Cycloscopy was performed in eyes with primary angle-closure glaucoma and non-glaucomatous wide-angle. In all eyes of primary angle-closure glaucoma, the ciliary processes were accessible through the small pupil by cycloscopy with minimal or no indentation. In fellow eyes of the previously acute-attack eyes, the ciliary processes were visualized through the small pupil without indentation. On the contrary, in primary angle-closure glaucoma eyes the significant shallow chamber depth was seen in 66%, and the positive prone-position test in 41%. The results obtained seem to suggest that morphological changes of the ciliary processes might be causally related to the manifestation of primary angle-closure glaucoma, and that cycloscopy is a reliable diagnostic method.