TITLE: Orbital Trauma
SOURCE: Department of Otolaryngology, UTMB, Grand Rounds
DATE: June 3, 1998
RESIDENT PHYSICIAN: Deborah P. Wilson, M.D.
FACULTY PHYSICIAN: Anna M. Pou, M.D.
SERIES EDITOR: Francis B. Quinn, Jr., M.D.
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The otolaryngologist is frequently called to evaluate the patient who has suffered peri-orbital trauma. Orbital injuries can involve the peri-orbital soft tissues, the lacrimal system and the bony orbit.Complex orbital lacerations and fractures are rarely isolated injuries. The force required to fracture certain facial bones indicates there is a greater chance of associated life threatening injuries.[1]
An ophthalmologist should always be consulted when evaluating a patient with peri-orbital trauma. The injury to the eye may not be obvious or may appear minor. Even minor injuries can lead to more complicated problems if not addressed early. Preservation or restoration of vision should be kept foremost in the mind of the otolaryngologist. The otolaryngologist's primary goal should be proper anatomic and physiologic repair of orbital bony and soft tissue structures. The surgeon's second priority should be to achieve the best cosmetic result.
The eyelids serve as the protective covering of the eye. The skin of the upper lid is extremely thin while the skin of the lower lid is somewhat thicker. The underlying orbicularis muscle serves as the sphincter of the eyelids. It is innervated by the temporal and zygomatic branches of the facial nerve. The muscle spreads over the eyelids and onto the forehead, temple, and cheeks. The muscle is divided into three parts: pretarsal, preseptal, and preorbital. The pretarsal portion overlies the upper and lower lid tarsal plates. The medial attachment of the muscle forms the medial canthal tendon while the lateral attachment forms the lateral canthal tendon. The lateral canthal tendon attaches to the periorbita of the lateral orbital tubercle posterior to the lateral orbital rim. The preseptal portion lies anterior to the orbital septum. It aids in winking, eyelid closure, and blinking. The preorbital portion covers the orbital rims. It functions in forced lid closure and expression.
The orbital septum is a thin sheet of fibrous tissue present in both the upper and lower eyelids. It originates from the periosteum of the orbital rims. In the upper lid, the septum extends inferiorly to the levator aponeurosis just above the superior tarsal border. In the lower lid, the septum extends superiorly to attach to the inferior tarsal border. The septa serve to provide a barrier between the orbit and eyelid skin. With age, the septa stretches which accounts for anterior protrusion of the fat pads. Vertical shortening of the septa may lead to ectropion.
The anterior portion of orbital fat lies just deep to the orbital septum. In the upper lid, the preaponeurotic fat lies between the septum and the levator aponeurosis. Medially, the yellow fat may protrude through the septum with age. Laterally, the lacrimal gland may also protrude in the aging patient and should not be mistaken for orbital fat.
The levator aponeurosis of the upper lid is the tendinous portion of the levator palpebrae superioris muscle. The levator arises from the periorbita of the posterior part of the orbit and runs anteriorly above the superior rectus muscle. The muscle becomes tendinous approximately 15mm above the superior tarsal plate and it's fibers interdigitate with the orbicularis oculi fibers forming the upper lid crease. Fibers also extend to the inferior tarsus to allow for lid elevation. Muller's sympathetic muscle arises from fibers of the levator and insert into the superior tarsal border. The Oriental eyelid differs from the Occidental (Western) lid in the way the retractors insert into both the upper and lower eyelids. In the Oriental upper eyelid, the levator inserts very low on the anterior surface of the tarsus resulting in a very low or frequently imperceptable eyelid crease. The orbital septum also inserts very low on the levator aponeurosis with inferior extension of the preaponeurotic fat pad, giving a full appearance to the upper lid.
The capsulopalpebral fascia of the lower lid is analogous to the levator aponeurosis of the upper lid. It arises from the inferior rectus muscle and attaches to the inferior tarsal border. The inferior tarsal muscle of the lower lid is the same as Muller's muscle of the upper lid. The capsulopalpebral fascia and lower tarsal muscle are referred to as the lower eyelid retractors. They function to pull the lower lid inferiorly and posteriorly with downward gaze. In the Oriental eyelid, the lower eyelid retractors insert high on the anterior tarsus resulting in a high eyelid crease.
