| Presumed ocular histoplasmosis syndrome | |
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| Retinal photograph of ocular histoplasmosis | |
| Specialty | Ophthalmology |
Presumed ocular histoplasmosis syndrome (POHS) is a syndrome affecting the eye, which is characterized by peripheral atrophic chorioretinal scars, atrophy or scarring adjacent to the optic disc and maculopathy.
The loss of vision in POHS is caused by choroidal neovascularization.
The diagnosis of POHS is based on the clinical triad of multiple white, atrophic choroidal scars, peripapillary pigment changes (dark spots around optic disc of the eye), and a maculopathy caused by choroidal neovascularization.
Completely distinct from POHS, acute ocular histoplasmosis may rarely occur in immunodeficiency. [1] [2]
Despite its name, the "presumed" relationship of POHS to Histoplasma capsulatum is controversial and has been questioned by a number of medical professionals. [3] [4] [5] The fungus has rarely been isolated from cases with POHS, [6] [ medical citation needed ] the condition has also been found in locations where histoplasmosis is rare, [7] and there appears to be a relationship with tobacco smoking.[ medical citation needed ]
Fluorescein angiography is usually performed for diagnosis and follow-up of patients with POHS.
Treatment requires careful consideration of angiographic findings when a choroidal neovascular membrane is suspected which is a condition that responds to treatment. A vitreo-retinal specialist (an ophthalmologist specialized in treatment of retinal diseases) should be consulted for proper management of the case.[ citation needed ]
Presumed ocular histoplasmosis syndrome and age-related macular degeneration (AMD) have been successfully treated with laser, anti-vascular endothelial growth factors and photodynamic therapy. Ophthalmologists are using anti-vascular endothelial growth factors to treat AMD and similar conditions since research indicates that vascular endothelial growth factor (VEGF) is one of the causes for the growth of the abnormal vessels that cause these conditions.[ citation needed ]
Chorioretinitis is an inflammation of the choroid and retina of the eye. It is a form of posterior uveitis. If only the choroid is inflamed, not the retina, the condition is termed choroiditis. The ophthalmologist's goal in treating these potentially blinding conditions is to eliminate the inflammation and minimize the potential risk of therapy to the patient.
Histoplasmosis is a fungal infection caused by Histoplasma capsulatum. Symptoms of this infection vary greatly, but the disease affects primarily the lungs. Occasionally, other organs are affected; called disseminated histoplasmosis, it can be fatal if left untreated.
The National Eye Institute (NEI) is part of the U.S. National Institutes of Health (NIH), an agency of the U.S. Department of Health and Human Services. The mission of NEI is “to eliminate vision loss and improve quality of life through vision research.” NEI consists of two major branches for research: an extramural branch that funds studies outside NIH and an intramural branch that funds research on the NIH campus in Bethesda, Maryland. Most of the NEI budget funds extramural research.
Neovascularization is the natural formation of new blood vessels, usually in the form of functional microvascular networks, capable of perfusion by red blood cells, that form to serve as collateral circulation in response to local poor perfusion or ischemia.
Intravitreal is a route of administration of a drug, or other substance, in which the substance is delivered into the vitreous humor of the eye. "Intravitreal" literally means "inside an eye". Intravitreal injections were first introduced in 1911 when Ohm gave an injection of air into the vitreous humor to repair a detached retina. In the mid-1940s, intravitreal injections became a standard way to administer drugs to treat endophthalmitis and cytomegalovirus retinitis.
Rubeosis iridis is a medical condition of the iris of the eye in which new abnormal blood vessels are found on the surface of the iris.
Optic disc drusen (ODD) are globules of mucoproteins and mucopolysaccharides that progressively calcify in the optic disc. They are thought to be the remnants of the axonal transport system of degenerated retinal ganglion cells. ODD have also been referred to as congenitally elevated or anomalous discs, pseudopapilledema, pseudoneuritis, buried disc drusen, and disc hyaline bodies.
Corneal neovascularization (CNV) is the in-growth of new blood vessels from the pericorneal plexus into avascular corneal tissue as a result of oxygen deprivation. Maintaining avascularity of the corneal stroma is an important aspect of corneal pathophysiology as it is required for corneal transparency and optimal vision. A decrease in corneal transparency causes visual acuity deterioration. Corneal tissue is avascular in nature and the presence of vascularization, which can be deep or superficial, is always pathologically related.
Acute posterior multifocal placoid pigment epitheliopathy (APMPPE) is an acquired inflammatory uveitis that belongs to the heterogenous group of white dot syndromes in which light-coloured (yellowish-white) lesions begin to form in the macular area of the retina. Early in the course of the disease, the lesions cause acute and marked vision loss that ranges from mild to severe but is usually transient in nature. APMPPE is classified as an inflammatory disorder that is usually bilateral and acute in onset but self-limiting. The lesions leave behind some pigmentation, but visual acuity eventually improves even without any treatment.
Choroidal neovascularization (CNV) is the creation of new blood vessels in the choroid layer of the eye. Choroidal neovascularization is a common cause of neovascular degenerative maculopathy commonly exacerbated by extreme myopia, malignant myopic degeneration, or age-related developments.
