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Correction of concealed strabismus with glasses
Last reviewed: 17.10.2021
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Points with prismatic properties cause deflection of the direction of the rays to the base of the prism. If the doctor includes the treatment of wearing such lenses, then he may pursue the following objectives:
- the elimination of visual fatigue, the optimization of vision in heterophoria;
- relief of diplopia in the disturbed work of the ocular musculature;
- restoration of simultaneous clear images in both eyes (with concealed strabismus in childhood).
Most often, lenses with prismatic properties are used to correct heterophoria. But such treatment is appropriate not in all cases of latent squint. It is prescribed, if the patient has excessive visual fatigue, there is soreness in the eye area and over the bridge of the nose.
Correction involves the use of a prism with the direction of the base in the opposite direction from the visual deflection. It means that for patients with exophoria, the base turns inwards, for patients with hyperpia - down, etc. The degree of correction for concealed strabismus is usually incomplete: the angle of prismatic deviation is always smaller than the hetero- phoric angle.
If the patient suffers from paresis of the ocular musculature, the prisms are placed in glasses intended for "near" - for example, for reading. The degree and linear directivity from the "top" to the "bottom" is revealed by the trial method. Good help in this is provided by special devices, which consist of a pair of prisms with variable capacity and seats for spherical and cylindrical lenses.
For correction purposes, prisms can be used for passive image restoration in two eyes, or for activating fusional abilities. If you want to passively correct binocular vision, then the degree and direction of the exposure is selected using the Maddox scale. If the use of such technology is impossible, then synoptophor (synopticoscope) is used - a special ophthalmologic device. The purpose of the prisms becomes expedient with a slight deviation (up to ten degrees) and relative stability of the angle. It is most optimal to use prisms with little vertical displacements.
If the purpose of correction is the activation of fusion abilities, the lenses are used in patients with a converging strabismus base to the bridge of the nose, and with diverging strabismus - the basis to the temporal region. These glasses should be worn for several hours daily, under regular supervision of the treating doctor.
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