Hydrogel episcleral exoplants (MIRAgel, MIRA Inc., Waltham, Massachusetts) were approved for use in the 1980s, for scleral buckle surgery. These exoplants were soft and elastic and were thought to have the advantage of decreased erosion. Furthermore, the small pores of the hydrogel exoplants were thought to be impenetrable to bacteria, while allowing the gradual release of antibiotics, thus minimizing the risk of infection.
While hydrogel exoplants were well-tolerated in the short-term, several authors have described the late complication of exoplant extrusion requiring explantation.[2–5] Roldan-Pallares and colleagues described buckle swelling from the hydrolytic degradation of MIRAgel exoplants. At an average of 15.5 years follow-up, they noted that 6.5% (27 of 415) required removal. Le Rouic and colleagues reported an average duration of 7.7 years between MIRAgel implantation and necessary explantation. Kawano and colleagues reported a case of hydrogel exoplant extrusion and fragmentation into the eyelid; only part of the exoplant could be removed due to fibrous encapsulation. Kearney and colleagues reported that 5 of 17 eyes (29%) developed recurrent retinal detachment after MIRAgel explantation.
Herein we describe a case of progressive diplopia and upper eyelid mass many years after placement of a hydrogel exoplant. Hydrogel expansion and extrusion is often difficult to manage due to the friability of the material. The patient underwent successful surgical removal of the entire hydrogel exoplant, however, some diplopia persisted.
A 43-year-old woman described a three-year history of progressive left upper lid swelling and ptosis. Her primary ophthalmologist treated her for a presumed chalazion with warm compresses and various ointments. She sought a second opinion at Wills Eye Institute. She denied loss of visual acuity, but noted progressive diplopia with eccentric gaze over the last several years. Sixteen years prior to presentation (1992) she had undergone placement of a scleral buckle for repair of rhegmatogenous retinal detachment, associated with high myopia. On examination, visual acuity measured 20/100 in the right eye and 20/400 in the left eye. External examination of the left upper eyelid revealed a firm, non-mobile subcutaneous lesion split into two pieces [Fig. 1]. Extraocular motility of the left eye was limited in all gazes, most notably in upgaze and abduction [Fig. 2]. An ocular examination revealed normal anterior segments and attached retinas with moderate myopic degeneration bilaterally. Of note, there was no buckle indentation in the left eye.
We diagnosed an anteriorly extruded scleral buckle, probably one composed of hydrogel. The patient underwent surgical removal of the buckle via an anterior orbitotomy. A lid crease incision was made with care to dissect into the orbit. The extruded hydrogel exoplant was located posterior to the orbital septum and was encased in a fibrotic capsule. The buckle proved to be a friable MIRAgel exoplant [Fig. 3] that was found in situ to be fragmented into two large pieces, which enabled it to migrate anterior to the superior rectus. It is possible that the hydrogel element migrated directly through the superior rectus. Dehiscence of the levator palpebrae allowed further migration anteriorly into the eyelid. The superior rectus and levator palpebrae were fibrotic, explaining the patient's decreased upgaze and ptosis. The hydrogel exoplant was removed in its entirety along with much of its fibrous capsule. Postoperatively, the patient no longer had an eyelid mass. Her ptosis and diplopia improved slightly, and her retina remained attached one year after surgery.
We describe a case of an extruded hydrogel episcleral exoplant manifesting as a large subcutaneous upper eyelid mass with diplopia and ptosis. The hydrogel exoplant required surgical explantation 16 years after initial scleral buckle surgery. The exoplant appeared to have migrated around the superior rectus and dehisced the levator palpebrae, leaving both muscles fibrotic; the exoplant remained encapsulated posterior to the orbital septum. The hydrogel exoplant was removed in its entirety via anterior orbitotomy through the upper eyelid crease. Although the retina remained attached, the patient's diplopia and ptosis persisted. Given the relatively high incidence of complications associated with the MIRAgel exoplants, they were discontinued by the manufacturer around 1994.
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2. Roldán-Pallarés M, Hernández-Montero J, Llanes F, Fernández-Rubio JE, Ortega F. MIRAgel: Hydrolytic degradation and long-term observations Arch Ophthalmol. 2007;125:511–4
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