Retinoschisis | |
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This condition is usually inherited in an X-linked recessive manner. | |
Specialty | Ophthalmology |
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 involve the peripheral retina and hereditary forms which are rare and involve the central retina and sometimes the peripheral retina. The degenerative forms are asymptomatic and involve the peripheral retina only and do not affect the visual acuity. Some rarer forms result in a loss of vision in the corresponding visual field. [1]
Almost all cases are X-linked recessive and caused by a mutation in the retinoschisin gene (RS1). [2]
This type of retinoschisis is very common with a prevalence of up to 7 percent in normal persons. Its cause is unknown. It can easily be confused with retinal detachment by the non-expert observer and in difficult cases even the expert may have difficulty differentiating the two. Such differentiation is important since retinal detachment almost always requires treatment while retinoschisis never itself requires treatment and leads to retinal detachment (and hence to visual loss) only occasionally. Unfortunately one still sees cases of uncomplicated retinoschisis treated by laser retinopexy or cryopexy in an attempt to stop its progression towards the macula. Such treatments are not only ineffective but unnecessarily risk complications. There is no documented case in the literature of degenerative retinoschisis itself (as opposed to the occasional situation of retinal detachment complicating retinoschisis) in which the splitting of the retina has progressed through the fovea. There is no clinical utility in differentiating between typical and reticular retinoschisis. Degenerative retinoschisis is not known to be a genetically inherited condition. There is always vision loss in the region of the schisis as the sensory retina is separated from the ganglion layer. But as the loss is in the periphery, it goes unnoticed. It is the very rare schisis that encroaches on the macula where retinopexy is then properly used. [3]
Hereditary retinoschisis is derived from a defective retinoschisin protein, which is due to an X-linked genetic defect. The genetic form of this disease usually starts during childhood and is called X-linked Juvenile Retinoschisis (XLRS) or Congenital Retinoschisis. Affected males are usually identified in grade school, but occasionally are identified as young infants.
It is estimated that this much less common form of retinoschisis affects one in 5,000 to 25,000 individuals, primarily young males. Schisis is derived from the Greek word meaning splitting, describing the splitting of the retinal layers from each other. However, schisis is a word fragment, and the term retinoschisis should be used, as should the term iridoschisis when describing splitting of the iris. If the retinoschisis involves the macula, then the high-resolution central area of vision used to view detail is lost, and this is one form of macular disease. Although it might be described by some as a "degeneration", the term macular degeneration should be reserved for the specific disease "age-related macular degeneration".
Very few affected individuals go completely blind from retinoschisis, but some sufferers have very limited reading vision and are "legally blind". Visual acuity can be reduced to less than 20/200 in both eyes. Individuals affected by XLRS are at an increased risk for retinal detachment and eye hemorrhage, among other potential complications.
Retinoschisis causes acuity loss in the center of the visual field through the formation of tiny cysts in the retina, often forming a "spoke-wheel" pattern that can be very subtle. The cysts are usually only detectable by a trained clinician. In some cases vision cannot be improved by glasses, as the nerve tissue itself is damaged by these cysts.
The National Eye Institute (NEI) of the National Institutes of Health (NIH) is conducting clinical and genetic studies of X-Linked Juvenile Retinoschisis. [4] This study began in 2003 and as of 2018 is continuing to recruit patients. A better understanding of why and how XLRS develops might lead to improved treatments. Males diagnosed with X-linked juvenile retinoschisis and females who are suspected carriers may be eligible to participate. In addition to giving a medical history and submitting medical records, participants submit a blood sample and the NEI will perform a genetic analysis. There is no cost to participate in this study.
This may be present in conditions causing traction on the retina especially at the macula. [5] This may occur in: a) The vitreomacular traction syndrome; b) Proliferative diabetic retinopathy with vitreoretinal traction; c) Atypical cases of impending macular hole.
Retinoschisis involving the central part of the retina secondary to an optic disc pit was erroneously considered to be a serous retinal detachment until correctly described by Lincoff as retinoschisis. Significant visual loss may occur and following a period of observation for spontaneous resolution, treatment with temporal peripapillary laser photocoagulation followed by vitrectomy and gas injection followed by face-down positioning is very effective in treating this condition. [6]
The diagnosis of the disease is usually made during an examination of the back of the eye (fundus) where any splits, tears or rips may be seen. One diagnostic tool is optical coherence tomography (OCT), which uses light waves to create images of the retina and based on ophthalmoscopy with scleral depression and contact lens examination. The fellow eye should also be examined.
Retinoschisis usually does not require treatment aside from glasses to improve vision [ citation needed ]. However, some children with X-linked retinoschisis may have bleeding in their eye. This can be treated with either laser therapy or cryosurgery. In rare cases, children may need surgery to stop the bleeding.
As of 2022, a clinical trial of gene therapy to treat XLRS was ongoing. [7] After 1 year, the paper concluded that the therapy "was generally safe and well tolerated but failed to demonstrate a measurable treatment effect" and a 5-year follow up will be conducted to assess long-term safety.
There may be various gene editing techniques to possibly treat hereditary retinoschisis. [8] [9]
The retina is the innermost, light-sensitive layer of tissue of the eye of most vertebrates and some molluscs. The optics of the eye create a focused two-dimensional image of the visual world on the retina, which then processes that image within the retina and sends nerve impulses along the optic nerve to the visual cortex to create visual perception. The retina serves a function which is in many ways analogous to that of the film or image sensor in a camera.
