GB241387A - An apparatus for training the ocular muscles and estimating binocular vision - Google Patents

Abstract

241,387. Smith, K. R. Oct. 20, 1924. Eye appliances.-Apparatus for estimating binocular vision and exercising the ocular muscles comprises an eyeshade A attached to one end of a lath B upon which slides a diaphragm D and a card holder C. The card holder C is positioned for the appropriate interpupillary distance and the sliding diaphragm D is placed at the position X at which position the letter A is seen with the right eye only and the letter G with the left eye only, the intervening letters being observed with both eyes. Movement of the diaphragm D towards the observer reduces the extent of binocular vision and renders' more of the extreme letters visible to a single eye only, until a position of the diaphragm D is reached at which half of the letters are seen by each eye and none by both simultaneously. Should binocular vision be defective, before this latter position is reached the letters will appear to run together or be partly obliterated and the direction of movement of the letters will give an indication of the character of the defect. The apparatus may be used as an exerciser for the muscles of the eye by sliding the diaphragm D, so that the defect may be corrected if due to the habit of using one eye insufficiently. The diaphragm D may be fitted with a shutter to permit the use of one eye only and the shade A may be provided with an aperture L for the examination of the surface of the cornea.