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Table of Contents    
Year : 2017  |  Volume : 65  |  Issue : 5  |  Page : 1094-1101

A neurosurgical perspective to approaches to the orbit: A cadaveric study

Department of Neurosurgery, Bangalore Medical College and Research Institute, Bangalore, Karnataka, India

Date of Web Publication6-Sep-2017

Correspondence Address:
S Balaji Pai
737, 14th Cross, Girinagar II Phase, Bangalore - 560 085, Karnataka
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/neuroindia.NI_726_17

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 » Abstract 

Neurosurgeons are getting increasingly involved in surgery for orbital tumours. The various approaches to the orbit can be challenging. The authors have demonstrated on cadavers the various approaches to the orbit which are required to be mastered by the neurosurgeon. The superior approaches which include the transcranial, supraorbital and the hybrid approaches are the most commonly utilized surgical approaches by the neurosurgeon for excision of orbital pathologies. The lateral orbitotomy is an elegant approach for excision of the tumours lateral to the optic Nerve and lacrimal gland tumours. The authors also demonstrate the medial approach through a medial orbitotomy which is a relatively unfamiliar approach to neurosurgeons. The importance of the various landmarks in each approach is emphasised along with the methods to minimize complications. It is imperative that neurosurgeons are intimately familiar with the microsurgical anatomy of the orbit and the various approaches to it.

Keywords: Hybrid approach, lateral orbitotomy, medial orbitotomy, orbital approaches, orbital tumours, supraorbital craniotomy, transcranial approach
Key Message:
This cadaveric study describes various approaches to the orbit in a stepwise manner.

How to cite this article:
Pai S B, Nagarjun M N. A neurosurgical perspective to approaches to the orbit: A cadaveric study. Neurol India 2017;65:1094-101

How to cite this URL:
Pai S B, Nagarjun M N. A neurosurgical perspective to approaches to the orbit: A cadaveric study. Neurol India [serial online] 2017 [cited 2021 May 13];65:1094-101. Available from:

Orbital lesions necessitating surgical intervention can be challenging in view of the restricted space available to the surgeon. Various specialists have been traditionally involved in the surgery of the orbit - ophthalmologists, plastic surgeons, otorhinolaryngologists and neurosurgeons. The neurosurgeon generally deals with lesions of the posterior orbit or those that overlap the posterior portion or the cranium.[1] However, many orbital lesions, irrespective of their situation in the orbit, are being increasingly referred to the neurosurgeons for surgical management. It is imperative that the surgeon is intimately familiar with the microsurgical anatomy of the area before venturing into this rather complex region. The authors, using cadaveric dissection, have demonstrated various surgical approaches to the orbit and their indications which are important to the neurosurgeon. An adequate understanding of the local anatomical details is necessary to ensure optimal surgical results. Formalin – embalmed cadaveric dissection is a well-established approach to gain knowledge of the morphological anatomy.[2]

Orbital lesions

It is beyond the scope of this article to discuss the various orbital pathologies in detail. The common orbital pathologies (and their usual locations in the orbital space) that require a surgical intervention include the following: the subperiosteal space (the space between the orbital bony wall and the underlying periorbita) that harbours bony tumours and dermoids; the peripheral surgical space (the space between periorbita and the muscular cone) that harbours a cavernous angioma, a fibrocystic histiocytoma and lacrimal gland tumours; the central surgical space (the space inside the muscular cone) that harbours optic nerve tumours (glioma and meningioma), cavernous angiomas and neurilemmomas; and, the Tenon's space (intraocular space) that harbours intraocular tumours

 » Surgical Approaches to the Orbit Top

Various surgical approaches to the orbit have been described. The choice of approach would depend on the site of the lesion and the orbital space in which it is present, its histopathology and the surgeon's experience. Some of the approaches have been described below from the neurosurgical perspective [Table 1].
Table 1: Comprehensive list of approaches to the orbit and their advantages and disadvantages

