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Esophoria is an eye condition involving inward deviation of the eye, usually due to extra-ocular muscle imbalance. It is a type of heterophoria. Cause. Causes include: Refractive errors; Divergence insufficiency; Convergence excess; this can be due to nerve, muscle, congenital or mechanical anomalies.
Prism dioptres. Prism correction is commonly specified in prism dioptres, a unit of angular measurement that is loosely related to the dioptre. Prism dioptres are represented by the Greek symbol delta (Δ) in superscript. A prism of power 1 Δ would produce 1 unit of displacement for an object held 100 units from the prism. [2]
Corrective lens. A pair of contact lenses, positioned with the concave side facing upward. A corrective lens is a transmissive optical device that is worn on the eye to improve visual perception. The most common use is to treat refractive errors: myopia, hypermetropia, astigmatism, and presbyopia.
In studies that used standardized definitions of convergence insufficiency, investigators have reported a prevalence of 4.2–6% in school and clinic settings. The standard definition of convergence insufficiency is exophoria greater at near than at distance, a receded near point of convergence, and reduced convergence amplitudes at near.
Amblyopia. Anisometropia is a condition in which a person's eyes have substantially differing refractive power. [1] Generally, a difference in power of one diopter (1D) is the threshold for diagnosis of the condition . [2] [3] Patients may have up to 3D of anisometropia before the condition becomes clinically significant due to headache, eye ...
Corrective lenses provide vision correction over a range as high as +4.0 diopters. People with presbyopia require a convex lens for reading glasses; specialized preparations of convex lenses usually require the services of an optometrist. Contact lenses can also be used to correct the focusing loss that comes along with presbyopia.
Esotropia is a form of strabismus in which one or both eyes turn inward. The condition can be constantly present, or occur intermittently, and can give the affected individual a "cross-eyed" appearance. [1] It is the opposite of exotropia and usually involves more severe axis deviation than esophoria. Esotropia is sometimes erroneously called ...
Aniseikonia. Aniseikonia is an ocular condition where there is a significant difference in the perceived size of images. It can occur as an overall difference between the two eyes, or as a difference in a particular meridian. [1] If the ocular image size in both eyes are equal, the condition is known as iseikonia. [2]
The multifocal lenses can correct defective vision in multiple focus, for example: near-vision as well as far-vision. This are particularly beneficial for presbyobia. Contact lenses. Alternatively, many people choose to wear contact lenses. One style is hard contact lenses, which can distort the shape of the cornea to a desired shape.
Eye glasses with an included prism power is the optical method to reduce a fixation disparity. Different procedures have been proposed to determine the required amount of prism for the individual. Based on prism-FD curves (Fig. 3b), one can find the aligning prism sP 0 that nullifies the naturally prevailing fixation disparity sFD 0. This test ...