- Email: [email protected]
Transorbital endoscopic surgery
Operative Techniques in Otolaryngology (2008) 19, 224-227
Transorbital endoscopic surgery Venkatesh C. Prabhakaran, MS, MRCOphth,a Dinesh Selva, FRANZCOb From the aDepartment of Orbital and Oculoplastic Surgery, Prabha Eye Clinic, Bangalore, India; and the b South Australian Institute of Ophthalmology and Department of Ophthalmology & Visual Sciences, University of Adelaide, Adelaide, South Australia. KEYWORDS Endoscopic; Orbital surgery; Subperiosteal; Orbital roof
Orbital surgery is traditionally performed through an open approach and often involves bone removal for better visualization. The use of an endoscope obviates the need for bone removal in certain situations, particularly for lesions involving the orbital roof. Transorbital use of the endoscope also provides better visualization when one is working deep within the orbit, for instance, on the deep lateral wall. However, the endoscope can only be situated in the subperiosteal space, thus limiting its utility. In the article, the authors describe their technique for transorbital endoscopic surgery and review the uses and limitations of transorbital endoscopic surgery. © 2008 Elsevier Inc. All rights reserved.
Endoscopic surgery plays a relatively small role in ophthalmology, chiefly because of the constraints of size and space. However, endoscopes are being used for orbital, oculoplastic, lacrimal, and even intraocular procedures. Endoscopic orbital surgery is performed primarily via sinonasal approaches by ENT surgeons. Transnasal endoscopic approaches are well established for orbital decompression,1 orbital medial wall fracture repair,2 and optic canal decompression.3 The use of a transmaxillary or transnasal endoscopic approach also has been described for the repair of orbital floor fractures.2 The ophthalmologist is familiar with the endoscope, primarily in the context of endoscopic dacryocystorhinostomy4 and endoscopic brow lift.5 Nasal endoscopy also has proven to be useful in the perioperative assessment for lacrimal surgery and probing of the nasolacrimal duct.6,7 Additional applications in oculoplastic surgery include transcanalicular endoscopy8 and endoscopic assistance in facelifts9 and in harvesting fascia lata.10 Intraocular endoscopes are used to perform endoscopic cyclophotocoagulation to reduce intraocular pressure in patients with intractable glaucoma.11 The purpose of this article is to review transorbital endoscopic surgery. The use of endoscopes in orbital surgery was first described by Norris and Cleasby in 1981.12 The initial reports by Norris detailed the use of the endoscope in biopsying Address reprint requests and correspondence: Venkatesh C. Prabhakaran, MS, MRCOphth, Prabha Eye Clinic, 504, 40th Cross, Jayanagar, Bangalore-560070, India. E-mail address: [email protected]. 1043-1810/$ -see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.otot.2008.09.004
orbital tumors13 and in removing foreign bodies from the orbit. Isotonic saline was used to provide visualization while the surgeon was dissecting in the orbit. However, its use increased the pressure within the orbit, and the tissues became quickly edematous. Norris and Cleasby also found that that use of air to aid in visualization was not successful.12 Braunstein and coworkers14 have also described the experimental use of flexible endoscopes in the orbits of dogs by using hyaluronate infusion through the endoscope tip to aid visualization. However, the potential for compressive collateral damage during the creation of an optical cavity has limited the use of the endoscope within the orbital fat. Hence, because of the lack of a safely distensible space, intraorbital endoscopy15 is not widely used. In 2004, Selva and Chen16 described the subperiosteal transorbital use of the endoscope during curettage of a cholesterol granuloma of the orbital roof. Since then, there have been reports of endoscopic approach to lesions of the orbital roof and also on the use of the endoscope as a surgical teaching aid.17,18
Indications Transorbital endoscopic surgery is only used for procedures involving the orbital bones because the subperiosteal space can be used for situating the endoscope. Lesions such as cholesterol granulomas, orbital dermoids, and Langerhans cell histiocytosis involving the anterior portion of the orbital roof and situated behind the superior orbital rim can be difficult to
Prabhakaran and Selva
Transorbital Endoscopic Surgery
Figure 1 Line diagram illustrating the use of an endoscope to visualize a lesion situated behind the superior orbital rim.
