Country Hills Eye Center
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Central Serous Retinopathy

Scott C. Richards, M.D.

 

Central serous retinopathy (CSR) is a relatively common retinal disorder that is characterized by clear or transparent (serous) fluid that accumulates under the retina in a circumscribed area, usually in the central area of the retina known as the macula.  It was initially described in 1866 by Von Graefe and was erroneously thought to be a retinal manifestation of syphilis.  Since that time it has been referred to by many names, including central serous chorioretinopathy, central serous pigment epitheliopathy, and central serous retinitis.  There is some controversy as to which name is most appropriate, but central serous retinopathy is probably the most commonly used name.

Clinical Findings

The most common initial symptoms of CSR are mild blurriness of vision and distortion of vision (metamorphopsia).  Some patients describe a central round gray or brown area in the vision with normal vision outside the dark area.  Other patients may describe micropsia (apparent decrease in size of objects seen), color desaturation, impaired dark adaptation, or prolonged recovery from bright light.  These findings are usually unilateral, but in some cases both eyes can be involved.  Some patients have also described migraine-like headaches preceding the onset of the visual disturbances.  There is typically no associated pain, redness, or inflammation of the eye.

 The visual acuity in the acute phase of CSR can range from 20/20 to as poor as 20/200, but is usually averages about 20/30.  In many cases this decreased vision can be corrected to some degree with a hyperopic (farsighted) lens correction.

 Examination of the eye in cases of CSR is unremarkable in most respects, with the anterior segment of the eye typically being normal.  The classic clinical finding is a transparent blister of fluid that accumulates between the retina and the underlying retinal pigment epithelium (RPE).  This is usually best seen through a contact lens designed for examination of the retina.  These blisters of fluid can be very difficult to see in some cases and sometimes are evidenced only by the absence of the normal retinal light reflexes.  The fluid within the blister is usually transparent, but may be somewhat turbid or yellowish in some patients.  Small dot opacities of the elevated retina can sometimes be seen, and may represent precipitated protein on the inner surface of the blister.

 After resolution of the serous detachment, small patches of yellow or gray discoloration can be seen on the normal orange/brown pigment epithelial background.  These changes are probably areas of localized damage to the RPE resulting in depigmentation in some areas and pigment clumping in other areas.  In many cases of active central serous retinopathy, these pigmentary changes can be seen in one or both eyes, possibly indicating previous resolved asymptomatic episodes of CSR. 

Within the area of serous fluid, oval yellow or gray elevations of the pigment epithelium can sometimes be seen.  These are usually less than one-fourth disc diameter in size.  These lesions correspond to the area of leakage within the blister in many cases.

The serous subretinal fluid usually has a very sharply demarcated border with the surrounding normal retina.  The height of the serous detachment can be quite variable, with some cases showing moderate to marked elevation and others demonstrating very subtle or shallow subretinal fluid. 

In most cases, the diagnosis of central serous retinopathy can be made based entirely upon the symptoms and the retinal examination.  However, fluorescein angiography can be used to confirm the diagnosis in more subtle cases, and to exclude other retinal conditions.  Fluorescein angiography is also useful in determining the extent of the lesion and location of the leakage that is producing the subretinal fluid.  The typical angiographic finding is that of a focal area of leakage of fluorescein dye from the pigment epithelium into the subretinal space.  This leakage can be from a single location or from several spots within the serous detachment.  In some cases, multiple leaking spots produce several distinct small serous elevations. 

The classic angiographic description of CSR is that of a focal area of leakage followed by “smokestack” configuration of the dye.  This occurs when the dye enters the subretinal space and begins to flow superiorly in a stream.  Upon reaching the superior edge of the serous detachment, the dye spreads laterally in a mushroom cloud or umbrella configuration and eventually fills the entire area of the serous detachment.  The precise reason for the “smokestack” configuration is not well known but may be the result of fluid movement within the blister caused by temperature or osmotic pressure gradients. 

