Questions:
1. Does a reduction in visual acuity due to a neurologic problem improve with the patient looking through a pinhole?
2. Can a reduction in the perceived brightness of a white light in one eye compared to the other be an early sign of optic nerve disease?
3. Can a reduction in the perceived saturation or brightness of colors in one eye compared to the other be an early sign of optic nerve disease?
4. Does a relative afferent pupillary defect ipsilateral to visual loss always indicate optic nerve dysfunction?
5. Does normal stereo vision indicate at least 20/20 visual acuity in each eye?
6. What level of vision does a positive response to the optokinetic nystagmus stimulus indicate?
7. What is the most common vascular cause of transient monocular visual loss?
8. What is amaurosis fugax?
9. What are 4 arteries in which reduced blood flow may cause amaurosis fugax?  

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Questions with answers:
1. Does a reduction in visual acuity due to a neurologic problem improve with the patient looking through a pinhole?
No.

2. Can a reduction in the perceived brightness of a white light in one eye compared to the other be an early sign of optic nerve disease?
Yes

3. Can a reduction in the perceived saturation or brightness of colors in one eye compared to the other be an early sign of optic nerve disease?
Yes 

4. Does a relative afferent pupillary defect ipsilateral to visual loss always indicate optic nerve dysfunction?
No. A relative afferent pupillary defect (RAPD) ipsilateral to visual loss indicates an optic neuropathy or severe retinal disease (in which case the retina looks abnormal on funduscopic examination). Ocular disease, such as corneal abnormalities, cataracts, and most retinal disorders, do not cause RAPDs.

5. Does normal stereo vision indicate at least 20/20 visual acuity in each eye?
Yes, normal stereo vision indicates at least 20/20 visual acuity in each eye. Stereovision may be a useful test when considering nonorganic visual loss. 

6. What level of vision does a positive response to the optokinetic nystagmus stimulus indicate?
At least 20/400. 

7. What is the most common vascular cause of transient monocular visual loss?
Retinal Ischemia. 

8. What is amaurosis fugax?
Amaurosis fugax is the term for ischemic transient monocular or binocular visual loss.

9. What are 4 arteries in which reduced blood flow may cause amaurosis fugax?
1. ophthalmic artery
2. central retinal artery and its branches
3. short posterior ciliary arteries (optic nerve and choroid)
4. long posterior ciliary arteries (choroid) can all produce transient monocular visual loss.

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The information below is from Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme 

5 Visual Loss: An Overview
Transient or permanent visual loss is a common complaint and may result from an ocular disorder, an optic neuropathy, or a lesion involving the intracranial visual pathways. The visual pathways (▶Fig. 5.1) represent one third of the supratentorial brain mass and are frequently affected by structural lesions and a wide range of neurologic disorders. This chapter gives a brief review of the approach to the patient with visual loss, then provides an overview of the many causes of monocular and binocular visual loss.

5.1 Approach to the Patient with Visual Loss
The most important part of the history, when evaluating a patient with visual loss, is to establish whether the visual loss is monocular or binocular. Monocular visual loss results from lesions anterior to the chiasm (i.e., the eye itself or the optic nerve), whereas binocular visual loss results from either bilateral anterior lesions or chiasmal or retrochiasmal lesions.

Clinical examination allows for anatomical localization of the lesion and determination of the mechanism of visual loss. Further workup looks for a specific cause.

Evaluation of the patient with visual loss also involves determining whether the loss is transient or permanent, acute or progressive. Identification of any associated symptoms, such as ocular pain, red eye, proptosis, chemosis, diplopia, and headache, as well as neurologic symptoms and elevated blood pressure, is essential.

Pearls
● If visual acuity can be improved by the patient looking through a pinhole, the problem is refractive or ocular, not neurologic in origin.
● Reduction in the saturation or brightness of colors may be an early sign of optic nerve disease.
● A relative afferent pupillary defect (RAPD) ipsilateral to visual loss indicates an optic neuropathy or severe retinal disease (in which case the retina looks abnormal on funduscopic examination). Ocular disease, such as corneal abnormalities, cataracts, and most retinal disorders, do not cause RAPDs.
● If nonorganic visual loss is suspected, stereovision should be tested first: normal stereovision implies 20/20 visual acuity in both eyes.
● A positive response to the optokinetic nystagmus stimulus indicates a visual acuity of at least 20/400 in the eye tested.

Reference: 1. Neuro-ophthalmology Illustrated-2nd Edition. Biousse V and Newman NJ. 2012. Thieme

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