Kissing Choroidals Despite Normal Intraocular Pressure Following Ahmed Clear Path Implantation in a Vitrectomized Eye

Introduction

Glaucoma drainage devices (GDDs) play a critical role in the management of refractory glaucoma, particularly when trabeculectomy is contraindicated or has failed. Choroidal effusion is a common complication of GDDs. Reported rates of choroidal effusions range from 9 to 35.1% after implantation of valved GDDs [1]. The rate of this complication is higher (36.8%) with the use of valveless tube implants [2]. However, with the introduction of complete ligature of the tube with absorbable sutures at the time of surgery, the rate of surgical intervention required for choroidal effusions was reduced to 2%, as this procedure helped mitigate the risk of early hypotony [3].

Choroidal effusion occurs when fluid collects in the potential space between the choroid and the sclera, called the suprachoroidal space. The most common cause of choroidal effusion and suprachoroidal hemorrhage is low intraocular pressure (IOP); however, inflammation can also sometimes play a role. Other risk factors include vitrectomized eyes, high myopia, hypotony, anticoagulation, prior ocular surgery, aphakia, straining, heart and respiratory disease, and hypertension. Conditions associated with increased episcleral venous pressure also predispose patients to choroidal effusion and suprachoroidal hemorrhage. These conditions include nanophthalmos, Sturge-Weber syndrome, carotid cavernous fistula, choroidal hemangioma, and others [4].

Most choroidal effusions resolve spontaneously with observation or medical treatment, provided the IOP is normalized. However, in severe or persistent cases, surgical drainage may be necessary. Indications for surgery include kissing choroidals, flat anterior chamber with lens-cornea apposition, persistent corneal edema with a shallow anterior chamber, combined serous retinal and choroidal detachment, and a prolonged duration of effusion. Persistent choroidal effusion can lead to complications, including a decrease in best-corrected visual acuity (BCVA) or the development of cataract [5].

The Ahmed Clear Path (ACP), developed by New World Medical, is a novel valveless GDD featuring a soft, foldable silicone plate available in 250 mm2 and 350 mm2 sizes. A key innovation is the inclusion of a pre-inserted intraluminal ripcord intended to further restrict early aqueous outflow, thereby minimizing postoperative hypotony. In the 36-month follow-up study by Boopathiraj et al [6], no cases of choroidal effusion were reported with the use of this enhanced device. While these advances have shown promising safety and efficacy profiles, demonstrating significant IOP reduction and medication burden relief and a low incidence of vision-threatening complications, certain anatomic states, such as prior vitrectomy, may still predispose patients to adverse outcomes. We report a rare case of serous “kissing” choroidals following ACP implantation in a vitrectomized, monocular eye. This case highlights the possibility of development of kissing choroidals despite normal IOP and the potential limitations of current mechanisms to avoid this in anatomically predisposed eyes. Moreover, our case emphasizes the role of conservative management in selected cases like these, despite the presence of kissing choroidals. To the best of our knowledge, such a complication has not been reported yet with the use of ACP in the literature. This may be because outcomes of ACP have not been studied in vitrectomized eyes.

Case Report

A 68-year-old monocular man presented with acute pain and decreased vision in his only seeing right eye. The left eye had no perception of light due to traumatic optic atrophy. His right eye had undergone cataract surgery with implantation of a sulcus-fixated polymethylmethacrylate intraocular lens 1.5 months prior, followed by pars plana vitrectomy 3 weeks earlier for retained lens material. No vitreous substitutes were used. His BCVA was 6/60.

On examination, IOP as measured by Goldmann applanation tonometry was 60 mmHg despite maximal topical therapy and oral acetazolamide. The anterior chamber was deep and quiet. Fundoscopy revealed advanced glaucomatous cupping and visual field loss.

