Diagnosis

Regarding the anterior segment status, corneal topography confirmed a diagnosis of keratoconus. Careful examination of the fundus revealed a superotemporal optic pit OD with fluid extending into the superonasal macula and a central spoke-like appearance of the fovea; OS was normal with absence of an optic pit (Figure 1). OCT confirmed the presence of intraretinal (both inner and outer retinal) fluid extending from the pit into the fovea OD with no fluid present OS (Figure 2). A diagnosis of ODP-M was made.

ODPs are rare congenital optic nerve anomalies that were first described by Wiethe in 1882.^1,2 The reported incidence is less than one in 10,000 and over 85% are noted to be unilateral in presentation with no racial or sex predilections.^1,2 The presence of optic disc pits appears to be sporadic with no associated genetic variant.^1,3 An acquired etiology has also been described in patients with (normal tension) glaucoma, producing a peripapillary retinoschisis appearance on OCT.⁴

Clinically, ODPs present as gray-brown, round-oval depressions found most frequently at the temporal or inferotemporal disc margin measuring approximately one-eighth to one-fourth disc diameter; central and nasal pits are less likely to produce maculopathy.^1,3,5,6 Affected patients are generally asymptomatic in the absence of maculopathy, though reports suggest that ODP-M occurs in up to 75% of patients with ODP.^1,3 Patients with ODP-M are most likely to present during the third to fourth decade of life (mean age of 31 years) with an average VA of 20/70 or worse.^1,7 Serous retinal detachments are generally confined within the temporal arcades.²

While the exact pathophysiology of ODP-M is not well understood, the leading theories are a communication between the vitreous cavity and subretinal space, between the subretinal and subarachnoid spaces or a three-fold vitreous-subretinal-subaracahnoid fistula.⁴ Gass reviewed a histopathological specimen of an enucleated globe with ODP-M and found a somewhat fibrous capsule over the pit, theorizing this could present a barrier into the intra- and subretinal spaces.⁴ As he also was unable to identify vitreous glycosaminoglycans within the optic pit or the macular fluid, he postulated that cerebrospinal fluid would be most likely to enter the subretinal space through bypassing the pit’s fibrous capsule and approaching either between the capsule and scleral rim or by entering directly beneath invaginated neuroectodermal tissue.^1,4

The hypothesis of vitreous subarachnoid fistulization was supported by documented migration of silicone oil from the vitreous cavity into both the subretinal space and intracranial cavity.^1,4 There is also a consensus that vitreous traction likely plays a mechanistic role in the development of maculopathy, suggesting that treatments targeted at relieving traction may subsequently resolve the serous detachments.^1,2

OCT is perhaps the most useful imaging modality for evaluating these patients, as fluid generally accumulates to produce a schisis-like cavity within the inner retina first, followed by the outer retina; this correlates with the clinical spoke-like appearance.² However, there are reports of patients presenting with combined outer-retinal schisis and subretinal fluid, notably without inner-retinal schisis.² It has been suggested that chronic outer-retinal schisis eventually results in lamellar hole formation, which provides an alternative pathway for the accumulation of subretinal fluid.^1,2,8