Bleb dystrophy of the cornea: histochemistry and ultrastructure.

Abstract

SUMMARY Corneal epithelial biopsies from two patients affected with asymptomatic bleb dystrophy were examined by light and electron microscopy. The basis of this disorder appears to be the deposition of a neutral mucopolysaccharide-protein complex as a continuous layer between the basement membrane and Bowman's layer. This material, although homogeneous in light microscopy, has a fine granular ultrastructure. It is friable, and in view of the apparent integrity of the basement membrane/hemidesmosome system it is suggested that the recurrent epithelial erosions which can occur in this disorder result from shearing of this layer. Fissures in the bleb material contain cells which may play a role in its degradation.A recently described group of superficial corneal disorders includes the fingerprint, net, bleb (Bron and Brown, 1971) and microcystic dystrophies (Cogan et al., 1964). Brown and Bron (1976) have shown that these dystrophies may be associated with recurrent epithelial breakdown. Thus, they were present in 59% of their patients with the recurrent erosion syndrome. Conversely the same authors (1971) had noted previously that 38% of patients with these superficial dystrophies were also afflicted with symptoms of recurrent epithelial dehiscence. These studies naturally suggest that this group of superficial corneal dystrophies is an important precursor of defective epithelial adherence.The common ultrastructural basis of these dis- Examination showed corrected vision OD=20/80, OS=20/20. A dendritic ulcer of the herpes simplex type was present in the epithelium of the right cornea. Profuse subepithelial blebs were present in clusters in the parapupillary zones of both corneae. Their distribution in the left cornea is illustrated in Fig. 1. The blebs, which varied in size, were on the average about 50 ,u wide. With the direct ophthalmoscope the blebs had an orange-skin appearance when set against the fundal reflex. Viewed by indirect slit-lamp illumination from the iris the blebs appeared as transparent bubbles with an unreversed lighting effect (Fig. 2), a phenomenon which, as noted, indicates a refractive index higher than that of the surrounding tissue. In focal illumination the blebs were seen as black dots set in a relucent background. There were no demarcation or other lines in either cornea. In the left eye it was possible to determine that there was no interference with the precorneal tear film and that

In vivo Laser Confocal Microscopic Findings in Patients with Epithelial Basement Membrane Dystrophy

“…Bleb-like corneal disorder is a lesserknown entity among the corneal dystrophies and should be considered in the differential diagnosis of microcystic corneal diseases, such as Meesmann epithelial cornea dystrophy. In bleb-like dystrophy, localized deposits of a fibrogranular material between the epithelium and Bowman layer and intrusion of this low refractive material into the epithelial layer produce an appearance on retroillumination identical to that of intraepithelial cysts (20). Using in vivo confocal microscopy, we showed hyporeflective, circular, or oval structures at the level of basal epithelium and the Bowman layer (Fig.…”

Cogan's microcystic dystrophy of the cornea: ultrastructure and photomicroscopy.

“…In contrast to this view of a continuum the present study serves to emphasise the differences between fingerprint and Cogan's dystrophy. Thus, the subepithelial seam and refractile striae in microcystic dystrophy consist of irregularly banded fibrils embedded in a fine granular matrix, in contrast to the granular ultrastructure of the striae and subepithelial seam seen in fingerprint dystrophy as described by Broderick et al (1974) and the subepithelial seam in bleb dystrophy by Dark (1977). Biomicroscopically the striae in Cogan's dystrophy are visible in focal illumination as fine grey lines unlike those of the fingerprint disorder, which are visible only in retroillumination.…”

Anterior Segment Swept Source Optical Coherence Tomography and In Vivo Confocal Microscopy Findings in a Case With Bleb-Like Epithelial Basal Membrane Dystrophy

“…3 Although most of the patients are asymptomatic, some may suffer from recurrent corneal erosions, ocular pain, photophobia, astigmatism, and blurred vision. Dark 4 described histochemical and ultrastructural characteristics of bleb dystrophy using light and electron microscopy. Vemuganti et al 5 reported the accumulation of fibrogranular neutral mucopolysaccharide–protein complex in the epithelium, which stained positively with periodic acid–Schiff.…”