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Risk factors for retinal detachment include severe myopia, retinal tears, trauma, family history, as well as complications from cataract surgery.
Retinal detachment can be mitigated in some cases when the warning signs are caught early. The most effective means of prevention and risk reduction is through education of the initial signs, and encouragement for people to seek ophthalmic medical attention if they have symptoms suggestive of a posterior vitreous detachment. Early examination allows detection of retinal tears which can be treated with laser or cryotherapy. This reduces the risk of retinal detachment in those who have tears from around 1:3 to 1:20. For this reason, the governing bodies in some sports require regular eye examination.
Trauma-related cases of retinal detachment can occur in high-impact sports or in high speed sports. Although some recommend avoiding activities that increase pressure in the eye, including diving and skydiving, there is little evidence to support this recommendation, especially in the general population. Nevertheless, ophthalmologists generally advise people with high degrees of myopia to try to avoid exposure to activities that have the potential for trauma, increase pressure on or within the eye itself, or include rapid acceleration and deceleration, such as bungee jumping or roller coaster rides.
Intraocular pressure spikes occur during any activity accompanied by the Valsalva maneuver, including weightlifting. An epidemiological study suggests that heavy manual lifting at work may be associated with increased risk of rhegmatogenous retinal detachment, but this relationship is not strong. In this study, obesity also appeared to increase the risk of retinal detachment. A high Body Mass Index (BMI) and elevated blood pressure have been identified as a risk factor in non-myopic individuals.
Genetic factors promoting local inflammation and photoreceptor degeneration may also be involved in the development of the disease.
Other risk factors include the following:
- Glaucoma
- AIDS
- Cataract surgery
- Diabetic retinopathy
- Eclampsia
- Family history of retinal detachment
- Homocysteinuria
- Malignant hypertension
- Metastatic cancer, which spreads to the eye (eye cancer)
- Retinoblastoma
- Severe myopia
- Smoking and passive smoking
- Stickler syndrome
- Von Hippel-Lindau disease
Retinitis pigmentosa is the leading cause of inherited blindness, with approximately 1/4,000 individuals experiencing the non-syndromic form of their disease within their lifetime. It is estimated that 1.5 million people worldwide are currently affected. Early onset RP occurs within the first few years of life and is typically associated with syndromic disease forms, while late onset RP emerges from early to mid-adulthood.
Autosomal dominant and recessive forms of retinitis pigmentosa affect both male and female populations equally; however, the less frequent X-linked form of the disease affects male recipients of the X-linked mutation, while females usually remain unaffected carriers of the RP trait. The X-linked forms of the disease are considered severe, and typically lead to complete blindness during later stages. In rare occasions, a dominant form of the X-linked gene mutation will affect both males and females equally.
Due to the genetic inheritance patterns of RP, many isolate populations exhibit higher disease frequencies or increased prevalence of a specific RP mutation. Pre-existing or emerging mutations that contribute to rod photoreceptor degeneration in retinitis pigmentosa are passed down through familial lines; thus, allowing certain RP cases to be concentrated to specific geographical regions with an ancestral history of the disease. Several hereditary studies have been performed to determine the varying prevalence rates in Maine (USA), Birmingham (England), Switzerland (affects 1/7000), Denmark (affects 1/2500), and Norway. Navajo Indians display an elevated rate of RP inheritance as well, which is estimated as affecting 1 in 1878 individuals. Despite the increased frequency of RP within specific familial lines, the disease is considered non-discriminatory and tends to equally affect all world populations.
STGD1 is the most common form of inherited juvenile macular degeneration with a prevalence of approximately 1 in 10,000 births.
In general, approximately one-third of congenital cataracts are a component of a more extensive syndrome or disease (e.g., cataract resulting from congenital rubella syndrome), one-third occur as an isolated inherited trait, and one-third result from undetermined causes. Metabolic diseases tend to be more commonly associated with bilateral cataracts.
Age-related macular degeneration accounts for more than 54% of all vision loss in the white population in the USA. An estimated 8 million Americans are affected with early age-related macular degeneration, of whom over 1 million will develop advanced age-related macular degeneration within the next 5 years. In the UK, age-related macular degeneration is the cause of blindness in almost 42% of those who go blind aged 65–74 years, almost two-thirds of those aged 75–84 years, and almost three-quarters of those aged 85 years or older.
Macular degeneration is more likely to be found in Caucasians than in people of African descent.
Low vitamin C intake and serum levels have been associated with greater cataract rates. However, use of supplements of vitamin C has not demonstrated benefit.
This condition is linked to the X chromosome.
- Siberian Husky - Night blindness by two to four years old.
- Samoyed - More severe disease than the Husky.
Cigarette smoking has been shown to double the rate of nuclear sclerotic cataracts and triple the rate of posterior subcapsular cataracts. Evidence is conflicting over the effect of alcohol. Some surveys have shown a link, but others which followed people over longer terms have not.
