Occult optic disc pit: Clinical observations and multimodal imaging correlates

INTRODUCTION

An optic disc pit is a rare congenital excavation of the optic nerve head. Although classically visible on clinical examination, a subset of patients may harbor occult disc pits, where the pit is not readily identifiable. These patients often present with chronic maculopathy, visual decline, and are frequently misdiagnosed with disorders such as central serous chorioretinopathy.^[1] Recent literature highlights the importance of optical coherence tomography-based detection, particularly using dense raster scanning and radial disc imaging, for identifying cavitations and micro-breaks in cases lacking a clinically evident pit. This report describes a young patient with an occult disc pit presenting atypically, emphasizing the value of multimodal imaging in establishing the diagnosis.

CASE REPORT

A 28-year-old male, previously diagnosed with amblyopia of the right eye, presented for evaluation. His best-corrected visual acuity was 6/12 (0.3 logMAR) in the right eye and 6/6 (0 logMAR) in the left eye. Anterior segment examination of both eyes was normal; however, fundus evaluation of the right eye revealed peripapillary hyperpigmentation, temporal disc pigmentary changes, and subtle macular alterations [Figure 1a]. The initial impression suggested central serous chorioretinopathy; however, the absence of risk factors and extension of fluid to the disc on optical coherence tomography, prompted further scrutiny. On examination, a prominent incongruity was found in optic disc size (right eye > left eye) with peri-papillary pigmentary changes. This raised suspicion of occult optic disc pit maculopathy. Fundus autofluorescence demonstrated a fluid tract extending toward the optic disc [Figure 1b]. Dense raster macular optical coherence tomography (OCT) showed ellipsoid zone-external limiting membrane disruption without schisis cavities or neurosensory detachment [Figure 1c]. Enhanced depth imaging (EDI) OCT with a 30° radial scan through the optic nerve head demonstrated temporal cavitations and a focal breach in the overlying tissue, consistent with an occult optic disc pit [Figure 1d], explaining the patient’s persistent visual reduction. Ganglion cell layer analysis was normal, ruling out glaucomatous optic neuropathy.

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Figure 1: (a) Ultra-widefield imaging of the right eye showing macular hypopigmentation and temporal peripapillary changes. (b) Fundus autofluorescence demonstrating a fluid tract. (c) Macular optical coherence tomography (OCT) line scan showing ellipsoid zone–external limiting membrane disruption. (d) Enhanced depth imaging OCT radial disc scan revealing temporal optic nerve head cavitation with a focal breach, confirming occult optic disc pit.

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DISCUSSION

Optic disc pits are rare congenital cavitary anomalies of the optic nerve head, with an estimated prevalence of ~1 in 10,000, and maculopathy develops in up to half of the affected eyes.^[1,2] Optic disc pit maculopathy (ODP-M) is characterized by the presence of serous macular detachment, which may occur with or without associated retinoschisis, in the context of a clinically identifiable optic disc pit. However, contemporary reviews emphasize that ODP-M actually lies on a broader spectrum of cavitary optic disc anomalies, in which the anatomical defect may be subtle, masked or even clinically invisible, and detectable only on high-resolution OCT.^[1-4] Our case fits at the very “occult” end of this spectrum: no obvious pit clinically, no macular detachment or schisis, but clear temporal disc cavitation with a focal breach and secondary photoreceptor damage on enhanced-depth OCT.

Recent literature has substantially refined the concept of “occult” or “subclinical” disc pits. Hedels and Krohn first used EDI-OCT to show peripapillary cavitations and lamina-cribrosa level defects in eyes with disc-related maculopathy but no visible pit, highlighting that the structural anomaly may lie deep and temporally rather than as a classic gray depression at the clinically visible disc margin.^[5] Esmaeil et al. further synthesized this into a unifying framework of congenital optic disc pits and related anomalies, stressing that multimodal imaging, EDI-OCT, swept-source OCT and OCT-angiography often reveal a complex of cavitations, membranes and channels that are not appreciated ophthalmoscopically.^[1,2] Our case illustrates this evolution in thinking: what would previously have been labeled “amblyopia with nonspecific macular changes” is now recognizable as occult ODP-related structural damage, once the disc is interrogated with targeted radial EDI-OCT. A key teaching point from this case is where to look and how to scan when clinical suspicion is high, but the disc appears normal. Banerjee et al. demonstrated that narrow-band (high-density) raster scans centered on the optic disc dramatically increase the detection of tiny pits and temporal cavitations compared with routine macular line scans.^[6] They advocate a deliberate protocol: (i) High-density horizontal/ vertical raster through the disc and (ii) multiple radial scans, especially in eyes with unexplained maculopathy or disc asymmetry.^[6]

