Ocular and Orbital Pain
There is a popular misconception that “eye strain” due to refractive errors and strabismus is a common cause of eye and head pain. Although refractive errors and strabismus should be corrected as appropriate, and such corrections may ameliorate pain, ocular or orbital pain has many more potentially serious causes. The eye is heavily innervated by sensory nerve fibers (see Chapter 1), and inflammatory, ischemic, and even neoplastic involvement of the eye and orbit can produce pain. True ophthalmic causes of eye pain include dry eye and other forms of keratitis, acute angle-closure glaucoma, and intraocular inflammation. These conditions are most commonly diagnosed through examination of the cornea, anterior segment, and anterior vitreous using a slit lamp. In addition, periocular pain may be referred facial pain (see the section Facial Pain).
Dry eye is a very common cause of ophthalmic discomfort (See Chapter 3 in BCSC Section 8, External Disease and Cornea). Exacerbated by visual tasks that decrease blink frequency, especially those involving long periods of computer use, it has various causes and results from conditions that either decrease tear production or increase tear evaporation. Pain on awakening may be related to recurrent corneal erosion syndrome.
Causes of ocular pain that are unrelated to keratitis include acute angle-closure glaucoma, which may be confirmed with gonioscopy and intraocular pressure measurements. Scleritis is usually accompanied by ocular tenderness. Posterior segment examination with indirect ophthalmoscopy or slit-lamp biomicroscopy may reveal evidence of choroidal or retinal inflammation or posterior scleritis. These causes of ocular pain are discussed in more detail in BCSC Section 7, Oculofacial Plastic and Orbital Surgery, and Section 9, Uveitis and Ocular Inflammation.
Orbital inflammation or infection (orbital cellulitis) usually produces severe eye pain or pain on eye movement, variably accompanied by ocular motility abnormalities, eyelid edema, and proptosis (see BCSC Section 7, Oculofacial Plastic and Orbital Surgery). Periorbital pain may be the initial manifestation of inflammation or thrombosis within the cavernous sinus. Pain with eye movement commonly accompanies an inflammatory or demyelinating optic neuropathy (see Chapter 4), often in association with decreased vision, visual field changes, and a relative afferent pupillary defect (RAPD). Rapidly expanding tumors of the orbit, orbital apex, and cavernous sinus may also produce eye pain. In these cases, other signs will likely be present, such as a visual field defect, proptosis, ocular motility deficit, resistance to retropulsion of the globe, an RAPD, or an abnormal optic nerve appearance. Microvascular cranial neuropathies (CN III, IV, or VI) can cause retro-orbital pain, with associated abnormal ocular motility.
Occipital neuralgia, which is discussed later in this chapter, produces pain and tenderness over the greater occipital nerve that radiates to the ipsilateral eye area.
Trochlear Headache and Trochleitis
Trochlear headache, or trochleitis, is an underdiagnosed orbital cause of headache. Patients with this condition typically present with a history of months to years of chronic orbital pain. Inflammation of the trochlea causes localized pain, swelling, and tenderness, and there may be associated limitation of eye movement. When there is no obvious orbital inflammation, the diagnosis can be made by eliciting pain with palpation of the involved trochlea. The etiology is usually idiopathic, but trochleitis can be associated with systemic autoimmune diseases. This condition primarily (90%) occurs in women. Treatment includes local injection of corticosteroids in the region of the trochlea or high doses of NSAIDs.
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Harooni H, Golnik KC, Geddie B, Eggenberger ER, Lee AG. Diagnostic yield for neuroimaging in patients with unilateral eye or facial pain. Can J Ophthalmol. 2005;40(6):759–763.
Levin LA, Lessell S. Pain: a neuro-ophthalmic perspective. Arch Ophthalmol. 2003;121(11): 1633.
Excerpted from BCSC 2020-2021 series: Section 5 - Neuro-Ophthalmology. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.