Eye Disorders Associated with Muscular Dystrophy
Everyone is highly dependent on their vision to stay aware of their external environment. Hence diseases of the eye are highly debilitating. It is especially worrisome if such a condition emerges along with muscular weakness. Degrees of visual impairment vary significantly between various muscular dystrophy diseases.
One may ask how can muscular dystrophy affect our vision. Eyes use muscles to focus themselves, and the movement of eyes is also required for proper vision. Muscular strength is needed to open and close them, and ocular muscles also play a role in maintaining the pressure in our eyeballs. Some of the mutations in genes that affect muscles may also affect internal parts of the eye, like the blood vessels, pigment, retina, and neural conduction. There are various mechanisms involved in visual disturbances related with muscular dystrophy.
As muscular dystrophy is a collective name for a group of diseases, ocular manifestations vary greatly between individuals, depending on the cause of MD.
To focus them, eye uses muscles and for proper vision movement of eyes is required. To open and close them muscular strength is needed and the pressure in our eyeballs is maintained by ocular muscles. Even the internal parts may be affected due to gene mutation that affects muscles. Visual disturbances with muscular dystrophy are various mechanisms. Depending on the cause of MD, between individuals, ocular manifestations may vary. Duchene and Becker muscular dystrophy are the two most common ones that occur. Mutation of the dystrophin gene causes it. To maintain strength muscular fibres need dystrophin. Also in the normal working of retinal pigment, specific brain centres and extra-ocular musculature, dystrophin gene plays a critical role. In brain synapses and retina, dystrophin is abundant. The effect of mutation of dystrophin gene on the eye sight has been studied. It is observed that in these disorders, there is little impairment of functioning of retina and more or less vision is preserved.
Myotonic dystrophy is characterized by muscular wasting and it is multi system disease. At very early stages it may show the symptoms of weak extra-ocular muscles, reduced visual activity and ophthalmoplegia. Also they may show symptoms of ptosis. The vision may be blurred and focussing on another object can be difficult. Also there is reduction in internal pressure. In those who have myotonic dystrophy, according to newer studies, the risk of macular degeneration is very high.
Oculopharynegal muscular dystrophy is a condition in which the ocular and pharyngeal muscles become progressively weak. One of the most initial sign is bilateral ptosis. When the person is tried at the end of the day the person may have difficulty in keeping the eyelids open. But this problem may arise at the start of the day as the disease progresses. There can also be slight ophthalmoplegia. Doubling of vision may be present.
Facioscapulohumeral muscular dystrophy due to retinal telangiectasia it causes weakening of loss of vision. The severe complication is retinal detachment that may result into blindness. Conditions such as ptosis and lagophthalmos may arise due to weakening of extra ocular muscles. Risk of various infections may increase due to dysfunction of eyelids.
Limb girdle muscular dystrophy is a condition in which there is wasting of shoulder and hip muscles. In this condition facial muscles are mostly spared. Compared to healthy people, risk of developing eye condition is slightly higher.
Distal muscular dystrophy affects primarily muscles of hands and feet. Rarely facial and extra-ocular muscles are involved. Compared to the healthy population, the risk of developing eye disease is more.
Congenital muscular dystrophy symptoms right from birth or may appear shortly after birth. Some symptoms may regress, progress or stabilize. There is a common association between ocular disease and congenital muscular dystrophies. Some may have compromised acuity whereas in some there may be complete loss of vision.
In people with MD, ocular function is often compromised. This can happen either due to weak extra-ocular muscles, retinopathy and macular degeneration. At an early stage it is important to identify this complication so that the further loss of vision is avoided.