Ultrastructural organisation of arthritis corneal stroma

Abstract

Abstract Purpose Normal corneal stroma consists of uniformly organised collagen fibrils regulated by corneal proteoglycans. The focus of the study is the ultrastructural organisations of the collagen fibrils and proteoglycans in patients suffering with corneal melting due to rheumatoid arthritis (RA). Methods Corneas of two patients (ages 50 & 61 years) suffering from RA were fixed in 2.5% glutaraldehyde containing cuprolinic blue in sodium acetate buffer. The tissue were dehydrated in a graded series of ethanol and embedded and polymerised in spurs resin. The sections were studied under an electron microscope. Results The epithelial cells were degenerated and Bowman’s layer was replaced by fibrous pannus containing large abnormal proteoglycans and lucent spaces. In the stroma, longitudinally running collagen fibrils were curled and fused to each other. In cross section, collagen fibrils were not rounded and were separated with large spacings. Large proteoglycans and lucent spaces were present throughout stroma. The Descemet’s membrane was followed by posterior collagenous layer. Degenerated keratocytes were present in the pannus and throughout the stroma. Conclusion The collagen fibrils and proteoglycans were severely degenerated which resulted in the disorganisation of the corneal stroma. We believed that due to the disease, alteration in keratan sulphate and chondroitin sulphate might occur which possibly affected the structure of the corneal proteoglycans (lumican, keratocan and mimican) which were responsible for the collagen fibrils organisation.