MEDDOKSA STICK, SCALE

From Big Medical Encyclopedia

MADDOX STICK, SCALE (E. E. Maddox — the English ophthalmologist, 1860 — 1933) — the device for definition of character and degree of a heterophoria (latent deviation).

the Cylinder and Maddox's scale for definition of character and degree of a heterophoria: 1 — Maddox's cylinder in the form of the raster inserted into a frame; 2 — Maddox's scale for definition of a heterophoria at a research from distance of 33 cm; 3 — Maddox's scale in the form of a cross for definition of the explicit and latent deviation from distance of 5 m (an upper number of figures) and 1 m (the lower number of figures); divisions on scales indicate degree of a vertical and horizontal heterophoria in angular degrees.

Stick (the cylinder is more correct) Maddox — the lens consisting of a number of the parallel glass, painted usually in red color cylinders to dia. 2 — 3 mm, densely adjacent to each other. The lens, as a rule, does not gather from separate cylinders, and represents a glass cylindrical raster (fig., 1). During the examining via Maddox's cylinder of a point source of light the last is presented in the form of a red strip, perpendicular to an axis of cylinders. Maddox's scale (fig., 2 and 3) — a linear scale, divisions a cut correspond to tangents of visual angles at its examining from certain distances. Use scales for distances of 5 m (rice. 3, upper number of figures), 33 cm (fig., 2), 1 m (fig., 3, lower number of figures). For a research from distance of 5 m the scale is usually produced in the form of a cross, in the center to-rogo the 15 W electrobulb is located, and the axis of its cylinder is guided perpendicularly to the plane of a scale. For definition heterophorias (see) at a look afar investigated observes a scale with a bulb from distance of 5 m. Before one of eyes place Maddox's cylinder in a nest of a trial frame. For measurement of a horizontal heterophoria it is oriented horizontally. At the same time investigated sees that eye, before the Crimea is the cylinder, a vertical red strip, and the second eye Maddox's scale. At two open eyes of investigated ask to specify from what party from a bulb and on what scale graduation there passes the red strip. If it passes from the same party from a bulb, about a cut there is Maddox's cylinder, then there is a deviation of an eye of a knutra — an esophoria if with opposite - a deviation of an eye of a knaruzha — ekzofornya. Scale graduation, on Krom there passes the strip, specifies degree of a heterophoria in angular degrees. For measurement of a vertical heterophoria Maddox's cylinder in a frame is oriented vertically. In the presence of a heterophoria the strip seems investigated passing above or bulbs are lower. The hidden deviation of an eye to opposite seeming shift of a strip, and scale graduation, through a cut she passes, specifies degree of a heterophoria. Coincidence of a strip to the center of a scale testifies to lack of a heterophoria, i.e. about orpthophorias (see).

More exact is the technique of definition of a heterophoria with Maddox's cylinder and the prismatic compensator (Gershel's biprism, a prism of variable force). Maddox's scale at the same time is not applied. Investigated observes a bulb from distance of 5 m. In a trial-point frame before one eye install Maddox's cylinder, and before another the prismatic compensator. The «top — the basis» line of the compensator is oriented as well as Maddox's cylinder: at measurement of a horizontal heterophoria — it is horizontal, at measurement of a vertical heterophoria — vertically. Investigated looks at a bulb and defines from what party from it there passes the strip. Investigating, changing prismatic operation of the compensator, finds such situation, at Krom the strip seems investigated passing precisely on a bulb. Scale graduation of the compensator will specify the size of a heterophoria in prismatic dioptries. Maddox's scale for distance of 33 cm (fig., 2) is used for definition of a heterophoria at a view of a short distance. At the same time division of fields of vision of two eyes is carried out usually by means of the prism of 10 prismatic dioptries placed before one eye the basis up or from top to bottom. For measurement of a horizontal heterophoria on zero scale graduation there is a vertical arrow 20 — 25 mm long. To an eye, before the Crimea there is a prism, the arrow is represented displaced aside, opposite to the direction of its basis. Visible shift of an arrow to the right or to the left from zero will specify character and size of a heterophoria.

Maddox's cylinder is used in various devices (e.g., foropter) intended for the similar purpose.

Maddox's scale for distance of 1 m sometimes is used for the purpose of definition of a corner explicit squint (see). At the same time investigated is at distance of 1 m before a scale, and investigating — directly against it under a bulb or behind it. Investigated in the beginning fixes the leading eye a bulb. Investigating at the same time notes the provision of a light patch of light from a bulb on a cornea of the mowing eye. Further investigated ask to move slowly a look on figures of the lower row on a horizontal scale and at the same time monitor the provision of a patch of light on a cornea of the mowing eye. The figure, at the time of fixing a cut a patch of light will appear in the center of a cornea, will specify a squint angle in degrees. However this way is not absolutely exact and is almost not applied.



Bibliography: Averbakh M. I. Ophthalmologic sketches, page 204, M., 1949; Avetisov E. S. Concomitant strabismus, M., 1977; Golovin S. S. Clinical ophthalmology, t. 1, the p. 3, page 678, M. — Pg., 1923; Maddox E. E. The clinical use of prisms and the decen-tcring of lenses, Bristol, 1889.


BB. 3. Rozenblyum.

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