A lack of strength of the proximal muscles.

Abnormal results of investigations using electromyography (EMG).

Gyrate atrophy of the choroid and retina, which is often shortened to gyrate atrophy, is an inherited disorder characterized by progressive vision loss. People with this disorder have an ongoing loss of cells (atrophy) in the retina, which is the specialized light-sensitive tissue that lines the back of the eye, and in a nearby tissue layer called the choroid. During childhood, they begin experiencing nearsightedness (myopia), difficulty seeing in low light (night blindness), and loss of side (peripheral) vision. Over time, their field of vision continues to narrow, resulting in tunnel vision. Many people with gyrate atrophy also develop clouding of the lens of the eyes (cataracts). These progressive vision changes lead to blindness by about the age of 50.\n\nMost people with gyrate atrophy have no symptoms other than vision loss, but some have additional features of the disorder. Occasionally, newborns with gyrate atrophy develop excess ammonia in the blood (hyperammonemia), which may lead to poor feeding, vomiting, seizures, or coma. Neonatal hyperammonemia associated with gyrate atrophy generally responds quickly to treatment and does not recur after the newborn period.\n\nGyrate atrophy usually does not affect intelligence; however, abnormalities may be observed in brain imaging or other neurological testing. In some cases, mild to moderate intellectual disability is associated with gyrate atrophy.\n\nGyrate atrophy may also cause disturbances in the nerves connecting the brain and spinal cord to muscles and sensory cells (peripheral nervous system). In some people with the disorder these abnormalities lead to numbness, tingling, or pain in the hands or feet, while in others they are detectable only by electrical testing of the nerve impulses.\n\nIn some people with gyrate atrophy, a particular type of muscle fibers (type II fibers) break down over time. While this muscle abnormality usually causes no symptoms, it may result in mild weakness.

Nearsightedness, also known as myopia, is an eye condition that causes blurry distance vision. People who are nearsighted have more trouble seeing things that are far away (such as when driving) than things that are close up (such as when reading or using a computer). If it is not treated with corrective lenses or surgery, nearsightedness can lead to squinting, eyestrain, headaches, and significant visual impairment.\n\nNearsightedness usually begins in childhood or adolescence. It tends to worsen with age until adulthood, when it may stop getting worse (stabilize). In some people, nearsightedness improves in later adulthood.\n\nFor normal vision, light passes through the clear cornea at the front of the eye and is focused by the lens onto the surface of the retina, which is the lining of the back of the eye that contains light-sensing cells. People who are nearsighted typically have eyeballs that are too long from front to back. As a result, light entering the eye is focused too far forward, in front of the retina instead of on its surface. It is this change that causes distant objects to appear blurry. The longer the eyeball is, the farther forward light rays will be focused and the more severely nearsighted a person will be.\n\nNearsightedness is measured by how powerful a lens must be to correct it. The standard unit of lens power is called a diopter. Negative (minus) powered lenses are used to correct nearsightedness. The more severe a person's nearsightedness, the larger the number of diopters required for correction. In an individual with nearsightedness, one eye may be more nearsighted than the other.\n\nEye doctors often refer to nearsightedness less than -5 or -6 diopters as "common myopia." Nearsightedness of -6 diopters or more is commonly called "high myopia." This distinction is important because high myopia increases a person's risk of developing other eye problems that can lead to permanent vision loss or blindness. These problems include tearing and detachment of the retina, clouding of the lens (cataract), and an eye disease called glaucoma that is usually related to increased pressure within the eye. The risk of these other eye problems increases with the severity of the nearsightedness. The term "pathological myopia" is used to describe cases in which high myopia leads to tissue damage within the eye.

Inability to see well at night or in poor light.

Blindness is the condition of lacking visual perception defined as a profound reduction in visual perception. On the 6m visual acuity scale, blindness is defined as less than 3/60. On the 20ft visual acuity scale, blindness is defined as less than 20/400. On the decimal visual acuity scale, blindness is defined as less than 0.05. Blindness is typically characterized by a visual field of no greater than 10 degrees in radius around central fixation.

A type of cataract affecting the posterior pole of lens immediately adjacent to ('beneath') the Lens capsule.

Splitting of the retinal layers in the macula.

Visual impairment (or vision impairment) is vision loss (of a person) to such a degree as to qualify as an additional support need through a significant limitation of visual capability resulting from either disease, trauma, or congenital or degenerative conditions that cannot be corrected by conventional means, such as refractive correction, medication, or surgery.

Atrophy of the choroid and retinal layers of the fundus.

Abnormal increase in retinal thickness in the macular area observed on fundoscopy or fundus imaging.