![]() A screening study of 359 unselected diabetic patients found that 21.7% had abnormally small pupils for age ( 78). The most common observation is that the pupil is miotic ( 71-77), particularly in darkness. The pupil is frequently abnormal in both types of diabetes mellitus: type 1 or insulin-dependent diabetes, which is commonly of early onset and type 2 or noninsulin-dependent diabetes, which is usually of later onset. Acute dysautonomia in cats and dogs also causes mydriasis, reduced or absent light reflexes, and supersensitivity to both pilocarpine and epinephrine ( 68-70). Recent observations suggest that these pupil abnormalities may result from widespread autonomic ganglionopathy and they are strongly linked to the presence of autoantibodies to ganglionic cholinergic receptors ( 65-67). Overall, the findings indicate that a high proportion of these cases involve both parasympathetic and sympathetic denervation of the pupil. The only exception is one reported case of the acute adrenergic type whose pupils were small and who appeared to have bilateral Horner syndrome ( 20). Mydriatic pupils are described as having a poor reaction to a light stimulus or a target viewed at reading distance (“near target”). The shape of the pupil is often oval or irregular in outline. Pupil abnormalities in various forms of acute and subacute dysautonomiaĭespite differences in clinical presentations, the pupil findings in cases within the different groups are essentially similar. Published cases ( Table 1) can be divided into several forms: a predominantly cholinergic type affecting the parasympathetic nervous system ( 5-19), an adrenergic type affecting the sympathetic nervous system ( 20,21), a mixed type ( 22-51,202), and forms with additional involvement of sensory ( 52-63) or sensorimotor peripheral nerves ( 64). In some cases, it follows an episode of influenza-like illness and recovery is variable.Īcute and subacute dysautonomia commonly involve the pupil. This acute or subacute condition is characterized by widespread dysfunction of one, or more usually both, branches of the autonomic nervous system coupled occasionally with somatic sensory or sensorimotor impairment. In all such instances, the pupil would be expected to show supersensitivity to topical administration of receptor agonists (2% or 2.5% methacholine and 0.1% or 0.125% pilocarpine at the sphincter muscle, 1% phenylephrine or 1% epinephrine at the dilator muscle). ![]() Selective sympathetic denervation should result in relative miosis in darkness with dilatation lag ( 2) and diminution of the startle reflex as seen in Horner syndrome ( 3,4). Selective parasympathetic denervation should result in relative mydriasis in light and diminution in constrictor reflexes with or without pupillotonia (which is thought to result from aberrant reinnervation ). Very few such instances of “pupilloplegia” are reported except in cases of acute or subacute pandysautonomia. The findings have been grouped according to etiology, and we have assessed the evidence for the pupil signs before attempting to draw sweeping conclusions.īecause the pupil constrictor muscle is supplied by parasympathetic fibers and the dilator by sympathetic fibers, complete failure of iris innervation should result in a pupil of medium diameter that is unresponsive to light, near, and alarm stimuli, although persistence of adrenal medullary function might allow slow dilator responses to stress from circulating catecholamines. With the exception of diabetes mellitus, there are no systematic studies of pupil involvement in these conditions. Most reports are anecdotal-based on clinical observations and only sometimes supported by confirmatory tests. In this review, we have used electronic (Medline, PubMed) and manual techniques to search the literature for published reports of pupil abnormalities in selected autonomic neuropathies. ![]() Pupil abnormalities have been widely reported in association with generalized autonomic failure but, except in diabetes, rarely investigated in detail. In most cases, sympathetic and parasympathetic branches of the autonomic nervous system are involved, although in a few instances, there is selective hypofunction in one or another branch. Autonomic neuropathy is characterized by cardiovascular, gastrointestinal, genitourinary, and sweat gland dysfunction.
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