The tarsal plates are made of dense fibrous tissue that form the firm structure of the eyelids. They are approximately 1mm thick and 25mm in horizontal length. Vertically, the upper tarsus measures 10mm while the lower tarsus is usually 5mm. Each tarsi contain approximately 30 Meibomian glands that open into the lid margin. The palpebral conjunctiva is the thin transparent mucous membrane that lines the posterior surface of each eyelid. It is adherent to the tarsal plate and does not require suturing if the tarsus is repaired.
The eyelid margin is divided into a ciliary portion and a lacrimal portion. The ciliary portion is the lash bearing portion which extends from the lateral canthal angle to the lacrimal punctum. The lacrimal portion extends from the punctum to the medial canthal angle. In the ciliary portion, the lashes protrude from the anterior edge of the margin. The grey line is an important lid landmark and is thought to be due to the visibility of the muscle of Riolan. Posterior to the grey line is the superior tarsus border with Meibomian gland orifices present and the palpebral conjuctiva firmly attached to the posterior tarsal border.
The lacrimal gland is located in the anterior superolateral quadrant of the orbit in the lacrimal fossa. Tears reach the nose by being drawn into the puncta of the canaliculi by negative pressure. This pressure is generated by contraction of preseptal orbiculalis oculi muscles when blinking. The lacrimal excretory system consists of the upper and lower canaliculi, the lacrimal sac, and the nasolacrimal duct. The canaliculi consist of a short vertical portion, a horizontal portion, and a joined area known as the common canaliculus. The short vertical portion usually measures about 2mm in length while the horizontal portion measures 6-8mm. The lacrimal sac is divided into a fundus and body. The fundus lies above the canaliculis (4mm) and the body lies below the canaliculis (10mm). The nasolacrimal duct travels in a bony canal for 12-15mm in an inferior and posterior direction before emptying into the inferior meatus.[2]
The orbits can be described as four-sided conical structures with the base forward and the apex projecting medially toward the optic foramen. The base, or orbital rim, is outlined by strong bony abutments: The supraorbital arch of the frontal bone above, the zygoma and the maxilla below, the zygoma laterally, and the frontal process of the maxilla medially.
The walls of the orbit consist of relatively thin bone. The orbit can be divided into four parts: The roof, the floor, the medial wall, and the lateral wall. The roof is composed of the orbital plate of the frontal bone and posteriorly the lesser wing of the sphenoid. The pulley for the superior oblique is lodged 4 mm behind the rim. The medial wall is formed by the frontal process of the maxilla and the lacrimal bone, which together form the lacrimal groove. Just behind the posterior lacrimal crest is the extremely thin lamina papyracea of the ethmoids, then lesser wing of sphenoid and optic foramen. The triangular orbital floor is formed by the zygomatic bone, the orbital process of the palatine bones, and for the most part, the orbital plate of the maxilla which is anterior to the infraorbital fissure. The lateral wall is composed of the frontal process of the zygoma and the frontal bone anteriorly as well as the greater wing of the sphenoid posteriorly. The thinnest bones of the orbit are the bones most frequently fractured. These include the contribution of the maxillary bone to the orbital floor (0.5mm thick) and the ethmoid bone (0.25mm thick).
The greatest diameter of the orbit is found 1.5 cm posterior to the the inferior orbital rim where the the orbital roof has an upward convexity that places it 5mm above the superior orbital rim. The orbital floor is concave at this point with a depth of approx 3mm in relation to the inferior orbital rim. The globe rests in this concavity. Posteriorly, the floor is convex and posteromedially it slopes upward into the medial orbital wall.[3]
Trauma to the eyelid can be quite unnerving because of the functional and cosmetic complications that can result from improper repair. A thorough knowledge of the anatomy and a few basic techniques will help in obtaining the best possible result. An ophthalmologist should be consulted. An injury to the eye such as a corneal abrasion is not always obvious. After obtaining a history, evaluation of the injury is performed. Visual accuities should be done. Radiographs can be performed if a fracture is suspected. Tetanus immunization history should be obtained. Extensive examination and handling of the wound should be minimized until a local anesthetic is given. Iced saline can be applied. Antibiotic prophylaxis should be given in a contaminated wound and/or if there is a delay in closure of the wound. The wound should be repaired as soon as possible. Minor lacerations can be repaired in the ER while extensive or complicated wounds are best managed in the OR. Preoperative photographs should be taken to document the injury.
