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The symptoms and signs associated with convergence insufficiency are related to prolonged, visually demanding, near-centered tasks. They may include, but are not limited to, diplopia (double vision), asthenopia (eye strain), transient blurred vision, difficulty sustaining near-visual function, abnormal fatigue, headache, and abnormal postural adaptation, among others.
Negative relative accommodation (NRA) was proposed by Joseph Kearney of Oxford University in 1967 as a measure of the maximum ability to relax accommodation while maintaining clear, single binocular vision.
Convergence insufficiency - usually associated with accommodative difficulties, the fusional convergence range of these patients is reduced. Divergence insufficiency- although rare and usually associated with a neurological condition, the PFR is able to detect a reduced divergence range.
Presbyopia, physiological insufficiency of accommodation due to age related changes in lens (decreased elasticity and increased hardness) and ciliary muscle power is the commonest form of accommodative dysfunction. [50] It will cause gradual decrease in near vision.
Convergence insufficiency – near exodeviation greater than distance deviation. These can be due to nerve, muscle, or congenital problems, or due to mechanical anomalies. Unlike exotropia, fusion is possible in this condition, causing diplopia to be uncommon.
Accommodative excess may occur secondary to convergence insufficiency also. In convergence insufficiency near point of convergence will recede, and positive fusional vergence (PFV) will reduce. So, the patient uses excessive accommodation to stimulate accommodative convergence to overcome reduced PFV.
The Brock string is commonly employed during treatment of convergence insufficiency and other anomalies of binocular vision. It is used to develop skills of convergence as well as to disrupt suppression of one of the eyes. [1] During therapy, the one end of the Brock string is held on the tip of the nose while the other is tied to a fixed point.
Pulmonary valve insufficiency (or incompetence, or regurgitation) is a condition where the pulmonary valve is not strong enough to prevent backflow into the right ventricle; Tricuspid insufficiency, a valvular heart disease also called Tricuspid regurgitation, refers to the failure of the heart's tricuspid valve to close properly during systole