Malignant glaucoma, also known as misdirection of aqueous humor or ciliary block, is a rare condition. It is characterized by elevated IOP, shallow anterior chamber, myopic shift [2], absence of suprachoroidal effusion [11], no response to miotics or peripheral iridectomy, and good response to cycloplegics [2, 5–7, 12]. It is associated with anatomical conditions (axial hyperopia, a narrow angle [8, 13], ciliary sulcus or plateau iris configuration [14]) or PEX-induced laxity of the zonule in the sunset syndrome [13] and in anterior IOL displacement [2],[13, 14]. MG is thought to be a deviation of aqueous flow accumulating behind a posterior hyaloid detachment, increasing vitreous pressure and leading to a forward displacement of the iris-lens diaphragm [9, 15]. It mostly occurs after filtration surgery in hyperopic eyes, but can follow laser iridotomy/capsulotomy, cyclophotocoagulation, cataract surgery [2], trabeculectomy scleral flap suture lysis, and trabeculectomy bleb needling [3, 4]. It appears with various latencies, from the immediate postoperative period up to 16 years after surgery [2]. Medical treatment consists of cycloplegic agents (relaxing the ciliary muscle) and aqueous suppressants (reducing the vitreous pressure)[16]. In refractory cases, laser or surgery may be of great help. A patent laser iridotomy shrinks the ciliary processes; Nd:YAG laser ruptures the posterior capsule and anterior hyaloid membrane which allows the aqueous flow between posterior and anterior segment. Prophylactic iridotomy/iridectomy in the fellow eye should be considered if the irido-corneal angle is narrow before any surgical intervention [16]. Pars plana vitrectomy or combined vitrectomy-iridectomy-zonulectomy (and phacoemulsification) have also been proposed [2, 16].
Our patient had normal axial length, no filtration surgery, no subluxation of PCIOL, iridocorneal angle was 360°-open in 2018. Her risk factors for MG were phacoemulsification 5 years prior and moderate PEX syndrome. An acute complete pupillary block was ruled out as no “iris bombé” was present on ultrasound biomicroscopy images and neither ISOPTOPILOCARPINE or patent Nd:YAG iridotomy decreased the IOP. Only ATROPINE and posterior capsulotomy with anterior hyaloidotomy were rapidly successful. Myopic shift and ultrasound biomicroscopy images showing a filling of the posterior chamber by massive EP (“plateau-like” configuration of the iris) and anterior displacement of the iris-IOL diaphragm led us to the track of MG. Indeed, EP were responsible for this “plateau-like”configuration and were thought to trigger a relative pupillary block [17, 18] with aqueous flow misdirection to the posterior segment leading to increased vitreous pressure, thus generating anterior displacement of the iris-lens diaphragm. This was most likely facilitated by a predisposed PEX-induced zonular weakness. This chronic aqueous humor misdirection by EP might be another predisposing factor of malignant glaucoma and should be taken in consideration with an anticipated Nd:YAG laser capsulotomy before planning any surgery.
EP are part of regenerative posterior capsular opacification. Residual equatorial lens epithelial cells migrate and proliferate between the posterior capsule and the IOL, first forming syncytial posterior capsular opacification and later EP. There has been a single report of MG in a context of EP in a patient with nanophthalmic eyes undergoing phacoemulsification and trabeculectomy complicated by immediate MG [19]. Treatment consisted in anterior vitrectomy and peripheral lens capsular hole with peripheral iridectomy [19]. Two months later, EP caused closure of the capsular hole with recurrence of MG treated by enlargement of the lens capsular hole. In this extremely predisposed patient for MG, EP acted as a direct obstacle to aqueous humor flow. In our case, EP were also thought to trigger MG by mechanical obstruction but in different ways: reducing physiological flow of the aqueous humour behind the iris (relative pupillary blockage) and narrowing iridocorneal angle (with a “plateau-like” configuration). To our knowledge, this is the second report of Elschnig’s pearls associated with a malignant glaucoma case.