visualize during surgery. Bone removal often is needed for adequate visualization in this situation. The use of a rigid videoendoscope can provide excellent visualization behind the superior orbital rim and is an excellent aid during surgical removal of these lesions (Figure 1). Similarly, endoscopes aid visualization during orbital decompression, especially of the deep lateral wall. They are also useful as a teaching aid in these and other situations, for example, in orbital floor fracture repairs. Thus, transorbital endoscopic surgery is currently indicated for lesions involving the orbital roof, for better visualization during orbital decompression, and the use of subperiosteal endoscopy as a teaching aid.
225
Figure 3 The orbital roof periosteum is reflected downwards with a malleable retractor and the superior orbital rim is visualized (arrow).
any orbital surgery with the addition of the endoscope with attached video camera. A rigid endoscope with 0-, 30-, or 70-degree tip is used depending on the situation. Two situations wherein transorbital endoscopy is useful are illustrated below:
Transorbital endoscopic surgery of orbital roof lesions
The procedure is performed in the operating room and under general anesthesia. The set-up and instrumentation is as for
After induction of general anesthesia a skin incision is placed in the upper eyelid skin crease. A suborbicularis dissection is performed to the superior orbital rim (Figure 2) and the periosteum is incised 5 mm above the arcus marginale. The periorbita is then elevated off the orbital roof and orbital contents retracted inferiorly with malleable retractors (Figure 3). As much of the lesion as possible is removed under direct visualization. A rigid video-endoscope with a 30- or 45-degree tip is then introduced posterior to the superior orbital rim (Figure 4). Endoscopic sur-
Figure 2 Intraoperative photograph demonstrating a lid-crease incision and dissection in the suborbicularis plane. The arrow points to the septum below the arcus marginale.
Figure 4 Intraoperative photograph demonstrating curettage of an orbital roof lesion under endoscopic visualization.
Technique
226
Operative Techniques in Otolaryngology, Vol 19, No 3, September 2008
vey reveals the extent of the lesion that can now be removed under visualization from areas that are not directly visible behind the orbital rim and any areas abutting the dura (Figure 1). A 70-degree tip is on occasion required for a better view of the internal aspect of the superior orbital rim and the anterior wall of the frontal sinus for those lesions that abut these areas. The periosteum is reattached and the skin incision closed.
Use of the endoscope as a teaching aid The small surgical field available when operating within the orbital confines makes it difficult for a supervising surgeon to view the trainee’s surgery. The subperiosteal space is a potential space that allows retraction of the orbital contents by placing a retractor against the orbital periosteum. The space thus created is ideally suited for placement of a video endoscope that can be used to observe surgery within the orbit.17 The supervising surgeon usually holds the endoscope while the operating surgeon may either view the surgical field directly or observe it on the video monitor. The light from the endoscope and the magnification provided also aid in the dissection. In most cases, the endoscope is rested on the orbital rim or, less frequently, on a retractor to provide the required view and also to minimize fogging. On occasion, a shorter and narrower endoscope such as a pediatric video-otoscope or a flexible endoscope may be used so as not to compromise the surgeon’s access or view. This may be particularly useful in the transcaruncular approach to the medial orbital wall, where the larger endoscope may impede the surgeon’s access through the small incision. Endoscopic supervision is most applicable to procedures such as deep lateral wall (Figure 5) or medial wall orbital decompression, orbital fracture repair and lesions involving the orbital roof. Endoscopes used may vary from 0- to 70-degree tips dependant on the location of the surgical field. In addition, the procedures may be recorded onto videotape and reviewed by both consultant and trainee. Surgical drains are not usually placed after transorbital endoscopic surgery. Postoperative
Figure 5 Endoscopic view of deep lateral orbital wall allowing excellent visualization during bone removal with a burr.
care includes monitoring of pupils and vision every 4 hours for the first day as for any orbital procedure.
