Focus on limbal stem cell deficiency and limbal cell transplantation

Immunological and histopathological changes in alkali burn-induced ocular surface pannus: Implication on success vs. failure of SLET

PURPOSE

This study aimed to investigate the histopathological and immunological characteristics of human alkali burn ocular surface pannus in successful and failed cases of simple limbal epithelial transplantation (SLET).

METHODS

Paraffin embedded pannus sections of limbal stem cell deficiency (LSCD) patients who underwent simple limbal epithelial transplantation were obtained from pathology. Samples included both cases of SLET failure (n = 12) and success (n = 7). Histological features were assessed using Hematoxylin-Eosin and Periodic acid-Schiff staining while infiltrated immune cells were characterised using immunohistochemistry. Data were represented as mean or median with the interquartile range and standard deviation. Multiple comparisons of means by linear mixed effect model with Tukey contrast and Bonferroni method were used.

RESULTS

Conjunctivalization of the cornea that led to fibrous pannus formation was confirmed by the presence of CK19+ and CK3/12- cells. The median percentage of immune cell infiltrates like T-cells (CD3; success (9 %; IQR-9.2) vs. failure (23.5 %; IQR-10.2), (CD5; success (2.2 %; IQR-3) vs. failure (13.4 %; IQR-18.3), B-cells (CD20; success (3.2 %; IQR-3.2) vs. failure (4.1 %; IQR-5.5), antigen presenting cells (co-stimulatory CD40; success (7.8 %; IQR-8.9) vs. failure (16.4 %; IQR-7.1), and plasma cells (CD138; success (1.1 %; IQR-2.1) vs. failure (3.6 %; IQR-3.5) were identified in the pannus.

CONCLUSIONS

This study highlights a significantly higher infiltration of immune cells in the pannus and surrounding ocular tissue in cases of SLET failure compared to successful outcomes. These findings suggest that, strategies to reduce immune infiltration such as immunotherapy, corticosteroids, or amniotic membrane grafting should be considered prior to SLET to improve the success of limbal transplant surgery.

Timeframe to Keratoplasty After Ocular Surface Stem Cell Transplantation

PURPOSE

The aim of this study is to report the actual time delay between ocular surface stem cell transplantation (OSST) and keratoplasty at a high-volume center for limbal stem cell deficiency (LSCD). Understanding expected timelines and reasons for any delays or deferrals can allow for more accurate expectation-setting discussions with prospective patients.

METHODS

A retrospective chart review was performed on all patients having undergone OSST between January 2013 and December 2022. Charts were reviewed to determine whether the need for keratoplasty was specified at the time of OSST planning. Parameters for these cases were then collected including underlying diagnoses, type of OSST performed, and time delay between OSST and keratoplasty (if performed). Results were then aggregated, and subgroup analysis was conducted.

RESULTS

A total of 219 eyes were included, of which, 128 eyes had initial intent for keratoplasty. Of these, 48% had keratoplasty within 6 months of OSST, 17% between 6 and 24 months, 5% beyond 2 years, and, interestingly, 30% had no subsequent keratoplasty. Most eyes with no eventual keratoplasty experienced unanticipated stromal clearing after OSST obviating the need for keratoplasty.

CONCLUSIONS

This is the first study to report realized time delay between OSST and keratoplasty at a large LSCD practice. Prospective patients can be counselled that 76% of compliant cases with initial intent for keratoplasty either had keratoplasty within 6 months or exhibited unanticipated stromal clearing after OSST alone. Patients with congenital aniridia or contact lens-related LSCD are more likely to have unanticipated stromal clearing.

Femtosecond Laser-Assisted Autologous Glueless Simple Limbal Epithelial Transplantation in Unilateral Limbal Stem Cell Deficiency: 12-Month Outcome of the First Clinical Cases

PURPOSE

Surgical treatment of unilateral limbal stem cell deficiency (LSCD) is based on limbal stem cell transplantation. Glueless simple limbal epithelial transplantation (G-SLET) technique implements several limbal micrografts harvested from the healthy eye of the same patient into the peripheral corneal tunnels without the use of fibrin glue and human amniotic membrane.

METHODS

A novel customized algorithm and software for a low-energy femtosecond laser (FSL) were developed and tested using 5 pairs of isolated porcine eyes. FSL-assisted G-SLET modification was assessed in 3 clinical cases of unilateral LSCD caused by chemical burns. Corneal epithelization efficacy, best-corrected visual acuity, corneal epithelial mapping, central corneal thickness, and impression cytology with immunohistochemical examination were evaluated. All patients were followed up for 12 months postoperatively.

RESULTS

The FSL set for 100% energy and the pattern of 8 nonpenetrating vertical cuts with oblique tunnel portions having variable incision depths and diameter of 8.5 mm and higher were selected for further clinical evaluation. Clinically, stable corneal epithelialization was achieved 2 to 3 weeks after intervention. At the 6-month follow-up, all patients had a healthy corneal epithelium with limbal micrografts visible inside the corneal tunnels. Best-corrected visual acuity markedly improved in 2 cases, but not in the third case with severe corneal stromal scarring. In addition, all patients noted a full-scale reduction in subjective complaints and substantial improvement in their quality of life.

CONCLUSIONS

The FSL-assisted G-SLET is a new technique for autologous limbal stem cell transplantation in patients with unilateral LSCD. It allows the standardization of corneal tunnel localization and dimensions, thereby increasing the safety of the surgical procedure.