Local anesthesia for repair of eyelid lacerations is best obtained by performing a regional block. Anesthesia of most of the lower eyelid can be obtained by injecting 1cc of anesthetic into the infraorbital foramen. The foramen can be located 1cm below the inraorbital rim in line with the supraorbital notch. Additional anesthetic may be necessary laterally where the zygomaticofacial and zygomaticotemporal nerves pass through the lateral orbital wall. Anesthesia of the upper lid is obtained by blocking the supraorbital nerve as it exits through the supraorbital notch and the supratrochlear nerve. Again, additional anesthesia may be necessary laterally because of the lacrimal nerve. Anesthesia to the medial canthal area and lacrimal sac is obtained by blocking the infratrochlear nerve by injecting above the medial canthal tendon approximately 1cm deep.
The eye should be anesthetized with tetracaine eye drops prior to prepping. A corneal shield lubricated with antibiotic ointment is useful. The surrounding skin should be prepped with Betadine but the solution should not be used to cleanse the wound. The wound should be irrigated profusely with warmed saline. All dirt and foreign particles should be cleansed, especially imbedded dirt which can cause permanent discoloration and tatooing. Wound edges should be minimally debrided of all necrotic tissue. Irregular edges should be freshened to allow for straight surgical margins to suture together. Identifiable landmarks such as eyebrows or eyelid margins should be sutured first.
Lacerations involving a small loss of eyelid skin with an intact eyelid margin can usually be closed primarily. Skin can be closed with 6-0 or 7-0 silk in adults and 7-0 chromic gut in children. If tissue closure results in some tension, the wound should be closed with horizontal tension rather than vertical tension to try avoid ectropion. If there is a larger loss of skin where primary closure would result in distortion of surrounding structures, small advancement flaps may be necessary. The incision for the flap should be placed in the upper or lower lid skin crease or just outside the lash line. If there is significant trauma to the eyelid skin, traction sutures should be used to keep the eyelid on vertical stretch. The suture can be taped to the forehead for lower lid trauma and the cheek for upper lid trauma. Sutures can be removed at 5-7 days and scar massage beginning in one week after suture removal. Larger loss of eyelid skin may require a skin graft, usually harvested from the opposite eyelid, post-auricular region, or supraclavicular area.
Lacerations involving the full-thickness of the eyelid margin require precise anatomic repair. Authors disagree on whether the tarsal plate or eyelid margin should be repaired first. Some feel that because the tarsal plate is the structure of strength to the lid, it should be repaired first followed by repair of the eyelid margin. Others feel that precise re-approximation of the margin is most important so it should be repaired first. Irregardless, the three suture technique for repairing the eyelid margin appears to be a good one. The wound edges should be sharply trimmed (minimally). A 6-0 or 7-0 silk is first placed through a Meibomian gland 3mm from eyelid margin to depth of 3mm. The suture is brought out the laceration and into the other side 3mm deep to the lid margin emerging 3mm from the laceration. The second suture is placed in a similar fashion through the posterior lash line. The third is placed between these in the grey line. They are tied anteriorly and left long. The tarsus is then closed by placing absorbable suture through 3/4 to 7/8 of the tarsal thickness. Full thickness bites of the tarsus in the upper lid would be exposed to the conjunctival surface and most likely cause a corneal abrasion. Heavier suture should be used for the lower lid tarsus (5-0 chromic) than the upper lid tarsus (6-0 chromic) because there is greater tension on the lower lid. The skin can then be closed with 6-0 or 7-0 interrupted silks with the eyelid margin sutures tucked under the eyelash margin sutures to keep from touching the cornea. Skin sutures can be removed in 5-7 days while the eyelid margin sutures should remain for 10-14 days.
For full-thickness lacerations with moderate loss of tissue, closure may be obtained by performing a lateral canthotomy with cantholysis. The lateral canthotomy is performed by making a horizontal cut from the lateral canthus to the orbital margin using a straight Stevens scissors. This maneuver splits the tendon into an upper and lower limb. An additional 3-5mm of length can be obtained by cutting either limb (depending on which eyelid is involved). The eyelid margin can then be closed as previously described. The skin of the lateral canthotomy can be closed with 6-0 silk. For defects greater than ½ of the eyelid, a tissue transfer procedure is indicated, usually from opposite eyelid or surrounding tissue.[4]
Lacerations of the lateral canthal area can usually be closed by direct repair. It is important to evaluate the possibility of injury to the lateral canthal tendon. This is usually identified by rounding of the lateral canthus. If the tendon has been severed, it should be repaired with 4-0 nonabsorbable sutures. If the lateral end cannot be found, the tendon should be sutured to the periorbita or through holes drilled through the lateral orbital rim at the orbital tubercle. It is important to remember that the lateral canthal tendon attaches to the orbital tubercle located 5mm posterior to the lateral orbital rim. If not repaired correctly, the lateral canthal angle will be displaced too far anteriorly.
