Nonrhegmatogenous Retinal Detachment

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Chapter 96 Nonrhegmatogenous Retinal Detachment

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Introduction

A wide variety of diseases may present with sensory retinal detachment without retinal breaks. Nonrhegmatogenous retinal detachment may be exudative in nature or caused by vitreoretinal traction. Some diseases with elevated retina may have both exudative and traction components. In exudative retinal detachment, the subretinal fluid may be confined to a localized area, usually the posterior pole, or may extend to the periphery, even forming bullous retinal detachment. The characteristic feature of a significant exudative retinal detachment is the presence of shifting subretinal fluid.1 The fluid shifts to the most dependent location when patients change body position. The surface of the detached retina is usually smooth; however, retinal folding may occur in some diseases associated with subretinal fibrosis. To reach an accurate diagnosis among many diseases presenting with exudative retinal detachment, careful fundus examination, fluorescein angiography (FA), indocyanine green angiography (ICGA), optical coherence tomography (OCT), ultrasonography, computer tomography (CT), and magnetic resonance imaging (MRI) may be necessary.

Pathophysiology

There are three potential sources for fluid accumulation within or under the retina: vitreous fluid, retinal vessels, and choroidal vessels. The main route for vitreous water turnover is by way of the retina, choroid and the vortex veins. Choriocapillaries of the choroidal circulation, a single-layered capillary structure with numerous fenestrations on the vessel walls are freely permeable to the intravascular fluid. The main mechanisms for keeping the retina in a dehydrated state are the presence of inner and outer blood–retinal barriers, and the fluid movement across the retinal pigment epithelium (RPE). The inner barrier is made of an endothelial tight junction of the retinal vessels; the outer barrier is produced by the tight junction of retinal pigment epithelial cells. Three mechanisms guarantee the one-way movement of fluid across the RPE: (1) active transport of the RPE; (2) plasma oncotic force, which is higher in the choroidal side, and (3) hydrostatic pressure. Thus, RPE and retinal vascular endothelium are of utmost importance to keep the retina dry in normal condition. When the RPE is injured, the tight junction may be damaged, causing breakdown of the outer retinal barrier; further, the active transport of fluid may be affected, compromising the unilateral way of fluid movement. Any disease capable of significantly increasing the permeability of the choroidal capillaries along with afflicting an injury on the RPE causing breakdown of the outer barrier may result in the accumulation of subretinal fluid. Alternatively, diseases affecting the retinal vascular endothelium causing significant breakdown of the inner barrier may lead first to fluid gathering in the intraretinal space then gaining access into the subretinal space, if the amount surpasses the intraretinal water retention capacity.

Besides the anatomical structures and physiological properties restricting fluid entering the subretinal space, adequate fluid outflow is required for the retina to maintain a dehydration state. There are several outflow pathways functioning for fluid drainage: vitreoretinal–choroidal outflow carries the vitreous fluid to the RPE and to the choroid through the pumping action of RPE as previously mentioned; uveoscleral outflow pathway in turn carries the fluid from the choroid to leave the eye through choroidal vortex outflow; transscleral outflow allows protein and fluid draining out through the emissary channels. When diseases cause outflow obstruction, fluid may accumulate in the subretinal space or/and suprachoroidal space, leading to exudative or hemorrhagic retinal detachment or choroidal detachment. In this chapter, commonly encountered disease categories associated with exudative retinal detachment will be summarized.

Idiopathic

Central serous chorioretinopathy

Central serous chorioretinopathy (CSCR) is a relatively benign retinal disease characterized by a circular area of serous detachment of the posterior retina usually in young and middle-aged healthy persons. While CSCR is mostly self-limiting, there are clinical variants of this disease that have atypical presentations and may reduce the vision tremendously. Most of these atypical CSCR or variant CSCR are associated with excessive accumulation of fluid beneath the sensory retina or RPE. These atypical manifestations can be separated into two major categories: acute bullous retinal detachment and chronic CSCR.

