1/2. The prism dissociation test in detecting unilateral functional visual loss.The prism dissociation test is useful in quantifying visual acuity in an eye with functional unilateral visual loss, whether severe or mild in degree. A small vertical prism is used to induce diplopia of a 20/20 or larger size projected Snellen letter, and the patient is asked to comment on the quality of each image seen. The acknowledgement of diplopia and comments on the clarity of the dissociated images serve as testimony to the actual level of visual acuity in each eye. In one case, a patient feigned 20/50 visual acuity in one eye after trauma. The prism dissociation test confirmed visual acuity of 20/20 in that eye, as well as excluding an abnormality of contrast sensitivity. In another case, an amblyopic eye previously noted to have 20/30 visual acuity, which allegedly had acute severe visual loss, was documented to have 20/30 visual acuity by the prism dissociation test.- - - - - - - - - - ranking = 1keywords = comment (Clic here for more details about this article) |
2/2. Sudden visual loss secondary to an orbital varix.A 45-year-old man presented with precipitous loss of vision and rapidly changing field defects in one eye. Computerized tomography and B-scan ultrasonography revealed a small orbital mass adjacent to the optic nerve. This was removed via lateral orbitotomy. On pathologic examination it was diagnosed as a small orbital varix. Drs. Frederick C. Blodi and Stephen Trokel comment on the case.- - - - - - - - - - ranking = 0.5keywords = comment (Clic here for more details about this article) |