Although the “smokestack” configuration is described as the classic CSR presentation, it actually occurs in less than 20% of cases.  In most CSR patients, the leaking dye spreads symmetrically in all directions until the serous detachment is filled.  Although the initial flow of dye into the blister is fairly rapid, it may not completely fill for 20 minutes or longer. 

The localization of the leaking spot(s) can be important, especially in cases where laser treatment of the leak is considered.  Although the subretinal fluid typically extends through the center of the macula, it is interesting that the leakage point is very seldom in the fovea.  Instead, the leakage is typically found within a ring-shaped area surrounding the fovea, usually within one millimeter.  For unknown reasons, leakage is somewhat more common in the upper nasal quadrant than in the other quadrants.  A single leaking spot is found in approximately 70% of cases.  Although the leakage area is usually not central, there is a definite tendency for the fluid to extend into the central region.  In recurrent cases the new leakage point typically is near the previous leakage point. 

Natural History

Left untreated, the subretinal fluid typically resolves within one to four months following the onset of symptoms.  As the subretinal fluid resolves, visual acuity typically returns to normal or near normal, and the hyperopia (farsightedness) induced by the elevation also resolves.  Visual recovery may lag behind the subretinal fluid reabsorption by weeks or months.  Many patients report subtle changes in their visual perception that may last for long periods of time or even indefinitely.  These visual changes can include metamorphopsia (waviness or distortion of vision), “dimness” of vision, abnormal color perception, or small patches of “missing vision” near the center.  It is not uncommon for patients with 20/20 or better vision following central serous retinopathy to complain that the vision is “just not the same as before.”  The reason for these subtle visual changes is unknown, but may be related to the presence of localized central detachment for weeks or months.  In fact, it is surprising that visual acuity is so well maintained following CSR, since patients with central retinal detachments caused by other conditions generally do not fare as well.

Recurrences of CSR are common and occur in approximately one-third to one-half of cases.  In approximately half of patients with recurrences the new episode develops within one year of the initial episode.  However, recurrences can occur many years later.

As the leakage decreases and eventually resolves, the subretinal fluid is gradually reabsorbed.  A pigment epithelial scar, seen as a localized area of yellow or gray discoloration of the pigment epithelium, is typically left behind in the area of leakage.  This RPE scar is usually somewhat larger than the original leakage point and is readily visible by fluorescein angiography, although it no longer leaks.

Types Of Central Serous Retinopathy

The clinical findings and natural history of central serous retinopathy as described above occur in over 90% of cases, and is referred to as Type I CSR.  Type II disease is characterized by localized elevation of the pigment epithelium (RPE detachment), with no overlying serous subretinal fluid.  In this case, the blister of fluid is confined to the space under the pigment epithelium rather than between the pigment epithelium and retina.  The surface of the detached pigment epithelium may have mottled hyperfluorescence, but does not show definite leakage. 

In Type III or intermediate CSR, there is a combination of sub-RPE fluid and subretinal fluid.  The fluorescein angiogram shows findings similar to that in Type II disease, but focal leakage points can be seen. 

In some cases of Type I disease, there is no defined leakage point but rather a diffuse area of leakage without RPE detachments.  There are also cases of what has been referred to as a “leaking scar.”  This is an area that looks clinically and angiographically like a scar that results from spontaneous healing of CSR, but shows some mild residual leaking. 

Central serous retinopathy can present as a large inferior peripheral retinal detachment.  It is theorized that in these cases, a track develops that allows the fluid to escape from the localized blister of central fluid into a more inferior peripheral location.  In some of these cases, differentiation from peripheral retinal detachments caused by retinal holes can be difficult. 

There is also a chronic form of central serous retinopathy, which occurs in approximately 5% of cases.  Chronic CSR seems to be the result of a more diffuse rather than focal abnormality of the pigment epithelium, which produces chronic, persistent, or intermittent subretinal fluid.  The subretinal fluid in these cases tends to be shallow rather than dome shaped, and complete visual recovery is probably less likely. 

