Eye problems account for 2% to 3% of all primary health care referrals and emergency room visits. Common eye conditions that can cause eye pain are conjunctivitis, corneal abrasions and stye, but also some of the more serious eye conditions, such as acute angle-closure glaucoma, orbital cellulitis and herpetic keratitis.
The ophthalmic assessment of ocular pain is, therefore, very important and, when a patient presents with ocular pain, it is essential to take a correct anamnesis and, subsequently, to arrive at a diagnosis in a methodical manner, through objective examination, functional assessment and imaging techniques.
Anamnesis
The initial assessment of the patient with ocular pain should include questions about vision loss or changes in visual function. Indeed, the presence of ocular pain accompanied by vision loss requires immediate ophthalmological consultation.
A foreign body sensation suggests a corneal problem, such as a corneal abrasion or keratitis. Conversely, a scratchy, grainy sensation is more likely to be associated with conjunctivitis. Other useful information for doctors is whether the patient uses contact lenses and how to clean them, for example to assess the presence of bacterial keratitis.
Photophobia, on the other hand, can be a sign of corneal involvement, but also of keratitis and uveitis.
Finally, the presence of headache with eye pain can be a sign of ophthalmological and neurological conditions, such as acute angle-closure glaucoma, scleritis, cluster headache and migraine.
Physical examination
It is important that physicians (including family doctors) are familiar with the basic anatomy of the eye so that they can perform an appropriate examination when assessing a patient with ocular pain. The most commonly available equipment for the assessment of ocular anatomy and function includes a table of Snellen, a tonometer, a torch, fluorescein dye and a Wood's lamp.
Functional assessment
All patients presenting with eye pain should be assessed for vision loss with an eye examination. In fact, conditions that cause eye pain and can cause reduced visual acuity include serious conditions such as acute angle-closure glaucoma, herpes simplex virus (HSV) keratitis, optic neuritis and orbital cellulitis.
It is also necessary to test extraocular movements, as an increase in intraocular pressure may indicate the presence of acute angle-closure glaucoma and may cause ocular motility disturbances or pain associated with eye movement. The latter may also be present in cases of scleritis, optic neuritis and orbital cellulitis.
The evaluation must also include the anatomical structures of the eye, both external (such as the eyelids, to assess the presence of swelling, erythema, blisters) and internal. In particular, the conjunctiva, sclera, cornea, pupil, opening of the anterior chamber (to highlight the presence of glaucoma) and uvea (to assess the presence of uveitis) must be assessed, to identify the presence of characteristic signs and symptoms that may be associated with ocular pain.
For instance, the conjunctiva may be reddened in the case of inflammation or infection. The bluish discolouration of the sclera, on the other hand, helps in the differential diagnosis between scleritis and episcleritis. Inflammation of the sclera is also usually very painful, whereas inflammation of the episclera is not.
In the case of the cornea, illumination with cobalt light or a Wood's lamp allows the identification of possible lesions and abrasions, as they are coloured fluorescent green.
Examination of the pupil is also important, as the presence of anisocoria (unequal pupil size), associated with ocular pain, can be a sign of anterior uveitis. While a dilated pupil may be present in the case of acute angle-closure glaucoma. Photophobia, on the other hand, can identify patients with uveitis or keratitis.
Imaging for ophthalmic assessment of ocular pain
There are some specific indications for imaging when ocular pain is to be assessed. For example, MRI with gadolinium contrast for imaging the brain and orbits is essential in cases of suspected optic neuritis. In orbital cellulitis, on the other hand, computed tomography of the orbits and sinuses helps to confirm the diagnosis and assess associated complications, such as the presence of an abscess. Neuroimaging is not, however, recommended in patients presenting with unilateral ocular or facial pain, normal findings on physical examination and no history suggestive of a specific diagnosis or pain syndrome.