Complications The complications encountered are those of the orbital procedure rather than attributable to use of the endoscope itself. In fact, use of the endoscope minimizes chances of complications such as dural tear during orbital roof lesion removal or deep lateral orbital decompression.
Discussion The primary advantage of transorbital endoscopic surgery is avoidance of bone removal for adequate exposure. Furthermore, the use of a more minimally invasive technique enables the surgeon to treat surgical patients on an outpatient basis, thus reducing length of hospitalization in comparison with the traditional postoperative management of a lateral orbitotomy or craniotomy. Additional advantages include increased illumination and magnification and an extended viewing angle, all of which enable good visualization of the surrounding bone and dura. This facilitates a safer and more meticulous removal of bone or tissue abutting the dura and perhaps also decreases the risk of a cerebrospinal fluid leak in comparison with procedures during which an endoscope is not used. Alternative approaches to the superior orbit and orbital roof include lateral orbitotomy, extended superolateral orbitotomy (removal of lateral wall with adjacent temporal or parietal bone), and transcranial orbitotomy.19 These approaches provide good exposure but are possibly associated with increased risk of morbidity because of the bone removal and greater tissue dissection. Although a supraorbital endoscopic approach to the anterior cranial base and frontal sinus (via a 1.5-cm craniotomy above the supraorbital rim) has also been described in the neurosurgical literature,20 its use may be limited in lesions which also extend into the superior orbit. Transorbital endoscopy is also specially useful while performing decompression of the deep lateral orbital wall. The removal of the deep lateral wall including the marrow space has been shown to increase the efficacy of orbital decompression in cases of thyroid orbitopathy.21 The use of the endoscope during this procedure aids in visualization and minimizes complications such as cerebrospinal fluid leaks. A clean operating field is essential to the success of transorbital endoscopic surgery, especially since the operating area is usually limited. Meticulous hemostasis aided by effective suction and judicious cautery greatly aids in visualization and prevents soiling of the endoscope. The use of different-sized malleable retractors is also essential to provide adequate viewing space. Because diffuse bleeding from the bone is commonly encountered, the use of an adrenaline-soaked tamponade (for approximately 5 minutes) or bone-wax may be required. Incorporating these guidelines will facilitate transorbital endoscopic surgery.
Prabhakaran and Selva
Transorbital Endoscopic Surgery