Bullous retinal detachment

Some patients with acute bullous retinal detachment (bullous RD) may have the following medical history: long-term corticosteroid taken for systemic diseases, such as systemic lupus erythematosus (SLE), rheumatoid arthritis (RA), or renal or cardiac transplantation; regular taking of herb drugs (some may contain steroid-like ingredients or have steroid added to the drug); or be under steroid treatment for presumed Harada disease. Other affected patients do not have a specific history of steroid intake.

Bullous RD usually has an acute onset with simultaneous or sequential involvement of the two eyes. Fundus examinations reveal multiple areas of serous RD in the posterior retina with lower bullous RD. There may be multiple retinal pigment epithelial detachment (RPED) and one or more grayish or yellow patches of subretinal exudates mimicking focal chorioretinitis (Fig. 96.1). In some cases, retinal folds may form by the contraction of fibrinous patches or fibrotic membrane or bands on the outer surface of the detached retina. Small scattered yellowish granular subretinal deposits may have a tendency to settle along the retinal vessels (Fig. 96.2). The vitreous is usually clear, but may have 1–2 plus cells. The disc is not hyperemic.

Fluorescein angiography shows multiple hyperfluorescent spots or patches with late enlargement; intense fluorescein leakage from the edge of the RPE detachment may be seen and correlates with the focal grayish-white or yellow patches seen in the color fundus. Retinal vessels show no leakage.

Indocyanine green angiography shows ill-defined hyperfluorescent area, which may become more intense in the late phase, suggesting choroidal permeability alteration.

Optical coherence tomography may show retinal pigment epithelial detachment with or without sensory detachment adjacent to or overlying it; the subretinal fluid may be clear or slightly turbid with multiple granular deposits above RPE and on the outer surface of the detached retina, sometimes forming incomplete septa within the subretinal space (Fig. 96.3); subretinal fibrinous mount with surrounding sensory detachment may be seen.2

Complications of bullous RD include: large RPE tear; broad retinal folding; submacular plaques or fibrotic bands; peripheral paravascular exudates; peripheral retinal telangiectasia, occlusion, or even fibrovascular proliferation.2,3 Peripheral vascular changes may be secondary to long-standing sensory detachment.

In treating bullous RD, systemic steroids should be discontinued; patients should keep the head elevated during sleep to prevent fluid shifting to the macular area; FA-guided laser to the leaking points may decrease the subretinal fluid. Once the fluid level recedes, FA should be repeated to identify persistent leaking points and other leaking sites previously hidden by the detached retina. Multiple sessions of laser treatment are usually needed for complete fluid reabsorption. If subretinal fluid (SRF) persists after the above measurements, external drainage of SRF may be undertaken.4 Care should be taken to make sure that the surgical drainage site is posterior enough to access the subretinal space, which is in the dependent area. Alternatively, pars plana vitrectomy with perfluorocarbon liquid injection and simultaneous external drainage through anterior sclerotomy may be performed, followed by focal laser to the exposed leaking sites and air–fluid exchange. The effect of vitrectomy with internal drainage and silicone oil tamponade is controversial. Recently, bevacizumab injection has been shown to rapidly reduce active fluid leakage into the subretinal space as well as decrease the deposition of fibrinous or proteinaceous substances.5 Photodynamic therapy (PDT) with reduced fluence may also reduce choroidal hyperpermeability and facilitate subretinal fluid reabsorption with RPE tear being the major complication.6 Prognosis of bullous RD is variable and is affected by the duration of macular detachment, the presence of submacular fibrosis, the development of submacular RPE tears, and occurrence of fibrovascular proliferation under the macula or in the periphery.