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Superior approach

The trans-frontal route to the orbit was initially employed by Walter Dandy and later popularized by Naffziger.[3] It is useful for surgical excision of lesions involving the superior portion of the orbit with or without intracranial invasion; and optic nerve (ON) lesions like an ON glioma or a ON meningioma. After placing the patient in a supine position, the orbit can be reached either through a frontal craniotomy or through a frontal craniotomy with an orbital osteotomy (a fronto-orbitotomy flap). The former is generally employed. After the frontal craniotomy, the dura over the orbital roof is detached and retracted. The periorbita, passing under the orbital rim, is also separated from the orbit, taking care to preserve the supraorbital vessels and nerve. An orbital roof bone flap can then be created using a craniotome or chisel. Care is taken not to injure the intraorbital contents during this step. Some surgeons remove the orbital roof in a piecemeal fashion using Kerrison punches and later use a titanium mesh to close the bone defect [Figure 1]. In case a fronto-orbitotomy flap is raised then it may be necessary to nibble the posterior orbital roof to obtain adequate access to the orbital pathology. The periorbita can then be incised and the first structure to come into view is the frontalis nerve (FN) which can be identified easily and serves as a reliable landmark [Figure 2]. Just below the frontalis nerve is the levator palpebrae superioris (LPS) and the superior rectus (SR) which traverse in the same axis as the orbit [Figure 2]. Intraconal lesions can then be approached through two corridors - medial and lateral. The medial corridor consists of approaching lesions between the superior muscles -LPS and SR and the superior oblique (SO) [Figure 3]. It is important to recognize and preserve the trochlear nerve (IV N), the ophthalmic artery (OA), ophthalmic vein (OV) and the nasociliary nerve (NN) while utilizing this corridor [Figure 4] and [Figure 5]. Retracting the medial rectus muscle (MR), one can reach the inferior portion of the orbit. The lateral corridor consists of retracting the superior muscles (LPS and SR) medially and the lateral rectus muscle (LR) laterally. It is important to identify and preserve the abducens nerve (VI N) which is located on the inner side of the LR [Figure 6]. The lacrimal artery and lacrimal nerve will also be encountered while utilizing this corridor. One can reach up to the inferior rectus muscle (IR) through this approach [Figure 7]. Rarely, one can approach the middle third of the upper part of the cone by retracting the LPS medially and the SR laterally.[3]
Figure 1: Transcranial approach: After a right frontal craniotomy, the dura has been retracted and the orbital roof is removed in a piecemeal fashion

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Figure 2: Transcranial approach: On opening the periorbita, the frontalis nerve (FN), levator palpebrae superioris (LPS) and the superior rectus (SR) can be seen

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Figure 3: Transcranial approach: On taking the medial corridor, the superior oblique (SO) and the trochlear nerve (IVN) are visualized

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Figure 4: Transcranial approach: On deeper dissection, the medial rectus (MR) and the ophthalmic artery (OA) can be seen

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Figure 5: Transcranial approach: On taking the lateral corridor, the optic nerve (ON) can be visualized

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Figure 6: Transcranial approach: On taking the lateral corridor, the lateral rectus (LR) with the abducens nerve (VIN) is seen

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Figure 7: Transcranial approach: Further deeper, the inferior rectus (IR) can be approached

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Supraorbital approach

This is a minimally invasive approach and traces its history back to Jane et al., in 1982, followed by Maus and Goldman.[4] Hassler and Schick have described the minimally invasive approach to the superior orbit.[4] It is useful for the excision of well- circumscribed pathologies of the superior orbit like cavernous angiomas and schwannomas. The patient is placed in a supine position with the head extended 15 degrees and rotated 15-30 degrees to the opposite side. An eyebrow incision is made of around 4 cm length along the orbital margin [Figure 8]. The periosteum is freed and the periorbita separated from the inner orbital roof. A frontonasal craniotomy is performed using a craniotome [Figure 9]. The orbital rim is then removed using an oscillating saw or chisel after fixing mini-plates on both sides of the rim [Figure 10]. This helps to make the closure cosmetically good. The basal dura is retracted and the orbital roof removed [Figure 11]a. The periorbita is incised and lesion excised [Figure 11]b. Extraconal lesions are excised easily. Intraconal lesions may require retraction of the intraorbital contents using self-retaining retractors. After haemostasis, the periorbita is closed and the craniotomy flap and orbital rim replaced and fixed with mini plates and screws. The main advantage of this elegant approach is minimal orbital and brain retraction. However, the drawback of this approach is the inability to reach the more posterior regions of the orbit.
Figure 8: Supraorbital approach: (a) Left supraorbital incision; (b) Scalp flap is raised and lateral key burr hole made

