Large orbital masses due to longstanding hydrogel retinal explants

Abstract

Aim

To describe the features of orbital masses occurring as a late complication of hydrogel retinal explants.

Patients and methods

Retrospective review of patients presenting with orbital masses at decades after retinal surgery.

Results

Two patients with huge orbital masses are described, their presenting 25 and 28 years after retinal detachment repair with expansile hydrogel explants. In one case, the preoperative diagnosis was pleomorphic adenoma, and the other—with extreme distortion of the globe—was considered to be lymphoma or chronic inflammation arising around prior retinal explants. At orbitotomy, the masses were found to be grossly expanded hydrogel explants that were removed piecemeal from their fibrous capsules. Histopathology showed very mild inflammation with occasional multinucleate giant cells and patchy capsular calcification, and an eosinophilic amorphous material staining strongly with Alcian-blue. Surgery was uncomplicated and both orbits healed with marked functional improvement.

Conclusion

Expansile hydrogel retinal explants were largely used in the 1980s and can present, often decades after the retinal surgery, with impaired orbital functions due to large parabulbar masses. The hydrophilic material appears to expand very slowly over decades, leading to gross distortion of neighbouring structures and a tumour-like mass.

Introduction

Hydrogel scleral explants (MIRAgel®; MIRA Inc., Waltham, MA) were introduced in 1979, their pliability and ability to absorb antibiotics being thought to reduce scleral erosion and infection [1, 2]. The explants appeared to be well tolerated with up to 2 years follow-up [3], but severe complications—due to long-term hydrolysis and explant expansion—led to their withdrawal in the mid-1990s [4], and continued recent reports of their complications [5].

MIRAgel explants were widely used in North America, where their complications are well-recognised, but relatively infrequently in the United Kingdom. We describe two patients who underwent retinal detachment surgery 25 and 20 years prior to presenting with large tumour-like orbital masses.

This study conformed to the Tenets of the Declaration of Helsinki, and permission to publish clinical images is held by the authors. Study data is held at Moorfields Eye Hospital and is not available in the public domain.

Case reports

Case 1

An 83-year-old female presented with mild chronic right periocular and frontal ache, together with intermittent right upper eyelid erythema, swelling and tenderness. At age 55, she had undergone repair of an ipsilateral retinal detachment in New Zealand. Her presenting acuities were 6/9 in each eye, with normal colour perception and no relative afferent pupillary defect; intraocular examination was unremarkable apart from evidence of prior retinal detachment. A firm, fixed mass in the right lacrimal gland fossa was causing hypoglobus, slight blepharoptosis, and restriction of supraduction and abduction.

Imaging revealed localised flattening of the globe due to a well-defined, low-density, ovoid mass in a slightly expanded right lacrimal gland fossa (Fig. 1A, B), a diagnosis of pleomorphic adenoma being considered. Through an upper-lid skin-crease incision, an encapsulated gelatinous mass was found abutting the globe and displacing residual lacrimal gland. The mass was removed piecemeal (Fig. 2A) and histology showed mild chronic inflammation around an amorphous material, with strong Alcian-blue staining, and occasional multinucleate giant cells (Fig. 2B).

Fig. 1. Imaging and histology for patients with hydrogel orbital masses.

A, B (Case 1) Computerised tomography (CT) suggestive of an ovoid mass in the orbital lobe of the right lacrimal gland, with some flattening of the globe and very subtle remodelling of the bony lacrimal gland fossa. C–F (Case 2) CT scans show a grossly distorted left globe, displaced supero-nasally cloaked by a mass with soft-tissue radiolucency; the mass surrounds a silicone retinal band (arrow-heads) and silicone plate (arrows in 1C & 1F). There is a patch of calcification on the posterior pole of the “soft-tissue” mass (dark highlight in 1D).

Fig. 2. Surgical appearance for 2 patients during excision of hydrogel orbital masses.