Differential diagnoses of bullous RD include diseases associated with large areas of retinal detachment. Harada disease is the most common disease confused with bullous detachment. Both have bilateral exudative detachment with multiple leaking sites and normal retinal vasculatures. Hyperemic discs, vitreous cells, pin-point leaking spots, subretinal RPE folding radiating from the disc, choroidal thickening, and the unique OCT pictures showing outer retinal septated spaces containing optically heterogeneous substances favor the diagnosis of Harada disease. Misdiagnosis may lead to the use of steroid and aggravation of bullous RD. The condition may sometimes be mistaken for rhegmatogenous RD and wrongly operated upon. Other causes of unilateral or bilateral exudative RD should be ruled out, such as: hypertensive retinopathy, collagen vascular diseases, leukemia, toxemia, choroidal metastasis, uveal effusion, posterior scleritis, multifocal choroiditis (tuberculosis, syphilis, lyme), chorioretinitis, sarcoidosis, and lymphoma. Polypoidal choroidal vasculopathy (PCV) may mimic CSCR, and severe PCV without subretinal hemorrhage may have similar manifestations to bullous detachment.

Chronic CSCR

Because of the characteristic angiographic picture of multiple areas of RPE disturbance with late staining or mild leakage, the condition is also named RPE decompensation, diffuse retinal pigment epitheliopathy. This entity should not be confused with typical CSCR with persistent subretinal fluid. It is more commonly seen in middle-aged patients of Latino or Asian extraction. Personal and medical history may elicit chronic steroid usage.

Typical clinical manifestation is the multiple poorly defined areas of chronic persistent or recurrent retinal detachment in the posterior pole. Subtle or obvious areas of RPE changes are noted in the posterior pole and in the juxtapapillary regions; gravity tract forming vertical band or reverse funnel-shaped depigmentation, along with pigment migration or bone-spicule pattern of pigmentary changes within the tract and in the inferior part of the retina are usually found (Fig. 96.4); shallow or bullous detachment in the inferior retina is a frequent finding.

FA may show patchy hyperfluorescent areas or mottled hyperfluorescent areas corresponding to, and more obvious than, those areas of pigmentary changes found ophthalmoscopically. These areas may show late dye leakage or staining of different degrees. Round enlarging spots or jet spots commonly seen in typical CSCR may be noticed within or in between the hyperfluorescent areas. Band- or reverse funnel-shaped gravity tract of window defect changes are usually present. Peripheral vessels within the area of retinal detachment may show leakage, vascular occlusion or neovascularization.

OCT examination may reveal subretinal fluid under the macula or several areas of retinal detachment separated by attached retina; some may have localized submacular fluid similar to acute CSCR. There may be cystic changes in the overlying retina, suggesting chronic condition.

Photocoagulation remains the main treatment method. Conventional laser or the more recently developed MicroPulse laser to leaking points and areas of RPE changes with late fluorescein staining and leakage may stop the leakage.7 PDT with reduced fluence has been advocated to treat leaking points and areas with late oozing shown in FA with good effect. Intravitreal bevacizumab has also been shown to have therapeutic effect.8 However, the prognosis is guarded because of multiple recurrence and permanent macular RPE disturbance.

Uveal effusion syndrome

Patients with idiopathic uveal effusion syndrome (IUES) are usually middle-aged men with normal ocular size, presenting with unilateral or bilateral serous choroidal, ciliary, and retinal detachment. There may be central vision decrease or distortion secondary to macular serous detachment or upper visual field defect from lower part serous retinal detachment. External eye examination may reveal episcleral vessel dilatation; the anterior chamber is usually free of cells; intraocular pressure (IOP) is normal; there may be blood in the Schlemm’s canal; vitreous cells are common findings. Initial disease severity ranges from macular serous detachment with insignificant ciliary and choroidal detachment to obvious ciliochoroidal detachment and bullous retinal detachment. The protein concentration of the subretinal fluid is 2.5–3 times that of the normal plasma. The fellow eye may be affected within a few weeks or a few months after lesions developed in the first eye. The disease may have a protracted course, with wax and wane of the subretinal fluid, eventually leaving areas of mixed RPE atrophy and pigment clumps, arranging in a leopard-spot pattern. Some patients may develop a yellowish plaque of exudation in the macular area or severe chorioretinal degeneration causing visual field loss.

FA may not show specific leaking points in the early stage of the disease. As disease progresses, FA may highlight the leopard-spot pattern, which was not obvious in fundus examination; choroidal perfusion may be slow, and focal leaking areas in multiple places may be seen.

