A 62 year-old Chinese female was diagnosed with right eye iridocorneal endothelial syndrome (ICE) in 2012 and her intraocular pressure (IOP) had previously been maintained in the mid-teens on timolol 0.5% alone.

The patient presented with sudden onset of right side headache, right eye pain, redness, and blurred vision in July 2014. Right eye visual acuity was hand movement, and 0.6 on left eye. IOP by Goldmann applanation tonometry were 67 mmHg on right eye and 20 mmHg on left eye. Slit lamp examination revealed right eye corneal edema, and fixed and dilated pupil. There was no pupil block or iris bombe. The left anterior segment was unremarkable. Gonioscopy revealed complete synechial closure over the right eye with gross peripheral iridocorneal adhesions at superior and temporal quadrants; left eye angle was open. Cup disc ratio (CDR) was 0.6 and 0.4 over the right and left eye respectively, which had remained static for more than 2 years. The rest of the retina was unremarkable. As the IOP remains elevated despite maximal topical and systemic glaucoma medications, Ahmed Glaucoma Valve (AGV) implantation was performed on the following day. The surgery was uneventful and the IOP was normalized in the early post-operative period.

However right eye IOP increased to 60 mmHg 2 weeks after the procedure. On slitlamp examination, the tube was retracted with its tip just barely remaining in the anterior chamber (Figure 1). Gonioscopy revealed that the tube opening was covered by a whitish membrane (Figure 2). After considering different surgical options including tube repositioning to a more anterior position and placement of extension tube, we decided to attempt a non-surgical strategy with application of Nd:YAG laser to the tube opening to puncture the ICE membrane with aid of the Latina goniolens (used for selective laser trabeculoplasty). The laser energy used was 5 mJ with a total of 23 shots given. The IOP returned to 14 mmHg after the laser membranectomy. The procedure was repeated 4 weeks later for a recurrent blocked tube with ICE membrane leading to IOP elevation of 24 mmHg. The tube remained patent up to the last follow-up 10 months after initial surgery. The IOP remained normal after the second membranectomy with the use of a single glaucoma medication for better IOP control.

Figure 1: Ahmed glaucoma valve tube lumen that just exited into the anterior chamber.

Figure 2: Gonioscopic finding showing the iridocorneal endothelial membrane obstructing the tube lumen.

ICE syndrome is a disorder characterized by corneal endothelial cells that behave like epithelial cells, migrating to adjacent structures like the iris and trabecular meshwork, and secreting an abnormal basement membrane, which is similar to Descemet’s membrane. Contraction of the membrane results in extensive peripheral anterior synechiae (PAS), iris (and pupillary) changes, and secondary angleclosure glaucoma. It comprises of three clinical variants: Chandler syndrome, progressive iris atrophy and Cogan-Reese syndrome. It is usually unilateral, and is diagnosed in young to middle-aged women. Glaucoma has been reported to occur in 50%-80% of patients [1]. Specular microscopy finding of disseminated or total involvement of the corneal endothelium with ICE cells, which have irregular size and shape, is a strong predictor of glaucoma development.

The management of glaucoma in ICE syndrome is challenging. Medical treatment may initially control the IOP but often becomes ineffective as the disease progresses [1]. Laser trabeculoplasty is technically not possible due to inaccessibility of the trabecular meshwork from synechial angle-closure and/or the overlying cellular membrane. Some investigators believe that laser trabeculoplasty in ICE syndrome may even exacerbate the condition [2].

The reported success rates for trabeculectomy with antifibrotic agents ranges from 60% to 73% at 1 year and 29% at 5 years [1,3]. However, failure occurs earlier than other types of glaucoma due to younger age of patients, more intense fibrotic response, membrane proliferation and formation of PAS [1,3]. Endothelialization and growth of abnormal basement membrane in the ostium also causes failure. Nd:YAG laser is a non-surgical option way to puncture the ICE membrane occluding the internal ostium.

Glaucoma drainage device (GDD) is a common first line surgical approach for patients with ICE syndrome. As in our patient, the extensive PAS would prevent the creation of an ostium that could communicate with the anterior chamber with trabeculectomy, GDD would be the only surgical option. Long-term surgical outcomes have been reported to be slightly better in GDD than in trabeculectomy [3]. Common complications in GDD include proliferation of the ICE membrane into the tube causing tube occlusion, and the formation of the iridocorneal adhesions and contraction of the membrane could also cause migration of the tube as in our patient. Surgical options include replacement of the retracted tube with a tube extender, tube repositioning to a more anterior position, and introduction of additional GDD. However, all these require an additional surgery and the long-term outcome is uncertain. The use of laser is a promising way to puncture the ICE membrane at the occluded lumen when the tube is still situated within the anterior chamber. It is much easier and faster to perform, eliminates the risks associated with intraocular surgery and the procedure is repeatable. There is a reported case on the use of Nd:YAG laser to restore the tube lumen patency, which was plugged by the PAS and iris and the IOP rose to 28 mmHg [4] and another case which used Nd:YAG laser to puncture the ICE membrane but later required surgical repositioning of the tube 10 weeks later [5]. However, it may be difficult to visualize the transparent membrane during the laser procedure to ensure the patency of the lumen and occlusion may be recurrent, requiring repeated laser treatment. Literature on the use of laser membranectomy is limited, more studies to look for its efficacy is warranted. Nonetheless, as intraocular surgery may be avoided, it is probably worthwhile to attempt laser treatment before considering further surgical intervention.

To conclude, occlusion of GDD tube in ICE patient is not uncommon and additional intervention is often needed to restore tube patency. Laser membranectomy is non-invasive and effective in our patient to restore tube lumen patency although its use was seldom reported in the literature. Further study is needed to compare the effectiveness of different modalities in the management of a blocked GDD tube. To our knowledge, this is the first reported case of treatment with Nd:YAG laser to restore the patency of the AGV tube lumen obstructed by the ICE membrane and the tube remained patent at least 15 months after the initial surgery without additional surgical intervention.