Approximately 50% of all congenital cataract cases may have a genetic cause which is quite heterogeneous. It is known that different mutations in the same gene can cause similar cataract patterns, while the highly variable morphologies of cataracts within some families suggest that the same mutation in a single gene can lead to different phenotypes. More than 25 loci and genes on different chromosomes have been associated with congenital cataract. Mutations in distinct genes, which encode the main cytoplasmic proteins of human lens, have been associated with cataracts of various morphologies, including genes encoding crystallins (CRYA, CRYB, and CRYG), lens specific connexins (Cx43, Cx46, and Cx50), major intrinsic protein (MIP) or Aquaporin, cytoskeletal structural proteins, paired-like homeodomain transcription factor 3 (PITX3), avian musculoaponeurotic fibrosarcoma (MAF), and heat shock transcription factor 4 (HSF4).
Studies indicate drusen associated with AMD are similar in molecular composition to Beta-Amyloid (βA) plaques and deposits in other age-related diseases such as Alzheimer's disease and atherosclerosis. This suggests that similar pathways may be involved in the etiologies of AMD and other age-related diseases.
It is known to occur in Scotch Collies (smooth and rough collies), Shetland Sheepdogs, Australian Shepherds, Border Collies, Lancashire Heelers, and Nova Scotia Duck Tolling Retrievers. Frequency is high in Collies and Shetland Sheepdogs, and low in Border Collies and NSDTRs. In the United States, incidence in the genotype of collies has been estimated to be as high as 95 percent, with a phenotypic incidence of 80 to 85 percent.
The incidence of retinal detachment in otherwise normal eyes is around 5 new cases in 100,000 persons per year. Detachment is more frequent in middle-aged or elderly populations, with rates of around 20 in 100,000 per year. The lifetime risk in normal individuals is about 1 in 300. Asymptomatic retinal breaks are present in about 6% of eyes in both clinical and autopsy studies.
- Retinal detachment is more common in people with severe myopia (above 5–6 diopters), in whom the retina is more thinly stretched. In such patients, lifetime risk rises to 1 in 20. About two-thirds of cases of retinal detachment occur in myopics. Myopic retinal detachment patients tend to be younger than non-myopic ones.
- Retinal detachment is more frequent after surgery for cataracts. The estimated long-term prevalence of retinal detachment after cataract surgery is in the range of 5 to 16 per 1000 cataract operations, but is much higher in patients who are highly myopic, with a prevalence of up to 7% being reported in one study. One study found that the probability of experiencing retinal detachment within 10 years of cataract surgery may be about 5 times higher than in the absence of treatment.
- Tractional retinal detachments can also occur in patients with proliferative diabetic retinopathy or those with proliferative retinopathy of sickle cell disease. In proliferative retinopathy, abnormal blood vessels (neovascularization) grow within the retina and extend into the vitreous. In advanced disease, the vessels can pull the retina away from the back wall of the eye, leading to tractional retinal detachment.
Although retinal detachment usually occurs in just one eye, there is a 15% chance of it developing in the other eye, and this risk increases to 25–30% in patients who have had a retinal detachment and cataracts extracted from both eyes.
This type of PRA has an early onset of severe vision loss. It is caused by a defect in the gene for cGMP-phosphodiesterase, which leads to retinal levels of cyclic guanosine monophosphate ten times normal.
Many people of East Asian descent are prone to developing angle closure glaucoma due to shallower anterior chamber depths, with the majority of cases of glaucoma in this population consisting of some form of angle closure. Higher rates of glaucoma have also been reported for Inuit populations, compared to white populations, in Canada and Greenland.
The long-term prognosis for patients with Stargardt disease is widely variable although the majority of people will progress to legal blindness.
Stargardt disease has no impact on general health and life expectancy is normal. Some patients, usually those with the late onset form, can maintain excellent visual acuities for extended periods, and are therefore able to perform tasks such as reading or driving.
No clear evidence indicates vitamin deficiencies cause glaucoma in humans. It follows, then, that oral vitamin supplementation is not a recommended treatment for glaucoma. Caffeine increases intraocular pressure in those with glaucoma, but does not appear to affect normal individuals.
Controversies exist around eliminating this disorder from breeding Collies. Some veterinarians advocate only breeding dogs with no evidence of disease, but this would eliminate a large portion of potential breeding stock. Because of this, others recommend only breeding mildly affected dogs, but this would never completely eradicate the condition. Also, mild cases of choroidal hypoplasia may become pigmented and therefore undiagnosable by the age of three to seven months. If puppies are not checked for CEA before this happens, they may be mistaken for normal and bred as such. Checking for CEA by seven weeks of age can eliminate this possibility. Diagnosis is also difficult in dogs with coats of dilute color because lack of pigment in the choroid of these animals can be confused with choroidal hypoplasia. Also, because of the lack of choroidal pigment, mild choroidal hypoplasia is difficult to see, and therefore cases of CEA may be missed.
