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3: Macular Disease : Idiopathic Choroidal Neovascularization



Idiopathic CNV is a catch-all category for CNV in which no underlying etiology is obvious at the time of evaluation. Such patients may have associated drusen that are not seen clinically or may have developed CNV associated with previous areas of RPE damage subsequent to healing of central serous retinopathy. Some cases of atypical central serous retinopathy may represent the newly described entity idiopathic polypoidal choroidal vasculature. Other causes of so-called idiopathic CNV are old chorioretinal inflammatory disease and trauma that may not be evident ophthalmoscopically.


CASE 9

This patient is a 50-year-old man who presented with a history of vision loss over a 3-month period preceding evaluation.

A green filter image (Figure 3-9A) highlights an area of subretinal and sub-RPE blood. The light arrow shows a scaphoid area of dependent subretinal blood, and the dark arrow a darkened area of diffuse sub-RPE blood. An old chorioretinal scar lies superior to the fovea.

The second frame (Figure 3-9B) is an ICG angiogram demonstrating hypofluorescence of the optic nerve, two nonspecific dark spots in the choroid, and an area of relative hyperfluorescence consistent with CNV underlying the previously noted area of subretinal blood (arrow). There is a surrounding halo of blockage of background choroidal fluorescence secondary to overlying sub-RPE blood.

The next green filter image (Figure 3-9C) repre-sents a digital overlay tracing surrounding the treatment margin from a post-treatment green photograph (outer circle) with hyperfluorescence demonstrated by ICG angiography (inner circle). These overlay tracings have been superimposed on the green filter stereo image to allow better visualization of the retinal vascular pattern, which is clinically critical for accurate guidance of laser photocoagulation therapy.

The transit phase ICG frame (Figure 3-9D) represents the post-treatment hypofluorescent zone consistent with blockage of choroidal fluorescence due to photocoagulation of the choroidal vasculature in that area (arrow). No residual hyperfluorescence is apparent, which is consistent with adequate treatment effect.

fig. 3-9a
A

fig. 3-9b
B

fig. 3-9c
C

fig. 3-9d
D

FIGURE 3 - 9


Peripapillary ChoroidaL Neovascularization with Chronic Papilledema

Chronic papilledema is typically a bilateral condition secondary to chronically elevated intracranial pressure.


CASE 10

This woman presented with chronic papilledema in both eyes and juxtapapillary subretinal hemorrhage with vision loss in the left eye.

The green filter photograph (Figure 3-10A) shows a massively elevated optic nerve with loss of optic cup. The nerve appears to have a well circumscribed border, implying a chronic process. The differential diagnosis includes buried optic nerve head drusen, chronic infiltrative processes such as sarcoidosis or leukemia, and pseudotumor cerebri. Of note is the presence of intraretinal lipid, seen at the base of the optic nerve at ten, two, and six o'clock. Subretinal hemorrhage on the surface of the RPE at the superior and nasal borders of the disc extends through the papillomacular bundle into the FAZ. There is serous elevation of the retina along the papillomacular bundle as well, with circumferential retinal folds (arrow). This pattern is consistent with CNV associated with papilledema. CNV emanating from the juxtapapillary area may also be associated with buried drusen. Stereo photography highlights both the symmetric elevation of the optic nerve and the serous sensory retinal detachment noted over the papillomacular bundle. No nerve fiber layer defects are apparent, as typically would be present in association with a buried optic nerve head drusen.

The arterial transit and early venous phase of the angiogram (Figure 3-10B) demonstrates the ground glass appearance of the optic nerve. There is no significant leakage of dye from nerve tissue at this stage, but the superficial peripapillary capillary bed appears dilated (dark arrow). Early, irregular hyperfluorescence underlying the papillomacular bundle (light arrow) is present. Blockage of background choroidal fluorescence is seen posterior to this area due to the presence of diffuse blood on the surface of the RPE.

Late staining of the optic nerve head (Figure 3-10C) is typical for papilledema. Note the blockage of background choroidal fluorescence at the base of the nerve nasally and by subretinal blood temporally. There is acute hyperfluorescence of an area of CNV under the papillomacular bundle where the geographic configuration of the CNVM is of much brighter fluorescence than the adjacent optic nerve (arrow). Fluorescein extravasates briskly through the incompetent vascular walls of the CNVM but leaks through the dilated capillary network of the optic nerve much more slowly.

The late recirculation phase of the fluorescein angiogram (Figure 3-10D) demonstrates a prominent elevation of the sensory retina over the papillomacular bundle due to fluid leakage from the CNVM. Note the late, diffuse staining of the optic nerve head with fluorescein dye. Stereo photography contrasts the elevated nature of the nerve head and the rather flattened appearance of the adjacent CNVM that lies in the plane of the RPE—Bruch's membrane complex. This CNVM is at risk of entering the FAZ. At this point, it has encroached on the nasal margin of the FAZ. Diffuse laser photocoagulation overlying this CNVM and extending over its borders for approximately one-half spot size (approximately 100-200 mm) may be indicated. The postphotocoagulation scotoma may not be as significant as predicted, because sensory elevation of the retina anterior to the zone of choroidal photocoagulation may protect the retinal photoreceptors from the secondary damaging effects of laser, particularly if a photocoagulation wavelength in the red spectrum is used.

fig. 3-10a
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fig. 3-10b
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fig. 3-10c
C

fig. 3-10d
D

FIGURE 3 - 10

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