AIM:To investigate the features of acute hydrops in patients with keratoconus by anterior segment OCT. METHODS: Eight consecutive keratoconic eyes of 8 patients with acute hydrops were examined by anterior segment OCT. RESULTS:Anterior segment OCT examinations revealed a rupture of Descemets membrane and intrastromal clefts in all eyes. The intrastromal clefts were connected to the anterior chamber. CONCLUSION:Formation of intrastromal clefts may be an important factor in the development of acute hydrops in keratoconic eyes. The clefts may cause severe corneal edema and delay the closure of Descemets membrane during the resolution of corneal edema.