Man referred for ongoing discomfort in right eye
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A 61-year-old man was referred to Tufts Medical Center for evaluation of discomfort in his right eye. He reported experiencing dull pain in the eye associated with redness and increased tearing for the past several months.
The patient used artificial tears in the past without significant relief of symptoms. Additionally, he reported “increased fat” beneath his right eye, causing his eye to point upward, and he was unhappy with the appearance. At the time of presentation, the patient denied visual changes in his unaffected left eye and was blind in his right eye since childhood trauma. Systemic review of systems was unremarkable, and his medical history was significant for only benign prostatic hyperplasia.
Source: Jonathan Caranfa, MD, and Alison Callahan, MD
His ocular history was notable for trauma to his right eye when he was hit with a rock at 9 years old, resulting in a total retinal detachment requiring a scleral buckle and subsequent retinal reattachment surgical repair 14 years later. His family history was noncontributory. He had no known drug allergies and denied current use of tobacco, alcohol or recreational drugs.
Examination
Upon examination, visual acuity was no light perception in the right eye and 20/25 without correction in the left eye. The right pupil was irregular and minimally responsive while the left pupil was round, brisk and reactive without relative afferent pupillary defect. Extraocular movements were diffusely limited in all directions in the right eye and full in the left eye. The patient was unable to participate in visual field and color vision testing in the right eye; however, the left eye was full for both examinations. IOP was 4 mm Hg in the right eye and within normal limits in the left eye. The right globe appeared phthisical, but Hertel exophthalmometer measurements were roughly symmetric, with measurements of 21 mm in the right eye and 20 mm in the left eye (base at 95 mm).
Anterior slit lamp examination of the left eye was unremarkable. Examination of the right eye demonstrated a superiorly displaced phthisical globe (hyperglobus) with a palpable inferior orbital mass extending from the lateral to medial canthus (Figure 1). Additionally, mild conjunctival injection and a small blue-tinged mass visible underneath the inferonasal palpebral conjunctiva were noted. The cornea was clear, and the anterior chamber was noted to be deep and quiet. The patient was aphakic as a result of the prior ocular trauma as described above. Posterior pole exam was not performed at the time of initial evaluation.
MRI of the face and orbits T2 postcontrast sequencing revealed a well-circumscribed large tubular hyperintense structure circumferentially wrapping around the right globe with mass effect upon the globe itself in addition to adjacent recti muscles and the lacrimal gland (Figure 2).
What is your diagnosis?
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Inferior orbital mass
The differential diagnosis in a patient with an inferior orbital mass causing hyperglobus must include traumatic, infectious, inflammatory/autoimmune and neoplastic processes.
Given the well-circumscribed appearance, homogenous enhancement and history of prior retinal reattachment surgery with a scleral buckle, this likely represents a hydrolyzed scleral buckle. However, in the absence of definitive imaging or with an unclear clinical history, one must consider and therefore rule out other etiologies such as traumatic foreign bodies and mucoceles in the setting of prior fractures. One must also consider orbital infections such as orbital cellulitis, subperiosteal abscess and invasive sino-orbital fungal disease. Inflammatory etiologies, although less likely, include sarcoidosis, thyroid eye disease, IgG4 orbital disease, granulomatosis with polyangiitis, rheumatoid and nonspecific orbital inflammation. Vascular abnormalities such as cavernous hemangioma, lymphaticovenous malformations and arteriovenous malformations should be considered given the bluish tinge noted clinically. Finally, benign and malignant lesions including dacryops, lymphoma, squamous cell carcinoma, pleomorphic adenoma, schwannoma, carcinoma, and metastatic disease should be ruled out.
Workup and management
In any patient presenting with a suspected orbital mass, it is important to evaluate for infectious, inflammatory, vascular and neoplastic etiologies, as stated above. Initial evaluation should include either CT or MRI of the face and orbits with contrast. The findings on imaging can help tailor a systemic workup, which may include a complete blood count, angiotensin-converting enzyme, lysozyme, thyroid function tests, serum immunoglobulins, pANCA/cANCA, rheumatoid factor and chest X-ray. If the diagnosis is uncertain or imaging findings are concerning for malignancy, then biopsy can be obtained.
To further investigate an underlying systemic malignancy, CT of the chest, abdomen and pelvis or PET scan is often recommended. Benign-appearing lesions are often monitored for changes over time without initial intervention or biopsy.
Discussion
Scleral buckling has been utilized since 1937 for repair of rhegmatogenous retinal detachments. Sealing of the retinal break is accomplished by externally pushing the diathermized choroid, retinal pigment epithelium and sclera closer to the detached retina. Historically, material such as polyethylene was utilized for the scleral buckle; however, small diameter size, chronic infections secondary to the non-absorbable suture in the tube’s lumen and incidence of scleral erosion have caused polyethylene scleral buckles to become antiquated. In 1979, hydrogel scleral buckles (MIRAgel) were introduced as an alternative, touted as superior to traditional polyethylene and silicone buckles given their inert nature, antibiotic penetration, small pore size to reduce microorganism colonization, and the development of a fibrous capsule surrounding the buckle to prevent implant migration.
