Vitreous occlusion of tube implant in a phakic patient with traumatic glaucoma.

Tube implants or glaucoma drainage devices have become an important method of intraocular pressure reduction when treating complex cases of traumatic glaucoma. However, it is not uncommon to have complications associated with tube implants. The optimal treatment of patients who have undergone glaucoma implant surgery complicated by vitreous incarceration is uncertain. If vitreous is present or is able to prolapse into anterior chamber, as in aphakic or pseudophakic patient without an intact posterior capsule, a concurrent anterior vitrectomy is usually performed. In such cases, pars plana vitrectomy has been found to be more effective in several studies. However, there are no set guidelines for management of such a case in a phakic eye and the management can be more challenging especially when there is no obvious deficiency in posterior capsule, zonular dialysis, or loose vitreous gel in the anterior chamber prior to or during tube implantation. We describe a case of 14-year-old phakic patient with traumatic glaucoma without vitreous gel in anterior chamber whose tube implant became occluded by vitreous resulting in increased intra ocular pressure. This is the first documented report of vitreous incarceration in a phakic patient and its successful management.

Introduction

Tube implants or glaucoma drainage devices (GDD) have become an important method of intraocular pressure reduction when treating complex cases of traumatic glaucoma.[12] However, GDD implantation is not without complications like hypotony, choroidal effusion, suprachoroidal hemorrhage, endophthalmitis, tube exposure and its occlusion by blood, fibrin, iris, or vitreous. Since there is no set guidelines for management of such complications, treatment needs to be individualized. Here, we report an unforeseen complication of vitreous incarceration following Ahmed Glaucoma Valve (AGV) implantation in a case of traumatic glaucoma.

Case Report

A 14-year-old male presented to us in 2008 following blunt trauma to right eye with cricket ball with complaints of severe pain, redness, and marked diminution of vision. There was no history of any systemic disease or blood disorders.

On examination, the left eye was essentially within normal limits. The vision in the right eye was decreased to perception of light with an Intraocular pressure (IOP) of 50 mm Hg. There was presence of corneal epithelial edema and diffuse hyphema. The pupil was irregular, semi dilated, and sluggishly reacting to light with multiple sphincter tears present superiorly. The rest of the anterior segment view was hazy on day 1. B scan showed signs of vitreous hemorrhage. Treatment was initiated in the form of tablet acetazolamide, timolol maleate 0.5%, cycloplegics, topical, and systemic corticosteroids. On day 4, hyphema had cleared sufficiently and examination showed presence of mild inferior iridodonesis [Figure 1]. However, there was no obvious zonular dehiscence or vitreous prolapse. The IOP was still high at 46 mm Hg. Consequently, the treatment was stepped up to maximal medical treatment (MMT). At the end of third week, vision had improved to 6/18; however, IOP still remained uncontrolled. Gonioscopy revealed angle recession extending to 180 degrees. The vitreous hemorrhage had significantly cleared by then and fundus examination revealed a cup disc ratio of 0.5:1. In view of uncontrolled IOP on MMT, we decided to intervene surgically. AGV implantation in the superotemporal quadrant proceeded routinely without any complications. On first post-operative day, IOP decreased to 8 mm Hg but on the fourth day, IOP again rose to 52 mm Hg with a band of vitreous blocking the tube, coming from the site inferiorly where mild iridodonesis was noticed [Figure 2]. Nd: YAG laser vitreolysis was attempted with Zeiss Visulas Yag II laser system. However, the IOP remained high. Vitreoretinal consultation was sought at this stage. Anterior vitrectomy was successfully performed using a 23G vitrectomy cutter via corneal approach followed by an attempt to disengage the vitreous incarcerated in tube using active suction and pulling the tag from lumen using end gripping forceps [Figure 3]. At 3-years follow up, IOP was 16 mm Hg with well-formed bleb, vision was 6/9 with stable disc, and visual fields [Figure 4]. So far, there have been no recurrences of vitreous incarceration or posterior segment complication [Figure 5].

Figure 1

Figure showing area of inferior irididonesis with suspected zonular dehiscence, no vitreous prolapse

Figure 2

Vitreous strand from behind the lens blocking the lumen of the tube

Figure 3

After vitrectomy, the tube was cleared of vitreous. Few vitreous strands were seen inferiorly in anterior chamber away from the tube

Figure 4

Follow-up at 3 years showing patent tube and well formed anterior chamber

Figure 5

At last follow-up, bleb was well formed and functional

Discussion

Traumatic glaucoma encompasses a spectrum of disease which can include damage to lens, zonules, peripheral retina, choroid, and macula and needs to be evaluated on individual basis. The barrier to success of trabeculectomy in children include a thick and active Tenon's capsule, a rapid wound healing response, and high risk of bleb-related infections.[3]

The GDD, however, maintains a channel for aqueous flow in the setting of exuberant fibrovascular wound healing and improves the surgical prognosis. GDD surgery avoids the development of a thin, avascular, filtering bleb associated with trabeculectomy, and Mitomycin-C, which may minimize the risk of delayed infection.

We acknowledge that GDD implantation is not without complications.[45] Desatnik et al. reported that vitreous incarceration in implant tubes occurred despite six of the series of eight eyes having previous anterior vitrectomy and concluded that anterior vitrectomy was insufficient in preventing vitreous occlusion in aphakic or pseudophakic eyes with deficient posterior capsule. However, in these eyes, the implant was either inserted into vitreous cavity or the vitreous was already present in the anterior chamber.[6] Since there was no obvious zonular dehiscence or vitreous in anterior chamber before and during surgery in our case, we did not perform anterior vitrectomy primarily. Desatnik et al. also reported that even when vitreous is not present in anterior chamber preoperatively, it can prolapse through an open or absent post capsule, particularly if choroidal effusion or haemorrhage reduces the vitreous cavity volume and displaces residual vitreous gel forward into anterior chamber.[6] However, the possibility of such an occurrence was remote in our case as there was minimal residual vitreous hemorrhage.

According to Y. Fernandez Barrientos et al., the presence of tube/stent modifies the physiological flow of aqueous with diversion of flow towards its lumen.[7] The tube in our case was directed inferiorly towards the site of suspected zonular dehiscence, which could have attracted the vitreous towards its lumen especially in presence of low IOP. So, we recommend that the direction and placement of the tube should be away from the site of suspected zonular dehiscence.

The optimal treatment of patients who have undergone glaucoma implant surgery complicated by vitreous incarceration is uncertain. Nd: YAG vitreolysis has been described by various authors with variable results.[89] We also attempted laser viteolysis without success. Combined glaucoma implant surgery and parsplana vitrectomy (PPV) has been reported to be safe and effective in controlling IOP and preventing tube occlusion with vitreous gel in aphakic and pseudophakic eyes without an intact posterior capsule and with vitreous prolapse in anterior chamber.[5] However, in pseudophakic patients without loose gel in anterior chamber, a concurrent PPV is not recommended as primary procedure. Since our patient was phakic and having good visual acuity, we decided to perform anterior vitrectomy with thorough cutting of vitreous strands in and around the tube taking utmost care not to touch the clear lens instead of PPV. In complex glaucomas, the complications may arise with GDD, but if treated timely with vigilance, most of it can be managed with a favourable prognosis. The treatment, therefore, should be individualized depending on the extent of damage and the visual prognosis.