Surgical anatomy of the orbit of Korean adults

Position of the anterior ethmoidal foramen and trauma to the cranial base during transconjunctival medial orbital decompression: a systematic literature review

PURPOSE

To review the literature on the location of the anterior ethmoidal foramen (AEF) and trauma during transconjunctival medial wall decompression.

METHODS

A comprehensive literature search was conducted using the PubMed, Embase, and Scopus databases, combining the terms "olfactory fossa" and "fovea ethmoidalis" with "trauma," "cerebrospinal fluid leak," "pneumocephalus," "orbital decompression," and "anterior ethmoidal artery" (AEA). All cases of cranial base trauma during medial orbital decompression and the anatomical studies on the location of the AEF and the course of the AEA were reviewed.

RESULTS

Ninety-four articles were identified, of which 37 were related to the AEF, 41 reported the course of the AEA, and 16 to reported cases of cranial base trauma. Out of these cases, 10 were related to transconjunctival medial orbital decompression, affecting 11 patients. Most AEFs are situated at the frontoethmoidal suture, but up to 38.15% of AEFs are located above the suture on the frontal bone. Most AEFs are adjacent to the roof of the ethmoidal sinus. The distance of the AEF to the cranial base increases in the presence of supraorbital ethmoidal cells (SOEC).

CONCLUSIONS

The position of the AEF is variable and should not be considered a safe landmark for all patients.

Morphometry of the Bony Orbit and Periorbital Structures: Personal Perspectives From Decades of Related Research

The author introduces his personal perspectives on the bony orbit, nerves, arteries, and ligaments relating to orbital re- construction surgery. A supraorbital fissure was 40.0 ± 2.5 mm from the supraorbital notch. Posterior ethmoidal foramen was 31.7 ± 3.0 mm from the anterior lacrimal crest. The infraorbital fissure, where the infraorbital groove started, was 26.4 ± 2.6 mm from the infraorbital foramen. The supraorbital fissure was 34.3 ± 2.7 mm from the frontozygomatic suture. The medial palpebral ligament consisted of 2 layers. The superficial layer of the palpebral ligament (SMPL) was from the anterior lacrimal crest to the upper and lower tarsal plates. The deep layer of the palpebral ligament (DMPL) lay from the anterior lacrimal crest to the posterior lacrimal crest, covering the lacrimal sac. Horner muscle was at the posterior lacrimal crest just lateral to the attachment of the DLPL and ran laterally to the tarsal plate deep to the SLPL. Three components of the lateral canthal area are: (1) lateral palpebral raphe, (2) superficial lateral palpebral ligament (SLPL), and (3) deep lateral palpebral ligament (DLPL). The lateral ends of superior and inferior orbicularis oculi muscles interlaced at the lateral commissure and formed the lateral palpebral raphe. The superficial lateral palpebral ligament extended from the lateral ends of the tarsal plate to the periosteum of the lateral orbital rim. The lateral palpebral ligament extended from the lateral ends of the tarsal plate deep to the origin of SLPL to the Whitnall tu- bercle on the zygomatic bone. The palpebral branch of the in- fraorbital artery emerged from the infraorbital foramen and ran superior and lateral to the orbital septum. After passing through the orbital septum, distributed to the orbital fat.

Anatomical Variations of Anterior Ethmoidal Foramen and Cribriform Plate: Relations With Sex

ABSTRACT

Position of anterior ethmoidal artery and height of lateral lamella of cribriform plate (LLCP) represent critical variants in endoscopy.In 200 maxillofacial computed tomography scans of patients the position of anterior ethmoidal foramen (AEF) in relation to ethmoid roof was recorded. The height of LLCP was measured and classified according to Keros classification.Differences in AEF position and distribution of Keros types, and LLCP height according to sex were assessed through chi-square test (P < 0.05) and 1-way analysis of covariance (ANCOVA) test, respectively (P < 0.05). Differences in LLCP height according to different AEF position were assessed through Mann-Whitney test (P < 0.05).No differences were observed in prevalence of AEF exposure according to sex (P > 0.05); LLCP height was higher in males than in females, with a higher frequency of Keros type 3 (P < 0.05). Moreover, subjects with AEF exposure had a significantly higher LLCP height (P < 0.01).Results highlighted innovative data useful for improving the knowledge of these sensitive variants.