References 1. Kasperbauer JL, Hinkley L: Endoscopic orbital decompression for Graves’ ophthalmopathy. Am J Rhinol 19:603-606, 2005 2. Pham AM, Strong EB: Endoscopic management of facial fractures. Curr Opin Otolarngol Head Neck Surg 14:234-241, 2006 3. Kuppersmith RB, Alford E, Patrinely JR, et al: Combined transconjunctival/intranasal endoscopic approach to the optic canal in traumatic optic neuropathy. Larngoscope 107:311-315, 1997 4. Wormald PJ: Powered endoscopic dacryocystorhinostomy. Larngoscope 112:69-72, 2002 5. Romo T, Jacono AA, Sclafani AP: Endoscopic forehead lifting and contuoring. Facial Plast Surg 17:3-10, 2001 6. Minasian M, Olver JM: The value of nasal endoscopy after DCR. Orbit 18:167-176, 1999 7. MacEwen CJ, Young JD, Barras CW, et al: Value of nasal endoscopy and probing in the diagnosis and management of children with congenital epiphora. Br J Ophthalmol 85:314-318, 2001 8. Mullner K, Bodner E, Mannor GE: Endoscopy of the lacrimal system. Br J Ophthalmol 83:949-952, 1999 9. Freeman MS: Endoscopic techniques for rejuvenation of the midface. Facial Plast Surg Clin North Am 13:141-155, 2005 10. Malhotra R, Selva D, Olver J. Endoscopic-assisted fascia lata harvesting. Ophthal Plast Reconstr Surg 23:358-362, 2007 11. Lin S: Endoscopic cyclophotocoagulation. Br J Ophthalmol 86:1434-8, 2002
227 12. Norris JL, Cleasby GW: Endoscopic orbital surgery. Am J Ophthalmol 91:249-52, 1981 13. Norris JL, Stewart WB: Bimanual endoscopic orbital biopsy. An emerging technique. Ophthalmology 92:34-38, 1985 14. Braunstein RE, Kazim M, Schubert HD: Endoscopy and biopsy of the orbit. Ophthal Plast Reconstr Surg 11:269-272, 1995 15. Rose GE: Endoscopic removal of periorbital lesions—where next? Orbit 21:261-262, 2002 16. Selva D, Chen C: Endoscopic approach to orbitofrontal cholesterol granuloma. Orbit 22:49-52, 2004 17. Malhotra R, Selva D, Wormald PJ, et al: Video-endoscope assisted teaching during sub-periosteal orbital surgery. Orbit 24:113-116, 2005 18. Prabhakaran VC, Hsuan J, Selva D: Endoscopic assisted removal of orbital roof lesions via a skin crease approach. Skull Base 17:341-345, 2007 19. Patrinely JR, Stal S, Weber RS: Periorbital and craniofacial surgery, in WB Stewart (ed): Surgery of the eyelid, orbit and lacrimal system, vol 3. San Francisco, American Academy of Ophthalmology, 1995, pp 60-79 20. Kabil MS, Shahinian HK: Application of the supraorbital endoscopic approach to tumors of the anterior cranial base. J Craniofacial Surg 16:1070-1074, 2005 21. Goldberg RA, Kim AJ, Kerivan KM: The lacrimal keyhole, orbital door jamb, and basin of the inferior orbital fissure. Three areas of deep bone in the lateral orbit. Arch Ophthalmol 116:1618-1624, 1998
Transorbital endoscopic surgery Venkatesh C. Prabhakaran, MS, MRCOphth,a Dinesh Selva, FRANZCOb From the aDepartment of Orbital and Oculoplastic Surgery, Prabha Eye Clinic, Bangalore, India; and the b South Australian Institute of Ophthalmology and Department of Ophthalmology & Visual Sciences, University of Adelaide, Adelaide, South Australia. KEYWORDS Endoscopic; Orbital surgery; Subperiosteal; Orbital roof
Orbital surgery is traditionally performed through an open approach and often involves bone removal for better visualization. The use of an endoscope obviates the need for bone removal in certain situations, particularly for lesions involving the orbital roof. Transorbital use of the endoscope also provides better visualization when one is working deep within the orbit, for instance, on the deep lateral wall. However, the endoscope can only be situated in the subperiosteal space, thus limiting its utility. In the article, the authors describe their technique for transorbital endoscopic surgery and review the uses and limitations of transorbital endoscopic surgery. © 2008 Elsevier Inc. All rights reserved.
