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Onset occurs in the first decade, usually between ages 5 and 9. The disorder is progressive. Minute, gray, punctate opacities develop. Corneal sensitivity is usually reduced. Painful attacks with photophobia, foreign body sensations, and recurrent erosions occur in most patients. Macular corneal dystrophy is very common in Iceland and accounts for almost one-third of all corneal grafts performed there.
Oguchi disease present with nonprogressive night blindness since young childhood or birth with normal day vision, but they frequently claim improvement of light sensitivities when they remain for some time in a darkened environment.
On examination patients have normal visual fields but the fundos have a diffuse or patchy, silver-gray or golden-yellow metallic sheen and the retinal vessels stand out in relief against the background.
A prolonged dark adaptation of three hours or more, leads to disappearance of this unusual discoloration and the appearance of a normal reddish appearance. This is known as the Mizuo-Nakamura phenomena and is thought to be caused by the overstimulation of rod cells.
Other conditions with similar appearing fundi include
- Cone dystrophy
- X-linked retinitis pigmentosa
- Juvenile macular dystrophy
These conditions do not show the Mizuo-Nakamura phenomenon.
Congenital stromal corneal dystrophy (CSCD), also called Witschel dystrophy, is an extremely rare, autosomal dominant form of corneal dystrophy. Only 4 families have been reported to have the disease by 2009. The main features of the disease are numerous opaque flaky or feathery areas of clouding in the stroma that multiply with age and eventually preclude visibility of the endothelium. Strabismus or primary open angle glaucoma was noted in some of the patients. Thickness of the cornea stays the same, Descemet's membrane and endothelium are relatively unaffected, but the fibrills of collagen that constitute stromal lamellae are reduced in diameter and lamellae themselves are packed significantly more tightly.
Since the "CHM" gene is located on the X chromosome, symptoms are seen almost exclusively in men. While there are a few exceptions, female carriers have a noticeable lack of pigmentation in the RPE but do not experience any symptoms. Female carriers have a 50% chance of having either an affected son or a carrier daughter, while a male with choroideremia will have all carrier daughters and unaffected sons.
Even though the disease progression can vary significantly, there are general trends. The first symptom many individuals with choroideremia notice is a significant loss of night vision, which begins in youth. Peripheral vision loss occurs gradually, starting as a ring of vision loss, and continuing on to "tunnel vision" in adulthood. Individuals with choroideremia tend to maintain good visual acuity into their 40s, but eventual lose all sight at some point in the 50-70 age range. A study of 115 individuals with choroideremia found that 84% of patients under the age of 60 had a visual acuity of 20/40 or better, while 33% of patients over 60 years old had a visual acuity of 20/200 or worse. The most severe visual acuity impairment (only being able to count fingers or worse) did not occur until the seventh decade of life. The same study found the rate of visual acuity loss to be about 1 eye chart row per 5 years.
The age of onset is in a child's infancy. Bilateral corneal opacification started in the second year of life and led to severe visual impairment. However, cornea surgery and replacement resulted in better vision.
Symptoms include a combination of spinocerebellar degeneration and corneal dystrophy. Mental retardation and slowly progressive cerebellar abnormalities were also diagnosed in patients. Other symptoms include corneal edema, thickening of Descemet membrane, and degenerative pannus. Abnormalities were found in muscle and sural nerves.
The initial retinal degenerative symptoms of retinitis pigmentosa are characterized by decreased night vision (nyctalopia) and the loss of the mid-peripheral visual field. The rod photoreceptor cells, which are responsible for low-light vision and are orientated in the retinal periphery, are the retinal processes affected first during non-syndromic forms of this disease. Visual decline progresses relatively quickly to the far peripheral field, eventually extending into the central visual field as tunnel vision increases. Visual acuity and color vision can become compromised due to accompanying abnormalities in the cone photoreceptor cells, which are responsible for color vision, visual acuity, and sight in the central visual field. The progression of disease symptoms occurs in a symmetrical manner, with both the left and right eyes experiencing symptoms at a similar rate.
A variety of indirect symptoms characterize retinitis pigmentosa along with the direct effects of the initial rod photoreceptor degeneration and later cone photoreceptor decline. Phenomena such as photophobia, which describes the event in which light is perceived as an intense glare, and photopsia, the presence of blinking or shimmering lights within the visual field, often manifest during the later stages of RP. Findings related to RP have often been characterized in the fundus of the eye as the "ophthalamic triad". This includes the development of (1) a mottled appearance of the retinal pigment epithelium (RPE) caused by bone spicule formation, (2) a waxy appearance of the optic nerve, and (3) the attentuation of blood vessels in the retina.
