Bilateral peripapillary staphyloma, a clinicoradiological report

Peripapillary staphyloma is a rare non‐hereditary congenital anomaly characterised by a relatively normal appearing optic nerve head located at the base of a staphylomatous excavation.¹,²,³ It is generally not associated with other congenital defects or systemic diseases.¹

Peripapillary staphyloma is generally unilateral with bilateral cases being extremely rare.⁴,⁵,⁶ To the best of our knowledge, there is no previous report of neuroimaging findings in peripapillary staphyloma. We report a case of bilateral peripapillary staphyloma with the magnetic resonance imaging (MRI) findings.

Case report

An 11 month old boy was referred to the neuro‐ophthalmology clinic by an ophthalmologist because of a suspected optic nerve mass noted on MRI. The patient was born to non‐consanguineous parents at 39 weeks of gestational age with a birth weight of 2800 g. The neonatal period was unremarkable. Development, other than ocular findings was normal. The boy was the first child of his parents and there was no history of significant ocular disease in his family. His parents' ocular examinations were normal.

Systemic physical examination including weight, length, and head circumference were normal for his age. Neurological examination was also normal except for vision.

He could only fix with his right eye. The eyes were orthotropic by Hirschberg examination. Cycloplegic refraction was −4.00 RE and −4.00 −2.5×180 LE. Slit lamp evaluation of both eyes was normal. Funduscopic examination (fig 1) revealed a deep posterior excavation with a normal appearing optic nerve head at its base in both eyes. Retinal vasculature was normal in both eyes. There was marked retinal pigment epithelium alteration surrounding the staphyloma especially in the left eye. No retinochoroidal coloboma was present.

Figure 1 Fundus photograph of right (A) and left (B) eyes, showing peripapillary staphyloma with surrounding mottled pigment epithelium and choroids. Normal appearing optic disc is located at the base of staphyloma. Retinal vessels are normal in number and distribution, emerging from the centre of the disc.

MRI of the orbits (fig 2) disclosed a deep excavation of posterior wall of the globe with connection to the vitreous cavity without any structural deformity of other parts of the globe.

Figure 2 T1 weighted axial without contrast (top left), T2 weighted axial (top right), T1 weighted axial with contrast (bottom left), and T1 weighted sagittal view (bottom right) of MRI show a posterior excavation of the globe connected to the vitreous cavity with sharp borders and no enhancement on both eyes, which are compatible with a bilateral peripapillary staphyloma.

Comment

Peripapillary staphyloma denotes deep fundus excavation surrounding a relatively normal appearing optic disc with normal retinal vasculature and without any retinochoroidal coloboma.¹,⁶ The pathogenesis remains speculative. It is thought to be the result of a developmental failure of the posterior sclera from neural crest cells occurring near the fifth month of gestation.¹,⁷ Peripapillary staphyloma is generally unilateral with only four bilateral cases reported previously.⁴,⁵,⁶ The staphylomatous depth varies in size, ranging up to about 10 mm with the fovea often involved by the excavation.⁶

Peripapillary staphyloma is often confused with other excavated congenital optic disc anomalies. In an optic disc coloboma, the optic disc itself is excavated while surrounding inferonasal retinochoroidal or iris tissue defects may also be present. In morning glory disc anomaly, the excavation may be shallower, cone‐shaped and containing a centrally located peripapillary glial tuft. In addition, the optic disc may be anomalously. As opposed to the central origin of vessels in peripapillary staphyloma, in morning glory syndrome, the vessels radiate more distinctly from the disc periphery. Other vascular anomalies such as moyamoya disease affecting the carotid arteries, as well as pituitary hormone insufficiencies may be present in morning glory syndrome.⁸,⁹,¹⁰

Our patient had been referred for evaluation of a suspected optic nerve mass noted on MRI. Detailed examination of the fundi, however, revealed a bilateral peripapillary staphyloma. Furthermore, MRI findings, including the posterior scleral location and connection of the presumed “mass” with the vitreous cavity, associated with sharp internal and external margins, with absence of pathological enhancement all highlighted a peripapillary staphyloma.

Eyes with peripapillary staphyloma may sometimes achieve visual improvement by occlusion therapy, but compliance and visual outcome is often poor.⁶ Often macular involvement or “capture” by the staphyloma is present, limiting final visual outcome. A few reports of retinal detachment associated with peripapillary staphyloma have been published.²,⁶ A complete ophthalmic examination and regular follow ups are therefore necessary because of associated ocular disease and refractive errors. Unlike in patients with morning glory anomaly, however, MRI is unnecessary.