What Is Argyll Robertson Pupil?
Argyll Robertson pupil is a condition that affects the pupils. The pupil is the circular black spot in the center of the eye. People with Argyll Robertson pupil have very small pupils that do not react to bright light. This eye condition is usually caused by syphilis, a sexually transmitted disease. Advanced stages of syphilis affect the nervous system and the eyes. It may cause symptoms such as light sensitivity, loss of balance, or tingling toes. The treatment for Argyll Robertson pupil consists of treating the underlying syphilis with antibiotics, which can be given intravenously or intramuscularly.
Key Takeaways
- Argyll Robertson pupil is a condition in which the pupils are small and cannot respond to bright light.
- It is most commonly caused by syphilis, a sexually transmitted disease.
- Argyll Robertson pupil is treated with antibiotics directed towards the underlying syphilis infection.
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Understanding Argyll Robertson Pupil
The pupil allows light to enter the eye. It looks like a black circle on the front of the eye. Normal pupils become larger and ‘dilate’ in the dark to allow more light to enter. Normal pupils get smaller, or ‘constrict’, when light is shined into them. The pupils should also naturally shrink when looking at near objects, such as when reading.
People with Argyll Robertson pupil have abnormal pupillary reactions. They have small pupils which do not dilate in the dark. Their pupils do not constrict when bright light is shined into them. However, their pupils still have a normal response (constriction) when looking at near objects. Argyll Robertson pupil is a sign of late-stage syphilis, known as neurosyphilis.
Causes
The most common cause of the Argyll Robertson pupil is late stage syphilis. Syphilis is a sexually transmitted disease caused by infection with Treponema pallidum bacteria.
The first stage of syphilis involves developing sores, which are skin lesions known as chancres. The painless sores may develop around the mouth, lips, or genitals. Next, a rash may develop on the hands or feet. Syphilis can also cause no symptoms. It’s possible for syphilis to spread throughout the body for years undetected. If untreated, syphilis can become tertiary syphilis or ‘neurosyphilis’. Neurosyphilis is a late-stage infection that causes damage to the organs and nervous system, including the eyes. Once syphilis spreads to the eyes, it can cause Argyll Robertson pupil.
Pathophysiology
Our pupils constrict, or shrink in response to light, due to the efferent pupillary pathway. Light signals enter the eye, strike the retina, and are transmitted to the brain through the optic nerve. The optic nerve carries the light signal to the pretectal area in the midbrain. Then, the light response is sent from the pretectal area to the Edinger Westphal nucleus in the midbrain. Argyll Robertson pupil results from damage to the Edinger Westphal tissue in the midbrain. When this area of the brain is damaged, the pupils fail to react to bright light.
Diagnosis
Diagnosis of Argyll Robertson pupil is made during an eye examination. An eye doctor will shine a bright light into the eyes to check if the pupils are responding normally. The eyes may be dilated in order to make the pupils larger and examine the health of the retina.
Signs of Argyll Robertson pupil include:
- Small ‘pinpoint’ pupils in both eyes
- The pupils do not constrict when light is shined into them
- The pupils do not dilate in the dark
- The pupils constrict when reading or looking at near objects
Syphilis can affect the eyes in many different ways, besides causing Argyll Robertson pupil. Eye symptoms of syphilis include:
- Red eyes
- Light sensitivity
- Eyelid swelling
- Eye pain
- Headache
- Blurry vision
If an Argyll Robertson pupil is diagnosed, a blood test may be ordered to check for syphilis. Examples of these blood tests include IgG, RPR or VDRL, and FTA-ABS or TP-PA. These tests will detect whether there is an active syphilis infection in the body.
Treatment
If laboratory blood tests are positive for syphilis, then treatment should be started promptly. Argyll Robertson Pupil and neurosyphilis are treated with antibiotics. Penicillin is the most common antibiotic of choice. Alternatively, doxycycline or ceftriaxone may be used if the person is allergic to penicillin. The antibiotics may be delivered intravenously or intramuscularly for 10 to 14 days.