A cadaveric study investigating the anatomy of the medial orbital wall

The purpose of this study is to investigate the applicability of the current surgical guideline, known as ‘24-12-6’ surgical guideline, in the Hispanic and European populations. This guideline is used during numerous orbital surgeries and states that the distance between the anterior lacrimal crest (ALC) to the anterior ethmoidal foramen (AEF) (24 mm), the AEF to the posterior ethmoidal foramen (PEF) (12 mm), and the PEF to the optic canal (OC) (6 mm) follows a Rule of Halves. Previous studies suggest this surgical guideline is not applicable for all ethnicities; however, to our knowledge, no data has been published regarding the accuracy of this guideline pertaining to the Hispanic population. An experimental study was performed on 79 orbits (52 cadavers) donated to the Human Anatomy Program at UT Health San Antonio. The ALC, AEF, posterior ethmoidal foramen, and OC were identified; the orbit was enucleated and all remaining soft tissue removed. The distance between each landmark was recorded using a digital caliper. For all cadavers studied, the distances between the ALC, AEF, posterior ethmoidal foramen, and OC were 24.76 mm, 13.89 mm, and 7.61 mm, respectively. Thus, the ‘24-12-6’ surgical guideline was not applicable to the sample studied. Based on ethnicity data, these relationships were also not true for the European or the Hispanic populations. Therefore, significant anatomical variations exist in the current surgical guideline. Clinicians may need to adjust their methodology during surgical procedures in order to optimize patient care.

Morphometric and Volumetric Measurements of Orbit With Cone-Beam Computed Tomography

PURPOSE

The purpose of this study was to determine cone-beam computed tomography (CBCT) as a tool for measuring morphometric and volumetric measurements of the orbit. Also, to assess gender and age variations and compare traditional methods of measurements in dry-skull, cadaveric, and other imaging modalities.

PATIENTS AND METHODS

Morphometric and volumetric values of 98 orbits (49 subjects, 21 men/28 women) were measured using CBCT. Their mean and standard deviation were measured and analyzed. The gender and age variability older and younger than 40 years were evaluated. They were compared with other dry-skull and imaging studies done among different populations.

RESULTS

CBCT could accurately measure the various morphometric and volumetric parameters of the orbit. From the reference point infraorbital foramen (I) to lacrimal fossa (F1), inferior orbital fissure (F2), inferior orbital rim (F3), and the optic canal (F4) were (in mm) (mean ± SD) 22.88 ± 1.08, 32.53 ± 0.88, 7.44 ± 0.71, and 51.45 ± 1.28, respectively. From the reference point, superior orbital notch/foramen (S) to superior orbital fissure (S1), lacrimal fossa (S2), and the optic canal (S3) were 49.29 ± 2.1, 26.39 ± 1.58, and 46.82 ± 0.88, respectively. From the reference point frontozygomatic suture (L) to lacrimal fossa (L1), superior orbital fissure (L2), the optic canal (L3), and inferior orbital fissure (L4) were 18.19 ± 0.88, 39.91 ± 1.44, 47.63 ± 1.11, and 35.19 ± 1.02, respectively. Orbital volume was found to show a significant difference between older and younger than 40 years of age, though not significant compared between men and women.

CONCLUSION

CBCT is a viable tool for morphometric and volumetric measurements of the orbit and other orocraniofacial structures. It can also assess age and gender variability. The low cost, high accuracy, low radiation, and ease of use can help in reproducibility among the different living populations.

A morphometric analysis of the immature human infraorbital canal

PURPOSE

The importance of the infraorbital canal in the growth of the maxilla and associated mid-facial region has significance for innervation of this region as well as the associated dentition, yet little is known about the development of the canal. An analysis of its dimensions and morphology during the late prenatal and early postnatal periods was thus undertaken. The aim of this study was to describe changes in the morphology, size and branching pattern of the infraorbital canal during the late prenatal and early postnatal stages of human growth.