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Figure 9: Supraorbital approach: Supraorbital craniotomy flap is raised

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Figure 10: Supraorbital approach: Osteotomy cuts for orbitotomy: (a) Lateral, (b) Medial, (c) Posterior

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Figure 11: Supraorbital approach: (a) Orbitotomy flap is raised, and periorbita visualised; (b) Intraorbital structures are seen after the T- shaped incision on the periorbita

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Lateral approach

Kronlein was the first to describe this approach in 1888, which was subsequently modified by other surgeons like Berke.[3] This elegant approach is useful for surgical extirpation of lesions lateral to the ON. It is generally used for the excision of lacrimal gland tumours and laterally situated cavernous angiomas and neurofibromas. It is less invasive than the transcranial approach to the orbit.[5]

The patient is placed in the supine position with the head turned to the opposite side. An elongated S-shaped incision is employed starting at the eyebrow, descending along the lateral border of the orbit and curving posteriorly along the superior border of the zygomatic arch [Figure 12]a.[3] The S-shaped incision may be inverted inferiorly if the lesion is situated in the inferolateral portion of the orbit.[5] After this, the frontal process of the zygoma is dissected off its overlying tissue [Figure 12]b. The periorbita is separated from the inner surface of the orbit. Kronlein described the osteoplastic flap by retaining the attachment of the muscles to the bone. However, some surgeons have advocated the non-osteoplastic technique. The osteotomy however, remains the same with a superior cut just above the fronto-zygomatic suture and the inferior cut at the level of the superior border of the zygomatic arch [Figure 13].[3] The posterior portion of the lateral wall of the orbit is nibbled using the bone nibbler as far posteriorly as required, sometimes reaching up to the inferior orbital fissure (IOF) [Figure 14]a. The periorbita is then incised horizontally or in a ‘T’ fashion [Figure 14]b. The first structure that can be identified at this juncture is the LR muscle [Figure 15]. A superior or inferior route is then taken above or below the LR muscle depending on the site of the pathology. The LR may be kept away using a suture to prevent retraction injury to the muscle. Using the superior route, one will encounter the lacrimal artery and lacrimal nerve going towards the lacrimal gland. Other structures that may possibly come in the way are the posterolateral ciliary artery, the short ciliary nerves and the superior branch of the oculomotor (III) nerve with branches to the SR and LPS.[3] Traversing below the LR (inferior corridor) in addition to the above, the ciliary artery and nerves, and the inferior division of the III nerve (with branches to the MR, IR and IO muscles) will be encountered. Rarely, the LR is divided and resutured back for better exposure. Bony closure is achieved with wires or plate and screws, ensuring a good cosmetic repair.
Figure 12: Lateral approach: (a) Shows the left lateral orbitotomy incision. (b) The incision is deepened until the periosteum

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Figure 13: Lateral approach: (a) Shows the exposure of the lateral margin and wall of the left orbit. (b and c) Shows the superior and inferior orbitotomy cuts

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Figure 14: Lateral approach: (a) Reveals the periorbita after excision of the lateral orbital wall. (b) A horizontal periorbital incision is made

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Figure 15: Lateral approach: The lateral rectus (LR) is visualized

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Superolateral “hybrid” approach

