Endothelial cell density in children with posterior polymorphous corneal dystrophy: a longitudinal case-control study

Descemet Membrane Endothelial Keratoplasty (DMEK) for Severe Verrucous Posterior Polymorphous Corneal Dystrophy with Uncommon Clinical and Ultrastructural Findings

PURPOSE

To report a case of severe verrucous posterior polymorphous corneal dystrophy (PPCD) and cataract, which was treated with Descemet membrane endothelial keratoplasty (DMEK) and simultaneous cataract surgery as a triple procedure (Triple-DMEK).

METHODS

A 62-year-old female patient presented to our department for co-evaluation of advanced PPCD with cataract and progressive light sensitivity in both eyes. The clinical examination demonstrated unusual clinical findings with prominent verrucous lesions on the posterior surface of the cornea without corneal decompensation. We performed a Triple-DMEK in case of simultaneous cataract. The corneal tissue was examined by light and transmission electron microscopy.

RESULTS

Intraoperatively, it was difficult to remove the verrucous structures completely after classical descemetorhexis. Light microscopic examination demonstrated epithelium-like transformation of the corneal endothelium by immunostaining (cytokeratin AE1/3 staining). Transmission electron microscopy revealed thickening of Descemet's membrane (18.5 to 30.0 µm). The anterior banded layer had a normal structure and was slightly thickened (3.5 to 5.5 µm). A normal posterior non-banded layer (PNBL) was observed but thinned (2.5 to 4.0 µm) or missing. It was followed by an altered PNBL with abnormal fibrillary inclusions, which was strongly and variably thickened (11.0 to 24.5 µm). The corneal endothelium was degenerated, partially absent, and epithelial-like altered. The nodular lesions were found to consist of a few degenerated cells that were embedded in an amorphous extracellular matrix interspersed with collagen fibers, which were not arranged in regular lamellae, forming the corneal stroma. The occurrence of pigment granules among the cellular debris suggested that the cells were endothelial cells. The corrected distance visual acuity improved from 20/50 to 20/30 in the right eye (+ 0.00/- 1.75/157°) and from 20/60 to 20/30 in the left eye (+ 0.00/- 1.75/33°), with significant improvement in light sensitivity.

CONCLUSION

The clinical and ultrastructural findings seem to be an unusual variant of the typical characteristic appearance of a PPCD. This case demonstrates that Triple-DMEK is feasible even in very advanced dystrophic changes of the posterior corneal surface, with good morphological and functional results.

Clearing the Haze: Navigating Corneal Refractive Surgery in Patients with Posterior Polymorphous Corneal Dystrophy

Posterior polymorphous corneal dystrophy (PPCD) is a corneal disorder of the endothelium and Descemet’s membrane. Although reports of corneal refractive surgery including laser-assisted in situ keratomileusis (LASIK), photorefractive keratectomy (PRK), and small incision lenticule extraction (SMILE) in PPCD are minimal, these procedures have been shown to be safe and effective in this patient population. Proceeding with corneal refractive surgery in eyes with PPCD raises concerns regarding corneal integrity, including long-term biomechanical instability, risk of ectasia, endothelial cell loss, disease progression, and corneal decompensation. Thus, LASIK, PRK, and SMILE should be considered with caution. This commentary explores the patient characteristics associated with favorable surgical outcomes and factors that weigh against proceeding with refractive surgery.