Photophobia

07/11/2018

Hasn't everyone been bothered by light at some stage? When this situation is extreme, we call it photophobia, and it’s a symptom that has no call to be associated with any diseases.

When light hits the eyeball, it passes through the cornea, the transparent layer on the eye's surface, then it crosses the pupil and crystalline lens and lastly hits the retina. Any alteration to this optic system may mean that ambient light bothers us.

The eye's surface

The eye’s surface may suffer lesions of a traumatic, infectious or inflammatory origin. They cause this reflection which makes us close our eyes to shut out the light.

• A common example of trauma could be something as simple as prolonged exposure to the sun without using proper protection. In this case, actinic keratitis may occur, causing small cuts on the cornea, the consequence of which is the unpleasant feeling of photophobia. It’s a good idea to use sunglasses to prevent this from happening.

Wearing contacting lenses for longer than recommended may have a similar effect.

• Diseases representative of infections include herpetic keratitis which causes lesions on the surface of the cornea and, in addition to photophobia, brings about pain.
• Lastly, in addition to being extremely annoying because of its aggressive nature and slow development (lasting around 15 days), viral conjunctivitis may cause a further complication: appearance of spots on the cornea that may lead to photophobia. Fortunately, it's reversible and treatable, although healing may take around a year.

The iris and pupil

In the centre of the iris, the tissue that gives colour to our eyes, lies the pupil, and there are a few pathologies that bring about this symptom. Yet again, trauma, infections or inflammation may be the cause:

• When it comes to serious trauma with penetration of the eyeball, iris diseases may cause the eyeball to rupture. In these cases, alterations to the shape of the pupil and holes in the iris may occur, which lead to an anomalous influx of light. Reconstructions and even an artificial iris might be the answer in these cases.
• In the event of blunt trauma without penetration of the eyeball, such as the impact of a tennis ball, we have seen how the pupil can become permanently dilated, causing a massive influx of light.
• Inflammation and infections may also make us feel photophobic. These cases usually range from uveitis to visual pathway pathologies. Their treatment depends on the cause.
• It’s important to bear in mind that people with lightly coloured pigmentation of the iris may manifest this symptom yet it may not be pathological.

The crystalline lens and the vitreous body

The crystalline lens could also be responsible for photophobia, mainly because it becomes opaque as time passes. Although the crystalline lens is a transparent tissue, as the years go by it loses this property and cataracts appear. There are different types of cataract and, furthermore, they cause a wide variety of symptoms such as a loss of vision or glare. They are treated with cataract surgery.

With regard to the vitreous body, which is the liquid filling the eye, given its transparent nature, its loss may bring about this symptom, however, as per the retina, its pathology usually leads to other issues.

In general, treatment for photophobia is related to its cause; using glasses with lenses suited to the sun and other filters is the most common procedure.

Dr. José Lamarca