This approach was first described by Karagjozov in 1967 and involves approaching through the roof and lateral wall of the orbit.[3] This approach is useful for larger lesions extending superiorly and laterally, and sometimes intracranially. As with the superior approach, almost all areas of the orbit can be reached except the medial portion of the orbit under the ON. The patient is placed in the supine position, as in the pterional craniotomy, with the head slightly turned to the opposite side and slightly extended. After the frontotemporal scalp flap is raised, two types of bone flaps have been described - a single bone flap or a double flap method. In the double flap technique, the first bone flap is the classical fronto-pterional-temporal craniotomy. The dura mater is detached from the lesser wing of the sphenoid, orbital roof and middle cranial fossa. The periorbita is detached from the inferior aspect of the roof and the lateral wall of the orbit. Osteotomy cuts are made medially, laterally and posteriorly after retraction of the dura. The posterior cut may be extended as far posteriorly as the superior orbital fissure (SOF). Further widening can be done, if required, using the bone nibbler. The two landmarks at this juncture are: the lacrimal gland in the superolateral corner and the beginning of the SOF posteriorly. The periorbita is incised in a ‘T’ fashion. The inner structures are already described in the superior approach, the only difference being a slightly more lateral angle of approach and vision.

Medial approach

The evolution of the medial approach to the orbit was driven by the need for a minimally invasive, cosmetic and safe approach to the medial contents of the orbit.[6] Although for neurosurgeons, this is a relatively unfamiliar territory, it provides an excellent exposure to the medial, superior and inferior compartments of the orbit. It is not suitable for larger lesions of the ON and those extending to the SOF and to structures within the cranium.[6]

The patient is placed supine with the head turned 15 degrees to the opposite side. The incision extends inferiorly from the medial orbit between the nose and orbit [Figure 16]a. The exposure is deepened by a subperiosteal and subperiorbital dissection, preserving the medial canthal ligament [Figure 16]b. The medial canthal ligament, which is attached to the anterior and posterior margins of the lacrimal groove, is divided in such a fashion that it can be reapproximated and sutured later. Anterior ethmoidal artery can be coagulated and cut [Figure 17]a and as the dissection proceeds posteriorly, the posterior ethmoidal artery too can be sacrificed. The distances of these vessels have been described as 20mm and 32mm, respectively, from the anterior lip of the lacrimal fossa by Deda et al.[7] The exposure can be further widened by drilling the medial wall of the orbit into the ethmoid sinus and removing its mucosa [Figure 17]b. The periorbita is incised longitudinally in the orbital axis exposing the medial rectus muscle, which is an unfailing and important landmark in this approach [Figure 18]. Gurkanlar and Gonul have described three subsequent corridors of approach after this step [Figure 19]:
Figure 16: Medial approach: (a) Right medial orbitotomy skin incision; (b) On deepening the incision to the periosteum, the medial canthal ligament (MCL) encountered

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Figure 17: Medial approach: (a) After detaching the MCL and deepening the incision anterior ethmoidal artery seen; (b) After further elevation of medial periorbita and cutting posterior ethmoidal artery the medial bony wall of orbit is drilled

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Figure 18: Medial approach: (a) After detaching the MCL and deepening the incision anterior ethmoidal artery seen; (b) After further elevation of medial periorbita and cutting posterior ethmoidal artery the medial bony wall of orbit is drilled

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Figure 19: Medial approach: This figure depicts the three approaches to the medial orbital contents: medial superior, medial inferior and medial central (in relation to the medial rectus)

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  1. The medial superior approach: The medial rectus is retracted inferiorly and the retrobulbar adipose tissue is retracted. After removal of the adipose tissue, the nerves and vessels can be seen. The superomedial aspect of the orbit can thus be reached
  2. The medial inferior approach: The medial rectus is retracted superiorly. The inferomedial portion of the orbit with its contents can be reached through this corridor. This includes the central retinal artery (CRA)
  3. The medial central approach: Additional ethmoidal bone is removed using the drill and small rongeurs. The posterior plate of the ethmoid sinus is thus removed. The medial rectus muscle is then disinserted and retracted. This provides exposure of the entire medial part of the orbit including the ON, the nerves to the SR, MR and IR, the apsidal vein, the posterior long and short ciliary arteries and the CRA. Disinsertion and retraction of the MR gives access to the entire medial orbit with a low risk of any damage to neural or vascular structures in this area.

