Results

Of 52 patients recorded as having choroidal folds, 32 had folds as a result of papilloedema. In 28 cases (56 eyes) the folds were bilateral (Table 1). The mean age at presentation was 45 years (range 21–65 years). The male to female ratio was 1.2:1.

Follow up ranged from 1 month to 20 years.

The aetiology of papilloedema in these patients (Table 2) included benign intracranial hypertension (20 cases), intracranial tumour (seven cases), dural arteriovenous malformation (one case), cerebellar ectopia with secondary hydrocephalus (one case), aqueduct stenosis (one case), and an intracerebral haematoma (two cases). The papilloedema was early in one case, acute in 14, chronic in 17 cases.

The final visual acuity ranged from 6/4 to perception of light (PL) (Table 3). In those eyes with a final best corrected visual acuity of 6/12 or less (n=10), optic atrophy was the cause in nine eyes, and a choroidal fold was responsible for poor vision in one eye. In this patient the heavily pigmented trough of a fold crossed through the fovea (Fig 1), and she complained of metamorphopsia.

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Figure 1

Visual loss due to macular folds. Colour photograph of the left fundus of a patient (patient no 8, Table 3) who developed papilloedema and choroidal folds as a result of benign intracranial hypertension. A heavily pigmented choroidal fold, which can be seen passing through the fovea, is responsible for permanent visual impairment. Visual acuity in the left eye is 2/60, and the patient describes severe left metamorphopsia.

All patients had fundus photography and fluorescein angiography. Choroidal folds were bilateral in 28 cases and all of these patients except three (Fig 2) had bilateral papilloedema. One of the patients, who had unilateral papilloedema and bilateral choroidal folds, had more choroidal folds on the side of the swollen disc. All four patients with unilateral choroidal folds had bilateral papilloedema. Choroidal folds as documented by fluorescein angiography were not observed clinically or on fundus photography in four cases (seven eyes) (Fig3).

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Figure 2

(A) Bilateral choroidal folds and unilateral papilloedema. Colour and fluorescein photographs demonstrating bilateral coarse choroidal folds and unilateral papilloedema in a patient (patient no 32, Table 3) with benign intracranial hypertension. (B) Distended nerve sheath and compressed globes. Computed tomograph scan of the same patient demonstrating dilated optic nerve sheaths. This patient presented with acquired hypermetropia. Examination revealed bilateral choroidal folds and a swollen left disc. The arrow denotes perineural cerebrospinal fluid.

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Figure 3

Subclinical choroidal folds. Colour fundus photography showing no evidence of choroidal folds in a patient with benign intracranial hypertension. Fluorescein angiogram of the same patient demonstrating the presence of “subclinical” choroidal folds.

Two types of choroidal folds were observed on fluorescein angiography—coarse folds, which consist of wide bands of alternating hyperfluorescence and hypofluorescence; and wrinkles, which manifest as fine bands of hyperfluorescence and hypofluorescence. These two distinct variations of choroidal folds may coexist in the same eye (Fig4A), and are easily distinguishable on fluorescein angiography. Folds were always horizontal or oblique in this group of patients and no vertical folds were observed. In the majority of eyes (67.2%) the choroidal folds formed a characteristic peripapillary/perimacular or posterior polar pattern. This pattern of choroidal folding, where the folds curve around the nasal aspect of the disc and then sweep superotemporally and inferotemporally, is the most common pattern of choroidal folding seen in association with papilloedema (Fig 4A). The folds were seen at the macula only in 17.2%, in the macular and perimacular region in 12.5%, at the perimacular area alone in 1.56%, and in the peripapillary area alone in 1.56% (Table4).

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Figure 4

(A) Classic appearance of choroidal folds and papilloedema. This pattern of choroidal folding, where the folds curve around the nasal aspect of the disc, and then sweep superotemporally and inferotemporally, is the most common pattern of choroidal folding seen in association with papilloedema. Note the presence of both choroidal wrinkles (red arrow) and coarse choroidal folds (green arrow). (B) Histological section showing a wrinkle (arrow) involving only the retinal pigment epithelium and Bruch’s membrane. The overlying retina is flat.  

