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May 21, 2005
Lisch Corneal Dystrophy
Cornea. 24(4):494-495, May 2005
Lisch established in his article in 1992 some clinical and histologic features that distinguish these cases from other epithelial dystrophies. These clinical findings and histopathologic results were characteristic of this new band-shaped microcystic epithelial dystrophy.
The lesions always have a gray, band-shaped, and feathery pattern and appear also sometimes in a whorled form. Slit-lamp examination reveals these opacities to consist of densely crowded clear intraepithelial microcysts, which are better seen with retroillumination. No fluorescein or rose bengal staining can be observed. No epithelial erosions are present.
Symptoms are usually gradual worsening of visual acuity (especially when the visual axis is affected), blurry vision, and sometimes monocular diplopia; in some cases, patients are asymptomatic and lesions are found incidentally. No concomitant alterations of palpebral conjunctivae or physical factors that suggest a mechanical pathogenesis have been described.
Light microscopy shows a bubbly vacuolization at all levels of the epithelial cytoplasm, most evident at the wing cell layer, with a sharp delineation from non affected areas.1 No periodic acid-Schiff nor Alcian blue acid mucopolysaccharide staining is present.3
Electron microscopy reveals intracytoplasmic vacuoles that look optically empty or containing weakly osmophilic, partly homogeneous, and partly lamellar material.The vacuoles tend to coalesce, finally resulting in a structureless transparent cytoplasm.
Lisch dystrophy should be distinguished from other corneal diseases that would have a similar appearance.
Meesmann dystrophy shows also small, discrete, grayish intraepithelial bubbles that appear as clear microcysts with retroillumination. These epithelial cysts present in a bilateral diffuse distribution that is more prominent in the interpalpebral area in contrast to the asymmetric, densely crowded pattern of Lisch dystrophy. The intracystic cellular debris in Meesmann disease stains Alcian blue and PAS positive. These patients report recurrent ocular pain because of epithelial erosions caused by rupture of superficial cysts, which does not occur in Lisch dystrophy. A recent genetic study also concluded that Lisch and Meesmann dystrophies are genetically distinct and mapped to different chromosomal loci.
Posted by mmiraftab at May 21, 2005 10:08 PM