CASE PRESENTATION
A 48-year-old white woman presented to Credit Valley Eyecare in Mississauga, Ontario, Canada, with nanophthalmos and acute chronic angle-closure glaucoma in her right eye. The latter was caused by a combination of marked phacomorphia and plateau iris syndrome previously confirmed by ultrasound biomicroscopy. She had patent laser peripheral iridotomies (LPIs), which had been performed on both eyes 4 years prior.
At presentation, the patient's IOP in the right eye was 29 mm Hg on maximal tolerated medical therapy, including pilocarpine, and she had no pain. Her anterior chambers were very shallow bilaterally (Figure 1). In her right eye, there were 90° of synechial angle closure, and the remaining 270° were appositionally closed. The LPI transilluminated well but was seen to be abutting cornea. The left eye had slit angles and a patent iridotomy, and the IOP was 16 mm Hg without medications.
The patient's BCVA was +10.50 D = 20/60 OD and +11.50 D = 20/50 OS. She had grade 1 nuclear sclerotic cataracts in both eyes. Biometric results in the right eye were consistent with nanophthalmos with a 17.9-mm axial length, a 0.84-mm anterior chamber depth, a corneal white-to-white diameter of 10.5 mm, and an average keratometric power of 47.00 D. Biometric results in the left eye showed similar values.
The patient had a healthy optic nerve and normal results with the Humphrey Field Analyzer (Carl Zeiss Meditec, Inc., Dublin, CA) in her right eye, but the visual field for her left eye demonstrated nasal steps, suggesting that the IOP might have been fluctuating in that eye (Figure 2).
HOW WOULD YOU PROCEED?
• Is there a role for iridoplasty as a first step given that
the patient has minimal cataract and ultrasound biomicroscopy
confirmed plateau iris?
• What, if any, special considerations would you have
when preparing for lens-based surgery on this patient?
• How might you create more working space in the
anterior chamber intraoperatively?
• Would you perform a combined cataract and glaucoma
procedure here, such as phacoemulsification with a
trabeculectomy or implantation of a tube shunt?
•Would you be concerned about postoperative malignant
glaucoma? If so, how might you prevent or manage it?
SURGICAL COURSE
Although iridoplasty can sometimes be helpful in plateau iris syndrome, it likely would not have been adequate in this case, which also involved significant underlying phacomorphia. Therefore, we opted for lens-based surgery consisting of a pars plana vitrectomy tap followed by phacoemulsification, implantation of a capsular tension ring (CTR), endocycloplasty (ECPL), and goniosynechialysis.
Preoperatively, IOL power calculations were performed using optical biometry. Because we anticipated an anterior effective lens position resulting in postoperative myopia, we selected a 40.00 D IOL and a target of slight hyperopia. Phacoemulsification in such a shallow anterior chamber would likely stress the corneal endothelium, so we performed preoperative specular microscopy.
Intraoperatively, we performed a planned pars plana vitrectomy tap to create additional working space in the anterior chamber. After phacoemulsification was complete, we inserted a CTR to help draw the IOL-capsule complex posteriorly. The plateau iris was addressed using ECPL, a modified endocyclophotocoagulation (ECP) technique. Goniosynechialysis released peripheral anterior synechiae.
Postoperatively, we prescribed a topical steroid every 2 hours as well as nonsteroidal anti-inflammatory, ß-blocker/α-agonist fixed-combination, and fluoroquinolone drops. One week postoperatively, the patient's IOL was well positioned, the anterior chamber was deep, and her spherical equivalent was +1.50 D. She returned at week 2, however, after the onset of blurred vision and was found to have an anteriorly positioned IOL, a shallow anterior chamber with narrow angles, and a manifest refraction of -4.50 D (Figure 3). She was diagnosed with malignant glaucoma.
We used a stepwise approach to management that started with cycloplegics and aqueous suppressants. Because the patient continued to exhibit progressive anterior shallowing and a myopic shift, therapy was augmented. We performed an irido-zonulo-hyaloidotomy (IZH) and then pushed back the IOL with a viscoelastic injection. Despite these measures, her malignant glaucoma persisted (Figure 3). Therefore, we performed a surgical irido-zonulo-hyaloid-vitrectomy (IZHV), reformed the anterior chamber with viscoelastic, and repeated her goniosynechialysis, as synechiae had reformed. Intraoperatively, we felt her iridectomy to be large and performed a pupilloplasty to prevent photophobia.
Postoperatively, we prescribed Diamox (Wyeth Pharmaceuticals) and a fixedcombination β -blocker/α-agonist to control the patient's IOP. She continued her use of cycloplegic, steroid, nonsteroidal anti-inflammatory, and fluoroquinolone drops.
OUTCOME
Ultimately, we tapered all of the patient's glaucoma drops and cycloplegics. Her anterior chamber remained deep, the IOL stayed in its normal posterior location, and her refraction returned to +1.75 D (Figures 4 and 5). Her angles remained wide open, and her IOP was 12 mm Hg off medications.
