Ординатура / Офтальмология / Английские материалы / Textbook of Vitreoretinal Diseases and Surgery_Natarajan, Hussain_2008
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Textbook of Vitreoretinal Diseases and Surgery
FFA as leakage of dye from the macular capillaries with collection of the dye in the cystic intraretinal spaces. The typical appearance of CME on the FFA has been classically described as a flower petal pattern.
This appearance can be graded into 5 grades:10 Grade 0: No perifoveal hyperfluorescence
Grade 1: Incomplete perifoveal hyperfluorescence Grade 2: Mild 360º hyperfluorescence
Grade 3: Moderate 360º hyperfluorescence with the area of hyperfluorescence being 1 disc diameter across
Grade 4: Severe 360º hyperfluorescence with the area of hyperfluorescence being 1.5 disc diameter across. However, while interpreting the area of dye leakage in relation to the visual acuity, one must remember that the two do not correlate well at times.11, 12
Three basic patterns of macular edema have been described in patients with uveitis.13 They are:
1.Diffuse macular edema: Increased retinal thickness, disturbance of the layered retinal structure and sponge like low reflective areas.
2.Clearly defined intraretinal cystoid spaces.
3.Serous retinal detachment seen as a clear separation of the neurosensory retina from the retinal pigment epithelium.
OCT is also helpful in assessing the results of the treatment of CME with intravitreal injection of
triamcinolone acetonide.14
Optic Disc Inflammation
In cases when the diagnosis of uveitis is doubtful or when there is a doubt regarding disease activity, leakage of the dye from the disc (hot disc) is an important sign (Figure 12-10).
FIGURE 12-10: Fundus fluorescein angiography of a patient with 138 Vogt-Koyanagi-Harada disease showing leakage of dye from the
disc in the late phase—'hot disc'
Imaging in Posterior Uveitis
FIGURE 12-11: Fundus fluorescein angiography of a patient with Vogt- Koyanagi-Harada disease showing pooling of dye in the sub-retinal space in the late phase
Exudative Neurosensory Detachments
These are seen on FFA as multiple focal leaks at the level of the RPE, with pooling of dye in the subretinal space (Figure 12-11). ICG shows patchy choroidal fluorescence.
Retinal Phlebitis
FFA shows retinal phlebitis as staining of the major retinal vessels in the area of localized inflammation with leakage of dye (Figure 12-12). In the presence of prominent vascular leakage, ICG can also be used to demonstrate choroidal vascular inflammation.15, 16
Macular Vascular Occlusion
FFA is a gold standard in documenting macular vascular occlusion as an enlargement of the foveal avascular zone especially in cases of unexplained loss of vision in patients with long standing uveitic entities like Behcet’s disease and herpetic necrotizing retinitis (Figures 12-13A and B).
Peripheral Retinal Vascular Occlusion
Peripheral retinal vascular occlusion as in Eales’ disease and tuberculosis is seen on FFA as a peripheral capillary dropout with an associated leakage of dye from the tortuous vessels at the border of the perfused and the non perfused areas.
Neovascularization of the Disc and Neovascularization Elsewhere
In cases of intermediate uveitis, sarcoidosis and Behçet’s disease,17 which are complicated with neovascularization of the disc (Figures 12-14 and 12-15) and elsewhere, FFA can be used to demonstrate dye leakage in the vitreous with obscuration of the underlying details during the late phase of the
angiogram. When vitreous haemorrhage obscures the retinal view, B scan can be used to assess the 139 condition of the retina.
Textbook of Vitreoretinal Diseases and Surgery
FIGURE 12-12: Fundus fluorescein angiography of a patient showing staining of major retinal vessels with leakage of dye in areas of inflammation
FIGURES 12-13A AND B: Patient with a localized retinitis showing macular vascular occlusion on fundus fluorescein angiography
Rubeosis of the Iris and the Angle
Iris and angle neovascularization is not an uncommon complication in long standing uveitis (Figure 12-16). Fluorescein angiography of the anterior segment can be used to reveal subtle active iris neovascularization in doubtful cases.
