Macular edema occurs when fluid and

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

deposits collect on or under the

macula The macula (/ˈmakjʊlə/) or macula lutea is an oval-shaped pigmented area in the center of the retina of the human eye and in other animals. The macula in humans has a diameter of around and is subdivided into the umbo, foveola, foveal avas ...

of the

eye An eye is a sensory organ that allows an organism to perceive visual information. It detects light and converts it into electro-chemical impulses in neurons (neurones). It is part of an organism's visual system. In higher organisms, the ey ...

(a yellow central area of the

retina The retina (; or retinas) is the innermost, photosensitivity, light-sensitive layer of tissue (biology), tissue of the eye of most vertebrates and some Mollusca, molluscs. The optics of the eye create a focus (optics), focused two-dimensional ...

) and causes it to thicken and swell (

edema Edema (American English), also spelled oedema (British English), and also known as fluid retention, swelling, dropsy and hydropsy, is the build-up of fluid in the body's tissue (biology), tissue. Most commonly, the legs or arms are affected. S ...

). The swelling may distort a person's central

vision Vision, Visions, or The Vision may refer to: Perception Optical perception * Visual perception, the sense of sight * Visual system, the physical mechanism of eyesight * Computer vision, a field dealing with how computers can be made to gain und ...

, because the macula holds tightly packed

cones In geometry, a cone is a three-dimensional figure that tapers smoothly from a flat base (typically a circle) to a point not contained in the base, called the ''apex'' or '' vertex''. A cone is formed by a set of line segments, half-lines, ...

that provide sharp, clear, central vision to enable a person to see detail, form, and color that is directly in the centre of the

field of view The field of view (FOV) is the angle, angular extent of the observable world that is visual perception, seen at any given moment. In the case of optical instruments or sensors, it is a solid angle through which a detector is sensitive to elec ...

Cause

The causes of macular edema are numerous and different causes may be inter-related. *It is commonly associated with

diabetes Diabetes mellitus, commonly known as diabetes, is a group of common endocrine diseases characterized by sustained high blood sugar levels. Diabetes is due to either the pancreas not producing enough of the hormone insulin, or the cells of th ...

. Chronic or uncontrolled diabetes type 2 can affect peripheral blood vessels including those of the retina which may leak fluid, blood and occasionally fats into the retina causing it to swell. *Age-related

macular degeneration Macular degeneration, also known as age-related macular degeneration (AMD or ARMD), is a medical condition which may result in blurred vision, blurred or vision loss, no vision in the center of the visual field. Early on there are often no sym ...

may cause macular edema. As individuals age there may be a natural deterioration in the macula which can lead to the depositing of

drusen Drusen, from the German word for ''node'' or ''geode'' (singular, "Druse"), are tiny yellow or white accumulations of extracellular material that build up between Bruch's membrane and the retinal pigment epithelium of the eye. The presence of a ...

under the retina sometimes with the formation of abnormal blood vessels. *Replacement of the

lens A lens is a transmissive optical device that focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements'') ...

as treatment for

cataract A cataract is a cloudy area in the lens (anatomy), lens of the eye that leads to a visual impairment, decrease in vision of the eye. Cataracts often develop slowly and can affect one or both eyes. Symptoms may include faded colours, blurry or ...

can cause pseudophakic macular edema (' pseudophakia' means 'replacement lens'), also known as

Irvine–Gass syndrome Irvine–Gass syndrome, pseudophakic cystoid macular edema or postcataract CME is one of the most common causes of visual loss after cataract surgery. The syndrome is named in honor of S. Rodman Irvine and J. Donald M. Gass. The incidence is mo ...

. The surgery involved sometimes irritates the retina (and other parts of the eye) causing the capillaries in the retina to dilate and leak fluid into the retina. This is less common today with modern lens replacement techniques. *Chronic

uveitis Uveitis () is inflammation of the uvea, the pigmented layer of the eye between the inner retina and the outer fibrous layer composed of the sclera and cornea. The uvea consists of the middle layer of pigmented vascular structures of the eye and ...

and

intermediate uveitis Intermediate uveitis is a form of uveitis localized to the vitreous and peripheral retina. Intermediate uveitis may either be an isolated eye disease or associated with the development of a systemic disease such as multiple sclerosis or sarcoidosi ...

can be a cause. *Blockage of a vein in the retina can cause engorgement of the other retinal veins causing them to leak fluid under or into the retina. The blockage may be caused, among other things, by

atherosclerosis Atherosclerosis is a pattern of the disease arteriosclerosis, characterized by development of abnormalities called lesions in walls of arteries. This is a chronic inflammatory disease involving many different cell types and is driven by eleva ...

high blood pressure Hypertension, also known as high blood pressure, is a long-term medical condition in which the blood pressure in the arteries is persistently elevated. High blood pressure usually does not cause symptoms itself. It is, however, a major ri ...

and

glaucoma Glaucoma is a group of eye diseases that can lead to damage of the optic nerve. The optic nerve transmits visual information from the eye to the brain. Glaucoma may cause vision loss if left untreated. It has been called the "silent thief of ...

