Antiphospholipid antibodies and retinal thrombosis in patients without risk factors: a prospective case-control study

To determine the prevalence of antiphospholipid antibodies and other immunologic abnormalities in patients with occlusive retinal vascular events, exempt from conventional risk factors of retinal thrombosis.

Forty patients with retinal vascular occlusion (26 with retinal vein occlusions, eight with arterial occlusions, two with combined venous and arterial occlusions, and four with venous occlusions plus vasculitis), free of main accepted risk factors for retinal thrombosis, were prospectively screened for antiphospholipid antibodies (anticardiolipin-antibodies and lupus anticoagulant) and other immunologic abnormalities. Fourteen patients were younger than 50 years. Prevalence and mean values of antiphospholipid antibodies (aPL) were compared with those in a homogeneous control group of 40 patients.

The prevalence of antiphospholipid antibodies in the study group was 22.5% (nine of 40). Comparison with control group prevalence (5% [two of 40]) showed a statistically significant difference (P = .04). Six patients in the study group disclosed positivity for IgG-anticardiolipin antibodies, one patient for IgM anticardiolipin antibodies, and two patients for both isotypes IgG and IgM anticardiolipin antibodies. The antibody assay for lupus anticoagulant was negative for all patients. Three patients were diagnosed as having primary antiphospholipid antibody syndrome and are undergoing systemic anticoagulant therapy. Relevant immunologic abnormalities were also found (27.5% with antinuclear antibodies, 35% with elevation of circulating immune complexes, 35% with complement deficiency, 30% with positive rheumatoid factor, and 17.5% with positive C-reactive protein). Thirteen patients (32.5%) had more than four parameters altered. No significant association was found between prevalence or mean values of anticardiolipin antibody and patients younger than 50 years.

The high prevalence of anticardiolipin antibodies in patients with vaso-occlusive retinopathy exempt from conventional risk factors, and the relevant diagnostic and therapeutic implications, lead us to recommend a systematic search for specific antiphospholipid antibodies in such patients.