These patients should have a corneal sensitivity test to check for the integrity of the Vth cranial nerve. Performed simply by making contact with the cornea with the corner of clean tissue or a cotton wool bud. Poor or no sensitivity may indicate a compressive lesion in the cavernous sinus with pressure on the meningeal covering around the Vth cranial nerve creating the sensation of pain, and squeezing the axons within the nerve producing Vth nerve dysfunction. This cause is rare.
The most common underlying cause of this symptom is a psychological problem. Clinically significant depression often manifests as headache or eye ache or both and is often associated with photophobia. This is called a conversion reaction, and is usually caused by stress or anxiety and occurs at a subconscious level. I would warn against making a specific comment in the patient record of depression since optometrists are not trained to make this diagnosis. This could be recorded as ‘emotional component to the patient’s chief complaint suspected’.
I do not tell patients that there is nothing wrong with them and suggest a course of reassurance, sympathy and empathy and perhaps even placebo therapy such as ocular lubricants with guidance to appropriate psychological care.