Prevalence of retinopathy in patients treated with oral anticoagulants

Purpose: 1-to define the prevalence of hemorrhagic retinopathy in patients treted with oral anticoagulants; 2-to test the protrombine time (PT) values (expressed as INR) as possible risk factor for fundus lesions; 3-to test age, sex, duration of therapy as possible risk factors for retinopathy; 4-to compare PT values at which retinal lesions and hemorrhagic side effects occur. Methods: 69 consecutive subjects, undergoing to dicumarolic therapy for periods variable between 6 months and 13 years, were evaluated for the presence of fundus abnormalities. Patients with diabetes, hypertension and other fundus diseases were excluded. Results: Retinopathy was found in 3 out of 33 (9.09%) patients with INR lower than 2, in 3 out of 32 (9.37%) with INR between 2 and 4, in 2 out of 4 (50%) with INR higher than 4. Sixteen patients have had hemorrhagic side effects during therapy. Among the variables tested, only the PT values measured the day of the fundus examination were significantly related to retinopathy at the single and multiple logistic regression (respectively χ2=4.41, 95% CI=1.04-2.83, p<0.05 and χ2=5.00, 95% CI=1.05-2.25, p<0.05). PT values at which retinal lesions and hemorrhagic side effects occurred were almost the same with no statistical difference (3.504±2.526 vs 3.551±2.156). Conclusions: Our data indicate that PT values are related to risk of retinopathy, independently of sex, age and duration of therapy.