Description, Causes and Risk Factors:
An idiopathic postganglionic denervation of the parasympathetically innervated intraocular muscles, usually complicated by signs of aberrant regeneration of these nerves: a weak light reaction with segmental palsy of iris sphincter, a strong, slow near response. Deep tendon reflexes are often asymmetrically reduced.
The exact cause of Adie's pupil is unknown. There are many potential causes, including a type of bacterial or viral infection that damages the nerves, but often Adie's pupil is idiopathic, meaning it has no known cause.
Adie's pupil starts out with dilitation or paralysis of the pupil called iridoplegia (paralysis of the musculus sphincter iridis). This can be differentiated from the iridoplegia caused by a third nerve lesion. In time the Adie's pupil iridoplegia is converted to an Argyll Robertson (AR) type with light near dissociation reaction. But Adie's differs in certain aspects from a true AR pupil. The Adie's pupil is unilateral and is the larger of the two pupils whereas the true AR pupil is a bilateral phenomenon with relatively small pupils. An Adie's pupil can be smaller when you examine it if the patient has been reading for a period of time before your examination. The tonic nature of the Adie's pupil applies to dilation as well as contraction. The Adie's pupil can be bilateral in 10% of cases. The pupils are not really rigid to light but react tonically, moving if the light is held in front of the eye for a minute. If a light such as the light from a slit lamp is continuously shone on the pupil, it reacts slowly and tonically rather than briskly. It is this tonic phenomenon that differs from a true AR pupil reaction. The tonic feature also affects the near reaction. This reaction occurs more rapidly than the light reaction thus giving it an AR like reaction. The different degree of reaction occurs because the ratio of fibers innervating the light reflex versus the near reflex is 40 to 1 in favor of the ciliary body near reflex.
The location of the lesion in Adie's is in the ciliary ganglion in the orbit. A long established physiologic principle is the more peripheral the nerve injury, the more responsive it is to its effector substance. This is why the Adie's pupils react to dilute Mechoyl or Pilocarpine. In the past we used 2.5% Mecholyl and the affected pupil reacted with miosis and the normal one did not. The percent of Mecholyl that would affect both pupils was 14%, which gives us a wide margin for a proper response. Mecholyl is no longer available. We now use .125% Pilocarpine. We make this by diluting commercially available 0.5% Pilocarpine
. There may be some reaction in the normal pupil but a much greater reaction in the Adie's pupil. How soon this sensitivity occurs after the onset in humans is not known. Sensitivity in cats occurs between 5 and 7 days. Even if the pharmacologic test for Aide's pupil is inconclusive, the physical features particularly the tonic reaction is diagnostic. This is best observed with the magnification of the slit lamp. The contraction is not symmetrical but segmental due to sector iridoplegia. Its contraction has been likened to the movement of a bag of worms.
About 50% of people with Adie's pupil recover fully within 2 years. In some people, the affected pupil becomes smaller than the normal pupil, and in others the near pupillary response never fully recovers.
The syndrome is recognized by three physical signs each of whichpoints to some interference with the nervous mechanism of theinternal muscles of the eye.
The pupillary reaction to light is absent or sluggish.
- The affected pupil is larger than its fellow but will dilatefurther in the dark, and to atropine.
- The pupillary reaction to convergence is slower than normalin spite of the fact that near vision is unaffected. The rest of theeye is normal in all respects. There is no external muscular paresis,no ptosis or nystagmus and no enophthalmos or exophthalmos. In a certainnumber of cases the knee jerks and ankle jerks are absent or reduced.
The first step in proper diagnosis isdetermining if the anisocoria (a condition in which the two pupils are not of equal size) is benign and physiologic, or acquired and pathologic; thiscan be done by comparing the amount ofanisocoria in bright and then dimillumination. Pupils which possessphysiological anisocoria will show a relativesize difference which does not vary from oneillumination level to the next. Pupilssuffering from sympathetic pathway lesions(Horner's syndrome
) will possess anisocoriawhich is greater in dim illumination, due tofailure of the iris dilator. Pupils sufferingfrom parasympathetic pathway interruptionswill demonstrate anisocoria which measureslarger in bright light. Secondly, thepupil's ability to react to light (both thedirect and consensual response) should beobserved and graded. Thirdly, the amount ofconstriction accompanying accommodativeeffort should be assessed and compared tothe light response, checking for LND. It isalso helpful to know how long the anisocoriahas been present, as a more acute onset ismore likely to herald a true neurologicalemergency. If the patient cannot offer a timeframe, a high plus power condensing lens canbe used to examine old photographs.
The Adie's Pupil can be diagnosed uponexamination with the biomicroscope (slitlamp). Withthe slit beam opened wide and directed froma 60? angle, the details of the iris can beeasily observed. When Adie's Pupil arepresent, as the lamp is turned on and off, thepractitioner will observe large sectors of theiris that do not constrict to light, but ratherare dragged by neighbouring functionalsegments.
In the absence of other signs and symptoms, an Adie's Pupil is a benign finding and heralds no systemic or neurological disease emergency. Until other etiologies have been ruled out, it is inappropriate to refer it as Adie's pupil. Each case should be handled individually. Gathering a complete history is the first step. An acute Adie's Pupil in patients over 60 years of age warrants an erythrocyte sedimentation rate to rule out giant cell arteritis. Adie's Pupil, especially if bilateral, should be tested for syphilitic infection (FTA-Abs and VDRL). A pupil with a weak light reaction but no segmental palsy usually indicates drug-induced mydriasis.
No definitive treatment for the Adie's Pupil exists. Patients may seek relief from glare caused by mydriasis and to improve the appearance of the anisocoria. In these cases, a specialty contact lens may provide a solution. Visual complaints associated with ciliary body dysfunction occasionally respond to low concentrations of cholinergic drugs.
Standard treatment for Adie's pupil usually includes prescribing a bifocal or reading glasses to help with near focusing issues. A drug called pilocarpine is sometimes prescribed to reduce the pupil size in people dealing with night driving glare or light sensitivity. Brimonidine, a glaucoma drug, has also been used to reduce pupil size. Excessive sweating can be treated with a surgical procedure called thoracic sympathectomy. Unfortunately, loss of deep tendon reflexes tends to be permanent.
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DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.