Simultaneous transplantation of limbal stem cells may reduce recurrences of granular dystrophy after corneal transplantation: 2 long-term case reports

Classic lattice corneal dystrophy: a brief review and summary of treatment modalities

PURPOSE

To provide a brief summary and comparison of the most recent literature on available and theorized treatment modalities for classic lattice corneal dystrophy (LCD). This paper aims to support practitioners in their management of this disease.

METHODS

A search was carried out on available literature through PubMed and Google Scholar of English language articles up to January 2023 that relate to the treatment of LCD. Due to scarcity of literature regarding specific novel therapies for LCD, results from other corneal pathologies (granular corneal dystrophy, corneal scarring) are sometimes included for contrast, which is clearly denoted.

RESULTS

LCD is a slowly progressive disease that leads to recurrent epithelial corneal erosions, stromal haze, corneal opacification, substantial discomfort, and visual impairment. Due to its autosomal-dominant inheritance pattern, this disease can persist throughout ancestral lines and requires consistent treatment and follow-up. An optimal management plan is necessary to (1) prolong years of life with best achievable visual acuity; (2) treat painful recurrent corneal erosions as they occur; (3) ensure proper follow-up throughout the life of a patient, as well as monitor at-risk offspring; and (4) monitor efficacy of treatment.

CONCLUSIONS

This paper addresses (1) treatment for early disease including corneal epithelial debridement, photo therapeutic keratectomy (PTK), femtosecond laser-assisted lamellar keratectomy (FLK), and others; (2) treatment for late disease including full thickness keratoplasties and anterior lamellar keratoplasties; and (3) potential future treatment considerations including a wide variety of topical/systemic, genetic, and regenerative approaches.

Management of Stromal Corneal Dystrophies; Review of the Literature with a Focus on Phototherapeutic Keratectomy and Keratoplasty

Corneal dystrophies are a group of non-inflammatory inherited disorders of the cornea. This review considers treatment options for epithelial-stromal and stromal corneal dystrophies: namely Reis–Bücklers, Thiel–Behnke, lattice, Avellino, granular, macular and Schnyder corneal dystrophies. Where there is visual reduction, treatment options may include either phototherapeutic keratectomy (PTK) or corneal transplantation. Due to the anterior location of the deposits in Reis-Bücklers and Thiel–Behnke dystrophies, PTK is considered the treatment of choice. For lattice, Avellino, granular and macular corneal dystrophies, PTK provides temporary visual improvement; however, with recurrences, repeat PTK or a corneal transplant would be needed. For Schnyder dystrophy, should treatment be required, PTK may be the preferred option due to the potential for recurrence of the disease in corneal transplantation. This review discusses the literature and evidence base for the treatment of corneal dystrophies in terms of visual outcomes and recurrence rate.

Influence of graft vascularization on graft survival following homologous limbo-keratoplasty

PURPOSE

Limbo-keratoplasty enables visual improvement and limbal stem cell transplantation at the same. During follow-up, most grafts show vascularization of the limbus. However, it is unclear whether vascularization is harmful due to immunologic effects or helpful to nourish the limbal stem cells and is therefore necessary for a clear graft. The aim of our study is to analyze the influence of graft vascularization on graft survival following homologous limbo-keratoplasty.

METHODS

In this retrospective study, we assessed all consecutive limbo-keratoplasties performed in our hospital. All eyes with suitable photo-documentation were included and divided into two groups (limbal stem cell deficiency and corneal dystrophy). We categorized the grade of vascularization (0, 1, 2, 3, 3b) and analyzed clear graft survival, recurrence of the underlying disease and the endothelial cell density (ECD) with regard to the reason for the graft. Event rates were estimated with the Kaplan-Meier method.

RESULTS

A total of 79 eyes with limbal stem cell deficiency and 15 with corneal dystrophies were analyzed. A high degree of graft vascularization had a tendency for better graft survival in limbal stem cell deficiency, whereas in corneal dystrophies, grafts with no vascularization had preferable outcomes. Recurrence-free graft survival was only seen in grade 1 and 3 vascularization in corneal dystrophies.

CONCLUSION

Vascularization of the limbus seems to have an impact on the long-term outcome of limbo-keratoplasty. The effect seems to be favorable in limbal stem cell deficiency and on recurrence rates in corneal dystrophies. However, the latter might be overshadowed by an unfavorable immunologic effect in corneal dystrophies where the baseline immunologic risk profile is commonly more favorable than in limbal stem cell deficiency.

Limbal and corneal epithelial homeostasis

PURPOSE OF REVIEW

The aim of this review is to describe the underlying mechanisms of corneal epithelial homeostasis in addition to illustrating the vital role of the limbal epithelial stem cells (LESCs) and the limbal niche in epithelial regeneration and wound healing.

RECENT FINDINGS

The shedded corneal epithelial cells are constantly replenished by the LESCs which give rise to epithelial cells that proliferate, differentiate, and migrate centripetally. While some recent studies have proposed that epithelial stem cells may also be present in the central cornea, the predominant location for the stem cells is the limbus. The limbal niche is the specialized microenvironment consisting of cells, extracellular matrix, and signaling molecules that are essential for the function of LESCs. Disturbances to limbal niche can result in LESC dysfunction; therefore, limbal stem cell deficiency should also be considered a limbal niche deficiency. Current and in-development therapeutic strategies are aimed at restoring the limbal niche, by medical and/or surgical treatments, administration of trophic factors, and cell based therapies.

SUMMARY

The corneal epithelium is constantly replenished by LESCs that are housed within the limbal niche. The limbal niche is the primary determinant of the LESC function and novel therapeutic approaches should be focused on regeneration of this microenvironment.