Lecithin: Cholesterol Acyl Transferase Deficiency Presenting as Visual Impairment, with Hypocholesterolaemia and Normal Renal Function

Abstract

A 20-year-old male of Indian extraction presented with visual impairment principally due to bilateral diffuse punctate corneal infiltration, with peripheral ring opacities. The diagnosis of LCAT deficiency was eventually confirmed by tissue and serum analysis together with enzyme studies, but there were some unusual features, notably persistent hypocholesterolaemia with normal range triglycerides but reduced levels of VLDL, LDL, and particularly HDL, without anaemia or detectable impairment of renal functions. This presentation has occasionally been described, and it is not clear whether it represents an early stage in the disease or whether a distinct sub-entity is involved. The corneal lesions differed from typical arcus in that the inner borders of the ring opacities were diffuse, and in particular outer lucid intervals were not apparent. Previous mild trachomal involvement was not considered to be responsible for these differences. The degree of visual affect was such that unilateral full-thickness keratoplasty was performed. The appearances of the corneal button by light and electron microscopy indicated the presence of diffuse sub-epithelial and principally extracellular deposit and a disorganized stroma with occasional myelin figures. Grossly the tissue contained excess phospholipid and unesterified cholesterol in comparison with normal cornea. Formation of the atypical corneal ring opacities in association with marked hypocholesterolaemia and diminished circulating LDL fraction suggests that processes other than insudation of intravascular lipoprotein were involved.

Key Words:

• cornea
• corneal arcus
• lipoproteins