Endoscopic surgery plays a relatively small role in ophthalmology, chiefly because of the constraints of size and space. However, endoscopes are being used for orbital, oculoplastic, lacrimal, and even intraocular procedures. Endoscopic orbital surgery is performed primarily via sinonasal approaches by ENT surgeons. Transnasal endoscopic approaches are well established for orbital decompression,1 orbital medial wall fracture repair,2 and optic canal decompression.3 The use of a transmaxillary or transnasal endoscopic approach also has been described for the repair of orbital floor fractures.2 The ophthalmologist is familiar with the endoscope, primarily in the context of endoscopic dacryocystorhinostomy4 and endoscopic brow lift.5 Nasal endoscopy also has proven to be useful in the perioperative assessment for lacrimal surgery and probing of the nasolacrimal duct.6,7 Additional applications in oculoplastic surgery include transcanalicular endoscopy8 and endoscopic assistance in facelifts9 and in harvesting fascia lata.10 Intraocular endoscopes are used to perform endoscopic cyclophotocoagulation to reduce intraocular pressure in patients with intractable glaucoma.11 The purpose of this article is to review transorbital endoscopic surgery. The use of endoscopes in orbital surgery was first described by Norris and Cleasby in 1981.12 The initial reports by Norris detailed the use of the endoscope in biopsying Address reprint requests and correspondence: Venkatesh C. Prabhakaran, MS, MRCOphth, Prabha Eye Clinic, 504, 40th Cross, Jayanagar, Bangalore-560070, India. E-mail address: [email protected]. 1043-1810/$ -see front matter © 2008 Elsevier Inc. All rights reserved. doi:10.1016/j.otot.2008.09.004
orbital tumors13 and in removing foreign bodies from the orbit. Isotonic saline was used to provide visualization while the surgeon was dissecting in the orbit. However, its use increased the pressure within the orbit, and the tissues became quickly edematous. Norris and Cleasby also found that that use of air to aid in visualization was not successful.12 Braunstein and coworkers14 have also described the experimental use of flexible endoscopes in the orbits of dogs by using hyaluronate infusion through the endoscope tip to aid visualization. However, the potential for compressive collateral damage during the creation of an optical cavity has limited the use of the endoscope within the orbital fat. Hence, because of the lack of a safely distensible space, intraorbital endoscopy15 is not widely used. In 2004, Selva and Chen16 described the subperiosteal transorbital use of the endoscope during curettage of a cholesterol granuloma of the orbital roof. Since then, there have been reports of endoscopic approach to lesions of the orbital roof and also on the use of the endoscope as a surgical teaching aid.17,18
Indications Transorbital endoscopic surgery is only used for procedures involving the orbital bones because the subperiosteal space can be used for situating the endoscope. Lesions such as cholesterol granulomas, orbital dermoids, and Langerhans cell histiocytosis involving the anterior portion of the orbital roof and situated behind the superior orbital rim can be difficult to
Prabhakaran and Selva
Transorbital Endoscopic Surgery
Figure 1 Line diagram illustrating the use of an endoscope to visualize a lesion situated behind the superior orbital rim.
visualize during surgery. Bone removal often is needed for adequate visualization in this situation. The use of a rigid videoendoscope can provide excellent visualization behind the superior orbital rim and is an excellent aid during surgical removal of these lesions (Figure 1). Similarly, endoscopes aid visualization during orbital decompression, especially of the deep lateral wall. They are also useful as a teaching aid in these and other situations, for example, in orbital floor fracture repairs. Thus, transorbital endoscopic surgery is currently indicated for lesions involving the orbital roof, for better visualization during orbital decompression, and the use of subperiosteal endoscopy as a teaching aid.
225
Figure 3 The orbital roof periosteum is reflected downwards with a malleable retractor and the superior orbital rim is visualized (arrow).
any orbital surgery with the addition of the endoscope with attached video camera. A rigid endoscope with 0-, 30-, or 70-degree tip is used depending on the situation. Two situations wherein transorbital endoscopy is useful are illustrated below:
Transorbital endoscopic surgery of orbital roof lesions
The procedure is performed in the operating room and under general anesthesia. The set-up and instrumentation is as for
After induction of general anesthesia a skin incision is placed in the upper eyelid skin crease. A suborbicularis dissection is performed to the superior orbital rim (Figure 2) and the periosteum is incised 5 mm above the arcus marginale. The periorbita is then elevated off the orbital roof and orbital contents retracted inferiorly with malleable retractors (Figure 3). As much of the lesion as possible is removed under direct visualization. A rigid video-endoscope with a 30- or 45-degree tip is then introduced posterior to the superior orbital rim (Figure 4). Endoscopic sur-
Figure 2 Intraoperative photograph demonstrating a lid-crease incision and dissection in the suborbicularis plane. The arrow points to the septum below the arcus marginale.