Diabetic retinopathy 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 world, even though there are many new therapies and improved treatments for helping people live with diabetes.
Vitrectomy is a surgery to remove some or all of the vitreous humor from the eye.
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. As peripheral vision worsens, people may experience "tunnel vision". Complete blindness is uncommon. Onset of symptoms is generally gradual and often begins in childhood.
Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye and causes it to thicken and swell (edema). The swelling may distort a person's central vision, because the macula holds tightly packed cones 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.
This is a partial list of human eye diseases and disorders.
Macular degeneration, also known as age-related macular degeneration, is a medical condition which may result in blurred or no vision in the center of the visual field. Early on there are often no symptoms. Over time, however, some people experience a gradual worsening of vision that may affect one or both eyes. While it does not result in complete blindness, loss of central vision can make it hard to recognize faces, drive, read, or perform other activities of daily life. Visual hallucinations may also occur.
Metamorphopsia is a type of distorted vision in which a grid of straight lines appears wavy or partially blank. In addition, metamorphopsia can result in misperceptions of an object's size, shape, or distance to the viewer. People can first notice they suffer from the condition when looking at mini blinds in their home.
Choroideremia is a rare, X-linked recessive form of hereditary retinal degeneration that affects roughly 1 in 50,000 males. The disease causes a gradual loss of vision, starting with childhood night blindness, followed by peripheral vision loss and progressing to loss of central vision later in life. Progression continues throughout the individual's life, but both the rate of change and the degree of visual loss are variable among those affected, even within the same family.
Stargardt disease is the most common inherited single-gene retinal disease. In terms of the first description of the disease, it follows an autosomal recessive inheritance pattern, which has been later linked to bi-allelic ABCA4 gene variants (STGD1). However, there are Stargardt-like diseases with mimicking phenotypes that are referred to as STGD3 and STGD4, and have a autosomal dominant inheritance due to defects with ELOVL4 or PROM1 genes, respectively. It is characterized by macular degeneration that begins in childhood, adolescence or adulthood, resulting in progressive loss of vision.
Optic pit, optic nerve pit, or optic disc pit (ODP) is rare a congenital excavation (or regional depression) of the optic disc (also optic nerve head), resulting from a malformation during development of the eye. The incidence of ODP is 1 in 10,000 people with no predilection for either gender. There is currently no known risk factors for their development. Optic pits are important because they are associated with posterior vitreous detachments (PVD) and even serous retinal detachments.
Retinoschisin also known as X-linked juvenile retinoschisis protein is a lectin that in humans is encoded by the RS1 gene.
The mission of the Foundation Fighting Blindness is to fund research that will lead to the prevention, treatment and cures for the entire spectrum of retinal degenerative diseases, including retinitis pigmentosa, macular degeneration, Usher syndrome, Stargardt disease and related conditions. These diseases, which affect more than 10 million Americans and millions more throughout the world, often lead to severe vision loss or complete blindness.
Retinal gene therapy holds a promise in treating different forms of non-inherited and inherited blindness.
Familial exudative vitreoretinopathy is a genetic disorder affecting the growth and development of blood vessels in the retina of the eye. This disease can lead to visual impairment and sometimes complete blindness in one or both eyes. FEVR is characterized by incomplete vascularization of the peripheral retina. This can lead to the growth of new blood vessels which are prone to leakage and hemorrhage and can cause retinal folds, tears, and detachments. Treatment involves laser photocoagulation of the avascular portions of the retina to reduce new blood vessel growth and risk of complications including leakage of retinal blood vessels and retinal detachments.
The Applied Genetic Technologies Corporation is a publicly traded biotechnology company that is part of the NASDAQ Biotechnology Index. It was founded in 1999 and has its headquarters in Alachua, Florida. In late June 2019, the company announced the appointment of Global Clinical and Medical Affairs Veteran, Theresa G.H. Heah, M.D., M.B.A., to Join as Chief Medical Officer.
Occult macular dystrophy (OMD) is a rare inherited degradation of the retina, characterized by progressive loss of function in the most sensitive part of the central retina (macula), the location of the highest concentration of light-sensitive cells (photoreceptors) but presenting no visible abnormality. "Occult" refers to the degradation in the fundus being difficult to discern. The disorder is called "dystrophy" instead of "degradation" to distinguish its genetic origin from other causes, such as age. OMD was first reported by Y. Miyake et al. in 1989.
Paul A. Sieving is a former director of the National Eye Institute, part of the U.S. National Institutes of Health. Prior to joining the NIH in 2001, he served on the faculty of the University of Michigan Medical School as the Paul R. Lichter Professor of Ophthalmic Genetics. He also was the founding director of the Center for Retinal and Macular Degeneration in the university's Department of Ophthalmology and Visual Sciences.
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.
Intravitreal gene therapy represents an approach to treating retinal diseases by delivering therapeutic genes directly into the vitreous humor of the eye. This method uses a viral vector, often an adeno-associated virus (AAV), to carry genetic material into retinal cells. Once inside, the therapeutic genes are expressed to address genetic deficiencies or modify biological pathways, offering a long-term or potentially permanent treatment for conditions like wet age-related macular degeneration (AMD), diabetic macular edema, and inherited retinal dystrophies. Unlike traditional therapies requiring frequent injections, intravitreal gene therapy aims to reduce the treatment burden while improving efficacy potentially providing lifelong benefit.