(Case 1) A Piecemeal removal of hydrogel material, with histology showing (B) large amounts of slightly “bubbly”, eosinophilic amorphous material, with a very sparse chronic inflammatory cell infiltrate (Haematoxylin & Eosin, x200); the material was positive for Alcian-blue staining. (Case 2) (C) 64-year-old woman presenting with a slowly-progressive left orbital mass, about 25 years after retinal detachment repair. (D) Transconjunctival exploration revealed an encapsulated mass, (E) from which hydrogel emerged under pressure and was excised piecemeal (F, G).

Surgery was without complication, and the patient remains asymptomatic with no restriction of orbital functions.

Case 2

Although the patient had noted left globe displacement for ~15 years, a 64-year-old female was referred with recent periocular pain and appearance of a subconjunctival mass (Fig. 2C). She had retinal detachment surgery in the UK after injury 25 years before referral. The patient had acuities of 6/6 right and perception of light on the left, with a dense left relative afferent pupillary defect. The eyelids were swollen and slightly tender, and the scarred left globe was displaced supero-medially by a large blue-grey subconjunctival mass with conjunctival hyperaemia and chemosis; motility was severely impaired. A preoperative diagnosis of lymphoma, or explant-associated chronic inflammation was considered likely.

Computerised tomography showed a grossly-distorted left globe, displaced by huge lobulated masses of soft-tissue (Fig. 1C–F). Silicone explants were visible, with some patchy marginal calcification present posteriorly (Fig. 1D), and imaging also suggested a degree of lateral bony remodelling (Fig. 1C).

Approached through an infero-temporal conjunctival peritomy, the encapsulated mass (Fig. 2D) was bulging with copious gelatinous material (Fig. 2E) that was completely removed (Fig. 2F, G), together with all silicone banding. Surgery was uncomplicated, with marked improvement in orbital signs and resolution of the chronic pain. Histology confirmed the hydrogel material, with strong Alcian-blue staining, and a very mild chronic inflammatory response in the surrounding fibrous capsule.

Discussion

Expansile hydrogel explants for scleral buckling were introduced in North America in the 1980s, in the belief that the soft material could absorb antibiotic solutions (thereby decreasing postoperative infections), and that early postoperative swelling of the material would enhance scleral indentation [4]. The hydrogel explants have been variously used for localised meridional buckling, as an intrascleral implant (with or without silicone encirclage), or as an episcleral buckle with or without encirclage [3]. Expansion due to early hydration of the hydrogel implant was well-tolerated; however, a plethora of late complications started being reported about 10 years later, most of these from North America (where usage was frequent) [4, 5]. Late complications include chronic pain, ocular dysmotility or diplopia [5, 6], progressive tissue distortion by an orbital mass [6], implant infection or extrusion [5], and optic neuropathy [2]; intraocular complications include chronic macular oedema [7], irreversible intraocular pressure elevation [8], and implant erosion into the globe [9].

The extremely slow expansion of hydrogel explants can simulate orbital or eyelid tumours [5, 6, 10], lead to orbital expansion [11], or sinus and intracranial erosion [12]. As imaging showed slight bony orbital expansion in the presence of smooth-edged orbital masses, our patients were both thought to have slow-growing tumours. Although there was considerable scleral thinning under the explants, complete piecemeal removal of the hydrogel material was not difficult, and both patients’ symptoms settled after explant removal.

Summary

What was known before

• Hydrogel (MIRAgel) explants for retinal detachment repair were popular in the 1980s, with a low early rate of complication.

• A large number of extremely varied late complications of MIRAgel explants became evident after about 10 years, the device being withdrawn from use in the mid-1990s.

• Whilst these complications are well reported in the North American literature, the relatively low usage of the device in the United Kingdom renders such cases very rare.

What this study adds

• Two patients presenting with slowly-growing orbital masses are reported, these masses distortion of the globe and expansion of the bony orbit.

• MIRAgel explants have been unavailable for ~25 years and, taken together with relatively sparse usage of them in the U.K., the possibility of massively-expanded hydrogel explants was not the primary preoperative diagnosis in our patients.

• Where there is a very remote history of retinal detachment surgery, the possibility of expanding hydrogel explants should be entertained in any patient with a slowly-growing parabulbar mass.

Author contributions

GER initiated the work; all authors contributed to patient care, data acquisition and manuscript preparation.

Competing interests

The authors declare no competing interests.