Manual of ophthalmology . Fig. 26. REFRACTIVE ERRORS AND THEIR DETECTION. 123 Myopic eyes do not usually produce headache from any effort ofaccommodation as do the hyperopic eyes. The myopic eye gives itsowner the consciousness of not being able to see at any great distancewithout glasses, and yet possesses good near Fig. 27. Fig. 28. Astigmatism.—This is defined as the condition in which rays oflight from a point, passing through a lens or series of lenses, do notfocus at a point, or astigmatism is that condition of an eye in whichthere are two principal meridians, of greatest and le
Manual of ophthalmology . Fig. 26. REFRACTIVE ERRORS AND THEIR DETECTION. 123 Myopic eyes do not usually produce headache from any effort ofaccommodation as do the hyperopic eyes. The myopic eye gives itsowner the consciousness of not being able to see at any great distancewithout glasses, and yet possesses good near Fig. 27. Fig. 28. Astigmatism.—This is defined as the condition in which rays oflight from a point, passing through a lens or series of lenses, do notfocus at a point, or astigmatism is that condition of an eye in whichthere are two principal meridians, of greatest and least ametropia,each having a different focal plane, usually at right angles to eachother. As rays of light in an astigmatic eye are not refracted equallyin all meridians, the resulting image of a point becomes an oval, aline, or a circde. (See fig. 29). Astigmatism is the condition of the
Size: 3432px × 728px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, bookpu, booksubjectophthalmology