METHODS

Fifty human fetal and neonatal maxillae were analyzed. The sample included 27 late prenatal individuals (30 gestational weeks and birth) and 23 early postnatal individuals (birth and 1 year). Maxillae were scanned using a Nikon XTH 225 L micro-CT unit and analyzed using VG studiomax v3.2. Measurements included the maximum width, height and surface area of each foramen associated with the infraorbital canal and the total length of the canal, bilaterally.

RESULTS

All the measurements of the canal were greater in the early postnatal group than in the late prenatal group, while the walls and branching pattern of the canal were better developed in the postnatal group. Bone development occurred within the walls as development proceeded. Variations in the branching pattern of the canal were found.

CONCLUSION

The morphology of the infraorbital canal reflected the developmental stage of associated structures such as the dentition, maxillary sinus and orbit.

Orbital Morphometry: A Computed Tomography Analysis

INTRODUCTION

The human orbit is a complex anatomic region, which plays predominant role in the evaluation of craniofacial complex. A thorough understanding of the relationship of the distance from orbital rim to the important vital structures of the orbital apex is required for the surgeon to perform safe and effective surgery.

OBJECTIVES

To evaluate and compare the depth and distances from various points of the orbital rim to the fissures and foramina of the orbital apex between genders in the local population.

METHODOLOGY

Linear measurements were conducted on 60 orbits from 30 patients who had undergone head computed tomography scan. These measurements were done utilizing the multiplanar reconstruction modes on computed tomography images with minimum slice thickness of 1 mm.

RESULTS

Males have statistically significant larger orbits than females with higher mean measurements in all parameters, except for the distance from posterior ethmoidal foramen to the optic canal which was the same. However, there were no significant differences in all parameters between the right and left orbits.

CONCLUSION

This study provides the absolute limit of safe internal orbital dissection in respect to the local population. Despite males having larger orbits than females, it is clinically negligible.

Anatomical Studies of the Orbital Cavity Using Three-Dimensional Computed Tomography

OBJECTIVE

This study was designed to analyze the morphometric characteristics of the orbital cavity using three-dimensional computed tomography in Asians.

METHODS

Two hundred seventy-six orbits in 142 Asians (74 men and 68 women) were examined and compared according to age, sex, and laterality (right and left).

RESULTS

Mean orbital morphometric values were as follows. Orbital cavity depth was 49.60 mm from optic foramen to orbitale (inferior) and 41.32 mm from optic foramen to lacrimal crest (medial). Anterior and posterior orbital medial wall heights were 17.73 and 12.76 mm, respectively. Medial, middle, and lateral orbital floor lengths were 39.08, 29.56, and 20.08 mm, respectively. Anterior and posterior orbital floor width was 21.87 and 12.00 mm, respectively. For the orbital inferior-medial angle, anterior, middle, and posterior value was 132.11°, 126.24°, and 136.88°, respectively. Inferior orbital cavity depth, anterior orbital medial wall height, and orbital floor length tended to increase with aging, whereas orbital floor width tended to decrease with aging. No significant differences were found in terms of laterality, and values were greater in men than in women.

CONCLUSIONS

This quantitative analysis of orbital measurements will allow surgeons to plan operations more accurately and will help predict outcomes.

Positional Relationship of Ethmoidal Foramens With Reference to the Nasion and Its Significance in Orbital Surgery

PURPOSE

The aim of the study was to elucidate the positional relationship of the ethmoidal foramens (EFs) with reference to the nasion to facilitate prediction of the exact location of EFs, the optic canal (OC), and the frontoethmoidal suture (FS), and thereby avoid complications during complex surgery involving the medial wall of the orbit.

