Choroidal Disease





Figure 9-1 Central serous chorioretinopathy. A, Color fundus photograph from a patient with central serous chorioretinopathy. B, Early-phase fluorescein angiography image demonstrates pinpoint hyperfluorescence. C, Late-phase fluorescein angiography image shows the expansile dot pattern of the leakage. D, Corresponding optical coherence tomography (OCT) scan illustrates the subretinal fluid accumulation. Accumulation of deposits on the outer surface of the photoreceptors is visible. This material is thought to represent shed photoreceptor outer segments or fibrin. (Courtesy of Richard B. Rosen, MD.)




In the classic smokestack pattern, a focal spot of hyperfluorescence appears early in the study, spreading vertically and finally laterally as the study progresses to the late phases, resembling a plume of smoke. This unique pattern is thought to be secondary to convection currents and to a pressure gradient between the protein concentration of the subretinal fluid and the fluorescein dye entering the detachment. Although characteristic, this angiographic presentation is present in only 10% of cases.


In rare cases, an extensive, often gravity-dependent serous detachment of the retina may develop from one or more leakage points outside the central area or may be associated with a diffuse pattern of fluorescein leakage. Often, there is no prominent leakage point.


Indocyanine Green Angiography


Indocyanine green (ICG) angiography can reveal choroidal vascular abnormalities, including filling delays in the choroidal arteries and choriocapillaris, venous dilation, hyperpermeability of the choroidal vessels, and characteristic multifocal choroidal hyperfluorescent patches that appear early in the study. These areas slowly enlarge during the angiographic study but are less prominent in late-phase views. In addition, a characteristic “washed-out” pattern is often evident that remains unchanged during clinically inactive phases. ICG angiography can be useful in helping distinguish atypical diffuse CSC in older patients from both occult choroidal neovascularization (CNV) in exudative age-related macular degeneration and idiopathic polypoidal choroidal vasculopathy.


Fundus Autofluorescence Imaging


Acutely, relative hypoautofluorescence can be observed corresponding to the site of the focal RPE leak depicted on fluorescein angiography (FA) and in the area of subretinal fluid. Chronically, areas in which subretinal fluid was present, especially for extended periods of time, can show mild to dramatic hypoautofluorescence. Fundus autofluorescence (FAF) imaging may show dramatic changes even when the clinical examination findings are normal or minimally abnormal, allowing visualization of the guttering mentioned earlier. Increased autofluorescence often observed in the area of serous detachment may be related to unmasking of RPE fluorescence by photoreceptor pigmentary atrophy.


Imamura Y, Fujiwara T, Margolis R, Spaide RF. Enhanced depth imaging optical coherence tomography of the choroid in central serous chorioretinopathy. Retina. 2009;29(10):1469–1473.


Spaide RF, Klancnik JM Jr. Fundus autofluorescence and central serous chorioretinopathy. Ophthalmology. 2005;112(5):825–833.


Differential Diagnosis


Perhaps the most difficult differential diagnoses to distinguish from CSC are age-related macular degeneration and idiopathic polypoidal choroidal vasculopathy. The presence of blood or significant amounts of lipid strongly suggests the diagnosis of CNV or idiopathic polypoidal choroidal vasculopathy. In the absence of these signs, the angiographic patterns of fluorescence and disease course may help differentiate these conditions. Other considerations in the differential diagnosis include optic nerve pits, idiopathic uveal effusion syndrome (IUES), and Vogt-Koyanagi-Harada syndrome. Older patients presenting with CNV occasionally may show pigment epithelial changes that suggest previous episodes of CSC.


Natural Course and Management


The visual prognosis of CSC is generally good except in chronic, recurrent cases and in cases of bullous CSC. Most (80%–90%) eyes with CSC undergo spontaneous resorption of subretinal fluid within 3–4 months; recovery of visual acuity usually follows but can take up to 1 year. Mild metamorphopsia, faint scotomata, abnormalities in contrast sensitivity, and mild deficits in color vision frequently persist. Some eyes have permanently reduced visual acuity, and many (40%–50%) experience one or more recurrences.


Initially, observation is appropriate, unless the patient’s livelihood is at risk because of the changes in vision. If fluid persists for more than 3–6 months, treatment using thermal laser photocoagulation, photodynamic therapy, or systemic medications should be considered.


