XEN-related hypotonous maculopathy from iatrogenic cyclodialysis cleft treated with argon laser gonio-cyclopexy

Abstract

We present a previously undescribed case of a persistent hypotony maculopathy secondary to an iatrogenic cyclodialysis cleft created during XEN-45 gel stent insertion. We present this case as a further analysis of the Karimi et al case of cyclopexy by the corresponding surgeon. Following right XEN-45 implantation, our patient developed immediate and persistent postoperative hypotony for 4 weeks. Gonioscopy revealed a small cyclodialysis cleft at the 1–2 o’clock position. The cyclodialysis cleft was sealed with direct gonioscopic argon laser cyclopexy. Two months after laser treatment and total of 6 months post XEN-45 insertion, right eye visual acuity returned to 6/4 with intraocular pressure 11 mm Hg without any glaucoma medication. Here, we present details of the non-invasive safe and successful management of hypotony maculopathy secondary to the cleft using Argon laser gonio cyclopexy, with no requirement of return to theatre.

Background

Hypotonous maculopathy remains the most frequent vision threatening complication with rates of 3.3% recorded up to 1-month post-XEN-45 implantation.¹ This is usually transient and associated with over drainage or leakage during the immediate postoperative period.

The XEN-45 gel implant (Allergan, Irvine, California, USA) uses the ab interno approach to create an aqueous outflow pathway from the anterior chamber to the subconjunctival space, bypassing the resistance of the trabecular meshwork and collector channels. Implantation is associated with a favourable safety profile in the medium term when used in the surgical management of open-angle glaucoma.^{2 3}

Young myopic males exposed to antifibrotic agents (Mitomycin-C) during XEN-45 insertion are associated with an increased risk of hypotonous maculopathy.⁴ The association may be attributed to reduced scleral rigidity in these patients, which leads to collapse of the scleral wall during hypotony.⁵ Persistent hypotony has been reported in uveitic patients with associated choroidal effusion requiring further surgical intervention.⁶

We are reporting the previously undescribed and successful management of a known complication related to XEN-45 insertion. In a retrospective study,⁷ Karimi et al acknowledged the frequency of complications following XEN surgery; reporting this case among other causes of hypotonous maculopathy following XEN procedure. We present this case as a further analysis of the Karimi et al case of cyclopexy by the corresponding surgeon. Our patient underwent non-invasive successful management of hypotony maculopathy secondary to the cleft using Argon laser gonio cyclopexy, with no requirement of return to theatre.

Case presentation

A 51-year-old Caucasian high myope (−11.75/ +1.75 × 180° right eye, −12.5/+1.75 175° left eye) man presented to the outpatient clinic with moderate pigment dispersion glaucoma. Medical history included obstructive sleep apnoea and epilepsy. Our patient was listed for surgery due to progressive glaucomatous changes and a preoperative raised intraocular pressure (IOP) of 19 mm Hg despite maximal topical therapy (bimatoprost +brinzolamide + timolol maleate). Preoperative visual acuity was 6/6–3 in the right eye and 6/5 in the left eye. The right eye had a dense superior arcuate scotoma, with mean deviation −12.91 dB. Central corneal thickness was 499 μm in the right eye and 508 μm in the left eye.

Our patient underwent right XEN-45 gel stent implantation under topical anaesthesia (figures 1 and 2), augmented by sub-Tenon’s injection of 0.1 mL Mitomycin-C 0.2 mg/mL.

Figure 1.

Right eye XEN-45 implant (arrow) shown as it exits from the subconjunctiva.

Figure 2.

Right eye anterior segment optical coherence tomography (OCT).

Following right XEN-45 implantation, he developed immediate post-operative hypotony with IOP of 4 mm Hg. Visual acuity was 6/36 in the right eye, with a homogeneous, diffuse supranasal bleb and clear evidence of hypotonous maculopathy and shallow peripheral chorioretinal folds. Gonioscopy revealed a small cyclodialysis cleft at the 1–2 o’clock position (figures 3–5).

Figure 3.

Right eye cyclodialysis cleft at the 1 o’clock position superonasally (arrow) shown.

Figure 4.

Right eye cyclodialysis cleft (arrow) shown.

Figure 5.

Right eye sealed small cyclodialysis cleft (arrow) shown.

After 4 weeks of treatment with topical atropine 1% two times a day, his visual acuity was fluctuating between 6/9 and 6/12, IOP 6 mm Hg in right eye. Three months after the XEN-45 implantation, unaided visual acuity deteriorated 6/24–6/12 with pinhole.

Differential diagnosis

The diagnosis described in this case is hypotonous maculopathy secondary to an iatrogenic cyclodialysis cleft created during XEN-45 gel stent insertion.

Treatment

Our patient was considered high risk for trabeculectomy surgery owing to pathologic myopia with degenerative fundal changes (lattice, chorioretinal atrophy) and pigment dispersion syndrome.

Therefore, XEN-45 implant was our operation of choice. In view of our patients’ preoperative risk factors to develop maculopathy, low-dose mitomycin-C was administered perioperatively.

It is worth noting that on insertion of the XEN-45 implant in the left eye, the dose of mitomycin used was 0.2 mL of 0.2 mg/mL which was double the dose used in the right eye, 0.1 mL (40 µg vs 20 µg). However, the left eye had no hypotony-related complications. This means that the prolonged anatomical hypotonous maculopathy with visual disturbance in the right eye was not associated with the dose of mitomycin-C used per se, but was rather related to the cyclodialysis cleft itself.

