Abstract
Purpose: :
Sclerocornea (SC) is a rare corneal condition in which the clinical and pathologic phenotype resembles sclera. This study was performed to immunolocalize Keratan sulfate core proteoglycan, lumican and collagen III (expressed in sclera and scar tissue) in SC specimens. The distribution was compared with control cornea, sclera and scarred corneas in congenital glaucoma (CGS).
Methods: :
Keratoplasty specimens with a clinical and pathologic diagnosis of SC (n=4) and CGS (n=4) were studied by light microscopy. Immunohistochemistry was performed using anti-lumican and anti-collagen III antibodies. Corneoscleral rims of adult eyebank eyes (n=3) were used as controls. Immunostaining was computed using automated ImagePro Software and analyzed using the Mann Whitney U test.
Results: :
By light microscopy the SC specimens shows typical features including absent Bowmans layer, thickened and irregular stromal collagen, stromal vascularization and variable absence of Descemet’s membrane (DM). The corneas with CGS showed fragmented DM, endothelial attenuation, corneal stromal edema and scarring. In the SC and CGS specimens, the corneal stroma showed moderate uniform anti-lumican labeling (14.34% ± 7.07% and 10.10% ± 5.03, respectively). The label intensity was slightly less in the normal control (5.80% ± 0.88%).but was not statistically significant. Also collagen III immunolabeling was absent in the stroma of SC specimens which was similar to that seen in normal controls. In contrast the scleral and episcleral tissues demonstrated strong anti-collagen III labeling (18.5% ± 1.65%).
Conclusions: :
Collagen type III and lumican staining in SC and normal corneas demonstrates that the immunophenotype of SC cornea resembles the normal adult cornea. Furthermore, the scarred corneal stroma in CGS appeared to demonstrate immunophenotypic characteristics similar to that seen in SC. Although the proteoglycans labeling was localized at similar levels in both conditions, it is possible that the lumican expressed in SC and CGS is functionally different resulting in abnormal corneal collagen fibrillogenesis without involvement of Type III collagen.
Keywords: cornea: stroma and keratocytes • immunohistochemistry • degenerations/dystrophies