DISCUSSION
Angle closure may persist following LPI and can occur due to underlying phacomorphia and/or plateau iris.1
Phacomorphia, also known as lens rise, can be addressed with phacoemulsification. Although this procedure is sometimes combined with filtering surgery when the IOP cannot be controlled medically, phacoemulsification alone has been found to be effective in reducing IOP and produces fewer complications than phacoemulsification combined with trabeculectomy and mitomycin C in angle-closure glaucoma.2,3 Phacoemulsification in an eye with a shallow anterior chamber can be challenging due to limited working space. Often, a cohesive viscoelastic such as Healon5 (Abbott Medical Optics Inc., Santa Ana, CA) can be used to deepen the anterior chamber. In extreme cases, when this measure is inadequate, a pars plana vitrectomy tap and the removal of a small amount of vitreous can help to create space and deepen the anterior chamber.
Plateau iris syndrome occurs when large, anteriorly positioned ciliary processes push the peripheral iris forward, causing an obstruction of the trabecular meshwork. Although laser iridoplasty can be helpful in cases of plateau iris syndrome without cataract (if one is planning lens-based surgery), we have found the addition of ECPL at the time of surgery to be highly effective at addressing the underlying mechanism of plateau iris. In this technique, the surgeon directs an 810-nm diode ECP laser toward the posterior aspect of the ciliary processes. As laser energy is delivered, the ciliary tissue contracts and pulls the process posteriorly, mechanically opening the angle. This procedure is performed under direct visualization through a fiber-optic camera and xenon light source mounted on the laser probe passed through the main cataract incision (Figure 6). Some aqueoussuppression effect also occurs, although this is not the primary goal of ECPL. Hypotony is rare with ECPL, as one tends to ablate a limited portion of the ciliary epithelium in treated areas, and typically, we would treat a maximum of 270° through the cataract incision.
Synechial closure can be addressed with goniosynechialysis. With this technique, the surgeon uses microinstruments to grasp the peripheral iris under gonioscopic visualization and draw it centrally. The angle structures are revealed as the synechiae are released. Goniosynechialysis tends to be most successful if performed within 6 months of synechial formation.4 Older synechiae may be harder to release, and the function of the underlying trabecular meshwork may be compromised.
Nanophthalmic eyes are at high risk of developing malignant glaucoma. We believe that the condition occurs when a decompressing event causes choroidal expansion, with a subsequent increase in the intraocular volume that results in a shallow anterior chamber and anterior displacement of the crystalline lens or IOL. A normal eye adjusts for this shift in the posterior segment's volume by allowing aqueous to diffuse transsclerally as well as across the vitreous and lens face through to the anterior chamber. A nanophthalmic eye may not be able to adjust due to its thicker sclera, which provides resistance to transscleral outflow, as well as poor vitreous conductivity and a smaller area at the lens-vitreous interface limiting the anterior migration of aqueous. Furthermore, anterior chamber shallowing tends to be more exaggerated in nanophthalmic eyes, because they have smaller intraocular volumes.5
The key to managing malignant glaucoma refractory to cycloplegia and aqueous suppression is first to create a unicameral eye and then to reset the anterior-posterior relationships in the eye. We would typically start with an Nd:YAG laser IZH. If the pupil dilated well, we would direct the laser energy peripheral to the IOL to penetrate the anterior capsule, posterior capsule, and anterior hyaloid face. If the pupil did not dilate well, we could perform this procedure through a large peripheral iridotomy. Often, the anterior chamber deepens after laser treatment, but in some cases, the IZH is blocked by the vitreous or ciliary processes. In the second step, we form the anterior chamber with viscoelastic and gently push the IOL posteriposteriorly using a 30-gauge needle; the goal is to reset the anteriorly rotated ciliary processes and push some of the fluid from the posterior segment through a patent IZH. In refractory cases, a surgical IZHV can definitively create a unicameral eye. In this procedure, a vitrectomy cutter is introduced through a pars plana incision. It is used to remove anterior vitreous and is then passed anteriorly through peripheral zonules and iris into the anterior chamber.
Interestingly, in this case, some vitreous was removed prior to phacoemulsification to create working space within the anterior chamber. However, because a unicameral eye was not established, the initial vitreous removal was not adequate to prevent malignant glaucoma. Instead, further vitrectomy combined with IZH (IZHV) was required. Because our patient's chronic angle closure was addressed early, she has developed only mild glaucomatous optic neuropathy, and her trabecular meshwork continues to function, allowing her to maintain an excellent IOP without medications. She currently awaits surgery on her second eye, during which we would likely plan for a prophylactic surgical IZHV given the stormy postoperative course of her first eye.
Iqbal Ike K. Ahmed, MD, FRCSC, is an assistant professor at the University of Toronto and a clinical assistant professor at the University of Utah in Salt Lake City. He acknowledged no financial interest in the products or companies mentioned herein. Dr. Ahmed may be reached at (905) 820- 3937; ike.ahmed@utoronto.ca.
Devesh K. Varma, MD, FRCSC, is a staff anterior segment and glaucoma surgeon at Trillium Health Centre in Mississauga, Ontario, Canada. He acknowledged no financial interest in the products or companies mentioned herein. Dr. Varma may be reached at deveshvarma@me.com.