The medial canthal area is important for lacrimal drainage as well as eyelid support. The lacrimal system must be evaluated when injury involves the medial canthus. The pretarsal fibers of the orbicularis oculi muscle of both eyelids divide medially into superficial and deep heads. The superficial heads form the medial canthal tendon and the deep heads pass posterior to the lacrimal sac to insert on the posterior lacrimal crest. The deep head is important to structural support of the eyelid as well as cosmesis to this area. Disruption of the deep head leads to lateral and anterior displacement of the medial canthal angle.
After ensuring no damage to the lacrimal system, the medial canthal region can be repaired directly. The superficial head of the medial canthal tendon should be repaired if possible but if the skin and orbicularis is re-approximated then no significant cosmetic deformity should result. If the deep head of the medial canthal tendon is injured, it must be repaired or the medial canthal angle will be distorted. If adequate soft tissue remains attached to the lacrimal bone, the tendon can be directly sutured using a heavy nonabsorbable suture. If no soft tissue remains or the medial orbital wall is fractured, the tendon can be wired to the adjacent intact medial wall, transnasally to the contralateral medial orbital wall, or to the contralateral medial canthal tendon.
Examination of the lacrimal system is essential in any injury medial to the punta or laceration involving the medial canthal area. The examination should be done using lacrimal probes and a cotton-tipped applicator. Anesthesia can be obtained with Tetracaine eye drops and the infratrochlear nerve block previously described. Repair of lacerations to the lacrimal drainage system should be performed as soon as possible.
Canalicular injuries should be repaired over a stent such as a Viers rod. The rod with attached 4-0 silk is placed through the punctum into the canaliculis and into the wound. The medial portion of the canaliculis may be difficult to find. It usually is located more posterior and inferiorly than expected. After locating the medial portion, repair of the canaliculis and medial canthal tendon is performed. Surgical loopes or the microscope is helpful. The suture ends of the Viers rod is then sutured to the skin of the medial canthal region. The rod should be left in place for 2-4 weeks. If there is more considerable damage to the lacrimal system with disruption of drainage system, silicone tubing should be placed through both canaliculi and down into nasolacrimal duct. The tubing should be left in place for 3 months.[2]
Extensive orbital fractures are likely associated with intracranial injury, neck and spine injury, chest and abdominal trauma, and long bone fractures. Nearly 52% of patients with facial fractures have an associated closed head injury. There has been some controversy over the years regarding timing of repair. Historically, the facial plastic surgery community seems to have supported early intervention in order to restore normal orbital volume and anatomic relationships. Early repair frequently yields better results than secondary reconstruction. The ophthalmic community has leaned toward a more conservative approach for recovery of visual function as many authors have shown that some patients with isolated orbital wall fractures and diplopia recover over time without treatment.[5]
The standard use of fine cut CT scanning through the orbit has lead to a better understanding of the anatomical deformity and prediction of soft tissue entrapment. There are no strict preoperative criteria for surgical repair but later I will review what many authors believe are indications for early exploration.
The blowout fracture is the most common fracture of the orbit. It occurs when an external force strikes the orbital rims causing a sudden increase in intraorbital pressure. This pressure is transmitted posteriorly to the thinnest walls of the orbit which buckle and fracture while the more resistant rim remains intact. These fractures are usually caused by blunt objects like fists, elbows, baseballs, and tennis balls. The orbital rim may also fracture, which must also be addressed. Regan and Smith coined the term blowout fracture. They studied cadavers and found fractures of the medial wall and floor most commonly.[5]
Fractures involving the orbital floor tend to produce greater functional problems. Diplopia and enophthalmos are the most common complications of the blowout fracture. Diplopia can be caused by direct entrapment of the inferior rectus muscle. It may also be secondary to injury to the innervation and hemorrhage/contusion of the inferior rectus and inferior oblique muscle. Some authors feel that diplopia may also result from the disruption of the fine ligament system that connects orbital soft tissues. Enophthalmos results from either prolapse of orbital tissue or increase in orbital volume. In later stages, enophthalmos may be caused by fat atrophy or contracting necrotic muscles.
Initial evaluation begins with the history to correlate the cause of the trauma with the injuries observed. If the patient complains of subjective visual loss, the onset of the vision loss should be noted. An immediate loss more likely indicates direct injury to the globe or optic nerve. A later, more gradual loss indicates possible orbital compression secondary to hematoma or emphysema.
