Mydriasis is a medical term for the abnormal dilation of the pupil. This condition can occur naturally or in response to various stimuli, such as light, medication or neurological disorders. Understanding this phenomenon is essential for eye health professionals and patients curious about how their eyes work.
The role of the pupil
The pupil, the small black opening in the center of the eye, allows light to enter the eye and reach the retina. Its size changes according to the amount of light available: it contracts (a phenomenon called miosis) when light is intense and dilates (mydriasis) in darker environments to let in more light.
Causes of mydriasis
Several factors can cause mydriasis, including:
- Lighting: In low-light conditions, the pupil naturally dilates to capture more light.
- Medication: Certain eye drops, especially those used during ophthalmological examinations, such as mydriatic drops, cause the pupils to dilate temporarily. These drops make it easier for the Optometrist to examine the retina and internal structures of the eye.
- Psychoactive substances: Drugs such as cocaine or ecstasy can also cause abnormal pupil dilation.
- Neurological conditions: Head trauma, stroke, or brain tumours can interfere with the autonomic nervous system, which is responsible for controlling pupil size.
- Emotions: Surprisingly, our emotions can also influence pupil size. For example, fear or excitement can cause temporary mydriasis.
When should you consult an Optometrist?
Although mydriasis is often harmless, it's important to consult a healthcare professional if dilated pupils are accompanied by other symptoms such as eye pain, headaches, blurred vision or increased sensitivity to light (photophobia). These signs may indicate a more serious condition requiring immediate attention.
Mydriasis is a common and usually benign phenomenon but can also indicate underlying problems requiring medical attention. If you notice abnormal dilation of your pupils or changes in your vision, don't hesitate to consult your Optometrist for a complete eye examination.
