VISUAL FIELDS
when we look at an object, we not only see that object but also a number of other objects in the neighborhood , more or less distinctly are seen. Visual field is limited by the area of the retina and by the margins of the orbit, nose and cheek.Objectives
To map out the field of vision of the subject by using perimeter and detect any defects in the visual fields .Blind spot: physiological scotoma corresponding to absence of photoreceptors where the optic nerve leave the eye. Central scotoma : a zone of loss of vision confined to the center of the field(lesion between optic n. head and the chiasma) Concentric diminution: loss of the visual field at the periphery. Hemianopia :loss of vision in one -half of the visual field Quadrantanopia: loss of vision in one quadrant of the visual field
1- Blind eye :lesion of the optic nerve. 2-Bitemporal hemianopia :lesion of the optic chiasma. 3-Right homonymous hemianopia :lesion of the optic tract in left side 4-Upper right quadrantanopia :lesion of the lower fibers of optic radiation in the temporal lobe in left side 5-lower right quadrantanopia :lesion in upper fibers of optic radiation in the anterior part of parietal lobe in left side 6-Right homonymous hemianopia with sparing of macula :lesion of all fibers of the optic radiation in the posterior part of parietal lobe in left side
OPHTHALMOSCOPY
Is a procedure to study the interior of the eye (optic disc, blood vessels and retina). It represents an important part of the C.N.S examination of the patients.Objectives
To examine the 1-Optic disc Shape. Colour . The physiological cup. The edge of the disc . 2-The retinal blood vessels (arteries and veins). 3-The macular region ( oval pigmented area near the center of the retina). 4-The periphery of the retina