A history of numbness of the ipsilateral cheek, nose, or upper gum line suggests injury to the infraorbital nerve. While the infraorbital nerve is not always associated with an orbital floor fracture, it is such a commonly associated finding that it's presence strongly suggests orbital floor fracture. Additionally, it's absence calls the diagnosis of orbital floor fracture into question. Careful and precise physical examination is necessary. Removal of blood, foreign bodies, and other debris is essential. A thorough and complete ophthalmic examination is necessary to rule out other ocular injuries and to help evaluate entrapment with forced duction testing.
The necessity of fracture repair depends on assessment of ocular motility and globe position. Significantly decreased ocular motility in the presence of minimal swelling or hemorrhage is strongly suggestive of muscle or ligament entrapment. Poor motility is most commonly due to muscle contusion but may represent entrapment. Forced duction testing and CT findings help differentiate the two.
Early globe position does not represent late globe position because of edema.[5] A large fracture on CT with normal globe position and moderate edema implies late enophthalmos will develop when the swelling resolves. CT scanning is the most accurate and definitive in localizing and characterizing orbital fractures.
Again, there are no strict indications for exploration and repair of orbital floor fractures but most authors
advocate exploration if:
Millman, et al is one group who advocates using a course of steroids to hasten the resolution of the edema in order to unmask patients whose diplopia will not resolve.[7]
There are several approaches to orbital floor exploration and repair of fractures. These include the subciliary, transconjuctival, and orbital rim approaches. The subciliary incision is the most commonly used but I will review an article comparing subciliary to transconjunctival later.
In general, anatomic reconstruction of orbital fractures requires complete dissection of the entire defect by identifying intact normal bone surrounding all edges of the fracture. Posterior intact bone is often referred to as the intact ledge. Muscle or ligament incarceration is released in the course of the dissection. An ipsilateral Caldwell-Luc incision may help with releasing soft tissue trapped in maxillary sinus. Muscle and ligament release is confirmed by duction testing. Forced ductions should be performed prior to the beginning of the procedure for a baseline as well. All rim fractures must be repaired, usually with plate and screw fixation. The intact or repaired rim and intact posterior ledge act as a guide for positioning and support of bone grafts or alloplastic implants.[5]
The best material for orbital wall reconstruction is debated. It seems many authors feel alloplastic implants (Medpor, Supramid foil, silastic) are suitable for smaller defects while larger defects are more difficult to bridge. [1] Custom metallic (titanium or vitallium) micromesh sheeting is flexible and allows for contouring of larger orbital wall defects. Calvarial bone grafts are also used but appear to be less flexible and are unpredictable due to resorption. Many authors use both, using the the metallic sheeting as a support for the bone graft. The curvature of the orbital walls must be reconstructed exactly in order to achieve proper orbital volume and globe position. The musculofibrous ligament system must have its freedom reconfirmed by repeat duction testing, especially after implant insertion. Any restriction in movement requires graft removal and reinsertion.
An article was just published in the Spring 1998 edition of the Journal of Cranio-maxillofacial Trauma comparing the subciliary approach to the orbital floor to the transconjunctival approach. The authors reviewed 60 fractures over 2 years. A total of 30 subciliary and 30 transconjunctival approaches were performed and reviewed. Adequacy of exposure and intraoperative and postoperative complications were compared. Exposure was noted to be adequate in all patients in both groups. A lateral canthotomy was required in 25 of the 30 transconjunctival approaches. Adequacy of postoperative repair was judged excellent in both groups, however the rate of complications was greater in the subciliary group.
The subciliary group had scleral show in 20% (6 cases), ectropion in 7% (2 cases ) and visible scar in 2 cases for an overall complication rate of 33%. The transconjunctival group had one case of pyogenic granuloma (3%), one case of scleral show (3%) and one case of a lower lid laceration for an overall complication rate of 10%. All cases of scleral show in both groups responded to conservative therapy (massage). The authors concluded that the transconjunctival approach to orbital fractures offers excellent exposure (when combined with lateral canthotomy) and significantly lower complications than the subciliary approach. [8]
Intraoperative complications include blindness secondary to hemorrhage or optic nerve ischemia from bone or implant impingement, failure to free entrapped muscles, orbital fat, or fibrous septa, and damage to the infraorbital nerve. Postoperative complications include residual diplopia, persistent enophthalmos, ectropion, scleral show, implant extrusion and infraorbital hypesthesia.
