Adie syndrome, or Holmes-Adie syndrome, is an uncommon neurological disorder affecting the autonomic nervous system. It is identified by a pupil that is abnormally large and responds poorly to light, alongside diminished or absent deep tendon reflexes. While Adie syndrome can cause bothersome visual symptoms, it is not considered a progressive or life-threatening disease.
Key Signs and Symptoms
The primary sign of Adie syndrome is the “tonic pupil,” usually present in only one eye. This pupil is larger than the unaffected eye’s pupil and reacts very slowly, if at all, to bright light. After constricting, it redilates just as slowly.
Another feature of the tonic pupil is its reaction to near-focusing. When a person focuses on a close object, the affected pupil will slowly constrict. It may then remain small for an extended period before gradually returning to its larger size.
The pupillary abnormalities result in other vision problems. Light sensitivity, or photophobia, occurs because the enlarged pupil allows too much light into the eye. Blurred vision is also common, particularly when trying to read or shift focus between distant and near objects, as the eye’s focusing mechanisms are affected.
Beyond ocular signs, Adie syndrome is characterized by diminished or absent deep tendon reflexes, such as the knee-jerk or Achilles tendon reflex. In some instances, individuals might also experience changes in sweating patterns.
Underlying Causes and Mechanisms
Adie syndrome is caused by damage to nerve structures controlling the eye and reflexes. The primary site of injury is the ciliary ganglion, a nerve cluster behind the eye. This ganglion and its nerve fibers control the iris sphincter, which constricts the pupil, and the ciliary muscle, which controls focusing.
Damage to these nerve pathways disrupts signals to the eye muscles, causing the pupil and focusing issues. The impairment of deep tendon reflexes is linked to similar damage in the dorsal root ganglia of the spinal cord, which are part of the reflex arc.
The specific cause of this nerve damage is often unknown (idiopathic). Potential triggers include viral or bacterial infections that cause inflammation of the nerve ganglia. Other possibilities are autoimmune disorders, where the body attacks its own nerve tissues, or physical trauma to the eye area.
The Diagnostic Process
Diagnosis involves a physical and neurological examination. A physician will review the patient’s medical history and test deep tendon reflexes, such as the knee and ankle jerks, for their absence or reduction.
A detailed eye examination by an ophthalmologist is also performed. The doctor observes the pupils’ responses to light and near-focusing tasks. They may find specific signs like vermiform (worm-like) iris movements or sectoral paresis, where only a section of the iris sphincter is paralyzed.
The definitive diagnostic tool is the pilocarpine test, where a weak solution of pilocarpine eye drops is administered to both eyes. In Adie syndrome, the affected pupil constricts significantly due to cholinergic denervation supersensitivity. A normal pupil will not react to such a dilute concentration, confirming the diagnosis.
Managing the Condition
Management of Adie syndrome focuses on alleviating symptoms, as there is no cure for the nerve damage. Reading glasses are prescribed to help with difficulty focusing on close objects, which compensates for the eye’s impaired accommodation.
To address light sensitivity, wearing sunglasses is recommended. Doctors may also prescribe daily pilocarpine drops. These drops constrict the pupil, which reduces glare and can be used for cosmetic reasons to make the pupils appear more symmetrical.
The prognosis for Adie syndrome is good, as the condition is benign and not linked to more severe neurological deterioration. While the loss of deep tendon reflexes is permanent, the ocular signs may change over time. For instance, the affected pupil can become smaller than the other pupil as a person ages.