MRI.

Bousser MG, Biousse V. Small vessel vasculopathies affecting the central nervous system. J Neuroophthalmol. 2004;24(1):56– 61.

Ocular and Orbital Causes of 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 can sometimes ameliorate pain, ocular or orbital pain has many more important 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 eyes and other forms of keratitis, acute angleclosure 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, discussed later.

Keratitis sicca, or dry eye, is a very common cause of ophthalmic discomfort. 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. Keratitis sicca is one of the characteristic features of the autoimmune Sjögren syndrome. Evidence of fluorescein or rose bengal staining, abnormal tear breakup time, or decreased tear production as revealed on a Schirmer test may help confirm dry eye syndrome. Pain on awakening may be related to recurrent corneal erosion syndrome.

Ocular pain unrelated to keratitis includes angle-closure glaucoma, which may be confirmed with intraocular pressure measurements and gonioscopy. Posterior segment examination with indirect ophthalmoscopy or slit-lamp biomicroscopy may reveal evidence of choroidal or retinal inflammation or posterior scleritis. Scleritis is usually accompanied by ocular tenderness. These causes of ocular pain are discussed in more detail in BCSC Section 7, Orbit, Eyelids, and Lacrimal System; Section 8, External Disease and Cornea; and Section 9, Intraocular Inflammation and Uveitis.

Idiopathic orbital inflammation usually produces severe eye pain or pain on eye movement, variably accompanied by ocular motility abnormalities, eyelid edema, and proptosis (see BCSC Section 7, Orbit, Eyelids, and Lacrimal System). Periorbital pain may be the initial manifestation of inflammation within the cavernous sinus (Tolosa-Hunt syndrome). 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 an afferent pupillary defect. 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 with retropulsion of the globe, an afferent pupillary defect, or an abnormal optic nerve appearance.

Trochlear Headache and Trochleitis

Trochlear headache, or trochleitis, is an underdiagnosed orbital cause of headache. Patients with this