MATERIALS AND METHODS

One hundred two intact orbits of 57 embalmed cadavers were dissected in this observational anatomic study. Nasion' (N') was defined as the intersection point of the medial orbit margin with the horizontal line through the nasion, and this was used as a reference point. N'-OC was defined as the straight line joining N' and OC. The locations of the anterior ethmoidal foramen (AEF), posterior ethmoidal foramen (PEF), and OC were determined with reference to N'. The vertical distances from N'-OC to EFs and to FS were also determined.

RESULTS

The N'-AEF, AEF-PEF, and PEF-OC distances were 18.4, 15.3, and 8.3 mm, respectively. Vertically, AEF and PEF were situated at 0.2 mm below and 0.4 mm above N'-OC, respectively. At the same reference points, N'-OC was situated at 0.4 and 0.6 mm above FS, respectively.

CONCLUSIONS

N', AEF, PEF, and OC were considered to be situated on the same straight line, and N'-OC could be regarded as coinciding with FS. This means that N' is an easily identifiable and reliable landmark for identifying EFs, OC, and FS. Our navigational parameters with reference to N' will help surgeons to enhance the safety of orbital surgery.

Considerations for the Management of Medial Orbital Wall Blowout Fracture

Recently, diagnoses of and operations for medial orbital blowout fracture have increased because of the development of imaging technology. In this article, the authors review the literature, and overview the accumulated knowledge about the orbital anatomy, fracture mechanisms, surgical approaches, reconstruction materials, and surgical methods. In terms of surgical approaches, transcaruncular, transcutaneous, and transnasal endoscopic approaches are discussed. Reconstruction methods including onlay covering, inlay implantation, and repositioning methods are also discussed. Consideration and understanding of these should lead to more optimal outcomes.

Clinical and surgical implications regarding morphometric variations of the medial wall of the orbit in relation to age and gender

The ethmoidal foramens are located on the medial wall of the orbit and are key reference points for intraoperative orientation. Detailed knowledge of the anatomy, bony landmarks and morphometric characteristics of the medial wall of the orbit is essential for various surgical procedures. The aim of this study was to determine the morphometric variations in the medial wall of the orbit and establish significant variations regarding age and gender. A total of 110 orbits were analyzed and subdivided by age (over or under 40 years) and gender. The distances of the medial wall of the orbit between the anterior lacrimal crest, the ethmoidal foramen, the optic canal and the interforamina were determined. Safe surgical areas were sought. Statistical tests were used to determine the differences between groups. In men, there is a safe surgical area proximal to the anterior and posterior ethmoidal foramen. In women, this area is in the posterior third of the medial wall of the orbit between the posterior ethmoidal foramen and the optic canal. Regarding variation according to age, the results of this study suggested that the anteroposterior diameter of the medial wall increases with age. This study showed that the anteroposterior total length of the medial orbit wall is similar between genders of similar age, increases with age, and has significant variations in the distances between the various structures that make up the medial orbit wall with regard to gender and age.

Complete reduction with traction of the infraorbital neurovascular bundle in a delayed patient with white-eyed blow-out fracture

In case of delayed surgery, if an orbital floor fracture involves the infraorbital canal, adhesions may form between the infraorbital neurovascular bundle and herniated muscle, and manipulations to reduce the fracture may lead to unexpected bleeding due to injury of the infraorbital artery. The author reports a case of a white-eyed blow-out fracture patient, who visited our clinic one-and-a-half months after the injury. Exploration of the fracture confirmed intensive fibrosis of the infraorbital neurovascular bundle and the entrapped inferior rectus muscle at the fracture site. The author was able to reduce the muscle completely with the release of the fibrotic tissue around the nerve bundle by using a vessel loop to safely retract the neurovascular bundle upwards, and obtained good results.

Anatomy of anterior ethmoidal foramen, medial canthal tendon, and lacrimal fossa for transcutaneous anterior ethmoidal nerve block in Japanese individuals

PURPOSE

To examine the anatomical relationships of the anterior ethmoidal foramen (AEF), medial canthal tendon (MCT), and lacrimal fossa (LF) in Japanese individuals.