Intraocular hemorrhage is a bleeding (hemorrhage) inside the eye. The bleeding can occur from any structure of the eye where there is a presence of vasculature or blood flow. It can bleed inside the anterior chamber, vitreous cavity, retina, choroid, suprachoroidal space, or optic disc. Intraocular hemorrhage can be subdivided depending on the location of the bleed. It may be the result of physical trauma, an uncommon side effect due to post op ocular surgery or other diseases, injuries or disorders. Severe bleeding may cause high pressures inside the eye, leading to blindness.
Macular telangiectasia is a condition of the retina, the light-sensing tissue at the back of the eye that causes gradual deterioration of central vision, interfering with tasks such as reading and driving.
Sohan Singh Hayreh was an ophthalmologist, clinical scientist, and professor emeritus of ophthalmology at the University of Iowa. As one of the pioneers in the field of fluorescein angiography, he was generally acknowledged to be a leading authority in vascular diseases of the eye and the optic nerve. For over 60 years, Hayreh was actively involved in basic, experimental, and clinical research in ophthalmology, publishing over 400 original peer-reviewed articles in various international ophthalmic journals, six classical monographs and books in his field of research, and more than 50 chapters in ophthalmic books. He made many seminal observations dealing with the ocular circulation in health and disease, the optic disc and the optic nerve, retinal and choroidal vascular disorders, glaucomatous optic neuropathy, fundus changes in malignant arterial hypertension, ocular neovascularization, rheumatologic disorders of the eye, and nocturnal arterial hypotension. He was an elected fellow of the National Academy of Medical Sciences.
Joan Whitten Miller is a Canadian-American ophthalmologist and scientist who has made notable contributions to the treatment and understanding of eye disorders. She is credited for developing photodynamic therapy (PDT) with verteporfin (Visudyne), the first pharmacologic therapy for retinal disease. She also co-discovered the role of vascular endothelial growth factor (VEGF) in eye disease and demonstrated the therapeutic potential of VEGF inhibitors, forming the scientific basis of anti-VEGF therapy for age-related macular degeneration (AMD), diabetic retinopathy, and related conditions.
Vogt–Koyanagi–Harada disease (VKH) is a multisystem disease of presumed autoimmune cause that affects melanin-pigmented tissues. The most significant manifestation is bilateral, diffuse uveitis, which affects the eyes. VKH may variably also involve the inner ear, with effects on hearing, the skin, and the meninges of the central nervous system.
Geographic atrophy (GA), also known as atrophic age-related macular degeneration (AMD) or advanced dry AMD, is an advanced form of age-related macular degeneration that can result in the progressive and irreversible loss of retinal tissue (photoreceptors, retinal pigment epithelium, choriocappillaris) which can lead to a loss of visual function over time. It is estimated that GA affects >5 million people worldwide and approximately 1 million patients in the US, which is similar to the prevalence of neovascular (wet) AMD, the other advanced form of the disease.
Indocyanine green angiography (ICGA) is a diagnostic procedure used to examine choroidal blood flow and associated pathology. Indocyanine green (ICG) is a water soluble cyanine dye which shows fluorescence in near-infrared range, with peak spectral absorption of 800-810 nm in blood. The near infrared light used in ICGA penetrates ocular pigments such as melanin and xanthophyll, as well as exudates and thin layers of sub-retinal vessels. Age-related macular degeneration is the third main cause of blindness worldwide, and it is the leading cause of blindness in industrialized countries. Indocyanine green angiography is widely used to study choroidal neovascularization in patients with exudative age-related macular degeneration. In nonexudative AMD, ICGA is used in classification of drusen and associated subretinal deposits.
Sickle cell retinopathy can be defined as retinal changes due to blood vessel damage in the eye of a person with a background of sickle cell disease. It can likely progress to loss of vision in late stages due to vitreous hemorrhage or retinal detachment. Sickle cell disease is a structural red blood cell disorder leading to consequences in multiple systems. It is characterized by chronic red blood cell destruction, vascular injury, and tissue ischemia causing damage to the brain, eyes, heart, lungs, kidneys, spleen, and musculoskeletal system.
Conbercept, sold under the commercial name Lumitin, is a novel vascular endothelial growth factor (VEGF) inhibitor used to treat neovascular age-related macular degeneration (AMD) and diabetic macular edema (DME). The anti-VEGF was approved for the treatment of neovascular AMD by the China State FDA (CFDA) in December 2013. As of December 2020, conbercept is undergoing phase III clinical trials through the U.S. Food and Drug Administration’s PANDA-1 and PANDA-2 development programs.
Polypoidal choroidal vasculopathy (PCV) is an eye disease primarily affecting the choroid. It may cause sudden blurring of vision or a scotoma in the central field of vision. Since Indocyanine green angiography gives better imaging of choroidal structures, it is more preferred in diagnosing PCV. Treatment options of PCV include careful observation, photodynamic therapy, thermal laser, intravitreal injection of anti-VEGF therapy, or combination therapy.
| Authority control: National |
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