Ординатура / Офтальмология / Английские материалы / Neuro-Ophthalmology_Kidd, Newman, Biousse_2008

61

Figure 3–1 Apparent right proptosis caused by an elongated, highly myopic globe—evident on computed tomography (CT) scan.

removal of the orbital roof, or with post-traumatic orbito-cranial fistulae. Acquired arterial pulsation is generally associated with orbital arteriovenous malformations or carotico-cavernous fistulae but is rarely seen in tumors with a significant arterial supply.

The direction of globe displacement is an important indication of the position of the lesion(s) within the orbit: posteriorly located masses cause axial proptosis, anterior lesions displace the globe away from the mass (Fig. 3–3). Enophthalmos occurs after blowout fractures of the orbital walls (Fig. 3–4), with scirrhous metastases (such as breast or bronchogenic carcinoma), with venous anomalies, with silent sinus syndrome, and with hemifacial atrophy.

Visual Loss

Acute visual loss suggests a vascular cause and, if associated with acute nausea, is often due to orbital hemorrhage; periorbital or subconjunctival bruising may not become evident for several days. Multiple cranial nerve deficits, including sudden blindness, may occur with vaso-obliterative diseases such as mucormycosis and Wegener’s granulomatosis. Slowly growing retrobulbar masses tend

CLINICAL EXAMINATION FOR ORBITAL DISEASE

Clinical signs are unlikely to be missed if a logical sequence of examination is followed.

Visual Functions

The best-corrected visual acuity (Snellen or LogMAR chart) and color perception are recorded before pupillary examination. Although Ishihara color plates were designed to assess hereditary dyschromatopsia, their wide availability facilitates detection of subtle degrees of optic neuropathy, and the test speed and number of errors should be recorded. Pupillary reactions are tested last, and the presence of a relative afferent pupillary defect is noted, with a quantitative estimate of severity.

Evidence of a Mass

Globe displacement is estimated in all three dimensions. When a manifest ocular deviation is present, the fellow eye should be covered to allow the index eye to take up fixation. Variation in position with arterial pulsation or Valsalva maneuver should also be sought, and the presence of a bruit or palpable thrill is recorded. An aspect of orbital examination, often overlooked, is the estimation of orbital tension—in which resistance of the globe to gentle retropulsion is recorded; this tension often is raised in thyroid orbitopathy.

The size, shape, texture, and fixation to underlying structures may provide important clues to the likely pathology for a palpable anterior orbital mass. Tenderness—as, for example, with acute dacryoadenitis—indicates an acute inflammation. A dermoid cyst in the superotemporal quadrant is usually mobile, firm, and nontender, although it may give rise to acute inflammatory symptoms if ruptured or incompletely excised (Fig. 3–5); some dermoid cysts may, however, be tethered with a local periosteal attachment or may extend, through

Figure 3–5 Marked periorbital inflammation secondary to lipid leakage from an occult intraorbital dermoid within the lacrimal gland fossa.

Periorbital Signs

Eyelid swelling is a common feature of orbital disease and may be due to the actual orbital mass, fat displacement by the mass, or venous congestion resulting from an apical orbital mass. Other eyelid signs include lid retraction, phase lag of the upper lid on slow down-gaze, and incomplete closure (“lagophthalmos”)—all of which are often observed in thyroid orbitopathy (Fig. 3–7). Lid retraction may be primary, resulting from primary levator muscle overaction, or secondary to fibrosis within the inferior rectus—the latter causes excessive co-contraction of the superior rectus and levator muscles. A persistent S-shaped upper lid contour is commonly seen with plexiform neurofibroma and, more rarely, with lacrimal gland infiltrative diseases; a similar, but transient, contour may be seen with dacryoadenitis, often with cutaneous erythema confined within the brow line. Anterior venous anomalies give a blue hue to eyelid skin and xanthomatous lesions may present as a yellow plaque.

Episcleral vessels may indicate underlying pathology; fine corkscrew vessels suggest a low-flow dural arteriovenous shunt (Fig. 3–8), whereas marked conjunctival edema (“chemosis”) with large vessels suggests carotico-cavernous fistula. A high-flow fistula or orbital arteriovenous malformation may have a palpable thrill or audible bruit. Embarrassment of venous outflow leads to loss of spontaneous pulsation of the central retinal vein, and the presence or absence of pulsation should be noted in both fundi; this sign is not specific, however, as it is absent in a fifth of normal eyes.

Corneal sensation should be checked before instilling drops into the conjunctival sac, and the periocular, cheek, and gum sensation should be assessed for localization of orbital disease along the various branches of the ophthalmic and maxillary divisions of the trigeminal nerve.

Examination of the nose and mouth can be contributory to orbital diagnosis: naso-sinus disease, such as lymphoma, carcinoma, or infections, readily spreads into the orbit through the thin bone of the ethmoidal lamina papyracea or the maxillary antral roof (orbital floor). Palatal necrosis may rarely be seen with sino-orbital tumor or infection (such as mucormycosis), and ipsilateral palatal varices (Fig. 3–9) support a putative diagnosis of orbital varices.

Figure 3–7 Marked left upper eyelid retraction caused by asymmetrical thyroid eye disease.

Figure 3–8 Dilated episcleral vasculature caused by a low-flow dural shunt.

Figure 3–9 Extensive palatal vessels in a patient with right hemifacial orbito-maxillary varices.

Signs of Intraocular or Systemic Disease

The ocular surface and the anterior and posterior segments of the eye should be examined by slit lamp biomicroscopy for tumor or inflammatory masses, vascular changes, iris pathology (such as the Lisch nodules of neurofibromatosis), and