Etiology and Pathogenesis

The actual cause of central serous retinopathy is not well understood.  Because of the benign nature of the disease and the tendency to occur in young patients, very few pathologic studies have been performed.  It is generally accepted that the source of the subretinal fluid is the choroid, and that this fluid passes through a focal defect in the pigment epithelium and from there into the subretinal space.  What is not well understood is how that leakage occurs and why certain patients are more prone to the disease than others. 

Several theories have been devised to explain the leakage of subretinal fluid.  In order to understand these theories, it is useful to have some understanding of retinal anatomy and physiology.  The blood vessels within the retina have tight junctions that do not allow leakage of fluid outside of the vessels.  Likewise, the layer of pigmented epithelial cells under the retina have tight junctions between the cells that do not allow passage of fluid into the subretinal space except through the cell membranes of the pigment epithelium.  The choroid consists of a dense collection of blood vessels under the pigment epithelium that provide much of the oxygenation and nourishment for the pigment epithelium and retina.  The choroidal blood vessels are fenestrated, meaning that they have many small holes that allow easy passage of water and small molecules out of the blood stream and into the surrounding tissue.  This extravascular fluid is not allowed into the subretinal space because of the tight junctions between the pigment epithelial cells.  In addition, the retinal pigment epithelium has an active pumping mechanism that moves water and ions from the retina and subretinal space into the choroidal space.  The suction force of this fluid being pumped out of the subretinal space is very important in keeping the retina attached to the pigment epithelium.  There are also some physical attachments between the retinal photoreceptors and the pigment epithelium.  The precise contribution of the physical RPE/retinal adhesion and the RPE pump are not fully understood, but the RPE pump probably plays a greater role. 

In a typical retinal detachment caused by trauma or aging, fluid from the vitreous cavity passes through a hole in the retina faster than it can be pumped away by the pigment epithelium.  To repair such a detachment, the retinal hole or tear needs to be closed to prevent further passage of fluid, allowing the RPE pump to remove the subretinal fluid and reattach the retina.  In central serous retinopathy, the subretinal fluid comes from a defect in the pigment epithelium that allows sufficient passage of fluid into the subretinal space to overcome the RPE pump and RPE/retinal adhesions. 

One theory of the pathogenesis of CSR is that there is a defect or hole in the pigment epithelium that allows passive movement of fluid into the subretinal space.  However, there are many retinal diseases characterized by defects or abnormalities of the pigment epithelium that do not necessarily result in subretinal fluid.  In fact, laser photocoagulation produces a localized breakdown in the pigment epithelium.  The theory of passive flow of fluid from the choroid through the RPE does not explain the beneficial effect of photocoagulation in eliminating leakage. 

Spitznas in 1986 theorized that the subretinal fluid accumulates due to a collection of abnormally hypersecreting pigment epithelial cells.  These impaired pigment epithelial cells seem to pump large numbers of ions in the wrong direction - that is, into the subretinal space rather than into the choroidal space.  The osmotic gradient produced by the ion movement then draws fluid into the subretinal space.  Initially this fluid movement would be through the cell walls.  As greater amounts of fluid passes through the RPE, the diffusion barrier would be disrupted, producing increasingly rapid flow of fluid into the blister.  The fluid would be absorbed by the surrounding normal RPE cells, leading to a stable blister, the size of which would be determined by the balance between the pumping of fluid in the two directions. 

This hypothesis of localized hypersecretion of the RPE explains many of the observed clinical changes in CSR but does not account for the presence of pigment epithelial detachments in some cases. 

Studies using indocyanine green angiography have shown areas of delayed filling of choroidal capillaries in areas of hyperpermeability in patients with CSR.  It has been proposed that this delayed filling represents areas of ischemia (lack of blood supply), which then produces increased leakage from the damaged choroidal vessels.  This would allow accumulation of fluid under the pigment epithelium, producing a pigment epithelial detachment.  As the RPE detachment grows, the tight junctions between the RPE cells are broken allowing rapid flow of fluid into the subretinal space.  Although this theory explains the presence of RPE detachments, especially in Type II and III CSR, it does not to my mind explain the absence of RPE detachments in the majority of cases.  It also does not explain why photocoagulation would eliminate the leakage, since the physical disruption of the RPE would most likely be worsened by photocoagulation rather than improved.   

