47.1 Clinical Features
Cystoid macular edema (CME) is a retinal condition in which there is thickening of the macula with cystic fluid spaces within the macula. In many cases, abnormal vascular permeability leads to the breakdown of the blood–retina barrier and subsequent intracellular and extracellular fluid accumulation. This process is thought to be driven primarily by retinal ischemia and/or increase in inflammatory mediators; direct macular traction after shifts in the vitreous has also been shown to play a role. Causes vary and can include vascular disease such as diabetes mellitus and vein occlusions, inflammatory conditions such as uveitis, inherited conditions such as retinitis pigmentosa (RP), and medication use including prostaglandins and epinephrine. One of the most common etiologies occurs following intraocular surgery, particularly after cataract surgery (referred to as Irvine–Gass syndrome) with an incidence ranging from 0.2 to 20%. CME can also occur after other types of intraocular surgical procedures, including penetrating keratoplasty, glaucoma drainage implant surgery, intraocular lens fixation procedures, pars plana vitrectomy with or without epiretinal membrane peeling, and scleral buckling. Nonleaking CME may also occur due to specific etiologies (e.g., juvenile retinoschisis, Goldmann-Favre disease, nicotinic acid maculopathy, certain subtypes of RP, and the use of antimicrotubule agents) that are not due to increased vascular permeability.
47.1.1 Common Symptoms
Decreased vision, blurred vision, loss of color vision or contrast sensitivity, metamorphopsia, central scotomas, and micropsia.
47.1.2 Exam Findings
Clinical signs include loss of the normal foveal reflex, retinal thickening, and cystic spaces in the foveal region on funduscopy. In some cases, vitritis and optic nerve swelling can be observed as well. Underlying vascular disease can be ascertained with clinical findings such as retinal exudates, cotton wool spots, retinal hemorrhages, and retinal vascular tortuosity.
47.2 Key Diagnostic Tests and Findings
47.2.1 Optical Coherence Tomography
Possible retinal thickening with the formation of intraretinal cystic fluid pockets within the outer plexiform layer and vitreomacular interface abnormalities such as vitreomacular traction or epiretinal membranes that can contribute to CME formation (▶ Fig. 47.1, ▶ Fig. 47.2).
Fig. 47.1 (a,b) Macular optical coherence tomography showing intraretinal cysts in the outer plexiform layer consistent with cystoid macular edema.
Fig. 47.2 Macular optical coherence tomography demonstrating vitreomacular traction with resultant cystoid macular edema.
47.2.2 Fluorescein Angiography or Ultra-Widefield Fluorescein Angiography
Dilation of the foveal capillaries in early phases and leakage into the cystoid spaces possibly forming classic petaloid leakage pattern in the foveal region in late phases. Late phases may also show leakage of the optic disc (▶ Fig. 47.3). Fluorescein angiography (FA) may also help assess macular ischemia and other potential underlying etiologies (e.g., diabetic retinopathy). Ultra-widefield fluorescein angiography can exhibit leakage in the peripheral retina that can have a honeycomb-like appearance. Lack of leakage on FA changes the differential diagnosis for the etiology.
Fig. 47.3 Late-phase fluorescein angiography images show leakage into the cystoid spaces forming the classic petaloid leakage pattern in the foveal region along with staining of the optic disc.
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