Choroidal folds persisted in all cases, even after resolution of papilloedema (Fig 5).

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Figure 5

Persistence of choroidal folds. Fluorescein photographs showing the persistence of choroidal folds 7 years after resolution of papilloedema. This patient had a left optic nerve sheath fenestration for benign intracranial hypertension. Left: choroidal folds with papilloedema; right: 7 years after resolution.

Discussion

Choroidal folds in association with papilloedema have been reported as case reports and in a few small series in the literature.1 14 17-20 We report the largest series to date of choroidal folds resulting from papilloedema.

Papilloedema results from the transmission of elevated intracranial pressure to the perioptic subarachnoid space21 resulting in elevated pressure in the optic nerve sheath. The elevated sheath pressure holds up axoplasmic flow in the optic nerve head, which results in papilloedema due to axonal swelling.22 Should the optic nerve sheath become distended it may in turn press on the globe causing distortion and hence choroidal folds.14 20This flattening of the globe is often associated with an acquired hypermetropia.2 5 13 20 23 24 In some cases the choroidal folds precede the development of papilloedema. This suggests that the elevated intra-sheath pressure produces indentation of the globe before there is any reduction in retrolaminar perfusion. Hence it is possible, though rare, to see unilateral papilloedema with bilateral choroidal folds (Fig 2A), or choroidal folds alone as a sign of raised intracranial pressure.20 However, in our experience, there are cases where severe papilloedema in conjunction with a grossly dilated nerve sheath is not associated with even subtle choroidal folding. Why some patients with distended nerve sheaths develop choroidal folds and others do not is not clear. It may be possible that variation of elastic properties of the sclera/scleral rigidity in different individuals could have some influence on how easily pressure can be transmitted through to the choroid. Variations of insertion of the sheath may also play a role in determining the formation of choroidal folds. While these matters remain unresolved, it is most important for the clinician to be aware that choroidal folds may in themselves be a sign of elevated intracranial pressure.

The two categories of choroidal folds we observed may be explained as follows. Choroidal wrinkles, which are fine lines of hypofluorescence with hyperfluorescent borders, appear to be folds which are confined to the retinal pigment epithelium and Bruch’s membrane (Fig 4B). Coarse folds, which are broader bands of alternating hyperfluorescence and hypofluorescence. This may result from folding of the full thickness of the choroid. The wrinkles are most often seen in the peripapillary area and coarse folds at the macula and perimacularly. However the reverse situation may occur. The mechanical factors which determine the category of choroidal fold are not known.

It is interesting to note that even after resolution of papilloedema, the choroidal folds persisted in all patients in this series. The final visual acuities in the majority of these patients did not appear to be affected by the persistence of folds, even though most patients with choroidal folds develop an acquired hypermetropia at the time of presentation. This acquired hyperopia is well docu- mented2 5 13 20 23 24 and is a result of flattening of the globe by a distended optic nerve sheath. It is possible that in the initial stages the globe is flattened together with distortion and folding of the choroid, and that later on when intracranial pressure is reduced and the papilloedema resolves, the mass effect of the distended nerve sheath on the globe is removed, allowing the refractive state of the eye to return to normal, but with the persistence of the choroidal folds. Unfortunately, as this was a retrospective study, it was not possible to include refraction or axial lengths in the clinical details. This is disappointing, as these variables may be associated with scleral rigidity, and therefore such information could shed more light on the possible mechanism of choroidal folding.

Conclusions

Choroidal folds exist in two forms, coarse folds and wrinkles, and can persist after the resolution of papilloedema, but only rarely do they have any long term effect on visual acuity. Choroidal folds can be a sign of raised intracranial pressure in the absence of papilloedema.