Choroidal Neovascularization Membrane (CNVM)
FFA can be used to differentiate between active choroidal neovascularization and chorioretinal 140 scars. Chorioretinal scars are characterized by hyperfluorescence first in the periphery and then
Imaging in Posterior Uveitis
FIGURES 12-14A AND B: Fundus fluorescein angiography showing leakage of dye in a patient with neovascularization of the disc
FIGURES 12-15A AND B: Fundus fluorescein angiography of a patient showing leakage of dye from new vessles elsewhere
FIGURE 12-16: Slit lamp photo of a patient showing |
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neovascularization of the iris—Rubeosis iridis |
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Textbook of Vitreoretinal Diseases and Surgery
spreading to the centre of the scar. In CNVM, hyperfluorescence begins first in the area of the CNVM and then spreads to the periphery of the lesion. Both show hyperfluorescence of the entire lesion in the late phase of the FFA. Active CNVM shows leakage of the dye into the overlying serous retinal detachment. ICG shows CNVM as a ‘hot spot’ of hyperfluorescence in the mid phase of the study with a late leakage. Chorioretinal scars show hypofluorescence throughout the entire ICG study. A CNVM on the OCT is seen as a ‘bump’ with a moderate slope extending upward or as a fusiform thickening with disruption of the reflective band.18
Posterior Scleritis
FFA, in a case of posterior scleritis shows multiple pinpoint leaks at the level of the retinal pigment epithelium which evolves in the later phases of the angiogram to fill the subretinal space with associated optic disc leakage, vascular staining and occlusion.19 ICG shows choroidal vascular hyperpermeability and hyperfluorescence in the mid-to-late phases of the angiogram.20 B-scan ultrasonography shows the classical ‘T sign’, which is virtually pathognomic of posterior scleritis. The ‘T sign’ is due to scleral edema with associated fluid within the Tenon’s space resulting in an echolucent area just posterior to the sclera. In nodular posterior scleritis there is a localized echolucency seen.
Diagnosis of Specific Uveitic Conditions
Now knowing the different imaging modalities and their applications to pick up various causes for loss of vision in patients with uveitis, we come to the diagnosis of specific uveitic conditions using various imaging modalities.
ACUTE POSTERIOR MULTIFOCAL PLACOID PIGMENT EPITHELIOPATHY (APMPPE)
FFA of a patient with APMPPE is characteristic21 and often imaging modality may be essential to diagnose this disorder. In the acute stage, a fundus fluorescein angiography (FFA) reveals a characteristic “block early, stain late” pattern (Figures 12-17A to C). The acute lesions are hypofluorescent due to a grayish white opacification of the retinal pigment epithelium and choroidal nonperfusion. The acute lesions become hyperfluorescent in the late phase of the angiogram. Hyperfluorescent lesions in the late phase of the study are lesser in number than the hypofluorescent lesions seen in the early phase in the acute stage of the disease. In the quiescent stage a varying degree of hyper or hypofluorescence is seen depending upon the degree of retinal pigment epithelial derangement. Indocyanine green angiography (ICG) reveals hypofluorescence of the active and healed lesions and thus highlights the choroidal nonperfusion.22 The etiology of APMPPE is unclear. Antecedent viral illness in 1/3rd of the patients points towards a viral etiology. Nonperfusion of the choroids as demonstrated by ICG may be another possible etiological mechanism. This choroidal nonperfusion may be secondary to a vasculitis as suggested by its association with systemic vasculitis.
SERPIGINOUS CHOROIDOPATHY
FFA is characteristic and shows early hypofluorescence of the active lesions. In the late phase there is hyperfluorescence of the active border (Figures 12-18A to C), which appears pseudopodal. This
142 hypofluorescence may extend centrally.
Imaging in Posterior Uveitis
FIGURES 12-17A TO C: Patient with acute posterior multifoal placoid pigment epitheliopathy (APMPPE). Fundus fluorescein angiography showing 'block early, stain late' pattern
ICG shows hypofluorescence of the lesions in all the stages except in the healing and the sub healing stage where hyperfluorescent lesions are seen.