A 250 mm2 ACP device was implanted using the “taco” technique. The flexible plate permitted placement via a minimal conjunctival incision (3–4 mm). The tube was ligated with 6-0 Vicryl suture, and the pre-inserted 4-0 polypropylene ripcord was retained. The plate was sutured 10 mm posterior to the limbus. A 24G needle was used to construct an intrascleral tunnel, and the tube was inserted into the ciliary sulcus in a single pass. A scleral patch graft and conjunctival closure completed the procedure. Throughout, the anterior chamber remained formed and intraoperative hypotony was avoided.

On postoperative day (POD) 1, visual acuity improved to 6/36; IOP measured 10 mmHg. The anterior chamber was well-formed, the tube was well positioned (Figure 1A), and there was no bleb leak (Figure 1B). On POD 3, however, the patient reported a sudden visual decline in perception of light. IOP was maintained at 10 mmHg. A slit-lamp exam revealed a stable anterior chamber without leaks or overfiltration. A yellowish posterior reflection of serous choroidal effusion was visible (Figure 2A). Bright-scan ultrasound (B-scan) confirmed kissing serous choroidals (Figure 2B). Hourly topical prednisolone acetate 1%, oral prednisolone 1 mg/kg, atropine 1%, and antibiotics were initiated.

On POD 9, signs of inflammation had subsided and early resolution of choroidals had begun (Figure 3A). By POD 13, visual acuity improved to 6/60, and the choroidal effusions became progressively more shallow. IOP stabilized at 15 mmHg (Figure 3B). Oral and topical steroids were tapered weekly over the next few weeks. By POD 32, the choroidals were only seen in the periphery of the fundus, and visual acuity had improved to 6/36. IOP remained at 13 mmHg, without anti-glaucoma medication; the tube remained well positioned and the anterior chamber remained stable (Figure 3D). Oral steroids and antibiotics were stopped at this point. At the last postoperative visit, POD 60, visual acuity had improved to 6/18 with complete resolution of the choroidals (Figure 4). Topical steroid and cycloplegic treatments were discontinued. IOP remained stable without antiglaucoma medications. The bleb was healthy and functional. No surgical drainage was required at any point. The rip cord was left intact (Figure 3D).

Discussion

Kissing choroidals represent a rare but vision-threatening complication following GDD implantation [7]. Typically, serous choroidal effusion is attributed to hypotony-induced transudation of plasma into the suprachoroidal space. The condition may be exacerbated in vitrectomized eyes due to diminished posterior segment resistance and compromised ocular rigidity, allowing even minimal pressure drops to precipitate effusion [8]. B-scan can clinch the diagnosis and should be used to differentiate serous from hemorrhagic choroidal detachment. Serous choroidal detachments typically appear as echolucent (dark) areas within the suprachoroidal space, while hemorrhagic choroidal detachments appear as echodense (bright) areas due to the presence of blood. Moreover, hemorrhagic choroidal detachment is almost always associated with elevated IOP, in contrast to serous choroidal detachment which can be associated with low or normal IOP.

The ACP, while valveless, is designed to mitigate such complications through its intraluminal ripcord. Grover et al [9] reported that the ACP achieved a 43% reduction in IOP and 47.7% reduction in medication use at 6 months, with a low hypotony rate (6.7%) – none of which were vision-threatening. Similarly, Boopathiraj et al [6] found no hypotony-related complications over a 36-month period in severe primary open angle glaucoma patients. However, neither study included vitrectomized eyes.

