Search results
Results From The WOW.Com Content Network
An accurate diagnosis of the cause of the effusion, transudate versus exudate, relies on a comparison of the chemistries in the pleural fluid to those in the blood, using Light's criteria. According to Light's criteria (Light, et al. 1972), a pleural effusion is likely exudative if at least one of the following exists: [31]
The anterior margin of the subretinal exudate enhances with contrast. Since the retina is fixed posteriorly at the optic disc, this enhancement has a V-shaped configuration. [2] On MRI, the subretinal exudate shows high signal intensity on both T1- and T2-weighted images. The exudate may appear heterogeneous if hemorrhage or fibrosis is present.
The usual criterion (included in Light's criteria) is that a ratio of pleural LDH to serum LDH greater than 0.6 [33] or 2 ⁄ 3 the upper limit of the normal laboratory value for serum LDH [34] indicates an exudate, while a ratio of less indicates a transudate.
When the test is performed in an eye with an afferent pupillary defect, light directed in the affected eye will cause only mild constriction of both pupils (due to decreased response to light from the afferent defect), while light in the unaffected eye will cause a normal constriction of both pupils (due to an intact efferent path, and an ...
Macular edema occurs when fluid and protein deposits collect on or under the macula of the eye (a yellow central area of the retina) and causes it to thicken and swell . The swelling may distort a person's central vision , because the macula holds tightly packed cones that provide sharp, clear, central vision to enable a person to see detail ...
Transudates are caused by disturbances of hydrostatic or colloid osmotic pressure, not by inflammation. They have a low protein content in comparison to exudates and thus appear clearer. [6] Levels of lactate dehydrogenase (LDH) [7] or a Rivalta test can be used to distinguish transudate from exudate. [citation needed]
A green filter ~540–570 nm is used to block out red wavelengths of light. This allows a better contrast for viewing retinal blood vessels and associated hemorrhages, pale lesions such as drusen and exudates, and subtle characteristics such as nerve fibre layer defects and epiretinal membranes. [12]
Advanced retinopathy lesions, such as microaneurysms, blot hemorrhages and/or flame hemorrhages, ischemic changes (e.g. "cotton wool spots"), hard exudates and in severe cases swelling of the optic disc (optic disc edema), a ring of exudates around the retina called a "macular star" and visual acuity loss, typically due to macular involvement.