METHODS

Thirty-eight orbits from 19 Japanese cadavers (7 men and 12 women; average age at death, 89.3 years) were used in this experimental anatomical study. The AEF, MCT, and superior border of the LF were exposed. The following distances were then measured: 1) from the point at the medial orbital rim directly anterior to the AEF to the superior border of the MCT (AEF-MCT), and 2) from the superior border of the LF to the superior border of the MCT (LF-MCT).

RESULTS

(AEF-MCT) and (LF-MCT) distances were 9.40±1.92 (mean±standard deviation) and 4.21±1.18 mm, respectively. No values of (LF-MCT) exceeded the mean (AEF-MCT) (9.40 mm).

CONCLUSIONS

The transcutaneous anterior ethmoidal nerve block can be reliably performed without injury to the lacrimal sac by inserting a needle approximately 9 mm superior to the superior border of the MCT.

Medial orbital wall landmarks in three different North American populations

PURPOSE

We sought to measure the medial orbital wall foramina distances in two previously unstudied populations, to describe a new bony medial wall feature, and to validate the accuracy of a new coordinate measurement device within the orbit.

METHODS

Dried, well-preserved, complete human skulls without orbital defects were studied. Age, gender, birthplace, ethnicity, and laterality of the orbit were recorded for each skull. Supranumerary ethmoidal foramina were recorded, and the fronto-ethmoidal groove depth was measured. The distances between the anterior lacrimal crest (ALC) - anterior ethmoidal foramen (AEF), AEF - posterior ethmoidal foramen (PEF), and PEF - optic canal (OC) were measured first by surgical ruler and wire and then by the Microscribe coordinate measurement device.

RESULTS

One hundred and forty-six orbits were studied. Fifty-seven orbits were of European or Caucasian descent, 68 orbits of African American descent, 2 orbits of West African descent, 11 orbits of Eskimo descent, and 8 orbits of unknown origin. No significant differences existed between the manual and Microscribe measurements for the ALC-AEF, AEF-PEF, and PEF-OF distances (p < 0.0001). A significant frontoethmoidal groove was observed in 27/146 (19%) orbits, in 6/57 (11%) Caucasian orbits, in 17/70 (24%) African American orbits, and in 4/11 (36%) Eskimo orbits. Supranumerary ethmoidal foramina were found in 50/146 orbits (34.2%) and in 17/27 (63%) orbits with a significant frontoethmoidal grooves.

CONCLUSIONS

No significant differences in medial wall foramina distances exist between African American and Caucasian orbits; however, a frontoethmoidal groove occurs more commonly in African American orbits. This groove often occurs in the presence of supernumerary ethmoidal foramina. The Microscribe coordinate measurement system represents a valid tool to measure distances within the orbit.

Morphometric study of the medial orbital wall emphasizing the ethmoidal foramina

PURPOSE

Ethmoidal foramina on the medial orbital wall show a higher incidence of variation. Surgeons performing endonasal, anterior cranial fossa and medial orbital wall surgeries must be aware of these variations as they are a source of hemorrhage and also serve as landmark in proximity to the orbital apex.

AIM

The present study aims to describe the morphometric distances of various ethmoidal foramina between anterior lacrimal crest to optic canal in south Indian dry human skulls.

MATERIALS AND METHOD

The study was done on 44 adult dry human skulls. The occurrence of Ethmoidal foramina was noted by direct inspection. The distance of Ethmoidal foramina from anterior lacrimal crest to optic canal was measured with the help of ruler, probe and magnifying glass.

RESULTS

The Posterior ethmoidal foramina were found in all 44 skulls bilaterally. Middle ethmoidal foramen was present in 12 and 13 skulls on right and left, respectively. Anterior ethmoidal foramen was found in 38 and 37 skulls on right and left, respectively. The distance between anterior lacrimal crest (ALC) and posterior lacrimal crest (PLC) was in the range of 3-8 mm and that of ALC to anterior ethmoidal foramen was in the range of 24-30 mm. The range of distance between anterior ethmoidal foramen to posterior ethmoidal foramen was 9-17 mm and that between posterior ethmoidal foramen to optic canal was 5-13 mm.