. *A number of drugs can cause changes in the retina that can lead to macular edema. The effect of each drug is variable and some drugs have a lesser role in causation. The principal medications known to affect the retina are

latanoprost Latanoprost, sold under the brand name Xalatan among others, is a medication used to treat increased pressure inside the eye (intraocular pressure). This includes ocular hypertension and open-angle glaucoma. Latanaprost is applied as eye d ...

epinephrine Adrenaline, also known as epinephrine, is a hormone and medication which is involved in regulating visceral functions (e.g., respiration). It appears as a white microcrystalline granule. Adrenaline is normally produced by the adrenal glands a ...

rosiglitazone Rosiglitazone (trade name Avandia) is an antidiabetic drug in the thiazolidinedione class. It works as an insulin sensitizer, by binding to the PPAR in fat cells and making the cells more responsive to insulin. It is marketed by the pharmaceut ...

timolol Timolol is a beta blocker medication used either by mouth or as eye drops. As eye drops it is used to treat increased pressure inside the eye such as in ocular hypertension and glaucoma. By mouth it is used for high blood pressure, chest ...

and

thiazolidinediones The thiazolidinediones , abbreviated as TZD, also known as glitazones after the prototypical drug ciglitazone, are a class of heterocyclic compounds consisting of a five-membered C3NS ring. The term usually refers to a family of drugs used i ...

among others. *A few congenital diseases are known to be associated with macular edema, for example

retinitis pigmentosa Retinitis pigmentosa (RP) is a member of a group of genetic disorders called inherited retinal dystrophy (IRD) that cause loss of vision. Symptoms include trouble seeing at night and decreasing peripheral vision (side and upper or lower visua ...

and

retinoschisis Retinoschisis is an eye disease characterized by the abnormal splitting of the retina's neurosensory layers, usually in the outer plexiform layer. Retinoschisis can be divided into degenerative forms which are very common and almost exclusively i ...

Diagnosis

Classification

Cystoid macular edema (CME) involves fluid accumulation in the outer plexiform layer secondary to abnormal perifoveal retinal capillary permeability. The edema is termed "cystoid" as it appears cystic; however, lacking an epithelial coating, it is not truly cystic. The cause for CME can be remembered with the mnemonic "DEPRIVEN" (diabetes, epinepherine, pars planitis, retinitis pigmentosa, Irvine-Gass syndrome, venous occlusion, E2-prostaglandin analogues, nicotinic acid/niacin). Diabetic macular edema (DME) is similarly caused by leaking macular capillaries. DME is the most common cause of visual loss in both proliferative, and non-proliferative

diabetic retinopathy Diabetic retinopathy (also known as diabetic eye disease) is a medical condition in which damage occurs to the retina due to diabetes. It is a leading cause of blindness in developed countries and one of the lead causes of sight loss in the wor ...

Treatment

Macular edema sometimes occurs for a few days or weeks (sometimes even much longer) after

cataract surgery Cataract surgery, also called lens replacement surgery, is the removal of the natural lens (anatomy), lens of the human eye, eye that has developed a cataract, an opaque or cloudy area. The eye's natural lens is usually replaced with an artific ...

, but most such cases can be successfully treated with

NSAID Non-steroidal anti-inflammatory drugs (NSAID) are members of a therapeutic drug class which reduces pain, decreases inflammation, decreases fever, and prevents blood clots. Side effects depend on the specific drug, its dose and duration of ...

cortisone Cortisone is a pregnene (21-carbon) steroid hormone. It is a naturally-occurring corticosteroid metabolite that is also used as a pharmaceutical prodrug. Cortisol is converted by the action of the enzyme corticosteroid 11-beta-dehydrogenase ...

eye drops ''Eye Drops'' is a television program on TechTV that showcased short computer animation movies and clips made using off the shelf 3D animation software. The show claimed to showcase all different types of animation, but only a very small number ...