Despite initial positive results, numerous case reports began to surface of patients requiring hydrogel scleral buckle removal given discomfort and disfigurement from conjunctival bulging, scleral erosion and, in rare cases, intraocular migration of the implant. In 2007, Roldan-Pallares and colleagues published an analysis of 415 patients who underwent scleral buckling with MIRAgel for retinal reattachment, finding that 7.6% required removal 7 years or more after initial placement. The most common cause for buckle removal was redness/discharge (93%) followed by protrusion of the implant behind the eyelid (70%), strabismus, motility disorder or diplopia (67%), extrusion (22%) and orbital fullness/pseudotumor (22%).
Several authors would go on to analyze the surgically explanted hydrogel scleral buckles to understand why these MIRAgel implants failed. Micro-Fourier transform infrared spectroscopy of the hydrogel demonstrated the presence of carboxylic groups indicative of hydrolytic implant breakdown over time. This degradation allowed for additional implant swelling beyond what was expected, up to four times the desired width and thickness. Additionally, the authors found the MIRAgel buckle transformed from a soft, spongy, whitish, compact material to a translucent, gel-like, cream-colored, friable material. Moreover, histological evaluation demonstrated giant cell granulomas around the implant and suture material. Follow-up immunohistochemical analysis was positive for CD3 (T-cell marker) and CD68 (macrophage marker), suggesting that following hydrolytic breakdown of the MIRAgel implant, it is seen by the immune system as a foreign body, leading to a delayed T-cell-mediated immune response and local inflammation, all suggesting that hydrogel is more immunogenic than originally thought. Finally, microscopic breakdown and fragmentation of the overlying fibrous capsule were noted on histopathology in approximately 50% of the explants. This led to a significant increase in hydration, up to 96%, causing the aforementioned clinical findings.
Diagnosis and treatment
The diagnosis of a hydrated scleral buckle is made through clinical history (previous scleral buckle retinal repair between 1972 and 1995) and physical/ocular examination. In many cases, the scleral buckle can be visualized externally via periorbital protrusion or lid elevation, revealing a soft uniform bulging mass underneath the conjunctiva. In rare cases, dilated fundus examination can reveal protrusion, uveal thinning or vitreous migration of the scleral buckle. CT or MRI can aid in the diagnosis, which will demonstrate a well-circumscribed soft tissue mass encircling the globe with decreased attenuation similar to that of fluid (hyperintense on T2-weighted and hypointense on T1-weighted MRI; low-density enhancement with surrounding hyperdense rim on CT). On CT, there is often peripheral mineralization or calcification of the buckle itself, which helps to differentiate a hydrolyzed scleral buckle from other orbital pathologies.
The only effective treatment is surgical removal of the offending scleral buckle. Given the changes in composition of the hydrogel from soft, spongy and compact to translucent, gel-like and friable, explantation often proves difficult as grasping of the buckle with forceps or scissor manipulation causes fragmentation and therefore requires piecemeal removal. In most cases, segmental or 360° conjunctival peritomy with subsequent opening of the fibrous capsule overlying the implant is employed. Removal of the implant can then be achieved by floating the hydrogel material out of the eye using copious amounts of balanced saline solution. Some surgeons propose stabilizing the implant with boric acid or cryotherapy before explantation in order to reduce friability. Finally, Richards and colleagues recommend a “push-pull technique” in which blunt instrumentation such as a muscle hook or Freer elevator is used to break apart the hydrolyzed buckle into sections, followed by manually pulling pieces forward with the same blunt instrument as suction is being applied.
After surgical removal of the buckle, retinal redetachment has been reported in up to one-third of cases. Additionally, given the possibility of progressive scleral thinning from the hydrated buckle, scleral perforation has been reported and poses a serious intraoperative complication.
Clinical course continued
Three months after his initial presentation, the patient underwent scleral buckle removal under the care of a vitreoretinal surgeon. A 360° peritomy with fibrous capsule dissection was performed. The MIRAgel implant was removed in a piecemeal fashion using a Freer elevator and aspiration. During surgical removal, significant scleral thinning was noted temporally with uveal tissue visualized through the sclera; however, perforation did not occur. Immediately after surgery, the patient’s right eye was noted to be more orthotropic with slight restricted gaze medially and laterally.
After removal of the implant, the patient was sent to the oculoplastics department for treatment options for his exophthalmic/phthisical right eye (Figure 3). Therapeutic approaches are geared toward filling out the orbit to improve the cosmetic appearance of the smaller eye. After a long discussion, the patient was advised to seek consultation by an ocularist for prosthetic shell fitting. If the patient cannot tolerate the prosthesis, then he can consider evisceration with implant and prosthesis given the fact that this is a non-seeing eye. Alternatively, although less desirable, orbital floor implant or retrobulbar filler to help push the right eye forward in the orbital socket can be pursued.
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- For more information:
- Edited by Yi Ling Dai, MD, and Teresa P. Horan, MD, of New England Eye Center, Tufts University School of Medicine. They can be reached at ydai@tuftsmedicalcenter.org and thoran@tuftsmedicalcenter.org.