Referral Patterns of Patients with Limbal Stem Cell Deficiency to a Specialized Tertiary Center in the United Kingdom

Profile of biological characterizations and clinical application of corneal stem/progenitor cells

Corneal stem/progenitor cells are typical adult stem/progenitor cells. The human cornea covers the front of the eyeball, which protects the eye from the outside environment while allowing vision. The location and function demand the cornea to maintain its transparency and to continuously renew its epithelial surface by replacing injured or aged cells through a rapid turnover process in which corneal stem/progenitor cells play an important role. Corneal stem/progenitor cells include mainly corneal epithelial stem cells, corneal endothelial cell progenitors and corneal stromal stem cells. Since the discovery of corneal epithelial stem cells (also known as limbal stem cells) in 1971, an increasing number of markers for corneal stem/progenitor cells have been proposed, but there is no consensus regarding the definitive markers for them. Therefore, the identification, isolation and cultivation of these cells remain challenging without a unified approach. In this review, we systematically introduce the profile of biological characterizations, such as anatomy, characteristics, isolation, cultivation and molecular markers, and clinical applications of the three categories of corneal stem/progenitor cells.

Clinical Characteristics and Severity Distribution of Tertiary Eye Center Attendance by Ocular Chemical Injury Patients

OBJECTIVES

To report demographic characteristics, types and grades of injury, regional distribution of injury severity, clinical findings, and long-term results of acute ocular chemical burns.

METHODS

Medical records of patients with chemical burns between 2010 and 2020 who were admitted to Ege University less than 72 hr after the injury were reviewed. Age, gender, cause of the burn, injury severity, initial and final best-corrected visual acuity, surgical intervention, and complications were recorded. The injury severity was graded according to Dua classification.

RESULTS

A total of 104 patients (137 eyes) were included. The mean age was 42.69±17.39 (7-90) years with a male-to-female ratio of 86:18. The most common causes were home (32.6%) and industrial accidents (45.1%). The causative agent percentages for alkaline, acid, and neutral were 49.0%, 35.5%, and 5.7%, respectively. The percentages of eyes in each grade (1-6) were 16.0%, 16.0%, 15.3%, 16.7%, 17.5%, and 18.2%, respectively. Complications mostly occurred in eyes with grade 2 or higher injuries (83.7%). The relationship between injury grade and limbal stem-cell deficiency was statistically significant (P<0.001). Surgery was mostly needed in grade 4 or higher injuries (44 eyes).

CONCLUSION

The severity of the burn is one of the most important prognostic factors in chemical burns. It is important to determine the spreading of the regional injury severity beside the global one to predict complication risk of the injuries. In the present study, the injury distribution was homogeneous in all grades. Limbal stem-cell deficiency development took place mostly in grade 5 and 6 burns as expected.

Corneal Epithelial Stem Cells-Physiology, Pathophysiology and Therapeutic Options

In the human cornea, regeneration of the epithelium is regulated by the stem cell reservoir of the limbus, which is the marginal region of the cornea representing the anatomical and functional border between the corneal and conjunctival epithelium. In support of this concept, extensive limbal damage, e.g., by chemical or thermal injury, inflammation, or surgery, may induce limbal stem cell deficiency (LSCD) leading to vascularization and opacification of the cornea and eventually vision loss. These acquired forms of limbal stem cell deficiency may occur uni- or bilaterally, which is important for the choice of treatment. Moreover, a variety of inherited diseases, such as congenital aniridia or dyskeratosis congenita, are characterized by LSCD typically occurring bilaterally. Several techniques of autologous and allogenic stem cell transplantation have been established. The limbus can be restored by transplantation of whole limbal grafts, small limbal biopsies or by ex vivo-expanded limbal cells. In this review, the physiology of the corneal epithelium, the pathophysiology of LSCD, and the therapeutic options will be presented.