Globe subluxation is a rare clinical entity. Although first reported in 1907 by Tucker, yet so far, the understanding of its pathomechanism is still limited [1]. It is described as partial (subluxation) or complete (dislocation) displacement of the eyeball from its normal anatomical position. Though rare, its occurrence can lead to a grievous impact in the form of irreversible vision loss which usually affects the younger and productive individuals of society.

The globe subluxation can be accompanied by avulsion or evulsion injury to the globe. The prefix ‘e’ suggests the pulling ‘out’ of the eyeball most commonly associated with optic nerve and muscle lacerations. The avulsion injury is described as pulling ‘away’ of any structure which is generally not associated with complete severing of optic nerve and muscles [2, 3]. However, out of the two, avulsion injuries have more often been described in literature. It is frequently used in conjunction with trauma to the optic nerve with partial or complete injury to it. The term globe ‘luxation’ is used for forward displacement of eyeball along with the spasmodic contraction of eyelids secondary to orbicularis oculi spasm [4]. In such situation, the equator of the globe crosses the orbital rim, often leading to severe pain, restriction of ocular movements and sometimes vision loss (Figs. 4.1 and 4.2).

The globe lies within a pyramid-shaped bony orbital cavity which is held in its position by the extraocular muscles, fascial sheaths, orbital fat volume and eyelid ligaments. These are externally well supported by bony orbital walls and act as a padded support which absorbs and dissipates the blunt trauma force. Hence, a force causing bony orbital wall fracture generally does not cause eyeball injury. If the fracture is large enough and the force to the globe is also significant, the subluxation of the globe into the maxillary sinus, ethmoidal sinus (see Fig. 4.3a, b) and cranial cavity can be seen [5–8].

Traumatic – Various types of mechanical injuries (major or minor) have been reported leading to globe subluxation, majority being motor vehicle accidents, finger poking, sports related (basketball, golf, snooker, swimming, cricket, etc.), kicked by animals and fall from height. The severity of impact and the direction of force contribute significantly in the pathomechanism of globe subluxation. The proximity of spacious bony cavities like maxillary and ethmoidal sinuses provides enough room for the orbital soft tissue to migrate into these through the fractured portions of the inferior and medial wall, respectively [5–13]. The different mechanisms proposed are mentioned in Fig. 4.4. Acute- and severe-forced medial rotation of the globe may also tear the optic nerve from the posterior sclera, causing the globe to luxate [14].

Morris et al. described three mechanisms of optic nerve injury leading to globe evulsion out of the orbital cavity. Firstly, total severance of optic nerve and its sheath due to direct sharp-edged object induced laceration. Secondly, wedge effect causing anterior push of the globe against lateral wall with stretch laceration of the optic nerve and its sheath. Thirdly, a lever and fulcrum effect can be caused by the object entering medially and as anterior nasal bone acting the fulcrum, anterior push by vector force, thus totally disrupting the optic nerve [15].

Besides trauma, globe subluxation can occur by voluntary effort, spontaneously or by self-mutilation. The pathomechanisms are described in Fig. 4.5. Spontaneous globe luxation has been reported in association with contact lens use, general anaesthesia, congenital craniofacial malformations, chronic obstructive pulmonary disease and thyroid-associated orbitopathy [16–18]. Rare cases have been reported in patients with histiocytosis X and Engelmann’s disease [19, 20] (Fig. 4.6).

Partial or total globe luxation can occur following auto-enucleation of the globe in functional psychosis like chronic psychotic depression and schizophrenia exhibiting clear paranoid traits. Historically, it has been linked to a method to achieve salvation after committing adultery. Though in general such self-mutilation is unilateral, bilateral self-enucleation has been reported up to 39 % without any gender preponderance. Patients abusing hallucinogenic drugs are also prone for inflicting such injuries to them [21].

Globe subluxation has variable presentations from being completely asymptomatic to total loss of vision which could be sudden and permanent, sudden with gradual partial recovery or chronic and progressive vision loss. In patients of traumatic globe subluxation, apart from a thorough ocular examination, orbital and surrounding area should be carefully examined for periocular emphysema and orbital rim defect. Both of these signs suggest medial or inferior orbital wall fracture. Important external signs include eyelid oedema, ecchymosis, conjunctival chemosis/haemorrhage, gross proptosis or severe enophthalmos (see Fig. 4.7). Restricted ocular motility and diplopia can also be associated with the latter. On fundus examination, an absent optic disc, scleral excavation at the optic disc site and circumferential retinal haemorrhages suggest an optic nerve avulsion injury, which is a very rare phenomenon [22, 23].

Severely reduced visual acuity, absent direct pupillary reaction, defective colour vision and abnormal confrontation suggest optic nerve injury attributing to poor prognosis. Floppy eyelids, corneal superficial punctate keratitis, corneal opacity, Descemet’s folds and corneal oedema favour voluntary or routine spontaneous globe luxation [24–26]. In psychiatric patients, we should examine for multiple irregular cut injuries in periorbital region, wrists, arms and legs. The abnormal status of nails and hairs can provide a hint about patient’s mental condition.