Questions:
17. Anisocoria more obvious in dim light indicates a sympathetic or parasympathetic lesion?
18. Dilation lag present when the lights are dimmed indicates a sympathetic or parasympathetic lesion?
19. How long after dimming the lights should one wait before checking for dilation lag?
20. Anisocoria more obvious in bright light indicates a sympathetic or parasympathetic lesion?

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Questions with answers:
17. Anisocoria more obvious in dim light indicates a sympathetic or parasympathetic lesion?
Sympathetic

18. Dilation lag present when the lights are dimmed indicates a sympathetic or parasympathetic lesion?
Sympathetic

19. How long after dimming the lights should one wait before checking for dilation lag?
The normal pupil will dilate in about 5 seconds. The Horner syndrome eye will have a lag of about 5 seconds before it dilates and takes 10-20 seconds to finish.

20. Anisocoria more obvious in bright light indicates a sympathetic or parasympathetic lesion?
Parasympathetic

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

1.9.2 Anisocoria

Anisocoria (unequal pupils; ▶Fig. 1.20) means there is an abnormality of the efferent (sympathetic or parasympathetic) portion of the pupil pathways. Lesions of the afferent pathways do not produce anisocoria. When evaluating a patient with anisocoria, pupil examination in the dark and light allows determination of which pupil is abnormal.

Pearls
A small pupil that does not dilate is more obvious in the dark, whereas a big pupil that does not constrict well is more obvious in the light.

1.10 Ocular Examination
This part of the examination is better performed in an office equipped with a slit lamp, which allows two- and three-dimensional views of the eyes through a microscope. Mirrors and a slit beam allow visualization of the anterior segment of the eye and anterior vitreous when the pupil is dilated (▶Fig. 1.21 and ▶Fig. 1.22).

For an examination of the patient at the bedside without the help of a slit lamp, you should look at the eyes with the help of a penlight (or the direct ophthalmoscope):
1. Look at the external appearance of the eye, eyelid, and orbit (▶Fig. 1.23, ▶Fig. 1.24,▶Fig. 1.25,▶Fig. 1.26).


2. Look for abnormalities of the cornea or lens that could be the cause of decreased vision or that could obstruct an adequate view of the fundus.
3. Abnormalities of the ocular media sufficient to cause significant visual loss usually result in a poor view of the ocular fundus. If you can’t see in, the patient can’t see out.

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

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