Our imaging protocol aligned with this strategy 30° radial EDI-OCT centered on the disc, revealing a temporal cavitation with a focal tissue breach that was not evident clinically. This supports the growing consensus that disc-centered high-density OCT should be standard in any “unexplained” macular pathology with disc-size asymmetry or peripapillary pigmentary changes.^[1,4,6]

The spectrum of “optic disc-related maculopathies without a visible pit” has been characterized by Fujimoto et al. as no optic pit retinoschisis (NOPIR), where peripapillary and macular retinoschisis occur in eyes lacking both a clinically evident pit and advanced glaucomatous cupping.^[7] Their series suggests that microscopic disc defects and cavitations can facilitate fluid migration even when the classical pit is absent, and that surgery may yield faster anatomical recovery in fovea-involving cases.^[7]

Our patient differs in that there was no schisis or serous detachment, only EZ–ELM disruption; nevertheless, the underlying mechanism, occult disc cavitation and focal breach, is conceptually similar to the NOPIR spectrum. This case, therefore, extends the phenotype further: ODP-related damage may present purely as chronic outer retinal disruption without overt fluid accumulation, especially in patients mislabeled as amblyopic from childhood.

Another important dimension is the relationship between cavitary disc anomalies and glaucoma. Pandit et al. described “double trouble,” where advanced glaucomatous cupping masked an underlying disc pit, and ODP-M was diagnosed only when OCT revealed cavitation and macular fluid.^[8] Earlier reports have also described occult ODP-M in glaucomatous discs, where deep cupping, peripapillary atrophy, and intrachoroidal cavitation make pit recognition challenging.^[4,8] Our patient was a known glaucoma case in whom a large disc with peripapillary pigmentary alteration might easily have been attributed solely to glaucomatous change. The detection of temporal cavitation and focal breach on EDI-OCT reinforces the message that glaucoma and ODP-related pathology are not mutually exclusive; in fact, structural remodeling from glaucoma may unmask or modify the expression of pre-existing cavitary anomalies.^[4,8,9]

From a pathophysiologic standpoint, multiple potential fluid sources have been proposed for ODP-M—vitreous, cerebrospinal fluid, subarachnoid space, and choroid, with fluid tracking through tiny channels at the disc into the retina and/or sub-retinal space.^[2,4] High-resolution OCT studies suggest that lamina-cribrosa level cavitations, peripapillary intrachoroidal cavitation and membranes spanning the pit all act as modulators of fluid flow and the formation of macular schisis or detachment.^[2-5,9] In our case, the absence of clinically visible fluid but the presence of chronic EZ–ELM disruption supports the idea that even low-grade or intermittent fluid seepage over time may produce irreversible photoreceptor damage, which then persists after fluid resorption. This may explain why the patient’s visual acuity plateaued at 6/12 despite the absence of active macular fluid at presentation.

Although our patient did not have schisis or serous macular detachment warranting immediate intervention, contemporary evidence on ODP-M management is still relevant when counseling and planning follow-up. A large systematic review and meta-analysis by Meng et al. reported that maculopathy develops in ~51% of eyes with optic disc pits, with serous macular detachment and retinoschisis present in ~49% and ~58% respectively; pars plana vitrectomy (PPV) achieves complete anatomic success and visual improvement in approximately 85% of cases overall.^[3] More recent surgical series and reviews confirm that PPV with variable combinations of posterior hyaloid detachment, internal limiting membrane peeling or flap, gas tamponade and/or juxtapapillary laser can yield favorable structural and functional outcomes, although the optimal combination remains debated.^[9,10] In cases without fluid-related structural damage, conservative management with close monitoring is reasonable; however, the patient should be counseled that future development of schisis or serous detachment could merit early PPV to preserve residual vision.^[2,9,10]

CONCLUSION

Occult disc pit maculopathy should be considered in young patients with unexplained macular changes, disc asymmetry, or atypical presentations mimicking central serous chorioretinopathy. Disc-focused OCT imaging, including dense raster and radial enhanced depth scans, is essential for timely diagnosis and prevention of permanent visual loss.