Chorioretinal folds Chorioretinal folds are wrinkles or undulations in the choroid, Bruch’s membrane and retinal pigment epithelium (RPE). Distortion of the choroid (as a result of mechanical force and/or vascular occlusion) is thought to exert pressure on the relatively inflexible Bruch’s membrane, which is thrown into folds. Some possible causes are listed in the Table.
Retinal folds Retinal folds involve only the sensory retina and are generally narrower 1 than choroidal folds. They most commonly develop when a tractional force is exerted ‘ upon a focal area of the retina. Causes include idiopathic epiretinal membranes, chorioretinal scars and fibrovascular proliferation associated with retinal detachment or diabetic retinopathy. In ^ addition, any of the above-listed causes of chorioretinal folds may occasionally produce folds limited to the sensory retina.
Symptoms predominantly relate to the cause, regarding which the patient’s past medical history may be informative, e.g. previous ocular surgery or retinal detachment. The folds themselves may result in focal areas of blurring, distortion or loss of vision.
Chorioretinal folds are visible as alternating light and dark bands or grooves on fundoscopy. The light bands correspond to the crests of the folds, where the RPE layer is stretched thin, and the dark bands correspond to the troughs. The folds are often horizontal and parallel, but they may be vertical, oblique or irregular, depending on the underlying cause, e.g. the folds are often multidirectional with ocular hypotony and concentric with optic disc swelling.
Retinal folds are usually thinner than chorioretinal folds, and often radiate from an area of visible pathology on fundoscopy (e.g. an epiretinal membrane). When viewed with the slit-lamp, the underlying RPE and choroid appear normal. Further testing to detect an underlying cause may include assessment of ocular motility, exophthalmometry, intraocular pressure and optic disc morphology.
Common (approximately 1 in 50).
Chorioretinal or retinal folds may be the presenting feature of a range of treatable ocular conditions.
See conditions listed in the Table.
Thyroid eye disease; Hypotony maculopathy; Papilledema.
Ocular tests, imaging investigations With fluorescein angiography, chorioretinal folds produce alternating streaks of hyperfluorescence (choroidal fluorescence visible through the thin RPE) and hypofluorescence (choroidal fluorescence obscured by thickened RPE). Retinal folds are not visible angiographically. Further imaging investigations are indicated when the cause of the folds is uncertain. This may include ultrasonography, computed tomography (CT) and/or magnetic resonance imaging (MRI) of the orbits. Optical coherence tomography (OCT) may be performed to delineate vitreous tractional membranes.
|Table 26.1 Causes of chorioretinal folds|
|Orbital space-occupying pathology||Orbital tumors and thyroid eye disease|
|Choroidal tumors||Melanoma of the choroid and metastatic carcinomas|
|Optic disc swelling||Expansion of the optic nerve at its entrance into the eye,causing compression of the surrounding choroid|
|Ocular hypotony||Low intraocular pressure, e.g. post-surgical, trauma|
|Hypermetropia||A single underlying pathology (e.g. inflammation during
infancy) may be responsible for both hypermetropia
and chorioretinal folds
|Previous scleral surgery||Such as scleral buckling procedures for retinal
|An incidental finding in an otherwise normal eye|
|Other causes||Intraocular tumors, choroidal neovascular membranes
and orbital cellulitis
Alternating light and dark lines between the optic disc and macula.
Surgery Intraocular or orbital surgery may be indicated depending on the underlying cause.
Advice Although treatment of the underlying condition sometimes results in resolution of the folds, they quite often persist indefinitely.