In the right eye (with ciliary cleft) XEN-bleb was decreasing in height and size while the cleft was actively open. We wanted to ensure adequate subconjunctival flow through the fellow, second eye (left) XEN-bleb, by increasing the dose of anti-metabolite, as the compromise of bleb efficiency and morphology in the first eye could be attributed to both supraciliary aqueous flow escape through the cleft or indeed fibroblast stimulation in a young myopic individual, which is counteracted by mitomycin-C.

The decision was made to seal the cyclodialysis cleft with direct gonioscopic argon laser cyclopexy. Uneventful argon laser cyclopexy with magnaview (Ocular Instruments) Gonio-Lens was performed under Pilocarpine and Apraclonidine hydrochloride cover. Topical anaesthesia was used with the following eyedrops administered with 3 min intervals between each eye-drop; proxymetacaine 0.5% minims, followed by oxybuprocaine 0.4% minims, followed by tetracaine 1% minims. These were all administered just before the induction of laser cyclopexy. The recommended spot size was 200–300 µm, duration of 300 μs and power ranged from 300 to 500 mW. The total number of burns was 84 shots and total energy was 1.20 Joules. Recommend 30–70 shots for a max of 1 clock-hour microcleft aiming at iris root and ciliary body band (using MagnaView goniolens, as in our case or Latina Selective Laser Trabeculoplasty (SLT) goniolens).

Outcome and follow-up

One month after argon laser cyclopexy, visual acuity was 6/7.5 in the right eye and IOP 11 mm Hg on no glaucoma drops. Two months after laser treatment and total of 6 months post-XEN-45 insertion, right eye visual acuity returned to 6/4 with IOP 11 mm Hg without any glaucoma medication. The superonasal XEN-bleb remained well preserved and still functioning 9 months after the XEN-45 implantation.

At this point, a decision was made to proceed with the left eye XEN-45 implantation. Extra care was taken to safely insert the XEN-45 stent with the correct amount of traction. Our patient underwent an uneventful left XEN-45 implant augmented with 0.2 mL mitomycin-C 0.2 mg/mL. On our most recent follow-up (32 months postoperatively) our patients IOP in the left eye remains well controlled between 11 and 13 mm Hg on no antiglaucoma medications.

Two years after the right XEN-45 implant, our patient required glaucoma drops Ganfort OD (bimatoprost and timolol maleate) and Simbrinza (brinzolamide and brimonidine tartrate) to maintain IOP control.

During the most recent review in May 2021, 4 years after the right XEN-45 implant, IOP in the right eye was 18 mm Hg and 21 mm Hg in the left. Our patient is on Ganfort OD (bimatoprost and timolol maleate) in both eyes and brimonidine in only the right eye to maintain IOP control, with a plan to review IOP in 8 weeks time.

Discussion

This case report describes a previously unreported complication of XEN-45 gel implant related hypotonous maculopathy. The small iatrogenic cyclodialysis cleft was treated effectively with Argon laser gonio-cyclopexy, as described previously.⁸

The literature reveals this complication was also encountered with other types of minimally invasive glaucoma surgery (MIGS) such as Kahook dual blade (KDB) goniotomy and ab interno trabeculotomy (AIT). Shue et al report a case of cyclodialysis cleft creation from 2:00 to 3:00 clock hours during KDB goniotomy, which was successfully treated with multiple sessions of argon laser photocoagulation.⁹ In contrast, one report¹⁰ highlights an inadvertent cyclodialysis cleft from a malpositioned AIT and resultant hypotony successfully treated by direct suture cyclopexy. Another case,¹¹ similarly reports good long-term prognosis results with direct cyclopexy surgery, following failed medical and laser treatment of cyclodialysis cleft secondary to cataract extraction, combined with an AIT with Trabectome. A recent case series¹² documented treatment after sulphur hexafluoride gas injection was efficacious.

This is one of the first cases of XEN-45 stent insertion for the surgeon and was part of a steep learning curve in the occurrence of this iatrogenic cyclodialysis cleft. The XEN-45 implant was deeply embedded into the posterior trabecular meshwork, as a result of excessive tractional forces applied during insertion. This is the likely mechanism for development of the focal (1 clock hour) cyclodialysis cleft. The proximal lumen is not visible gonioscopically post-insertion, with four mm of the implant visible in the subconjunctival space and less than two mm in the sclera.

Learning points.

• This case report describes a previously unreported complication of XEN-45 gel implant related hypotonous maculopathy.

• Any patient presenting with persistent ocular hypotony must undergo careful clinical assessment, including gonioscopy with effective communication between multidisciplinary team members involved. This will ensure correctly identifying the cause of the hypotony maculopathy and treating it immediately, as delayed treatment may result in irreversibly changes to the retina. The multidisciplinary team are invaluable to monitor the IOP post-treatment and need for further investigations or topical medications.

• A cyclodialysis cleft occurrence as a result of surgical or non-surgical ocular trauma must be considered in cases of persistent ocular hypotony.

• Argon laser gonio-cyclopexy can be an effective and safe technique for the management of a small cyclodialysis cleft, and particularly useful when cleft suturing is likely to compromise the survival of an already constricted focal XEN-bleb.

Ethics statements

Patient consent for publication

Consent obtained directly from patient(s)