Other approaches

Other approaches like the inferior orbitotomy approach, and the anterior approaches like the transconjunctival and transcaruncular approaches[8] are not considered to be in the domain of the neurosurgeon and hence are not included in this study.

 » Discussion Top

There is a high degree of participation of neurosurgeons in the management of orbital tumours. This is because of involvement of the posterior-third of the orbit and the intracranial extension of many lesions which require a neurosurgical approach.[9] There are various approaches to the orbit - strictly intraorbital, epidural and intradural approaches. The choice of the approach will depend on the site, the shortest route, the least disruptive trajectory, the most cosmetic result that may be obtained and the surgeon's experience.[3] The various approaches have been described in this cadaveric study. As a general rule, the transcranial approach is used for ON tumours and for tumours with an intracranial extension.[4] The hybrid approach or the pterional approach is useful for tumours in the optic canal, the SOF or the IOF, and the lateral extra- and intraconal tumours. LG tumours as well as lateral intra- and extraconal tumours and those around the orbital apex are best approached by the lateral orbitotomy. Medially placed tumours can be approached by the medial orbitotomy. The supraorbital craniotomy is an ideal approach for well-circumscribed intra- and extraconal tumours above the ON.[4] These approaches are not without their share of complications. The important ones include blindness due to ON injury or central retinal artery compromise; diplopia due to oculomotor dysfunction, due to intraocular muscular injury or damage to one or more of the nerves supplying the extraocular muscles; the Bernard - Horner syndrome due to injury to the ciliary ganglion or the sympathetic nerves; enophthalmos due to loss of orbital fat during surgery; pulsatile exophthalmos due to transmission of brain pulsation through a dehiscent orbital roof; brain injury due to excessive brain retraction; or, seizures and neurological deficits due to brain injury.

These complications may be avoided if the surgeon is familiar with the microsurgical anatomy of the orbit. Some constant anatomical landmarks are useful during surgery and are helpful in avoiding complications. In the transcranial approach, the FN, LPS and SR serve as useful landmarks, followed by the tendinous ring around the SOF in the epidural approach. The LG and LR with the VI N are the landmarks in the lateral approach. In the medial approach, the medial canthal ligament and the MR are the guiding structures. Familiarity with these landmarks and the adjacent structures helps in avoiding most of the complications associated with these approaches.

Special considerations in orbital surgery

a. Differences between surgery for intraconal and extraconal pathology

The common lesions of the intraconal compartment include optic nerve tumours (glioma and meningioma), neurilemmoma, lymphangiomas, etc., The most common extraconal lesions include bony tumours, dermoid, fibrocystic histiocytoma, lacrimal gland tumours, orbitosphenoidal meningiomas, plexiform neurofibromas, histiocytic tumours, leukaemic deposits, lymphoma and metastases. Some tumours like cavernous angiomas, capillary haemangiomas, rhabdomyosarcomas and epidermoids can present both intra- and extraconally. While approaching intraconal lesions, it is always preferable to have adequate exposure to prevent optic nerve injury. Hence, generally transfrontal or other superior approaches are preferred. However, extraconal lesions are away from the optic nerve and are generally benign. Hence, these can be approached through corridors that provide a smaller access like the supraorbital craniotomy or the extracranial lateral approach. These approaches are less invasive and ensure cosmesis.[7]

b. Differences between surgery for tumours close to the globe and orbital apex lesions

The common pathologies close to the globe are teratomas, rhabdomyosarcomas, leukaemic or lymphomatous deposits and metastases; while, the orbital apex lesions include orbitosphenoidal meningiomas, extensive optic nerve gliomas/nerve sheath meningiomas. The lesions located close to the globe can be approached through extracranial approaches or through less invasive intracranial approaches like the supraorbital or subfrontal extradural approach; whereas, tumours close to the apex and those with an intracranial extension will require a wide exposure. Hence a combination of intra- and extradural approaches with intradural exploration are used.[7]

