To the Editor. —Dr Mafee 1 has summarized the benefits of the computed tomographic (CT) scan in the evaluation of paranasal disease. He feels that this is the diagnostic procedure of choice for patients with complicated acute sinusitis, but implies that a plain-film sinus series is adequate for uncomplicated sinusitis. Unfortunately, disease of the ethmoid sinuses is often missed on plain roentgenograms. Andrew and Swart 2 found six patients to have significant ethmoidal sinusitis on CT scans who all had previously "normal" plain-film radiographs of the sinuses. I have found ultrasound to be a valuable screening technique for this blind spot between roentgenographic and CT detection of ethmoid sinus disease. Most nonophthalmologists are unaware of the value of orbital A-scan ultrasound in the detection of sinus disease, especially the ethmoid sinuses. Bockmann et al 3 found a good correlation between echography and plain-film roentgenograms vs sinus "proof puncture" of the