Detection of arteriolar narrowing in fundoscopic examination: evidence of a low performance of direct ophthalmoscopy in comparison with a microdensitometric method.

BACKGROUND: Retinal abnormalities, particularly arteriolar narrowing, are powerful predictors of cardiovascular events. The precision of internists and ophthalmologists in the assessment of retinal vessels widths has been disputed but not evaluated against a technology of edge detection.
METHODS: Fifty-two patients with hypertension had optic fundi examination done by an internist and an ophthalmologist, and had retinographies taken and digitized to determine vessel diameters by a new technology of edge detection (microdensitometric method). Physicians asserted the presence of arteriolar narrowing (<or=0.67) through direct ophthalmoscopy and projected retinography. The microdensitometric method measures automatically the vessel widths based on the subpixel resolution of the edge of vessel walls. Sensitivity (SE), specificity (SP), positive (PPV) and negative predictive values (NPV), and kappa statistics were calculated, taken the microdensitometric method as reference.
RESULTS: The performance of the direct examination by the internist to detect arteriolar narrowing was SE: 68.7 (67.0-70.4); SP: 72.7 (68.0-77.4); PPV: 88.0 (85.9-90.0); and NPV: 44.4 (41.5-47.4). For the ophthalmologist the figures were: SE: 74.4 (72.9-75.7); SP: 53.8 (49.8-57.8); PPV: 82.9 (81.3-84.4); and NPV: 41.2 (38.0-44.3). Kappa statistics were 0.34 (0.07-0.62) for the internist, and 0.26 (-0.03-0.53) for the ophthalmologist.
CONCLUSIONS: The performance of internists and ophthalmologists to detect hypertensive microangiopathy based on low arteriolar venous ratio is low and casts doubt about the usefulness of this examination in clinical practice.