Ultrasonography or ultrasound biomicroscopy (UBM) can clearly demonstrate ciliochoroidal detachment, and usually form an annular pattern in the periphery, even before detectable fundus changes. There is no thickened sclera and subtenon fluid adjacent to the optic nerve to form the classic T-sign of the posterior ocular coat typical of posterior scleritis.

Histopathological examination shows accumulation of protein-rich extracellular materials in the suprachoroidal and subretinal spaces. Choroidal vessels are dilated without inflammatory cell infiltration. Subarachnoid space around the optic disc is enlarged. The sclera shows deranged fibers with deposition of glycosaminoglycans within.9 Cell culture of the scleral cells reveals intracellular deposition of a glycogen-like substance.10

The pathogenesis is unclear, possibly related to congenital anomaly of the sclera and vortex veins hypoplasia. Excessive glycosaminoglycans accumulate within the sclera combined with defective vortex veins resulting in decreased drainage of extravasated protein through scleral emissary channels of the transscleral outflow pathway; fluid drainage is also compromised from the decreased function of uveoscleral outflow pathways, leading to excessive protein and fluid accumulation in the suprachoroidal space. Later on, the protein and fluid enter the subretinal space when the extracellular protein concentration becomes equal to that within the vessels. Protein in the suprachoroidal space around the disc may gain access to the subarachnoid space and subdural space resulting in an increase in the CSF protein content even without pleocytosis in 50% of the patients.11 Forrester and associates believe that IUES is a kind of ocular mucopolysaccharidosis, with the initial defect resting in the proteodermatan synthesis and/or degradation of the fibroblast of the sclera.12 Other evidence also shows that abnormal mucopolysaccharides of the sclera play an important role in the pathogenesis of IUES. IOP is usually within normal limits because the IOP rising tendency from uveoscleral outflow obstruction is neutralized by decreased aqueous production from the ciliochoroidal detachment.

Best treatment methods have been debated. Vortex vein decompression with scleral resection was initially advocated to treat uveal effusion associated with nanophthalmos. Gass believed that the treatment effect had less to do with vortex vein decompression than with scleral resection to facilitate protein and fluid drainage through the sclera.13 He suggested partial-thickness sclerectomies or full-thickness sclerectomies. After treatment, exudation may gradually disappear within a few months. However, chorioretinal degeneration may continue to develop from chronic mild recurrence of exudation or abnormal metabolism of mucopolysaccharide.

Other diseases capable of causing uveal effusion include: nanophthalmos, dural arteriovenous fistula, scleritis, Harada disease, diffuse tumors of the uveal tract, prolonged hypotony, etc..

Leopard-spot pigmentation may appear in systemic large cell lymphoma, leukemia, bilateral uveal melanocytic proliferation, and organ transplant chorioretinopathy.

Vascular

Coats disease

This is a non-familial developmental retinal vasculopathy. The disease is more common in males, is usually unilaterally affected and may occur in infants. Symptoms often develop in children or young adults; one-third had symptoms onset over 30 years of age. All vessels, arteries and veins alike, would be affected, showing telangiectasis combined with a large amount of hard exudates; hemorrhagic retinopathy is occasionally seen. On the other hand, a minor form of the disease mainly involving juxtafoveolar areas may occur; decreased vision will not occur until adulthood when hard exudates and edema develop in the macula. The prognosis is directly influenced by the size of the involved area. Occasionally, other vascular anomalies may appear in the lesion eye or the fellow eye, such as macular macrovessels or arterial tortuosity (Fig. 96.5). The condition may be occasionally associated with other abnormalities such as progressive facial hemiatrophy, facial scapulohumeral muscular dystrophy and deafness, or Alport syndrome.14 It may rarely accompany systemic vascular anomalies.