Medial wall fractures most commonly occur in combination with orbital floor fractures. Indirect, or medial wall blowout fractures, are those in which the orbital rim is intact but the very thin wall (mainly the lamina papyracea) is fractured. The mechanism of the medial wall blowout fracture is thought to be the same as orbital floor fractures. Medial wall fractures are reported to occur in 20-33% of cases of orbital floor fractures but are frequently missed. A medial wall fracture should be suspected if the patient complains of horizontal diplopia, epistaxis, subcutaneous emphysema in the eyelids or orbit following blunt trauma.
We usually consider orbital emphysema to be a benign condition, which it usually is, and simply ask the patients to refrain from blowing their nose. However, there have been cases of blindness secondary to central retinal artery occlusion from orbital emphysema. CT scanning usually reveals the orbital emphysema, displacement of the medial wall, and clouding of the ethmoid air cells. The medial rectus muscle is rarely entrapped. When the muscle is entrapped, horizontal motility disturbances are observed.
Indications for surgery include horizontal diplopia not resolving in 10-14 days, painful ocular motility with retraction of the globe, enophthalmos, and severe orbital emphysema. The most successful approach to medial wall fractures is through a direct medial canthal approach. Alloplastic implants or bone grafts may be used to reconstruct wall defects.
Complications include orbital hemorrhage (from anterior ethmoid), residual diplopia, and enophthalmos. [10]
An orbital roof fracture is a potentially life-threatening condition. Priority is directed toward evaluation of any intracranial injury. Neurosurgical consultation is usually required to manage any brain injury, intracranial foreign body, pneumocephalus, or dural tear with CSF leak. Moderate swelling in the roof of the orbit or downward displacement of the rim and roof bone fragments produce a characteristic downward and forward position of the globe. This is one of the most accurate clinical signs of a displaced roof fracture. It may be necessary to reduce displaced bone fragments that mechanically restrict the superior rectus muscle or impinge the levator muscle.
Fractures may be approached directly through pre-existing lacerations. A bi-coronal incision may also be used because orbital roof fractures frequently involve the frontal sinus or nasofrontal duct. Sinus obliteration should be considered at the time of the initial surgical repair in order to avoid the late complications such as a frontal sinus mucocele. Large orbital roof defects are commonly contiguous with a frontal sinus fracture. Because the risk of infection is increased with an exposed sinus, autogenous bone grafts are usually preferred over alloplastic materials.[11]
1) Wesley RE. Current techniques for repair of complex orbital fractures. Ophthalmology 99: 1766-1772, 1992.
2) Rathbun JE. Eyelid Surgery. Boston: Little, Brown and Company
3) Nesi FA, Spoor TC. Orbital Fractures. In: Smith BC, ed. Ophthalmic Plastic and Reconstructive Surgery. St. Louis: The C.V. Mosby Company, 1987:473.
4) Garber PF, Macdonald D, Beyer-Machule CB. Management of trauma to the eyelids. In: Smith BC, ed. Ophthalmic Plastic and Reconstructive Surgery. St. Louis: The C.V. Mosby Company, 1987:437.
5) Dutton J, Slamovits T. Management of blow-out fractures of the orbital floor. Survey of Ophthalmology 35: 279-298, 1991.
6) Putterman AM, Smith BC, Lisman RD. In: Smith BC, ed. Ophthalmic Plastic and Reconstructive Surgery. St. Louis: The C.V. Mosby Company, 1987: 477.
7) Millman AL, Della Roca RC, Spector s, et al: Steroids and orbital blow-out fractures: A new systematic concept in medical management and surgical decision making. Adv Ophthal Plast Reconst Surg 6:291-300, 1987
8) Patel PC, Sobota BT, Patel NM, et al. Comparison of transconjuctival versus subciliary approaches for orbital fractures: A review of 60 cases. J of Cranio-maxillofacial Trauma 4:17-21, Spring 1998.
9) Jackson IT. Trauma to the lacrimal system. In: Hornblass A, ed. Oculoplastic, Orbital and Reconstructive Surgery. Baltimore:Williams and Wilkins, 1990: 1470.
10) Allen V, Levine MR. Medial wall fractures. In: Hornblass A, ed. Oculoplastic, Orbital and Reconstructive Surgery. Baltimore:Williams and Wilkins, 1990: 1168.
11) Manson PN, Iliff NT. Fractures of the orbital roof. In: Hornblass A, ed. Oculoplastic, Orbital and Reconstructive Surgery. Baltimore:Williams and Wilkins, 1990:1139.