Oxygen dissociation curve in Eales's disease

The oxyhaemoglobin dissociation curve (ODC) was investigated in 15 patients with Eales's disease and 11 controls to test the hypothesis that Eales's disease is caused by retinal hypoxia secondary to impaired oxygen release from the blood. Patients with the peripheral form of Eales's disease did not have any significant difference in the P50 values when compared with the controls. However, the P50 values were significantly lower (P < 0.005) for the patients with mixed retinopathy. This degree of increased oxygen affinity is not physiologically significant but may reflect an intrinsic abnormality of the red cells in these cases.