Fifty normal eyes underwent a provocative test with pilocarpine 4 per cent. Slit-image photography before and 30 minutes after the instillation of pilocarpine 4 per cent into one eye demonstrated the range of response of the anterior segment to pilocarpine. Those eyes whose axial anterior chamber depth shallowed by greater than or equal to 0.1 mm demonstrated shallowing of the periphery of the anterior chamber, while those eyes whose axial anterior chamber depth shallowed by less than 0.1 mm showed deepening of the peripheral anterior chamber. The relevance of these findings to the development of peripheral anterior synechiae is discussed.