Drusen and 'choroidal filling defects': a cross-sectional survey.

The present study was designed as a cross-sectional survey to assess the association between soft drusen and 'choroidal filling defects'. Sixty-eight eyes presenting hard drusen and 58 eyes with soft drusen of 126 subjects with an age range of 45-83 years were examined in the present study. Choroidal filling defects were present in 13 out of 68 (19.1%) patients with hard drusen and 29 out of 58 (50%) with soft drusen (chi 2 square = 13.4; p < 0.0001 and an odds ratio = 4.2 with 95% CI 1.9-9.3). Age, ocular and systemic hypertension, and diabetes did not influence the results. The association between soft drusen and choroidal filling defects, found in our study, suggests that these abnormalities are possibly due to changes in the staining or permeability properties of Bruch's membrane rather than to a defect in the choroidal blood supply. Soft drusen and choroidal filling defects may both be caused by an accumulation of hydrophobic material within the Bruch's membrane, which is discrete in the case of drusen and diffuse in the case of choroidal filling defects. Choroidal filling defects and soft drusen may represent useful clinical sign of hydrophobicity of Bruch's membrane.