There may also be localized areas of hyperfluorescence outside these areas. These latter lesions do not correspond to any clinically visible change of the retina, RPE, and choroid, and could represent areas of subclinical choroidal inflammation. ICG angiography may also be useful in distinguishing between new active inflammatory lesions, which are hypofluorescent, and CNVM, which may appear as a localized hyperfluorescent lesion during the mid-to-late phases of the ICG study.23
BIRDSHOT CHORIORETINOPATHY
FFA may show active retino-vascular leakage along the large and small vessels and cystoid or diffuse macular edema. The birdshot lesions are seen only if there is a loss of retinal pigment epithelium over them creating a window defect. ICG shows birdshot lesions appearing to line up along the large choroidal veins (Figures 12-19A and B) as areas of blockage in the early mid and sometimes in the late phase of the angiogram.24 The early appearance of the spots differentiates these lesions with the late spots seen with multifocal choroiditis. Many more spots can be seen with
ICG angiography than with either ophthalmoscopy or FA. The hypofluorescent spots on ICG 143 angiography are similar in size to the clinically detectable lesions.
Textbook of Vitreoretinal Diseases and Surgery
FIGURES 12-18A TO C: Patient with serpiginous choroidopathy. Fundus fluorescein angiography showing early hypofluorescence of the active lesions and hyperfluorescence of the active borders in the late phase
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FIGURES 12-19A AND B: Patient with birdshot chorioretinopathy. Fundus fluoresceing angiography showing |
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hypofluorescent spots along the major chroidal vessels with leakage of dye from the disc |
Imaging in Posterior Uveitis
These hypofluorescent ICG spots are larger than the lesions seen with multifocal choroiditis and multiple evanescent white spot syndrome, and are usually smaller than the hypofluorescent plaques seen in AMPPPE and VKH disease. The hypofluorescent spots have a predominant distribution along the major choroidal vessels. Sometimes, hyperfluorescent spots appear during the mid phase of the ICG study and persist into the late phase. These hyperfluorescent areas seem to correspond to localized areas of retinal vasculitis seen clinically. Despite hyperemia or frank swelling of the optic nerve head seen clinically and confirmed by FFA, disc abnormalities are seldom noted on ICG study, and there is no convergence of hypofluorescent spots in the peripapillary area, as seen in multiple evanescent white spot syndrome and multifocal choroiditis.25 OCT and the retinal thickness analyzer can both be used to measure the retinal thickness in the macular area and in the typical fundus spots in patients with birdshot retinochoroidopathy.26
MULTIPLE EVANESCENT WHITE DOT SYNDROME (MEWDS)
FFA shows early and late hyperfluorescence of the dots in a wreath like pattern (Figure 12-20) around the fovea with a late disc staining.21 ICG shows more numerous hypofluorescent round spots in the posterior and midperipheral fundus.27 During the convalescent phase there is disappearance of the hypofluorescent spots, and sometimes an appearance of hyperfluorescent spots of uncertain significance.
FIGURE 12-20: Fundus fluorescein angiography of a patient with multiple evanescent white dot syndrome (MEWDS) showing hyperfluorescent dots around the fovea in a 'wreath like pattern
VOGT-KOYANAGI-HARADA DISEASE
Typically the early stages of the FFA show multifocal pinpoint areas of leakage originating from the 145 RPE. This leakage increases in intensity during the recirculation phases, filling overlying serous
Textbook of Vitreoretinal Diseases and Surgery
FIGURES 12-21A TO C: Patient with Vogt-Koyanagi-Harada disease. Fundus fluorescein angiography showing multiple hyperfluorescent dots around in the early phase with pooling of the dye into the subretinal space in the late phase
pigment epithelium detachments and neurosensory retina elevations (Figures 12-21A to C). Optic nerve leakage is usually seen, and occasionally perivenous retinal staining is observed as well. ICG of VKH disease shows multiple hypofluorescent spots scattered throughout the fundus. In the posterior pole they coalesce and the filling of the large choroidal vessels cannot be visualized. The hypofluorescent spots correlate with the Dalen–Fuchs-like nodules seen clinically. Presumably they represent blockage of underlying fluorescence by inflammatory infiltration of the choroid and by overlying RPE changes. Sometimes ill-defined areas of hyperfluorescence not necessarily correlating with the pattern of hyperfluorescent spots or neurosensory detachments representing a more diffuse type of choroidal staining are seen. After treatment, with resolution of the leaks and the neurosensory detachment, both the abnormal hypofluorescence and hyperfluorescence fades.28
Conclusion
The importance of imaging tools in the evaluation and management of posterior uveitis cannot be over emphasized. The information afforded by these techniques provides insight into various aspects
146 of inflammation of the posterior segment.
Imaging in Posterior Uveitis
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