Non-syndromic RP usually presents a variety of the following symptoms:
- Night blindness
- Tunnel vision (due to loss of peripheral vision)
- Latticework vision
- Photopsia (blinking/shimmering lights)
- Photophobia (aversion to glare)
- Development of bone spicules in the fundus
- Slow adjustment from dark to light environments and vice versa
- Blurring of vision
- Poor color separation
- Loss of central vision
- Eventual blindness
Affected individuals commonly suffer from photophobia, nystagmus and achromatopsia. Other symptoms affecting vision may include night vision difficulties; optic disc pallor; narrow vessels; macular atrophy with pigment mottling; peripheral deep white dot deposits or retinal pigment epithelium (RPE) alterations in the inferonasal retina; decreased foveal and retinal thickness; attenuation of retinal lamination; hyperreflectivity in the choroids (due to RPE and choriocapillaris atrophy); impairment of color vision; and progressive loss of vision with advancing age.
In line with ameleogenesis imperfecta, affected members may display teeth yellow-brown in colour, dysplastic, presenting numerous caries; reduced enamel layer prone to posteruptive failure; and abnormality of morphology involving dentine.
Some symptoms consistent with Becker muscular dystrophy are:
Individuals with this disorder typically experience progressive muscle weakness of the leg and pelvis muscles, which is associated with a loss of muscle mass (wasting). Muscle weakness also occurs in the arms, neck, and other areas, but not as noticeably severe as in the lower half of the body.Calf muscles initially enlarge during the ages of 5-15 (an attempt by the body to compensate for loss of muscle strength), but the enlarged muscle tissue is eventually replaced by fat and connective tissue (pseudohypertrophy) as the legs become less used (with use of wheelchair).
In terms of the signs/symptoms of Fukuyama congenital muscular dystrophy it is characterized by a decrease in skeletal muscle tone as well as an impairment in brain and eye development.Initial symptoms of FCMD present in early infancy as decreased ability to feed. Marked differences in facial appearance occur due to decreased muscle tone. Further characteristics include:
- Seizures
- Delay in developmental
- Cardiac issues
- Swallowing difficulty
- Neurological problems
Fukuyama congenital muscular dystrophy also affects the nervous system and various associated parts. FCMD affects normal development of the brain producing a broadly smooth, bumpy shaped cortex named cobblestone lissencephaly as well as various other malformations, notably micropolygyria. Children also experience delayed myelination in the brain.
Macular corneal dystrophy, also known as Fehr corneal dystrophy named for German ophthalmologist Oskar Fehr (1871-1959), is a rare pathological condition affecting the stroma of cornea. The first signs are usually noticed in the first decade of life, and progress afterwards, with opacities developing in the cornea and attacks of pain. The condition was first described by Arthur Groenouw in 1890.
The presentation of Ullrich congenital muscular dystrophy in an affected individual is as follows:
- Muscle weakness
- Difficulty walking
- Contractures (neck)
- Joint looseness
Patients with Reis-Bücklers dystrophy develop a reticular pattern of cloudiness in the cornea. This cloudiness, or opacity, usually appears in both eyes (bilaterally) in the upper cornea by 4 or 5 years of age. The opacity elevates the corneal epithelium, eventually leading to corneal erosions that prompt attacks of ocular hyperemia, pain, and photophobia. These recurrent painful corneal epithelial erosions often begin as early as 1 year of age.
With time, the corneal changes progress into opacities in Bowman's membrane, which gradually becomes more irregular and more dense. Significant vision loss may occur. However, vascularization of the cornea is not present.
Possible complications associated with MD are cardiac arrhythmias.(BMD) Becker muscular dystrophy also demonstrates the following:
- Mental impairment (less common in BMD than it is in DMD.)
- Pulmonary failure
- Pneumonia
Vitelliform macular dystrophy causes a fatty yellow pigment (lipofuscin) to build up in cells underlying the macula. The retinal pigment epithelium also degenerates. Over time, the abnormal accumulation of this substance can damage the cells that are critical for clear central vision. As a result, people with this disorder often lose their central vision and may experience blurry or distorted vision, and loss is rarely symmetric. Scotomata appear, first with red light and then for green; finally, relative (or in more serious cases, absolute) scotomata occur with white light. Vitelliform macular dystrophy does not affect side (peripheral) vision or the ability to see at night.
