The corneal surface is covered with a layer of epithelium. Like the rest of the skin from which it is derived embryologically, the epithelium is continuously shed. Replacement cells in the form of stem cells reside in a band of tissue surrounding the cornea that we refer to as the limbus (Latin: “edge; boundary”). The limbus has two very important functions regarding corneal health. First, the limbus is the nursery from which new corneal epithelial cells are born. Second, it serves as a barrier between the avascular cornea and the highly vascular conjunctiva.¹

Failure of the limbal stem cells can have many adverse consequences. These include persistent epithelial defects (PEDs), loss of clarity, visual impairment, and even blindness.² Limbal stem cell deficiency (LSCD) may be the result of genetic disorders, chemical or thermal burns, ocular cicatricial pemphigoid, Stevens-Johnson syndrome, or persistent contact lens friction. The latter may include findings such as corneal conjunctivalization, whorl-like epitheliopathy, and late fluorescein staining for at least six clock hours.³ Staining of a cornea affected by LSCD is abnormal due to the fact that conjunctival epithelium is more permeable compared to corneal epithelium.⁴

While the diagnosis is often based on clinical observations, the definitive confirmation can be obtained histologically with impression cytology, which will detect goblet cells originating from conjunctival epithelium.⁴ Definitive diagnosis is important when surgery is contemplated, as patients who have this condition are poor candidates for keratoplasty procedures.

Interestingly, patients may be candidates for autograft transplantation if only one eye is affected. In this procedure, healthy tissue from the fellow eye is transplanted into the distressed eye. If the condition is bilateral, then what is known as an allograft is indicated. Allograft tissue may come from living relatives who have human leukocyte antigen (HLA)-matching tissue.⁴ If this is not available, cadaver eyes may be used if recently harvested. Postoperative care typically involves steroid eyedrops, topical antibiotics, and viscous artificial tears.

References

1. Ahmad S. Concise review: limbal stem cell deficiency, dysfunction, and distress. Stem Cells Transl Med. 2012 Feb;1:110-115.
2. Haagdorens M, Van Acker SI, Van Gerwen V, et al. Limbal Stem Cell Deficiency: Current Treatment Options and Emerging Therapies. Stem Cells Int. 2016;2016:9798374. Epub 2015 Dec 14.
3. Chan CC, Holland EJ. Severe limbal stem cell deficiency from contact lens wear: patient clinical features. Am J Ophthalmol. 2013 Mar;155:544-549.e2.
4. Dua HS, Saini JS, Azuara-Blanco A, Gupta P. Limbal stem cell deficiency: concept aetiology, clinical presentation, diagnosis and management. Indian J Ophthalmol. 2000 Jun:48:83-92.