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7: Other Retinal Conditions : Chorioretinal Folds



Chorioretinal folds are produced by wrinkling of the inner choroid, Bruch's membrane, the retinal pigment epithelium (RPE), and the outer retinal layers due to decreasing surface area of the innermost sclera. Stereo fluorescein angiography accentuates the typical variegated, alternating pattern of the folds, which involve primarily the posterior pole of the eye. Ophthalmoscopically, the folds may appear medium-yellow with alternating dark streaks. These striking, angiographically discernible alternating patterns of Light and dark folds represent the transmission and blockage of fluorescence that is pathognomonic of this entity. The folds are commonly located near the macula and surrounding the optic nerve. They may be oriented in a very irregular fashion, horizontally or vertically and oblique or stellate; various patterns of folding may be present within a single eye. The larger the folds, the longer they have been present.


CASE 1

This patient is a man in his third decade with normal vision in both eyes, unilateral choroidal folds, and normal computed tomographic and magnetic resonance imaging scans. Stereo fluorescein angiography of the right eye (Figure 7-1A) dramatizes the profound wrinkling of the surface area between the sclera and choroid. Islands of folding that look like patchwork are visible nasal to the optic nerve, and the dark lines representing the troughs of the choroidal folds are prominently seen throughout the macula temporally (arrow). An impression of subtle subsensory retinal fluid is superior and inferonasal to the nerve head as well.

Venous phase stereo fluorescein angiography (Figure 7-1B) demonstrates the two most commonly seen forms of chorioretinal folding. The macula shows very regular parallel folds with broad, lightly pigmented, relatively hyperfluorescent crests separated by thin dark lines. The broad crests represent areas where the RPE screen has been thinned and relatively stretched, thus transmitting more background choroidal fluorescence. In the troughs of the folds, where the tissue is more compressed, denser RPE blocks the background choroidal fluorescence and appears as a series of radiating black lines traversing the macula. Nasal to the optic nerve, the folding pattern is much more wrinkled and irregular. In this area, the crests appear even more fluorescent, implying more pronounced attenuation of the RPE tissue, and the troughs are darker, implying more RPE compression. The configuration of the folds may vary depending on the etiology and duration of the causative factor. Folds may be idiopathic, secondary to a retro-orbital mass, optic nerve sheath enlargement, or ocular hypotony. Hyperopia is a risk factor as well.

The early recirculation phase of the angiogram (Figure 7-1C) highlights the patchy, loculated appearance of the choroidal folds as they course around the nasal portion of the nerve circumferentially. The dark lines representing troughs are most prominent nasally, and the center of the broad crests appears increasingly hyperfluorescent (arrow). The overlying inner retina itself appears to be mildly undulating at the eleven and four o'clock meridians. Treatment of choroidal folds requires therapy for the etiologic factor. If the folds are relatively short-lived (weeks to months in duration), then removal of the intraorbital tumor or correction of ocular hypotony may lead to a fairly rapid resolution of the folds. If the folds have formed over many months, the patient is typically asymptomatic, but if they are relatively acute (days to weeks), the patient usually notes vision loss.

fig. 7-1a
A

fig. 7-1b
B

fig. 7-1c
C
FIGURE 7 - 1


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