Thermal laser photocoagulation at the site of fluorescein leakage can induce rapid remission; similar results have recently been reported for subthreshold laser photocoagulation to the leakage site. If laser photocoagulation is performed, a follow-up examination within 3–4 weeks may help detect the rare complication of postlaser CNV. Although rare, CNV has been reported to develop in as many as 2% of patients with typical CSC, even without laser treatment.


Verteporfin photodynamic therapy (PDT), using standard fluence (600 mW/cm2) or reduced fluence (300 mW/cm2), resolves the fluid leakage, which may also result in improved vision. In addition, several authors have described the use of sub–visible threshold or micropulse laser to help resolve the chronic serous fluid in CSC. These treatments, however, are not supported by level 1 evidence.


Several systemic drugs have been variably reported to be effective in resolving cases of chronic, recurrent, or resistant CSC; medications include mifepristone, finasteride, ketoconazole, spironolactone, valproic acid, and eplerenone. The rationale for their use rests largely on their impact on steroid metabolism.


Loo RH, Scott IU, Flynn HW Jr, et al. Factors associated with reduced visual acuity during long-term follow-up of patients with idiopathic central serous chorioretinopathy. Retina. 2002;22(1):19–24.


Choroidal Perfusion Abnormalities


Although most of the blood flow to the eye goes to the choroid, perfusion abnormalities in the choroid are more difficult to diagnose. Retinal vascular occlusion is readily visible by ophthalmoscopy and corroborated by FA. Choroidal vascular occlusion, however, may produce changes that are quite subtle. In addition, it is not uncommon for choroidal vascular abnormalities to be obscured by overlying retinal vascular abnormalities such as cotton-wool spots and intraretinal hemorrhages. The entities that cause choroidal vascular abnormalities may affect the circulation from the ophthalmic artery to the choriocapillaris. Although individual variation is high, there often are a nasal and a temporal posterior ciliary artery, which have a vertical watershed that transects the fundus at or near the optic nerve head. From the posterior ciliary arteries arise the short and long posterior ciliary arteries, each of which supplies patches of choroid that are essentially triangular. Figure 9-2 illustrates a typical pattern of choroidal vascular distribution in the temporal fundus with its watershed areas. As a result of this anatomy, short posterior ciliary artery occlusions usually result in triangular areas of choroidal ischemia.






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Figure 9-2 Diagrammatic representation of the choroidal distribution of the short posterior ciliary arteries (PCAs) and long PCA branches arising from the temporal (lateral) PCA, and their watershed zones. Details of the branches from the medial PCA are not indicated. Dashed circle indicates the macular region. (Used with permission from Hayreh SS. Submacular choroidal vascular pattern: experimental fluorescein fundus angiographic studies. Graefes Arch Clin Exp Ophthalmol. 1974;192(3):181–196.)


Hayreh SS. Posterior ciliary artery circulation in health and disease: the Weisenfeld lecture. Invest Ophthalmol Vis Sci. 2004;45(3):749–757; 748.


Increased Venous Pressure


Although rare, choroidal blood flow abnormalities may be related to venous outflow problems, including those caused by dural arterial malformations and carotid cavernous fistulas. Diagnosis of choroidal blood flow abnormalities often requires both fluorescein and ICG angiography, and occasionally a stethoscope, to detect a bruit.


Hypertension


The most commonly observed diseases that lead to choroidal vascular compromise are those that cause severe, acute elevations in blood pressure, such as in malignant hypertension, eclampsia, or severe cocaine abuse. In addition to retinal abnormalities, these disorders commonly lead to serous detachment of the retina associated with areas of yellow placoid discoloration of the RPE (Fig 9-3). The perfusion abnormalities may range from focal infarction of the choriocapillaris to fibrinoid necrosis of larger arterioles. Although the choroid has a rich circulation, the blood flows in a functionally terminal fashion at the level of the choriocapillaris, so there is very little collateral flow after a focal occlusion. Resolution of smaller infarcts, which initially appear tan in color, produces small patches of atrophy and pigmentary hyperplasia called Elschnig spots. Linear aggregations of these spots are called Siegrist streaks.


Mar 12, 2017 | Posted by in OPHTHALMOLOGY | Comments Off on Choroidal Disease
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