Original article
Myofibroblast Metaplasia After Descemet Membrane Endothelial Keratoplasty

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Purpose

To describe myofibroblastic metaplasia of corneal endothelial cells in 2 cases with impaired visual function despite complete graft adherence after Descemet membrane endothelial keratoplasty (DMEK).

Design

Interventional case series.

Methods

In 2 of 90 consecutive DMEK surgeries, the cornea failed to clear up to 6 months postoperatively despite complete graft attachment. After secondary penetrating keratoplasty, both corneal buttons were examined using histopathologic analysis and transmission electron microscopy.

Results

Light microscopy revealed distinct corneal endothelial cell attenuation with the presence of an abnormal posterior collagenous layer in both cases. Most of the remaining endothelial cells had an elongated fibroblast-like appearance with immunopositivity for α-smooth muscle actin indicative of myofibroblast metaplasia. Transmission electron microscopy showed a slightly thickened Descemet membrane with an abnormal posterior fibrillar collagenous layer and a myofibroblast-like transformation of the remaining endothelial cells. Descemet membrane grafts closely adjoined the collagen lamellae of the host corneal stroma similar to the Descemet membrane–stroma interface of a normal cornea.

Conclusion

Myofibroblastic metaplasia of attenuated corneal endothelial cells with formation of an abnormal posterior collagenous layer may contribute to an impaired visual function despite complete graft adherence after Descemet membrane endothelial keratoplasty (DMEK).

Section snippets

Methods

Ninety consecutive DMEK surgeries were performed over a period of 12 months starting in June 2009. While 85 grafts stayed clear with marked improvement of visual acuity, 5 grafts were classified as early graft failure. Descemet membrane was chronically detached and graft failure was attributed to this fact in 3 of the 5 patients, while slit-lamp optical coherence tomography (SL-OCT, Heidelberg Engineering, Lübeck, Germany) confirmed complete graft adherence in the 2 patients who are presented

Results

Light microscopy revealed distinct corneal endothelial cell attenuation. Mean endothelial cell count was 4.2 ± 0.8 cells (range, 3-5) and 5.0 ± 2.5 cells (range, 1-7) (normal range: >120 cells) measured in 8 consecutive high-power fields (magnification ×400) per slide in 5 consecutive serial sections (Figure 2, Left). Most of the remaining endothelial cells had an elongated fibroblast-like appearance (Figure 2, Top right). Immunostaining revealed the presence of α-smooth muscle actin (α-SMA)

Discussion

To date, little information exists to explain impaired function after posterior lamellar surgery in patients with clinically attached grafts. Our findings are consistent with histopathologic observations after failed DSAEK, indicating that endothelial cell loss might be a reason for persistent corneal edema and malfunction after surgery.7, 8, 9, 10 However, DMEK grafts can also fail in patients where a close to normal endothelial cell count was obtained by in vivo microscopy.5 This finding may

Ludwig M. Heindl, MD, is a staff member of the Department of Ophthalmology at the Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany. He graduated from the Erlangen Medical School in 2006 and received training in clinical ophthalmology with Professor Kruse and ophthalmic pathology with Professor Naumann. His research interests include applied pathology of the eye, in particular of the cornea as well as (peri-)ocular tumors.

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Ludwig M. Heindl, MD, is a staff member of the Department of Ophthalmology at the Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany. He graduated from the Erlangen Medical School in 2006 and received training in clinical ophthalmology with Professor Kruse and ophthalmic pathology with Professor Naumann. His research interests include applied pathology of the eye, in particular of the cornea as well as (peri-)ocular tumors.

Friedrich E. Kruse, MD, is Professor and Chairman, Department of Ophthalmology at the Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany since 2004. After graduation from Heidelberg Medical School in 1984, he worked from 1988 to 1991 at the Bascom Palmer Eye Institute, Miami, Florida. His research interests include cellular and molecular biology of the ocular surface corneal transplantation and laser application.

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