Ординатура / Офтальмология / Английские материалы / Fluorescence Angiography in Ophthalmlogy_Dithmar, Holz_2008

Fig. 5.24a–d. A 77 year old patient with metamorphopsia and loss of acuity to 20/100 in the right eye. The fluorescein angiogram shows a classic subfoveal CNV with clearly defined leakage of dye in the late phase. b The patient received anti VEGF treatments

(altogether 7 injections of intravitreal Pegaptanib in the course of one year). c,d One year later the CNV is inactive. Fluorescein angiography shows the CNV with irregular, drawn out, sharply defined margins without leakage in the late phase, acuity of 20/80

Fig. 5.25a–f. A 79 year old patient with reduced acuity and metamorphopsia in the right eye. a Fundoscopy reveals a subfoveal area of edema. Incidentaly noted are myelinated nerve fibers on the superior margin of the optic disc. c,e Fluorescein angiography shows a classic subfoveal CNV membrane with clear

leakage of dye in the latephase e. The patient was treated with intravitreal injection of an anti-VEGF antibody and PDT. b Six weeks after treatment fundoscopy demonstrates no subretinal fluid. d,f The CNV membrane is no longer detectable by fluorescein angiography. In the late phase f there is no leakage.

5.2Cystoid Macular Edema

Cystoid macular edema (CME) originates in a disturbance of vascular permeability in the perifoveal capillaries and/or in the retinal pigment epithelium. CME appears as an accumulation of fluid in the outer plexiform layer of the retina (Henle’s fiber layer), in which characteristic cyst-like fluid filled spaces form. It is a non-specific reaction of the macular tissues that can arise in association

5with many different disorders, including diabetic retinopathy, tributary retinal vein occlusions, uveitis, epiretinal membranes, and postoperatively following ophthalmic surgical procedures.

Autofluorescence

In the region of cyst formation there is a thinning of the macular pigments that normally attenuate the autofluorescent signal, causing the cysts to appear hyperfluorescent.

Fundus

Cystic prominences form in the macula, frequently having a clover-leaf-like pattern (radially arranged tear drops with their pointed ends toward the fovea). With chronicity cystoid macular edema can cause a tear to form in the inner retinal layers with formation of a macular hole and profound loss of acuity.

Fluorescein Angiography

In the early phase a faint hyperfluorescence is present in the region of the cysts, due to increased transmission of background fluorescence, caused by a reduced density of macular pigment. In the course of the angiogram there is a progressive leakage of fluid from the perifoveal capillaries. Fluorescein collects in the fluid filled spaces, which becomes clearer as the background fluorescence fades. In the late phase of the angiogram the dye filled cavities look like multiple cysts.

5.3Hereditary Macular Disorders

5.3.1 Stargardt’s Disease

Stargardt’s disease is the most common hereditary macular dystrophy. Usually an autosomal recessive trait (mutations in the ABCA4 gene) it is characterized by excessive lipofuscin storage in the RPE cells and a subsequent loss of the RPE cells. The process can remain limited to the

5macula (Stargardt’s disease) and/or affect the periphery (fundus flavimaculatus). Stargardt’s disease usually manifests itself in the second decade of life, but can also appear in later decades (late onset, Fig. 4.6e).

Symptoms

Presents as a loss of acuity and a central visual field defect.

Fundus

The clinical picture of Stargardt’s disease can be highly variable. Early in the course of the disease the fundus can still have a normal appearance. Then the foveal reflex fades from view and the fovea acquires a granular and indistinct appearance. Surrounding the fovea there arise a number of concentrically oriented, pale yellow specks at the level of the RPE. This is caused by a marked accumulation of lipofuscin within the RPE cells, which displaces the melanin granules towards the cell borders. Later, an obliquely oval zone of degeneration develops containing fine flecks of RPE destruction. The fovea appears dark and is

surrounded by hypoand hyperpigmented rings (so-called target maculopathy). The central RPE can show many areas of geographic atrophy.

Autofluorescence

In areas where the RPE has been destroyed, autofluorescence is extinguished. An increase in autofluorescence can be found corresponding to areas of lipofuscin deposition in the regions with the pale yellow flecks.