Fundus examinations reveal changes of various severities. The mild form presents with focal telangiectasia and microaneurysms usually at the temporal side of the macula, with or without mild hard exudates. The moderate form ranges from cystoid macular edema with significant hard exudates surrounding the area containing telangiectatic vessels or microaneurysms, to the more extensive vascular abnormalities with massive exudates which may gain access to the subretinal space. The severe form shows wide and scattered vascular lesions, with hard exudates accumulating around the disc and in the posterior pole, causing exudative detachment. The macula may be detached with massive intra- and subretinal exudates, which later may transform to organized subretinal disciform mass or atrophic scar. These changes are likely to be found in infants and children, who visit the ophthalmic clinic because of manifest strabismus secondary to unilateral poor vision or abnormal red reflex from massive exudates in the posterior pole. The accumulation of exudates in the macula may be due to gravity-induced migration of subretinal exudates toward the central area during sleep. The deposition of lipid-rich substance along with macrophage evolves into fibrous tissue. Retinal or choroidal vessels may grow into the lesion to form a disciform scar. The most advanced form presents with bullous detachment with the retina coming in direct contact with the crystalline lens; cholesterol crystals accumulate in the subretinal space.15 There may be dilated abnormal vessels, hard exudates or hemorrhage on the surface or in the retina. However, the abnormal tortuous vessels do not dip into the subretinal space, a sign typical of exophytic retinoblastoma.

FA clearly demonstrates aneurysmal dilatation of retinal vessels, including arteries, veins and capillaries; capillary nonperfusion is also obvious. Normal-appearing vessels do not show dye leakage. Cystoid macular edema may be noted.

The clinical course varies. The macula may not be involved initially until later in life if the lesions are peripherally located, especially in the lower part of the retina. Some severe cases develop increasing capillary nonperfusion leading to neovascularization with subsequent vitreous hemorrhage, vitreous membrane formation, exudative and traction retinal detachment, neovascular glaucoma, resulting in no light perception; others may develop intraocular inflammation or even acute orbital cellulitis secondary to stimulation from toxic products. Some patients develop peripheral elevated, organized exudative nodule or mass, yellowish in color and mixed with hemorrhagic patches, similar to granuloma, exophytic retinal capillary hemangioma or melanoma. Occasionally, spontaneous resolution may occur.

Histopathological studies show irregular dilatation of affected retinal arteries, veins and capillaries; PAS-positive exudates may be seen in the outer retinal layer; lipid-laden macrophages are seen in the outer retina and the subretinal space. In the severe form of the disease in infants, severe vascular endothelial proliferation and hemorrhagic infarction may be observed. Genetic testing has revealed a somatic mutation on the NDP gene on chromosome Xp11.2.

Treatment usually involves laser or cryo aiming at the lesions to decrease exudates and preserve vision (Fig. 96.6). For severe exudative detachment, external drainage should be performed first, followed by cryo to the abnormal vessels. Scleral buckling may facilitate retina reattachment, enhance cryo effect and promote regression of abnormal vessels. However, new lesions may develop in nearby or remote areas. Follow-up is crucial to detect and treat new lesions. Sector panretinal photocoagulation (PRP) may be used for a nonperfusion area. For severe cases, vitrectomy to release vitreous traction with external subretinal fluid drainage, laser or cryo may be considered. Recently, repeated intravitreal injection of bevacizumab has been reported to reduce subretinal fluid, facilitating subsequent laser or cryo.16

Differential diagnoses include all possible causes of white pupil in infants. Localized telangiectasis associated with arterial and venous aneurysms and exudates may be similar to cavernous hemangioma of the retina, acquired retinal macroaneurysm, old branch retinal vein occlusion, bilateral multiple retinal arterial aneurysms with neuroretinitis.

Accelerated hypertension and pregnancy-induced hypertension

Prolonged or severe hypertension may damage the retinal vascular system, choroidal circulation, and disc circulation. The difference in vascular structures, autoregulation and tissue resistance determines the different susceptibility of these three systems to increased blood pressure. Hypertension-induced choroidopathy is the main category that causes exudative retinal detachment.