Persistent choroidal effusion can occur in spite of normal IOP. Sakurai et al [10] suggested that chronic ocular inflammation and impaired production, outflow, or circulation of the aqueous humor might cause these complications. Similarly, our patient presented with a kissing choroidal for 9 days, followed by gradual resolution over the next 2 months, in the setting of a normal IOP. However, unlike in the report by Sakurai et al [10], no definitive ocular inflammation was observed during the follow-up period in our case. Importantly, there was also no evidence of overfiltration, peritubal leakage, tube malposition, or bleb leakage (Figure 3C, 3D). The anterior chamber remained formed and intraocular inflammation was minimal, suggesting a controlled egress of aqueous humor. Thus, the effusion likely resulted from altered pressure dynamics in the vitrectomized globe – specifically, decreased posterior tamponade and scleral rigidity leading to a breakdown in hydrostatic equilibrium. Vitrectomized eyes have lower scleral rigidity and diminished posterior segment tamponade, making them more prone to uveal effusion even with slight decreases in IOP [11]. In our case, there was a significant drop in IOP post GDD implantation, augmenting the above phenomenon. The presence of air in the vitreous cavity from recent surgery could have exacerbated this instability, failing to provide adequate posterior pressure against sudden aqueous diversion through the ACP. This case also emphasizes that despite device enhancements, the protection provided by ACP use may be insufficient in eyes with compromised posterior segment support.

The literature supports conservative management in most scenarios. Most serous choroidals resolve spontaneously with medical treatment and IOP normalization. Schrieber and Liu [12] emphasized that conservative approaches (eg, corticosteroids and cycloplegics) often yield better outcomes, in terms of vision, than early surgical drainage. De Barros et al [13] demonstrated that patients treated conservatively for flat anterior chamber and choroidal effusion had significantly better vision outcomes than those who underwent early surgical intervention. Spontaneous resolution of 360-degree peripheral choroidals have been reported even after 9 months [14].

The popular belief has been that surgical drainage should be considered for choroidal effusions that persist despite conservative treatment, especially kissing choroidals. Deciding when to perform surgical intervention can be challenging due to the potential risks involved, and there are currently no established guidelines or consensus regarding the ideal timing. A recent retrospective review of 605 patients who underwent glaucoma drainage implant surgery found that choroidal effusions occurred in 110 eyes (18%), with surgical interventions – such as effusion drainage or implant tube ligation – required in 19 of those eyes (17%). On average, these procedures were performed 49 days after the effusion was first identified. Similarly, WuDunn et al [15] reported a median interval of 47 days between the initial glaucoma surgery and subsequent choroidal drainage. However, in cases of kissing choroidals, immediate surgical intervention is indicated when there is lens-corneal contact or suprachoroidal hemorrhage, to prevent corneal decompensation, retinal adhesion, or detachment, which can result in permanent vision loss.

In the present case, choroidal drainage was not pursued due to the patient’s poor systemic condition and reluctance to undergo further surgery. As the anterior chamber remained well-formed and IOP was stable, no anterior segment procedures were needed. The patient was managed conservatively with medical therapy alone, including topical steroids and atropine. The early normalization of IOP was a positive indicator for observation in this case. By POD 9, the kissing choroidals started regressing, and by month 2, complete spontaneous resolution of choroidal effusion, without any visual impairment, was observed.

In a case like this, we recommend posterior segment pressurization over and above an airtight anterior chamber at the end of filtration surgery, to mitigate the risk of early hypotony. In vitrectomized eyes, which are anatomically prone to effusions, we advocate for intraoperative injection of balanced salt solution (BSS) into the vitreous cavity to augment posterior chamber volume and minimize effusion risk. BSS is a commonly used short-term vitreous substitute with pH and osmolarity isotonic to ocular tissues [16].

Conclusions

This is the first known report of kissing choroidals following ACP implantation in a vitrectomized eye, in the setting of normal IOP. It underscores the importance of tailoring surgical approaches to individual ocular anatomy. The enhanced ripcord feature aids in the controlled egress of aqueous humor. However this protective effect may be limited in anatomically predisposed eyes. Conservative management of cases of kissing choroidals, in the setting of normal IOP, can be done for up to 9 days without perceivable risk of permanent vision loss. Surgeons should anticipate altered pressure dynamics in vitrectomized eyes and, to mitigate the risk, the authors recommend injection of BSS into the vitreous cavity intraoperatively.