What are pupil diseases?
Diseases of the pupil affect this ocular structure, responsible for bringing light from the external area of the eye to the posterior area, where the photoreceptors of the retina are located. The pupil has the ability to dilate or contract, depending on the amount of light it perceives.
Pupillary conditions cause abnormal pupil sizes or differences between the two eyes, leading to:
- Miosis: constricted pupils and therefore reduced size
- Mydriasis: dilated and enlarged pupils
Pupillary diseases are varied and can cause a condition called anisocoria, which is characterized by a difference in size between both pupils.
There are 2 types of anisocoria :
- Physiological anisocoria, generally present from birth
- Pathological anisocoria, which is caused by an ocular process or neurological disease
Why are they produced?
Pupil diseases can be due to congenital factors, which occur from birth, accidents, as well as ocular and systemic diseases of various kinds.
As for anisocoria, the physiological type appears from birth and does not usually cause visual health problems, beyond the difference in size between the two pupils.
For its part, pathological anisocoria occurs due to different diseases or conditions, the most frequent being:
Third cranial nerve palsy
This nerve is one of those responsible for the movements of the external and internal ocular muscles, among which are those of the iris. Therefore, when paralysis occurs, depending on its severity, affected patients cannot move their eyes correctly in one or more directions.
This condition may be accompanied by an enlargement or dilation of the pupil, depending on the area of the nerve that is affected. Normally, it occurs when there is external compression (aneurysm, tumour, etc.).
Adie’s tonic pupil
Although its exact cause is currently unknown, this disease could be related to viral or bacterial infections, together with neurological involvement of the autonomic nervous system.
As a consequence, patients with Adie syndrome experience anisocoria with a dilated pupil, which causes accommodation problems. It mainly affects women (70% of cases), between 20 and 40 years old. It can be associated with hyporeflexia and is then called Holmes-Adie syndrome.
Argyll Robertson syndrome
It is characterized by giving rise to a very small and irregularly shaped pupil, which does not respond when it receives light stimuli (it does not contract). It is usually associated with neuro-syphilis, although it also affects people with diabetes or brain tumours.
Horner syndrome
It is caused by damage to the nerves that connect the brain, face and eyes. It is generally associated with other diseases, such as brain haemorrhage, tumours or lesions of the spinal cord or lung apex, or arterial dissections.
In addition to presenting miosis (smaller pupil), patients with Horner Syndrome may also have ptosis (drooping eyelid) or, if the cause is congenital, the irises of both eyes of different colours, among others.
Symptoms
The main symptom of pupil diseases is an abnormal size, sometimes combined with other visual or neurological clinical manifestations. These conditions can be:
- unilateral (affects one eye)
- bilateral (occur in both eyes)
Among the possible accompanying symptoms we find
| Third cranial nerve palsy | Adie’s Tonic Pupil | Horner syndrome | |
| Blurred vision (especially close-up) | x | x | |
| Double vision (diplopia) | x | X (in some cases) | |
| Ocular and periocular (around the eyes) pain | x | ||
| Drooping eyelid (ptosis) | x | x | |
| Pupil size enlargement | x | x | |
| Pupil size reduction | x | ||
| Irregular pupil shape | x | ||
| Photophobia (abnormal intolerance to light) | x | x | |
| Headaches | x | x |
Treatments
The treatment of pupil diseases usually involves clinically addressing their cause, since they are generally a symptom of other ocular, neurological or systemic conditions.
In the case of physiological anisocorias, treatment is usually not necessary if they do not cause visual impairment.
Other pupillary alterations, such as pathological anisocoria, may require specific ocular treatment which is describe below by JL Rohatgi Hospital!
- Adie syndrome produces visual disturbances that are compatible with a normal lifestyle. Generally, glasses are recommended for reading or when using screens, as well as sunscreens in outdoor environments, since affected patients often experience photophobia (light intolerance). If it is not enough, treatment with Pilocarpine diluted to 0.125% can be prescribed.
- Patients with Argyll Robertson syndrome usually require antibiotic treatment, if the cause is syphilis or another bacteria.
- In people who suffer from cranial nerve III palsy, treatment of the cause can be reinforced to correct double vision with the use of ocular occluders (patches), use of injectables, prisms or strabismus surgery.
