Limbal Stem Cell Deficiency: A Review Focusing on Staging, Diagnostic and Treatment Modalities

Abstract

The cornea being a transparent tissue acts as a refractive surface as well as a protective barrier of the eye. The corneal epithelium is being continuously replaced and renewed by the Limbal Stem Cells (LSC). The turnover of corneal epithelium is brought about by asymmetrical differentiation and self-renewal of LSCs, their migration to the cornea and desquamation of current corneal epithelium. LSC are undifferentiated cells that acts as progenitors of corneal epithelium and maintains corneal homeostasis. LSC resides in its own microenvironment known as LSC niche, which are capable of sustaining these tissue regenerating cells. Any intrinsic factors (e.g., toxic epidermal necrolysis or mucous membrane pemphigoid), extrinsic factors (e.g., thermal burns, radiations, chemical burns) or genetic defects (e.g., aniridia) cause impairment of LSC or its niche leading to Limbal Stem Cell Deficiency (LSCD). LSCD is associated with invasion of cornea by conjunctival epithelium, corneal opacity, and visual impairment. The diagnostic modality of LSCD includes fluorescein staining and slit lamp examination, impression cytology, confocal scanning and anterior chamber optical coherence tomography. The staging of LSCD is important for deciding the treatment modalities. In LSCD, the most common treatment modality includes LSC transplant from a healthy eye. Non LSC transplantation techniques are being used to prevent allograft rejection. In this review article, the authors aim to summarise the existing knowledge of the aetiology, staging and treatment modalities of LSCD.