Squint : its causes, pathology and treatment . of binocularvision is its intensity. A person whose fusionsense is feebly developed may possibly, underfavourable conditions, have the highest gradeof binocular vision. But the intensity of histendency to fusion will be slight, so that, underunfavourable conditions, he easily abandons theeffort and uses one eye only. One, however,whose fusion sense is well developed will havesuch an intense tendency to binocular vision thatnothing will make him abandon it while botheyes are open. (Except, of course, a muscularparalysis, in which case he will suffe
Squint : its causes, pathology and treatment . of binocularvision is its intensity. A person whose fusionsense is feebly developed may possibly, underfavourable conditions, have the highest gradeof binocular vision. But the intensity of histendency to fusion will be slight, so that, underunfavourable conditions, he easily abandons theeffort and uses one eye only. One, however,whose fusion sense is well developed will havesuch an intense tendency to binocular vision thatnothing will make him abandon it while botheyes are open. (Except, of course, a muscularparalysis, in which case he will suffer frompersistent and intolerable diplopia.) Tests for Binocular Vision. Four dot test. — A convenient clinical test,which I have used constantly for some years,is an adaptation of Snellens coloured want of a better name, it may be calledthe Four dot test. A pure red glass allows BINOCULAR VISION only the red rays of light to pass through pure green glass transmits only the greenrays. Therefore light which has passed through. Fig. 7- the red glass cannot be seen at all through thegreen glass, and vice versa. A piece of plain ground glass, 12 inches by 9inches, is covered on the back with opaque blackpaper. The black paper has four round holes cutin it, each 3 inches in diameter, as shown in the I 6 BINOCULAR VISION diagram. The lower hole is left clear. Behindthe upper hole is cemented a piece of red each of the other two is cemented a pieceof green glass. The arrangement is mounted inthe front of a box which contains an electric orother bright light. The patient, standing five or six yards away,wears a trial frame with a red glass before theright eye and a green glass before the left. Ifnow he sees two dots (white and red) he isusing the right eye only. If he sees three dots(white and two green) he is using the left eyeonly. If he sees four dots (white, red, and twogreen) he uses both eyes, and has at least gradei binocular vision. If he sees fiv
Size: 1378px × 1814px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, bookpublisherphila, bookyear1903
