Introduction
A 31-year-old Chinese male presented for a routine examination. Ocular and family history were unremarkable and there was no history of trauma. He denied knowledge of any ocular abnormality. Refractive error was right eye −0.75/-0.25 × 85 and left eye −0.75/-0.25 × 120 with corrected acuities of 6/6 in each eye. Intraocular pressures measured with applanation tonometry were 20 mmHg bilaterally. There was no relative afferent pupillary defect. The anterior segments were unnoteworthy.
Dilated fundoscopy showed a unilateral localised posterior ectasia intimately involving the left optic disc which itself appeared normal with an orthodox vascular pattern, inconsistent with morning glory disc anomaly, and no evidence of coloboma (). The right fundus was unremarkable.
Figure 1. Drsplus colour fundus images. A: unexceptional right optic disc. B: the left optic disc lies slightly decentred at the base of a peripapillary staphyloma. Pigmentary changes involving the walls and inferotemporal margin of the ectasia are evident.
Ocular coherence tomography confirmed the ectasia (). The macular anatomy was unaffected although attenuation of the retinal layers between the macula and optic disc was evident.
Figure 2. Zeiss Cirrus 6000 ocular coherence tomography scan of the left eye delineating the posterior ectasia and macula. Asterix denotes the nasal disc margin.
Standard automated perimetry, using the SITA Faster algorithm, showed an enlarged blindspot and a modest reduction in the centrocecal threshold values in the affected eye (). A diagnosis of left peripapillary staphyloma was made.
Figure 3. Left eye central 24–2 Threshold visual field test displaying an enlarged blindspot and a reduction in the centrocecal threshold values.
Peripapillary staphyloma (Curtin’s staphyloma classification Type III) is the rarest morphological variant of the congenital posterior ectasias.Citation1 Curtin identified this form in only one and a half per cent of staphylomatous eyes. It typically presents as an isolated, unilateral finding with visual acuity worse than 6/60. While bilateral cases are seen, only a few eyes have ever been reported with acuities better than 6/60.Citation2–5 In the largest case series of 19 patients reported by Kim et al.Citation2 only two eyes achieved corrected acuities better than 6/60 at 6/30 and 6/9. Two patients had bilateral peripapillary staphylomas. No patient had a familial history of optic disc anomalies and the disorder is considered nonhereditary.Citation2 Involved eyes are usually emmetropic or manifest low myopia though high myopia has been reported in one third of eyes.Citation2,Citation6 Atrophic alterations in the retinal pigment epithelium and choroid may involve the sides and margin of the staphyloma.Citation6 The defect is believed to result from the developmental compromise of the posterior sclera from the neural crest cells around the fifth month of gestation.Citation6
Although peripapillary staphyloma typically presents as a solitary anomaly, associated ocular abnormalities and complications have been reported including congenital cataract, microphthalmia, persistent primary hyperplastic vitreous, retinal detachment and acquired cataract.Citation2 Peripapillary staphyloma is seldom associated with systemic abnormalities.Citation2
Differential diagnoses include the other congenital excavated optic disc pathologies, morning glory disc anomaly and coloboma, and can ordinarily be made on the basis of the fundus appearance. Morning glory disc anomaly is characterised by an enlarged optic disc lying within the margins of a funnel shaped peripapillary excavation. Glial tissue overlies the central aspect of the optic disc and the blood vessels emanate from the margins of the optic disc. In optic disc coloboma the excavated defect lies within the confines of the optic papilla. Iris or retinal coloboma frequently accompany optic disc coloboma and there are often systemic associations.
This case was particularly noteworthy given the normal visual acuity of the involved eye which is an extremely rare finding in this condition.
The patient’s permission to use their images was obtained.
Disclosure statement
No potential conflict of interest was reported by the author(s).
References
- Curtin BJ. The posterior staphyloma of pathologic myopia. Trans Am Ophthalmol Soc 1977; 75: 67–86.
- Kim SH, Choi MY, Yu YS et al. Peripapillary staphyloma: clinical features and visual outcome in 19 cases. Arch Ophthalmol 2005; 123: 1371–1375. doi: 10.1001/archopht.123.10.1371.
- Blair MP, Blair NP, Rheinstrom SD et al. A case of peripapillary staphyloma. Arch Ophthalmol 2000; 118: 1138–1139. doi: 10.1001/archopht.118.8.1138.
- Caldwell JBH, Sears ML, Gilman M. Bilateral peripapillary staphyloma with normal vision. Am J Ophthalmol 1971; 71: 423–425. doi: 10.1016/0002-9394(71)90421-1.
- Webber A, Prior C, Vingrys AJ. Peripapillary staphyloma. Clin Exp Optom 1992; 75: 220–230. doi: 10.1111/j.1444-0938.1992.tb00769.x.
- Brodsky MC. Congenital optic disk anomalies. Surv Ophthalmol 1994; 39: 89–112. doi: 10.1016/0039-6257(94)90155-4.