When there is an increased response to light it is a sign of Photophobia. Some causes are:
- If too much light gets into the eye due to damages like retinal damage or corneal abrasion, the pupil is unable to properly constrict one might experience the condition.
- Lack of pigment coloration in the eye such as Albinism the Iris does not completely block light out.
- If the photo-receptors in the retina are over stimulated.
- If the Optic Nerve experiences excess electric impulses.
- If the central nervous system responds excessively.
- Due to jaw misalignment which causes elevated Trigeminal Nerve a substance P production is high leading to hypersensitivity.
There are conditions which are associated with photophobia and some of them and their causes are anterior segment diseases which include blepharitis, iritis and cyclitis are conditions associated with photophobia. Blepharitis is a chronic condition is characterized by long-term swelling of the eyelash follicles and eyelids. The condition can be caused by poor eye hygiene, seborrheic dermatitis, allergic reactions are acne. Iritis affects the eye iris by way of inflammation and if left unattended to it can lead to loss of vision or glaucoma. Cyclitis is when the ciliary body is inflamed causing redness to sclera which is adjacent to the cornea of the eye. These conditions are due to the cornea and the eye being directly irritated. Also, dry eye syndrome or the dry eyes are common causes of photophobia.
Posterior segment diseases; these are cone dystrophy, retinitis pigmentosa and the retinal dystrophies. Cone dystrophies are rare disorders of the eye affecting the cone cells which are found in the retina. The condition is characterized by increased sensitivity to light, decreased visual clarity and limited ability to clearly see colors. Retinitis pigmentosa is a set of inherited conditions leading to gradual reduction of vision which is progressive. This condition is common in Australia. Retinal drystrophies is a set of diseases which are inherited and they are characterized by the retinal degeneration. Retinal dystrophy is a condition that one is born with and it relates to the retina. Photophobia is among the early signs of these conditions.
Intracranial conditions include sub-arachnoid hemorrhage, irritation from meningitis (meningeal), apoplexy or pituitary tumors. Sub-arachnoid hemorrhage is a condition where bleeding occurs in the thin tissues that cover the brain. The bleeding can be as a result of a disorder, a tangle of blood vessels, cerebral aneurysm, idiopathic, head injury of blood thinners. Meningeal is inflammation of meninges. Apoplexy is a condition where the bleeding in the internal organs. Pituitary tumor can cause low production of hormones due to abnormal growths in the pituitary gland. Migraines have photophobia as an early symptom during its attack. Traumatic brain injury which is acute causing irritation, displacement or injury in the pain-sensitive structures. Blepharospasm is involuntary squeezing, blinking and closure of the eyelids. Even if this condition has been related to photophobia but the association is believed to be minimal. Progressive supranuclear Palsy (PSP) is more specifically used to as a sign to differentiate this condition from Corticobasal.