 years and older.
• Signed informed consent, given by the participant or his/her legal representative.
• Ability to understand Russian spoken and written language.
• Sanitated oral cavity.
• Bilateral limbal stem cell deficiency diagnosed by two or more symptoms during slit-lamp examination: corneal conjunctivalization, absence of palisades of Vogt, superficial corneal neovascularization, recurrent or persistent corneal epithelium erosion.
• Bilateral limbal stem cell deficiency non-immunogenic etiology (burns, irradiation, contact lens related, etc.).
• Best-corrected visual acuity less than 0.3 (6/18 Snellen chart)
• Intraocular pressure in normal range.
• Schirmer's test I more than 5 mm.

Exclusion Criteria:

• Inability to give signed informed consent.
• Age under 18 years.
• Pregnancy and/or breastfeeding.
• Hormonal contraceptives intake.
• History of allergic reactions to antibiotics, glucocorticosteroids, remedies for treatment dry eye syndrome, medications for local and general anesthesia.
• Participation in other clinical trials.
• Systemic immunosuppression intake.
• Diagnosed neoplastic process or treatment for it.
• Positive tests for infectious: HIV, syphilis, Hepatitis B, Hepatitis C.
• Any medical, psychiatric and/or condition, including cachexia, or social conditions that the investigator believes would interfere with or contraindicate adherence to the research protocol or the ability to provide signed informed consent.
• Immune-mediated limbal stem cell deficiency (Stevens-Johnson syndrome, ocular cicatricial pemphigoid and other.), unknown and/or inherited etiology.
• Best-corrected visual acuity more than 0.3 (6/18 Snellen chart)
• Ocular burns earlier than 12 months.
• Keratoplasty earlier than 12 months.
• Limbal grafting (from postmortem or living-related donors).
• Keratoprosthetic device or history of its implantation.
• Cellular therapy for treatment of limbal stem cell deficiency.
• Cellular transplantation for treatment of limbal stem cell deficiency.
• Active ophthalmic infection.
• Symblepharon, ectropion, trichiasis, lagophthalmos and/or other lid and/or conjunctival fornixes abnormalities.
• Surgery on ocular adnexa earlier than 9 months.
• Corneal stromal thickness less than 300 mkm.
• Dry eye with Schirmer test I less than 5 mm and/or keratinized ocular surface.
• Uncontrolled glaucoma and/or presents of a glaucoma drainage device.
• Retinal defunctioning (no light perception and/or retinal detachment).
• Absence of the electric activity of the optic nerve and/or retina.

We plan to share Clinical Study Report, present and publish results of the study.

During the study and after.

upon request