Epidemiology

Central serous retinopathy is a disease that typically affects men between the age of 20 and 50.  No cases of central serous retinopathy have been reported in a patient under the age of 20.  The findings of central serous retinopathy are in some ways very similar to those of macular degeneration, and cases with these findings in patients over the age of 50 are usually ascribed to macular degeneration.  It is unclear whether this upper age limit of 50 represents a purely artificial distinction or if there is some overlap between the two diseases. 

Men are affected approximately eight or nine times more often than women.  When CSR occurs in women, it is more likely to occur between age 30 and 40. 

Central serous retinopathy has been associated with the use of vasoconstrictive agents and corticosteroids as well as elevated cortisol levels.  It can be produced in animals by injection of intravenous epinephrine. 

There are also studies that suggest that central serous retinopathy may be caused or modulated to some degree by psychological factors.  Personality tests administered to patients with CSR and a matched controlled group showed higher values on the hyperchondria and hysteria scale in the group with CSR.  There seems to be an increased frequency of CSR in intelligent individuals undergoing physical or emotional stress or individuals with “Type A personalities.”  The association with migraine headache in some cases and the association with corticosteroids and epinephrine also implies a possible connection with stress. 

Differential Diagnosis

Several of the findings in central serous retinopathy can be found in other ocular diseases, and CSR must be differentiated from these problems.  Serous elevations of the retina in the macula region can be caused by multiple diseases, including optic nerve pits, uveitis, optic neuritis, vitreous traction, high blood pressure, macular holes, age related macular degeneration, and shallow retinal detachment caused by retinal holes or tears.  Most of these conditions can be differentiated from central serous retinopathy based on the ocular examination, fluorescein angiogram, and history.  Differentiation from subretinal neovascularization (abnormal new vessels growing under the retina, often caused by macular degeneration) can be particularly difficult, especially since the two conditions share many ophthalmoscopic and angiographic findings.  Intraocular tumors such as amelanotic melanomas or metastatic tumors to the choroid may have overlying subretinal fluid and should also be ruled out. 

Treatment

Since most cases of central serous retinopathy resolve spontaneously, treatment is often not indicated.  Many patients are willing to wait for spontaneous resolution once they are aware that the condition is usually self-limited. 

The only treatment that has consistently proved beneficial for central serous retinopathy is laser photocoagulation.  Laser treatment can be used to stop the focal leakage and induce resolution of the subretinal fluid in many cases.  In order for photocoagulation to work, the area of focal leakage must be treated.  Therefore, in cases where the leakage is in the most central part of the macula, treatment is contraindicated because of potential visual damage induced by the photocoagulation. 

Several studies have documented that laser treatment shortens the duration of central serous retinopathy significantly.  Watzke showed that the medium duration of disease decreased from 23 weeks in untreated eyes to five weeks in treated eyes.  There is some evidence to suggest that photocoagulation also reduces the recurrence rate, although this has not been shown in all studies.  The final visual acuity and residual visual deficits appear to be similar for both treated and untreated patients. 

There are potential complications from laser treatment for CSR.  These include scotoma (missing spots in the vision) caused by laser damage, inadvertent photocoagulation of the fovea, and subretinal neovascularization induced at the site of the laser scar.  Although these complications are rare, they can be quite devastating visually.  Because of this risk of complications, and because so many cases of CSR resolve spontaneously, photocoagulation is not generally advocated for all cases.  Laser treatment is typically reserved for patients who have had no resolution of their serous fluid within several months.  In some patients with more visually demanding professions, treatment may be considered somewhat earlier. 

No medication has been proven to be effective in the treatment of central serous retinopathy.

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