Dr. rojas

Br J Ophthalmol 1999;83:1409–1414
1 Dua HS, Azuara-Blanco A. Allo-limbal transplantation in patients with limbal stem cell deficiency. Br J Ophthalmol 1999;83:414–9. 2 Rao SK, Rajagopal R, Sitalakshmi G, et al. Limbal allografting from related live donors for corneal surface reconstruction. Ophthalmology 1999;106:822–8. 3 Lam DS. Corneal transplantation and infectious hepatitis. Br J Ophthalmol1995;79:1057. 4 Tseng SCG, Prabhasawat P, Barton K, et al. Amniotic membrane transplantation with or without limbal allografts for corneal surface reconstruction in patients with limbal stem cell deficiency. Arch Ophthalmol 1998;116:431–41.

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MAILBOX
Allo-limbal transplantation in patients with limbal stem cell deficiency EDITOR,—We read with great interest the recent article by Dua andAzuara-Blanco,1 describing the use of a new immunosuppressive agent FK-506 in patients receiving allo-limbal transplantation. The authors also describe a modified surgical approach. Although FK-506 appears to be a safe and eVective treatment option in these patients, the follow up is longer than 1 year in only two of the six patients. These two patients experienced a limbal graft rejection episode inthe postoperative period and we therefore feel that longer follow up is necessary before the eYcacy of FK-506 can be properly established. It would also be interesting to compare FK-506 with cyclosporin A in future studies to assess the relative safety and eYcacy of the two drugs. The potential advantage of HLA matching was cited in the discussion by the authors. Although a recent study2 indicatesthat HLA matching may not totally obviate the need for immunosuppression, we believe that it will allow reduction of dosage and or duration of treatment with these potentially toxic drugs. In countries with a paucity of corneal donor tissue, where even hepatitis B positive donor tissue is sometimes used,3 live related donor tissue is a valuable source of stem cells. However, the modified surgicaltechnique described by the authors1 would not be suitable for live related transplantation, as extent of tissue excision would prove detrimental to the donor eye. We concur with the authors that adequate reconstitution of the ocular surface microenvironment is critical to the success of limbal transplantation procedures. We feel that the use of amniotic transplantation4 would have helped achievethis goal during surgery. We feel also that there are still many unanswered questions in limbal grafting for ocular surface reconstruction including the best surgical approach, the optimum amount of limbal stem cell transfer, the ideal microenvironment for survival of the transplanted limbal cells, the usefulness of HLA matching, and the role of newer immunosuppressive agents like FK-506. Wesuggest that before new information is available, the use of HLA matched live related limbal tissue, combined with amniotic membrane transplantation and long term immunosuppression of the recipient would be a viable option in the treatment of advanced ocular surface disease.

Reply EDITOR,—The authors have commented on the use of FK-506 as an immunosuppressive agent in patients with allo-limbaltransplantation. Our experience with tacrolimus (FK506, Prograf, Fujisawa Ltd, London) has been very good thus far. Since publication of the report, several of our patients have been followed for over 1 year now. Attempts to reduce FK-506 (with a view to stopping treatment) have resulted in rejection reactions in two patients (one more since publication of the paper), but resolved on increasing thedose. Young et al have expressed concern over the two patients who had developed rejection while on treatment with FK-506. They have interpreted this as implying poor eYcacy of the drug. While we agree that the eYcacy of this drug does need to be evaluated over a longer period of time, it needs to be emphasised that in one of these patients, where a rejection reaction was observed 4 months after...