Until recently, the only way to know if a dog was a carrier was for it to produce an affected puppy. However, a genetic test for CEA became available at the beginning of 2005, developed by the Baker Institute for Animal Health, Cornell University, and administered through OptiGen. The test can determine whether a dog is affected, a carrier, or clear, and is therefore a useful tool in determining a particular dog's suitability for breeding.
RP may be:
(1) Non-syndromic, that is, it occurs alone, without any other clinical findings,
(2) Syndromic, with other neurosensory disorders, developmental abnormalities, or complex clinical findings, or
(3) Secondary to other systemic diseases.
- RP combined with deafness (congenital or progressive) is called Usher syndrome.
- Alport's syndrome is associated with RP and an abnormal glomerular-basement membrane leading nephrotic syndrome and inherited as X-linked dominant.
- RP combined with ophthalmoplegia, dysphagia, ataxia, and cardiac conduction defects is seen in the mitochondrial DNA disorder Kearns-Sayre syndrome (also known as Ragged Red Fiber Myopathy)
- RP combined with retardation, peripheral neuropathy, acanthotic (spiked) RBCs, ataxia, steatorrhea, is absence of VLDL is seen in abetalipoproteinemia.
- RP is seen clinically in association with several other rare genetic disorders (including muscular dystrophy and chronic granulomatous disease) as part of McLeod syndrome. This is an X-linked recessive phenotype characterized by a complete absence of XK cell surface proteins, and therefore markedly reduced expression of all Kell red blood cell antigens. For transfusion purposes these patients are considered completely incompatible with all normal and K0/K0 donors.
- RP associated with hypogonadism, and developmental delay with an autosomal recessive inheritance pattern is seen with Bardet-Biedl syndrome
Other conditions include neurosyphilis, toxoplasmosis and Refsum's disease.
This may be present in conditions causing traction on the retina especially at the macula. This may occur in:
a) The vitreomacular traction syndrome; b) Proliferative diabetic retinopathy with vitreoretinal traction; c) Atypical cases of impending macular hole.
"Best disease" is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder. In most cases, an affected person has one parent with the condition.
The inheritance pattern of adult-onset vitelliform macular dystrophy is definitively autosomal dominant. Many affected people, however, have no history of the disorder in their family and only a small number of affected families have been reported. This is because the penetrance of the condition is incomplete; therefore, it is possible for an individual to have a copy of the mutant allele and not display the VMD phenotype. The ratio of males to females is approximately 1:1.
Vitelliform macular dystrophy or vitelliform dystrophy is an irregular autosomal dominant eye disorder which can cause progressive vision loss. This disorder affects the retina, specifically cells in a small area near the center of the retina called the macula. The macula is responsible for sharp central vision, which is needed for detailed tasks such as reading, driving, and recognizing faces. The condition is characterized by yellow (or orange), slightly elevated, round structures similar to the yolk (Latin "vitellus") of an egg.
Familial transmission is now recognized in a small proportion of people with MacTel type 2; however, the nature of any related genetic defect or defects remains elusive. The MacTel genetic study team hopes that exome analysis in the affected population and relatives may be more successful in identifying related variants.
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.
Macular telangiectasia describes two distinct retinal diseases affecting the macula of the eye, macular telangiectasia type 1 and macular telangiectasia type 2.
Macular telangiectasia (MacTel) type 1 is a very rare disease, typically unilateral and usually affecting male patients. MacTel type 2 is more frequent than type 1 and generally affects both eyes (bilateral). It usually affects both sexes equally. Both types of MacTel should not be confused with Age-related macular degeneration (AMD), from which it can be distinguished by symptoms, clinical features, pathogenesis, and disease management. However, both AMD and MacTel eventually lead to (photoreceptor) atrophy and thus loss of central vision.
The etiology of both types of MacTel is still unknown and no treatment has been found to be effective to prevent further progression. Because lost photoreceptors cannot be recovered, early diagnosis and treatment appear to be essential to prevent loss of visual function. Several centers are currently trying to find new diagnostics and treatments to understand the causes and biochemical reactions in order to halt or counteract the adverse effects.
Contemporary research has shown that MacTel type 2 is likely a neurodegenerative disease with secondary changes of the blood vessels of the macula. Although MacTel type 2 has been previously regarded as a rare disease, it is in fact probably much more common than previously thought. The very subtle nature of the early findings in MacTel mean the diagnoses are often missed by optometrists and general ophthalmologists. Due to increased research activity since 2005, many new insights have been gained into this condition since its first description by Dr. J. Donald Gass in 1982.
Coloboma of optic nerve, is a rare defect of the optic nerve that causes moderate to severe visual field defects.
Coloboma of the optic nerve is a congenital anomaly of the optic disc in which there is a defect of the inferior aspect of the optic nerve. The issue stems from incomplete closure of the embryonic fissure while in utero. A varying amount of glial tissue typically fills the defect, manifests as a white mass.