Question: When bilateral lesions of the retrochiasmal visual pathways produce a decrease in visual acuity which of the following are correct?
1. Such lesions produce symmetric VA loss in both eyes.
2. The VA loss from such lesions will be worse on the opposite side of the largest lesion.
3. The VA loss from such lesions will be worse on the same side of the largest lesion.
4. With the presence of retrochiasmal visual pathway lesions and different VA in the two eyes, an additional problem anterior to the chiasm must be present.
1
________________________________________________
Correct Answers:
1. Such lesions produce symmetric VA loss in both eyes.
4. With the presence of retrochiasmal visual pathway lesions and different VA in the two eyes, an additional problem anterior to the chiasm must be present.
Explanation: “Occipital Lobe: Bilateral Lesions
Bilateral occipital lobe lesions will produce bilateral homonymous hemianopias, which may be asymmetric (▶Fig. 3.30).
In addition to the visual field defects, there may be decreased visual acuity, which is always the same in both eyes (▶Fig. 3.31).
Pearls
When bilateral lesions of the retrochiasmal visual pathways produce a decrease in visual acuity, the degree of visual acuity loss is always symmetric in both eyes, unless there are other, more anterior, reasons for a decrease in visual acuity (e.g., asymmetric refractive errors, cataracts, or a superimposed asymmetric or unilateral retinopathy or optic neuropathy).”1
Reference: 1. Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Theme
More than 600 additional neuro-ophthalmology questions are freely available at http://EyeQuiz.com.
Questions prior to September 2016 are archived at http://ophthalmology.stanford.edu/blog/
After that, questions are archived at https://neuro-ophthalmology.stanford.edu
Follow https://twitter.com/NeuroOphthQandA to be notified of new neuro-ophthalmology questions of the week.
Please send feedback, questions and corrections to tcooper@stanford.edu.