Diagnostic features of tonic pupils include sluggish, segmental pupillary responses to light and better response to near effort followed by slow redilation. A tonic pupil is caused by postganglionic parasympathetic pupillomotor damage. Seventy percent of patients are female. Tonic pupils are unilateral in 80% of cases, although the second pupil may later become involved (4% per year). Holmes-Adie syndrome includes other features, notably diminished deep tendon reflexes and orthostatic hypotension.
In the initial stages, a tonic pupil is dilated and poorly reactive. The examiner at the slit lamp can usually distinguish segments of sphincter paralysis and contraction. The iris crypts stream toward the area of normal sphincter function, bunching up along the pupillary border in areas of normal function and thinning in the areas of paralysis (Fig 10-5). After a few weeks, a tonic pupil constricts to near effort with a slow, tonic movement and redilates just as slowly, whereas a normal pupil redilates promptly (Fig 10-6). This may account for symptomatic complaints of difficulty refocusing for distance.
The denervated iris sphincter is supersensitive to topical parasympathomimetic solutions. Pilocarpine drops (0.1%) can be used to demonstrate this, as the normal pupil will constrict slightly, if at all. (This strength of pilocarpine can be obtained by diluting commercial 1% solution with sterile saline for injection.) After 60 minutes, the pupils are reexamined, and if Adie is present, the affected pupil (dilated pupil) will constrict more than the normal pupil (Fig 10-7). About 80% of patients with a tonic pupil show cholinergic denervation supersensitivity.
Patients with tonic pupils may have accommodative symptoms or photophobia, but just as often they have no symptoms and report that anisocoria was first noticed by a friend or relative. Accommodative symptoms are difficult to treat. Fortunately, they usually resolve spontaneously within a few months of onset. When photophobia from a dilated pupil is a problem, topical dilute pilocarpine (0.1%) may be helpful. With time (months to years), an Adie tonic pupil gets smaller. Histopathologic examination of the ciliary ganglion in patients with Adie tonic pupil has shown a reduction in the number of ganglion cells.
Systemic conditions associated with tonic pupils only rarely include varicella-zoster, giant cell arteritis, syphilis, and orbital trauma. Bilateral tonic pupils may be seen in patients with diabetes, alcoholism, syphilis, cancer-associated dysautonomia, and amyloidosis.
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