BACKGROUND: We present the case report of a patient who presented with malignant glaucoma following deep sclerectomy with collagen implant in both eyes. To assess the IOP spike mechanisms in ciliary bloc glaucoma, we performed ultrasound biomicroscopy before and after the second filtration surgery (right eye). MATERIALS AND METHODS: A 60-year-old hyperopic patient with bilateral medically uncontrolled open-angle glaucoma underwent deep sclerectomy with collagen implant in the left eye and one month later in the right eye. Both eyes presented postoperatively a ciliary bloc glaucoma. Ultrasound biomicroscopy was performed pre- and postoperatively during the malignant glaucoma crisis in the right eye. RESULTS: Preoperative ultrasound imaging showed an anterior rotation of the ciliary body. That disappeared with local application of cycloplegics. During the malignant glaucoma crisis, the ciliary body came again in touch with the lens, thus blocking the aqueous humor pathway to the anterior chamber. Malignant glaucoma occurred despite the nonperforation of the eye undergoing deep sclerectomy with collagen implant. CONCLUSIONS: In our patient, the anterior rotation of the ciliary body and its subsequent malignant glaucoma might be either a consequence of a ciliary muscle spasm due to postoperative inflammation or of acute IOP drop. Finally, in hyperopic eyes, the ciliary muscle may be hypertrophied due to constant accommodation.