Further topical therapy was given and the right IOP fell to 32 mmHg, but the patient still complained of feeling unwell. The IOP in his left eye was checked and found to be 52 mmHg with an associated shallow anterior chamber. A diagnosis of acute angle closure glaucoma was made. Further systemic and topical treatment was given and the respective IOPs fell to 31 and 21 mmHg in the right and left eyes with associated relief of the symptoms. A left YAG peripheral iridotomy was subsequently performed.
CommentThe most likely cause of the acute glaucoma in the unoperated eye was the prolonged posturing in the face down position. Indeed, one provocative test for glaucoma is to place patients in the prone position. 2 The mechanism for this is the shifting of the lens-iris diaphragm anteriorly. This shallows the anterior chamber and narrows the angle. In our patient, the problem was compounded by the dilatation of the eye. Although it is unlikely that the episode of angle closure was solely precipitated by dilatation as both eyes had been dilated previously at vitreo-retinal clinic without incident. Also, gonioscopy had found a slightly narrow angle and the axial length was not particularly short. Biometry prior to the cataract surgery found axial lengths of 24 and 23.7 mm in the right and left eyes, respectively. Furthermore, it is unlikely that there was a phacomorphic component as there was no significant cataract in the left eye.Raised IOPs can, therefore, be found in both the operated and unoperated eyes following pars plana vitreous surgery. Indeed for the unoperated eye this is not surprising, as vitreoretinal surgery often requires prone posturing and dilatation, both of which may precipitate angle closure glaucoma in those at risk.