Researchers have described two forms of vitelliform macular dystrophy with similar features. The early-onset form (known as Best disease) usually appears in childhood; however, the onset of symptoms and the severity of vision loss vary widely. The adult-onset form begins later, usually in middle age, and tends to cause relatively mild vision loss. The two forms of vitelliform macular dystrophy each have characteristic changes in the macula that can be detected during an eye examination.
Patients may complain of severe problems with dry eyes, or with visual obscurations. It can also be asymptomatic, and only discovered because of subtle lines and marks seen during an eye exam.
EBMD is a bilateral anterior corneal dystrophy characterized by grayish epithelial fingerprint lines, geographic map-like lines, and dots (or microcysts) on slit-lamp examination. Findings are variable and can change with time. While the disorder is usually asymptomatic, up to 10% of patients may have recurrent corneal erosions, usually beginning after age 30; conversely, 50% of patients presenting with idiopathic recurrent erosions have evidence of this dystrophy.
Reis-Bücklers corneal dystrophy, also known as corneal dystrophy of Bowman layer, type I, is a rare, corneal dystrophy of unknown cause, in which the Bowman's layer of the cornea undergoes disintegration. The disorder is inherited in an autosomal dominant fashion, and is associated with mutations in the gene TGFB1.
Reis-Bücklers dystrophy causes a cloudiness in the corneas of both eyes, which may occur as early as 1 year of age, but usually develops by 4 to 5 years of age. It is usually evident within the first decade of life. This cloudiness, or opacity, causes the corneal epithelium to become elevated, which leads to corneal opacities. The corneal erosions may prompt attacks of redness and swelling in the eye (ocular hyperemia), eye pain, and photophobia. Significant vision loss may occur.
Reis-Bücklers dystrophy is diagnosed by clinical history physical examination of the eye. Labs and imaging studies are not necessary. Treatment may include a complete or partial corneal transplant, or photorefractive keratectomy.
The X-linked varieties of congenital stationary night blindness (CSNB) can be differentiated from the autosomal forms by the presence of myopia, which is typically absent in the autosomal forms. Patients with CSNB often have impaired night vision, myopia, reduced visual acuity, strabismus, and nystagmus. Individuals with the complete form of CSNB (CSNB1) have highly impaired rod sensitivity (reduced ~300x) as well as cone dysfunction. Patients with the incomplete form can present with either myopia or hyperopia.
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.
Corneal-cerebellar syndrome (also known as Der Kaloustian-Jarudi-Khoury syndrome) is an autosomally resessive disease that was first described in 1985. Three cases are known: all are sisters in the same family.
Most infants with CMD will display some progressive muscle weakness or muscle wasting (atrophy), although there can be different degrees and symptoms of severeness of progression. The weakness is indicated as "hypotonia", or lack of muscle tone, which can make an infant seem unstable.
Children may be slow with their motor skills; such as rolling over, sitting up or walking, or may not even reach these milestones of life. Some of the more rarer forms of CMD can result in significant learning disabilities.
Posterior amorphous corneal dystrophy (PACD) is a rare form of corneal dystrophy. It is not yet linked to any chromosomal locus. The first report describing this dystrophy dates back to 1977.
Thiel–Behnke dystrophy, or Corneal dystrophy of Bowman layer, type II, is a rare form of corneal dystrophy affecting the layer that supports corneal epithelium.
The dystrophy was first described in 1967 and initially suspected to denote the same entity as the earlier-described Reis-Bucklers dystrophy, but following a study in 1995 by Kuchle et al. the two look-alike dystrophies were deemed separate disorders.
The main pathological features in this dystrophy are mulberry-shaped gelatinous masses beneath the corneal epithelium. Patients suffer from photophobia, foreign body sensation in the cornea. The loss of vision is severe. The amyloid nodules have been found to contain lactoferrin, but the gene encoding lactoferrin is unaffected.
This form of corneal amyloidosis appears to be more frequent in Japan.
Subepithelial mucinous corneal dystrophy (SMCD) is a rare form of corneal dystrophy. It was first described in 1993 by Feder et al. Anterior to Bowman layer, deposits of glycosaminoglycan were detected and identified as chondroitin-4-sulfate and dermatan sulfate.