While chronic moderate hypertension is rarely associated with choroidopathy, choroidal ischemia is more frequently associated with accelerated hypertension. Unlike retinal circulation, choroidal vessels do not possess autoregulation; the blood flow during fluctuation of systemic blood pressure is mainly regulated by sympathetic tone. When blood pressure is high, raised sympathetic tone can prevent direct pressure damage to the choriocapillaries; however, if there is a rapid rise in blood pressure, excessively increased sympathetic tone may prompt severe constriction of choroidal arteries and arterioles, leading to ischemic changes of the choriocapillaries. Choroidopathy may be separated into three stages: (1) acute ischemic phase; (2) chronic occlusive phase; (3) chronic reparative phase.17 In the first two phases, fundus examination may observe white or reddish patches in the outer retina, possibly caused by RPE necrosis; exudative detachment is often present. FA may show a large confluent area or scattered areas of choroidal filling delay; in the mid and late phases, multiple dots or a mosaic pattern of hyperfluorescence from RPE leakage may be seen. In the reparative phase, large areas of irregular REP atrophy, Elschnig spots (central hyperpigmented and peripheral hypopigmented lesion of RPE changes), or Siegrist spots (spots of pigmentary changes similar to Elschnig spots arranged linearly along choroidal vessels in the equatorial region) may be seen; exudative detachment disappears, but choroidal delayed filling remains.

Pregnancy-induced hypertension

About 1–2% of pregnant women develop exudative retinal detachment pre- or immediately post-delivery, causing visual impairment. Exudative detachment may be limited to the macular area or appear as bullous detachment. The retina may or may not show cotton-wool patches or other changes secondary to hypertension retinopathy (Fig. 96.7). Yellowish-white patches of RPE necrosis may be seen. FA shows delayed choroidal filling and multiple leaking points where RPE has been damaged. After delivery, with control of hypertension, exudative detachment rapidly subsides. Most patients have good visual recovery. The posterior pole may show RPE changes forming hyperpigmented lines or patches mixed with yellow spots of RPE atrophy. The bilateral changes may be mistaken for macular dystrophy. Severe cases may have extensive exudative detachment. Widespread RPE changes similar to tapetoretinal dystrophy and severely compromised vision may result. The cause of chorioretinal changes in pregnancy-induced hypertension is not clear. Blood pressure may not be very high before the onset of exudative detachment. Affected patients may have other symptoms and signs related to disseminated intravascular coagulation, such as hemolysis, low platelet count, and elevation of liver enzymes. It is possible that mechanisms capable of inducing disseminated intravascular coagulation (see below) are also functional in the choroid, causing choroidal ischemia, RPE damage and exudative detachment.

Diabetic retinopathy

Severe diabetic macular edema may sometimes accompany localized macular detachment. Fluid leaking out from the vessels first accumulates within the retina; beyond a certain critical point, fluid may gain access into the subretinal space causing sensory detachment. Severe macular edema not only leads to detachment but may be associated with massive hard exudates (Fig. 96.8). Hard exudates are one of the independent risk factors for vision decrease.18 In addition to vascular hyperpermeability related to diabetic vasculopathy, taut posterior hyaloid membrane may also contribute to macular edema and localized detachment either from the mechanical traction force or from traction-induced increased vascular permeability.

