Argyll Robertson Pupil | The pupillary response to light is weak

Argyll Robertson Pupil | The pupillary response to light is weak

Argyll Robertson Pupil

Loss of the pupillary reflex to direct light stimulation and conservation of the pupillary constriction which accompanies the convergence of the eyeballs and the accommodation of the lens. Specifically, Argyll Robertson pupils don’t constrict in response to light but do constrict to focus on a nearby object.

Pupils with this sign are small, uneven, and irregularly shaped. While the eyes can focus on objects both near and far, the direct and contralateral (opposite side of the body) response to light is reduced or absent. Normally, both of an affected individual’s eyes have AR pupils, but the condition may be present in only one eye on rare occasions.

Argyll Robertson’s usually affects both eyes and manifests as smaller-than-normal pupils that don’t respond to light. This health problem is rare and the cause is usually unknown, but it is associated with syphilis, diabetic neuropathies and multiple sclerosis.

What causes the Argyll Robertson pupil?

1. Neurosyphilis

Argyll Robertson’s sign has long been considered by Babinski to be pathognomonic for syphilis nervosa (+ abolition of ROT + lymphocytosis of the CSF).
Although it is observed almost exclusively in nervous syphilis, other etiologies have subsequently been described, in particular in the context of atypical, unilateral or incomplete forms. These other etiologies remain completely marginal dependent:

2. Diabetes

more rarely in hereditary degenerative neuropathies (Déjerine-Sottas disease, Thévenard)

3. Multiple sclerosis

Protuberant lesions (tumors, vascular damage) in the peri-aqueductal region are exceptionally involved.

Differential diagnosis

Eye examinations:
complete areflexia by attack of the parasympathetic fibers,
iris reactivity
instillation of miotic eye drops.

Depending on the suspected cause, various tests or imaging.

After eye examinations, serologic testing of cerebral spinal fluid (CSF), the fluid that surrounds the brain and spinal cord, is often conducted in order to determine the presence of tertiary syphilis.

A serology test requires a lumbar puncture or spinal tap, procedures that remove a sample of CSF by inserting a long needle into the lower back near the spinal cord. A diagnosis of diabetes can be confirmed or ruled out by performing a blood test called a Hemoglobin A1c. Finally, multiple sclerosis can be diagnosed using magnetic resonance imaging (MRI) of the brain.

Treatments

Treatment for AR pupils depends on the underlying cause. Penicillin G, an antibiotic, is the treatment for tertiary syphilis, and it can be administered either into the veins (i.e., intravenously) or into muscle (i.e., intramuscularly). Typically, treatment of tertiary syphilis also includes oral probenecid, which increases penicillin levels in the individual’s body. If nerve damage due to diabetes is the cause, medications, such as antidepressants (e.g., duloxetine) or antiseizure medications (e.g., pregabalin), are generally prescribed. Multiple sclerosis can be treated with steroids initially, possibly followed by other medications, like glatiramer acetate, to prevent relapse of symptoms.


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Information: Cleverly Smart is not a substitute for a doctor. Always consult a doctor to treat your health condition.


Sources: PinterPandai, National Center for Biotechnology Information (NCBI), Science Direct, North American Neuro-Ophthalmology Society

Photo credit: Marcio Luiz Figueredo Balthazar / ResearchGate

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