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Chronic progressive external ophthalmoplegia (CPEO) is a genetic disorder of mitochondrial DNA characterised by progressive ocular dysmotility and eyelid ptosis.1 Other ophthalmological manifestations of mitochondrial eye disease include optic atrophy and retinal pigmentary changes. There have also been several reports of corneal opacification associated with Kearns–Sayre syndrome and ophthalmoplegia‐plus.2,3,4,5 Corneal decompensation secondary to exposure from lagophthalmos and absent Bell's phenomenon has been reported in CPEO, but few have progressive peripheral corneal oedema.6,7 We describe a patient presenting initially with bilateral segmental corneal oedema, in whom the subsequent diagnosis of CPEO followed the corneal changes.
A 38‐year‐old black woman with a diagnosis of primary ovarian failure presented with 5 years of bilateral progressive corneal oedema. Initial visual acuity was 20/60 OD (right eye) and 20/40 OS (left eye). Ptosis and diplopia were absent whereas funduscopy was unremarkable. Gradually, the segmental corneal oedema progressed to involve her visual axis OS (fig 11 A,B). Gonioscopy showed a pigmented retrocorneal membrane extending to the peripheral cornea, but not involving the angle structures (fig 11 C,D). Confocal microscopy showed a network of highly reflective bodies corresponding to the pigment spicules seen clinically with endothelial guttae, polymegathism, pleomorphism and reduced endothelial cell density (fig 22 A,B). Bilateral eyelid ptosis was evident within 2 years (fig 1E1E),), with global limitation of extraocular movements. The patient underwent penetrating keratoplasty OS in December 2004. Histopathological examination of the corneal button showed corneal epithelial bullae, stromal oedema and a normal Descemet's membrane. The attenuated, one‐cell layered endothelium showed focal loss of cells and phagocytosis of melanin pigment (fig 2C2C).). Additionally, there was a thin retrocorneal membrane, which was negative for cytokeratin (Kermix; fig 2D2D).). In June 2005, the patient underwent muscle biopsy to evaluate the aetiology of her eyelid ptosis and reduced ductional amplitudes. Skeletal muscle analysis showed myopathy (ragged red fibres with intramitochondrial paracrystalline inclusion bodies) consistent with a mitochondrial disorder. Biochemical analysis was remarkable for reduced oxidative metabolism, whereas a known genetic mutation for CPEO was not found.
Mitochondrial disease presents with a wide variety of ocular, neurological and systemic manifestations. Although corneal endothelial abnormalities have been reported in association with mitochondrial disease, the diagnosis of mitochondrial myopathy is generally manifest before the corneal disease. Moreover, the clinical picture of segmental bilateral oedema in association with a pigmented retrocorneal membrane is unique and previously unreported in CPEO (although pigment deposition is seen with many types of endothelial dysfunction).8 This finding is more characteristic of the Brown–McLean syndrome, which is typically seen after ocular surgery, particularly after intracapsular cataract extraction.9 Additionally, Rutzen et al10 described a patient with myotonic dystrophy and peripheral corneal endothelial pigmentary changes without retrocorneal membrane, consistent with the Brown–McLean syndrome. The unique features of peripheral corneal oedema, pigmented retrocorneal membrane and subsequent ocular dysmotility are a unique presentation of CPEO. We recommend that mitochondrial myopathy be considered in the differential diagnosis of young patients with idiopathic corneal oedema.
Competing interests: None declared.
The opinions expressed in this abstract are solely those of the authors and do not represent the views or official policies of the United States Army or Department of Defense.