Fluorescein Angiography

Due to the lipofuscin accumulation in the RPE, the background fluorescence of the choroid is blocked or weakened (dark choroid). In areas where the RPE is missing the choroidal fluorescence is unobstructed, a phenomenon referred to as window defects. The RPE defects can be demonstrated much more effectively by angiography than by ophthalmoscopy. The ophthalmoscopically visible pale yellow flecks appear hyperfluorescent during fluorescein angiography.

5.3.2 Fundus Flavimaculatus

The pale yellow flecks at the RPE level, as described above for Stargardt’s disease, can also appear without any macular involvement. In this form the disese is called fundus flavimaculatus. It is thought that Stargardt’s disease and fundus flavimaculatus are two different phenotypic expressions of the same disease. Both phenotypes can also be found together.

Fig. 5.27a–f. A 30 year old patient with Stargardt’s disease. a Fundoscopy of the right eye shows an obliquely oval central area of degeneration with tiny spots of RPE damage. Within the area of degeneration there is an island of preserved RPE. Surrounding the zone of degeneration one can see scattered white flecks. b Autofluorescence imaging shows that within the zone of degeneration the RPE is completely atrophic and there is no longer any visible autofluorescence. The small island of preserved RPE

cells is marked by a patch of persistent autofluorescence. Surrounding the zone of degeneration there is a ring of flecks with markedly elevated autofluorescence. These spots correlate with the funduscopically visible white flecks, and reflect the elevated levels of intracellular RPE lipofuscin. c,d Fluorescein angiography shows transmitted background choroidal fluorescence in the area of missing RPE cells (a type of window defect). No leakage is apparent. e,f The left eye has a similar appearance.

5.3.3Best’s Disease (Vitelliform Macular dystrophy)

Best’s disease is an autosomal dominant macular dystrophy with incomplete penetrance, caused by a mutation in the so-called VMD2-gene, expressed in the RPE. This disorder is usually first manifest in the second decade of life, although late presentations have also been described. It affects both eyes and has a course that goes through

5several stages. Characteristic is a reduced or absent light rise in the electrooculogram (EOG). A complicating factor in some cases is the appearance of choroidal neovascularization with the dystrophic macula.

Fundus

Initially thee is an egg-yolk-like (vitelliform), yellow, disc-shaped change in the macula with a diameter larger than one disc diameter. This is caused by a massive accumulation of lipofuscin in the cells of the RPE. Visual function at this stage is normal. Later on there is destruction of the RPE

with increasing release of lipofuscin into the subretinal space. This gives the clinical impression of a destruction and liquefaction of the contents of the macular lesion, accompanied by formation of a »pseudohypopyon«. Later on there is a mixture of yellow material and scar tissue, and in the atrophic stage there is no longer any visible yellow pigment.

Autofluorescence

The disc shaped accumulation of lipofuscin is easily seen, given its strong autofluorescence.

Fluorescein Angiography

Given the unmistakeable ophthalmoscopic appearance of Best’s disease and positive EOG findings, a fluorescein angiogram is not necessary. Angiography merely confirms the attenuation of the background fluorescence by lipofuscin. In advanced stages the areas of RPE destruction are visible as window defects, meaning that the background fluorescence is transmitted. A fluorescein angiogram is indicated when there is a suspicion of a CNVM.

Fig. 5.28a–f. a The right eye of a young patient with a highly reflective fundus image and the central vitteliform changes of Best’s disease. Visual acuity is 20/20, and EOG shows reduced light rise. b Markedly increased autofluorescence in the visibly affected central area. c The contralateral eye likewise has a vitelliform lesion, in which additional vessels can be seen. Visual acuity is 20/125 and there is a reduced light rise in the EOG. The vitelliform lesion is sur-

rounded by a region of subretinal fluid and shallow hemorrhages. Its borders are sharply demarcated by distinct retinal surface reflections. d–f Fluorescein angiography of the left eye shows attenuation of the background fluorescence by the subretinal blood and exudation. In the area of the vitteliform lesion one can see a secondary CNV membrane, which shows leakage of dye during the course of the angiogram f.