. Prophylactic use of

Nonsteroidal anti-inflammatory drug Non-steroidal anti-inflammatory drugs (NSAID) are members of a Indication (medicine), therapeutic drug class which Analgesic, reduces pain, Anti-inflammatory, decreases inflammation, Antipyretic, decreases fever, and Antithrombotic, prevents bl ...

s has been reported to reduce the risk of macular edema to some extent. Higher frequency use of topical steroids provides benefit in difficult to treat cases. Diabetic macular edema may be treated with laser photocoagulation, reducing the chance of vision loss. In 2010, the US

FDA The United States Food and Drug Administration (FDA or US FDA) is a federal agency of the Department of Health and Human Services. The FDA is responsible for protecting and promoting public health through the control and supervision of food ...

approved the use of

Lucentis Ranibizumab, sold under the brand name Lucentis among others, is a monoclonal antibody fragment (Fab) created from the same parent mouse antibody as bevacizumab. It is an anti-angiogenic that is approved to treat the "wet" type of age-related ...

intravitreal injections for macular edema. Iluvien, a sustained release intravitreal implant developed by

Alimera Sciences Alimera Sciences, Inc. was a biopharmaceutical sales company based in Alpharetta, Georgia that specialized in the commercialization and sales of prescription ophthalmic pharmaceuticals. The company's main selling focus was on diseases affecting ...

, has been approved in Austria, Portugal and the U.K. for the treatment of vision impairment associated with chronic diabetic macular edema (DME) considered insufficiently responsive to available therapies. Additional EU country approvals are anticipated. In 2013 Lucentis by intravitreal injection was approved by the

National Institute for Health and Care Excellence The National Institute for Health and Care Excellence (NICE) is an executive non-departmental public body of the Department of Health and Social Care (United Kingdom), Department of Health and Social Care. As the national health technolog ...

in the UK for the treatment of macular edema caused by diabetes and/or retinal vein occlusion. On July 29, 2014, Eylea (

aflibercept Aflibercept, sold under the brand names Eylea and Zaltrap among others, is a medication used to treat wet macular degeneration and metastatic colorectal cancer. It was developed by Regeneron Pharmaceuticals. It is an inhibitor of vascular en ...

), an intravitreal injection produced by

Regeneron Pharmaceuticals Regeneron Pharmaceuticals, Inc. is an American biotechnology company headquartered in Westchester County, New York. The company was founded in 1988. Originally focused on neurotrophic factors and their regenerative capabilities, giving rise to ...

Inc., was approved to treat DME in the United States. On January 28, 2022, Vabysmo, a different injectable eye medication produced by Genentech was approved to treat both Wet AMD and DME in the United States.

Research

In 2005, steroids were investigated for the treatment of macular edema due to retinal blood vessel blockage such as CRVO and BRVO. A 2014 Cochrane Systematic Review studied the effectiveness of two

anti-VEGF Anti–vascular endothelial growth factor therapy, also known as anti-VEGF () therapy or medication, is the use of medications that block vascular endothelial growth factor. This is done in the treatment of certain cancers and in age-related macu ...

treatments,

ranibizumab Ranibizumab, sold under the brand name Lucentis among others, is a monoclonal antibody fragment (Fab) created from the same parent mouse antibody as bevacizumab. It is an anti-angiogenic that is approved to treat the "wet" type of age-related ...

and

pegaptanib Pegaptanib sodium injection (brand name Macugen) is an anti-angiogenic medicine for the treatment of neovascular (wet) age-related macular degeneration (AMD). It was discovered by NeXstar Pharmaceuticals (which merged with Gilead Sciences in 199 ...

, on patients with macular edema caused by CRVO. Participants on both treatment groups showed a reduction in macular edema symptoms over six months. Another Cochrane Review examined the effectiveness and safety of two intravitreal steroid treatments,

triamcinolone acetonide Triamcinolone acetonide, sold under the brand name Kenalog among others, is a synthetic compound, synthetic corticosteroid medication used topical medication, topically to treat various skin conditions, to relieve the discomfort of mouth sores, ...

and

dexamethasone Dexamethasone is a fluorinated glucocorticoid medication used to treat rheumatic problems, a number of skin diseases, severe allergies, asthma, chronic obstructive pulmonary disease (COPD), croup, brain swelling, eye pain following eye su ...

, for patients with from CRVO-ME. The results from one trial showed that patients treated with triamcinolone acetonide were significantly more likely to show improvements in visual acuity than those in the control group, though outcome data was missing for a large proportion of the control group. The second trial showed that patients treated with dexamethasone implants did not show improvements in visual acuity, compared to patients in the control group. Intravitreal injections and implantation of steroids inside the eye may result in a small improvement of vision for people with chronic or

refractory In materials science, a refractory (or refractory material) is a material that is resistant to decomposition by heat or chemical attack and that retains its strength and rigidity at high temperatures. They are inorganic, non-metallic compound ...

diabetic macular edema. There is low certainty evidence that there does not appear to be any additional benefit of combining

and intravitreal steroids when compared to either treatment alone. Anti‐tumour necrosis factor agents have been proposed as a treatment for macular oedema due to uveitis but a Cochrane Review published in 2018 found no relevant randomised controlled trials.

References

External links

{{DEFAULTSORT:Macular Edema Disorders of choroid and retina Medical signs