The following is an aid for diagnosing pupil abnormalities that utilizes simple bedside observations in a sequential choice manner. For each entry, read the various options carefully. Erroneous selections will lead to an erroneous diagnosis. An erroneous choice can be undone by clicking the browser's BACK button. If you happen to go astray, use the TOP link to return to the starting point.
The following characteristics need to be observed: pupil sizes, reactions to light and convergence, and positions of eyelids. Reactions to light are best judged using the Swinging Flashlight Test. In case of poor reactions, it is helpful to use magnification to look for spontaneous "vermiform" sphincter movements. These are similar to peristaltic waves that slowly travel back and forth in one or more segments of the sphincter muscle and they cause localized deviations from circular shape and so-called draping of the iris structures. Vermiform movements point to extensive parasympathetic denervation with some aberrant regeneration, e g, with pupillotonia or aberrant 3rd nerve lesions.
For examples of live pupil disturbances on video, see the Neuro-Ophthalmology Virtual Education Library,
NOVEL, or the
EOM+ Library on this site.
NOTE: this aid is not applicable in the case of congenital malformations,
after ocular surgery, or when two or more lesions are combined.
A large, nonreactive pupil combined with ipsilateral retraction of the upper
eyelid signifies abberent regeneration after damage to the IIIrd cranial
nerve.
Bilaterally defective light reactions with normal convergence reactions
indicates symmetrical lesions of the retinas, the optic nerves or the
optic chiasm, IF there is advanced visual loss.
If vision is normal, and pupils are LARGE, the loss of light reaction
is attributable to a pretectal lesion.
If vision is normal, and the pupils are very SMALL, the diagnosis is
Argyll Robertson's syndrome.
The following characteristics need to be observed: pupil sizes, reactions to light and convergence, and positions of eyelids. Reactions to light are best judged using the Swinging Flashlight Test. In case of poor reactions, it is helpful to use magnification to look for spontaneous "vermiform" sphincter movements. These are similar to peristaltic waves that slowly travel back and forth in one or more segments of the sphincter muscle and they cause localized deviations from circular shape and so-called draping of the iris structures. Vermiform movements point to extensive parasympathetic denervation with some aberrant regeneration, e g, with pupillotonia or aberrant 3rd nerve lesions.