Figure 4 Intraoperative photograph demonstrating curettage of an orbital roof lesion under endoscopic visualization.
Technique
226
Operative Techniques in Otolaryngology, Vol 19, No 3, September 2008
vey reveals the extent of the lesion that can now be removed under visualization from areas that are not directly visible behind the orbital rim and any areas abutting the dura (Figure 1). A 70-degree tip is on occasion required for a better view of the internal aspect of the superior orbital rim and the anterior wall of the frontal sinus for those lesions that abut these areas. The periosteum is reattached and the skin incision closed.
Use of the endoscope as a teaching aid The small surgical field available when operating within the orbital confines makes it difficult for a supervising surgeon to view the trainee’s surgery. The subperiosteal space is a potential space that allows retraction of the orbital contents by placing a retractor against the orbital periosteum. The space thus created is ideally suited for placement of a video endoscope that can be used to observe surgery within the orbit.17 The supervising surgeon usually holds the endoscope while the operating surgeon may either view the surgical field directly or observe it on the video monitor. The light from the endoscope and the magnification provided also aid in the dissection. In most cases, the endoscope is rested on the orbital rim or, less frequently, on a retractor to provide the required view and also to minimize fogging. On occasion, a shorter and narrower endoscope such as a pediatric video-otoscope or a flexible endoscope may be used so as not to compromise the surgeon’s access or view. This may be particularly useful in the transcaruncular approach to the medial orbital wall, where the larger endoscope may impede the surgeon’s access through the small incision. Endoscopic supervision is most applicable to procedures such as deep lateral wall (Figure 5) or medial wall orbital decompression, orbital fracture repair and lesions involving the orbital roof. Endoscopes used may vary from 0- to 70-degree tips dependant on the location of the surgical field. In addition, the procedures may be recorded onto videotape and reviewed by both consultant and trainee. Surgical drains are not usually placed after transorbital endoscopic surgery. Postoperative
Figure 5 Endoscopic view of deep lateral orbital wall allowing excellent visualization during bone removal with a burr.
care includes monitoring of pupils and vision every 4 hours for the first day as for any orbital procedure.
Complications The complications encountered are those of the orbital procedure rather than attributable to use of the endoscope itself. In fact, use of the endoscope minimizes chances of complications such as dural tear during orbital roof lesion removal or deep lateral orbital decompression.
Discussion The primary advantage of transorbital endoscopic surgery is avoidance of bone removal for adequate exposure. Furthermore, the use of a more minimally invasive technique enables the surgeon to treat surgical patients on an outpatient basis, thus reducing length of hospitalization in comparison with the traditional postoperative management of a lateral orbitotomy or craniotomy. Additional advantages include increased illumination and magnification and an extended viewing angle, all of which enable good visualization of the surrounding bone and dura. This facilitates a safer and more meticulous removal of bone or tissue abutting the dura and perhaps also decreases the risk of a cerebrospinal fluid leak in comparison with procedures during which an endoscope is not used. Alternative approaches to the superior orbit and orbital roof include lateral orbitotomy, extended superolateral orbitotomy (removal of lateral wall with adjacent temporal or parietal bone), and transcranial orbitotomy.19 These approaches provide good exposure but are possibly associated with increased risk of morbidity because of the bone removal and greater tissue dissection. Although a supraorbital endoscopic approach to the anterior cranial base and frontal sinus (via a 1.5-cm craniotomy above the supraorbital rim) has also been described in the neurosurgical literature,20 its use may be limited in lesions which also extend into the superior orbit. Transorbital endoscopy is also specially useful while performing decompression of the deep lateral orbital wall. The removal of the deep lateral wall including the marrow space has been shown to increase the efficacy of orbital decompression in cases of thyroid orbitopathy.21 The use of the endoscope during this procedure aids in visualization and minimizes complications such as cerebrospinal fluid leaks. A clean operating field is essential to the success of transorbital endoscopic surgery, especially since the operating area is usually limited. Meticulous hemostasis aided by effective suction and judicious cautery greatly aids in visualization and prevents soiling of the endoscope. The use of different-sized malleable retractors is also essential to provide adequate viewing space. Because diffuse bleeding from the bone is commonly encountered, the use of an adrenaline-soaked tamponade (for approximately 5 minutes) or bone-wax may be required. Incorporating these guidelines will facilitate transorbital endoscopic surgery.
