Macular corneal dystrophy in Saudi Arabia: a study of 56 cases and recognition of a new immunophenotype

To determine the immunophenotype or immunophenotypes of macular corneal dystrophy in Saudi Arabia.

We studied 56 cases of macular corneal dystrophy. Tissue from 60 corneal transplant buttons was stained by the avidin-biotin complex method using an anti-keratan sulfate monoclonal antibody. The serum antigenic keratan sulfate was measured in 23 of the 56 patients, four unaffected relatives, and 13 individuals with chronic actinic keratopathy. Serum and corneal tissue were studied in 17 of the 50 affected individuals with corneal transplant material.

Thirty-five corneas (58.3%) of 29 of 50 patients did not react with anti-keratan sulfate monoclonal antibody. The stroma and abnormal intracellular and extracellular corneal accumulations reacted with anti-keratan sulfate monoclonal antibody in seven corneas (11.7%). The stroma in the other 18 corneas (30.0%) from 15 patients did not react with the anti-keratan sulfate monoclonal antibody, but corneal fibroblasts did. Twenty-one of the 23 patients with macular corneal dystrophy had no detectable serum antigenic keratan sulfate (< 9 ng/ml); two had values of 12 and 51 ng/ml, respectively, and their corneal stroma and abnormal accumulations reacted with anti-keratan sulfate monoclonal antibody.

We detected macular corneal dystrophy type IA, a new immunophenotype characterized by the lack of detectable antigenic keratan sulfate in the serum (< 9 ng/ml), and a corneal stroma that did not react with the keratan sulfate monoclonal antibody but in which corneal fibroblasts did react with keratan sulfate monoclonal antibody (in 15 of 50 patients).