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The visual pathway consists of structures that carry visual information from the retina to the brain.Lesions in that pathway cause a variety of visual field defects. In the visual system of human eye, the visual information processed by retinal photoreceptor cells travel in the following way:
Thus, if there is a question of papilledema on fundoscopic examination or if the optic disc cannot be adequately visualized, ultrasound can be used to rapidly assess for increased intracranial pressure and help direct further evaluation and intervention. Unilateral papilledema can suggest a disease in the eye itself, such as an optic nerve glioma.
Lesions in the pathway cause a variety of visual field defects. The type of field defect can help localize where the lesion is located (see figure). A lesion in the optic nerve of one eye causes partial or complete loss of vision in the same eye, with an intact field of vision in other eye.
However, papillitis may be unilateral, whereas papilledema is almost always bilateral. Papillitis can be differentiated from papilledema by an afferent pupillary defect (Marcus Gunn pupil), by its greater effect in decreasing visual acuity and color vision, and by the presence of a central scotoma. Papilledema that is not yet chronic will not ...
For those with visual field defects optical coherence tomography has been recommended for follow-up of nerve fiber layer thickness. [12] Associated conditions such as angioid streaks and retinitis pigmentosa should be screened for. Both the severity of optic disc drusen and the degree of intraocular pressure elevation have been associated with ...
Figure 1 - Humphrey field analyser. Humphrey field analyser (HFA) is a tool for measuring the human visual field that is commonly used by optometrists, orthoptists and ophthalmologists, particularly for detecting monocular visual field. [1] The results of the analyser identify the type of vision defect.
Peripheral vision is usually spared since the pattern of loss typically involves a central or cecocentral scotoma, a visual field defect at or surrounding the point of fixation. This pattern can be revealed via visual field testing. Upon examination, the pupils usually demonstrate a normal response to light and near stimulation. In those who ...
The visual field of each eye can be divided in two vertically, with the outer half being described as temporal, and the inner half being described as nasal. "Bitemporal hemianopsia" can be broken down as follows: bi-: involves both left and right visual fields; temporal: involves the temporal visual field; hemi-: involves half of each visual field