Prabhakaran and Selva
Transorbital Endoscopic Surgery
References 1. Kasperbauer JL, Hinkley L: Endoscopic orbital decompression for Graves’ ophthalmopathy. Am J Rhinol 19:603-606, 2005 2. Pham AM, Strong EB: Endoscopic management of facial fractures. Curr Opin Otolarngol Head Neck Surg 14:234-241, 2006 3. Kuppersmith RB, Alford E, Patrinely JR, et al: Combined transconjunctival/intranasal endoscopic approach to the optic canal in traumatic optic neuropathy. Larngoscope 107:311-315, 1997 4. Wormald PJ: Powered endoscopic dacryocystorhinostomy. Larngoscope 112:69-72, 2002 5. Romo T, Jacono AA, Sclafani AP: Endoscopic forehead lifting and contuoring. Facial Plast Surg 17:3-10, 2001 6. Minasian M, Olver JM: The value of nasal endoscopy after DCR. Orbit 18:167-176, 1999 7. MacEwen CJ, Young JD, Barras CW, et al: Value of nasal endoscopy and probing in the diagnosis and management of children with congenital epiphora. Br J Ophthalmol 85:314-318, 2001 8. Mullner K, Bodner E, Mannor GE: Endoscopy of the lacrimal system. Br J Ophthalmol 83:949-952, 1999 9. Freeman MS: Endoscopic techniques for rejuvenation of the midface. Facial Plast Surg Clin North Am 13:141-155, 2005 10. Malhotra R, Selva D, Olver J. Endoscopic-assisted fascia lata harvesting. Ophthal Plast Reconstr Surg 23:358-362, 2007 11. Lin S: Endoscopic cyclophotocoagulation. Br J Ophthalmol 86:1434-8, 2002
227 12. Norris JL, Cleasby GW: Endoscopic orbital surgery. Am J Ophthalmol 91:249-52, 1981 13. Norris JL, Stewart WB: Bimanual endoscopic orbital biopsy. An emerging technique. Ophthalmology 92:34-38, 1985 14. Braunstein RE, Kazim M, Schubert HD: Endoscopy and biopsy of the orbit. Ophthal Plast Reconstr Surg 11:269-272, 1995 15. Rose GE: Endoscopic removal of periorbital lesions—where next? Orbit 21:261-262, 2002 16. Selva D, Chen C: Endoscopic approach to orbitofrontal cholesterol granuloma. Orbit 22:49-52, 2004 17. Malhotra R, Selva D, Wormald PJ, et al: Video-endoscope assisted teaching during sub-periosteal orbital surgery. Orbit 24:113-116, 2005 18. Prabhakaran VC, Hsuan J, Selva D: Endoscopic assisted removal of orbital roof lesions via a skin crease approach. Skull Base 17:341-345, 2007 19. Patrinely JR, Stal S, Weber RS: Periorbital and craniofacial surgery, in WB Stewart (ed): Surgery of the eyelid, orbit and lacrimal system, vol 3. San Francisco, American Academy of Ophthalmology, 1995, pp 60-79 20. Kabil MS, Shahinian HK: Application of the supraorbital endoscopic approach to tumors of the anterior cranial base. J Craniofacial Surg 16:1070-1074, 2005 21. Goldberg RA, Kim AJ, Kerivan KM: The lacrimal keyhole, orbital door jamb, and basin of the inferior orbital fissure. Three areas of deep bone in the lateral orbit. Arch Ophthalmol 116:1618-1624, 1998