Clinically, early fundus changes leading to severe macular edema may present as a central retinal vein occlusion-like picture with flame-shaped hemorrhage around the disc and scattered perivascular exudates but without fluorescein angiographic evidence of disc leakage and venous delayed filling. In other cases, multiple clusters of microaneurysms may distribute in the posterior pole, accompanied by significant capillary nonperfusion. Sensory detachment and massive exudates may later develop. Exudative detachment combined with macular edema represents severe break down of the inner retinal barrier. Laser alone has little effect in such cases. Multiple sessions of intravitreal anti-VEGF (vascular endothelial growth factors) alone or in combination with subtenon or intravitreal steroid administration may effectively flatten down the retina in most cases. The effect has not been confirmed if subsequent focal laser to the leaking vascular segments or microaneurysms may obtain a more lasting effect. In some cases, exudative detachment is present without significant cystoid macular edema. It may be because the edema is in a resolving phase; thus the response to treatment may be quicker. In severe cases, exudates may consolidate and deposit within or below the macula. If the condition does not improve after several sessions of medical treatment, pars plana vitrectomy combined with hyaloid membrane removal may be performed to reduce edema and hard exudates (Fig. 96.9).19 Because the development of massive hard exudates indicates that the retina is in a relatively hypoxic state or has already gone into the early proliferative stage, panretinal photocoagulation during the operation is required to inhibit production of angiogenic factors, which may induce further macular edema or neovascularization, leading to postoperative vitreous hemorrhage or even neovascular glaucoma.19 In the case of pre-existing posterior vitreous detachment, epiretinal membrane peeling and internal limiting membrane peeling may be considered.20 Massive exudates usually form submacular plaques, affecting vision severely. After surgery, the plaque may reduce in size but does not disappear completely, leaving residual fibrosis or crystal-like deposition, causing permanent decrease of vision. Surgical removal of subretinal exudates through iatrogenic retinotomy has been reported21; the effect has not been firmly established. Patients with severe edema should have a systemic check-up, including blood pressure, blood lipid, and renal function; any abnormalities should be treated, as these may interfere with local response to the treatment.

Vascular occlusive diseases

Severe retinal vein occlusion occasionally is accompanied by serous retinal detachment. Exudative detachment has been described in branch, hemispherical, and central retinal vein occlusion (CRVO). Vascular leakage from congested retinal veins outside the macular area is the major source of subretinal fluid at the fovea. In addition, ischemic retina produces angiogenic factors, such as VEGF, which in turn increase vascular permeability. Both increased intravascular pressure and vascular permeability cause leakage of fluid and blood components into the subretinal space. In eyes with retinal vein occlusion, serous RD is typically located beneath the fovea, and the height of the RD was greatest in the fovea (Fig. 96.10).

Recent studies with OCT revealed that macular serous retinal detachment is a common complication of retinal vein occlusion. Serous RD secondary to branch retinal vein occlusion was first described by Spaide et al.22 Of the 14 eyes included in that study, 10 (71.4%) had serous RD. Yamaguchi et al. studied 109 eyes with branch retinal vein occlusion (BRVO) by OCT examination, and found that the incidence of serous RD is higher in the group with major BRVO (63%) than in the group with macular BRVO (21%).23 Ozdemir et al. found a high incidence (81.8%) of serous macular detachment in CRVO.24 In a series of 91 patients with retinal vein occlusion examined by OCT, Tsujikawa et al. reported that 76 eyes (83.5%) had serous RD involving the fovea.25 They suggested from their observations that in eyes with retinal vein occlusion, a small pointed RD developed initially just beneath the fovea, but subsequently changed into a dome-shaped RD; the foveal architecture, especially that of the Müller cell cone might be involved in the formation of serous RD.

Application of laser photocoagulation to the affected area of branch retinal vein occlusion has been reported to treat serous RD and can lead to resolution of subretinal fluid. The beneficial effect of laser treatment may be due to the ablation of ischemic retina, decrease of the production of VEGF, closure of incompetent vessels, and stimulation of RPE to enhance the reabsorption of fluid. Intravitreal injection of triamcinolone or bevacizumab has been reported to treat serous RD due to retinal vein occlusion26,27; repeated injection may be necessary for frequent recurrence of macular edema.

The visual prognosis of serous RD in retinal vein occlusion is variable. In an eye with serous RD associated with retinal vein occlusion, the outer retinal discontinuity does not necessarily lead to poor vision. If the surrounding outer segment of the foveal photoreceptors is preserved, good visual acuity will retain after macular edema and serous RD resolve. However, even after complete resolution of the macular edema and serous RD, diffuse disorganization of the outer photoreceptor layer beneath the fovea often results in poor visual acuity (see Fig. 96.11, online). In addition, a dome-shaped RD sometimes accompanies a focal defect of the outer segment of the photoreceptors above the serous RD. When the defect involves the fovea, visual prognosis is usually poor.