c. Surgery for tumours extending from the orbit to the chiasma

Lesions like the optic nerve gliomas and extensive meningiomas usually extend to the intracranial cavity and chiasma. These lesions will require a combination of intracranial and extracranial approaches and an adequate exposure for radical excision (provided generally by various superior and superolateral approaches). Reconstruction of roof of the orbit should be done to avoid the occurrence of a pulsatile exophthalmos. These can be associated with CSF leak and hence attention must be paid to duroplasty and other reconstructive techniques. Post-operative visual deficits are common due to the nature of these lesions. Hence, radical surgery is considered only when preoperative vision is grossly affected.[1]

d. Differences in approach to optic nerve sheath meningiomas and optic nerve gliomas

Both these lesions may be limited to the intraconal space or may extend posteriorly to the intracranial compartment. Hence, to achieve a good exposure, superior approaches like the trans- frontal approaches are preferred. Optic nerve gliomas are tumours which involve the substance of the optic nerve and surgical excision will result in a gross visual deficit. Radical surgery for these tumours should only be considered when preoperative vision of the involved optic nerve is grossly diminished or is absent. Meningiomas of the optic nerve are extra axial lesions and hence all measures to preserve the function of the optic nerve should be undertaken.[1]

 » Conclusions Top

The neurosurgeons are being increasingly involved in orbital tumour surgery, especially in those involving the posterior two-thirds of the orbit. Hence, it is imperative that they are intimately familiar with the microsurgical anatomy of the orbit and with the various approaches to it. The authors also emphasize the need for gaining laboratory experience by performing cadaveric studies prior to venturing into the field of orbital surgery.


The authors acknowledge the help of Dr. Priya Ranganath, Head, Department of Anatomy, Bangalore Medical College for providing the infrastructure and in helping with the cadaveric dissections.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

 » References Top

Marchal JC, Civit T. Neurosurgical Concepts and Approaches for Orbital Tumours. In: Pickard JD, Akalan N, Di Rocco C, Dolenc VV, Fahlbusch R, Lobo Antunes J, et al., editors. Advances and Technical Standards in Neurosurgery. Vienna: Springer Vienna; 2006. p. 73-117.  Back to cited text no. 1
Krohn-Hansen D, Nicolaissen B, Meling TR, Haaskjold E. Surgical approach to the superior mid-orbit. J Plast Surg Hand Surg. 2013;47:320-3.  Back to cited text no. 2
Hayek G, Mercier P, Fournier HD. Anatomy of the Orbit and its Surgical Approach. In: Pickard JD, Akalan N, Di Rocco C, Dolenc VV, Fahlbusch R, Lobo Antunes J, et al., editors. Advances and Technical Standards in Neurosurgery. Vienna: Springer Vienna; 2006. p. 35-71.  Back to cited text no. 3
Hassler W, Schick U. The supraorbital approach - A minimally invasive approach to the superior orbit. Acta Neurochir (Wien). 2009;151:605-11.  Back to cited text no. 4
Gonul E, Timurkaynak E. Inferolateral microsurgical approach to the orbit: An anatomical study. Minim Invasive Neurosurg. 1999;42:137-41.  Back to cited text no. 5
Gurkanlar D, Gonul E. Medial microsurgical approach to the orbit: An anatomic study. Minim Invasive Neurosurg. 2006;49:104-9.  Back to cited text no. 6
Deda H, Ugur HC, Yorulmaz I, Kucuk B. Anteromedial approach to the orbit. Skull Base. 2001;11:233-9.  Back to cited text no. 7
Moe KS. The precaruncular approach to the medial orbit. Arch Facial Plast Surg. 2003;5:483-7.  Back to cited text no. 8
Li P, Yang Z, Wang Z, Liu P. Bilateral cranio-orbital neurofibromas in a 16-year-old child with neurofibromatosis 1. Neurol India. 2016;64:835-6.  Back to cited text no. 9


  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9], [Figure 10], [Figure 11], [Figure 12], [Figure 13], [Figure 14], [Figure 15], [Figure 16], [Figure 17], [Figure 18], [Figure 19]

  [Table 1]


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