CONCLUSION

These observations would help to predict the anatomical variations in the position of ethmoidal foramina with respect to anterior and posterior lacrimal crest and ensure the safe and precise performance of medial orbital wall surgeries to avoid injuries to the important neurovascular bundles passing through various foramina and fissures.

Morphometric analysis and anatomical variations of infraorbital foramen: a study in adult North Indian population

PURPOSE

Various studies have been conducted on morphometric variations of infraorbital foramen to provide data to surgeons for nerve block in infraorbital region. This study aims to analyse the anatomical variations by comparing various morphometric measurements of infraorbital foramen in dry skulls of adult North Indian population. This study becomes relevant in the present study group as very scant data is available about the variations and morphometric measurements in Indian population. The data thus collected can be standardized and become useful for the surgeons working in this area of face.

MATERIALS AND METHODS

The study was conducted on 75 dry adult human skulls, which were a part of Department of Anatomy, used for teaching purposes in medical colleges. Straight distance of the Infraorbital foramen from the infraorbital rim, supraorbital foramen and sagittal plane was measured. The position of the infraorbital foramen was determined in relation to maxillary teeth and supraorbital foramen. The data thus obtained was analysed.

RESULTS

The distance of infraorbital foramen from infraorbital rim, supraorbital foramen, sagittal plane in the present study was found to be 6.71 ± 1.11 mm, 42.02 ± 4.31 mm and 31.94 ± 4.88 mm respectively. The position of infraorbital foramen was lateral in relation to supraorbital foramen (in 88% of cases). Infraorbital foramen was above the 1st premolar tooth in most of the cases. Accessory infraorbital foramen was found in 11.2% cases (double foramen).

CONCLUSION

The data thus obtained will perhaps be helpful to the surgeons in identifying the extent of the operative field thereby reducing procedural risks.

Anatomy of deep lateral and medial orbital walls: implications in orbital decompression surgery

BACKGROUND

Isolated deep lateral and combined medial orbital wall decompressions (balanced decompression) are well accepted for treatment of disfiguring proptosis and compressive optic neuropathy in patients with Graves' orbitopathy. However, cerebrospinal fluid leakage and/or optic nerve injury occasionally occur during these operations.

PURPOSE

To describe the anatomy of the deep lateral and medial orbital walls and its surgical implications in orbital decompression.

METHODS

We reviewed literature on the anatomy of the deep lateral and medical orbital walls. In addition, we performed cadaver dissection and computed tomographics studies to illustrate the anatomy.

RESULTS

We provided an anatomical overview and elucidated the detailed surgical anatomy of the posterior and superior borders of the deep lateral orbital wall, the posterior and accessory ethmoidal foramina, and the frontoethmoidal suture.

CONCLUSIONS

The anatomy of the deep lateral and medical orbital walls presented here will warrant safe and confident performance of orbital decompression surgery.

Location of the supraorbital and infraorbital foramen with references to the soft tissue landmarks in a Chinese population

The purpose of the current study was to determine the supraorbital foramen (SOF) and infraorbital foramen (IOF) based on soft tissue landmarks, to facilitate prediction of the location of this structure during facial surgery. Forty-two hemispheres of 21 adult cadavers (16 men and 5 women; aged 30-75 years) were dissected to expose the SOF and IOF. The locations of the SOF and IOF were evaluated with direct and photographic measurements. The data gained were analyzed by statistical method. The SOF localized 23.11 ± 2.35 mm superior and 9.48 ± 3.06 mm lateral to the angulus oculi medialis (AOM). The vertical angle from AOM to SOF was 68.3 (SD, 6.44) degrees. The SOF localized 24.81 (SD, 3.39) mm inferior and 10.89 (SD, 2.78) mm lateral to the AOM on the front view. The vertical angle from AOM to IOF was 66.5 (SD, 5.18) degrees. The SOF localized 11.22 (SD, 2.01) mm inferior and 6.09 (SD, 2.32) mm lateral to the ala of the nose (AL) on the front view. The vertical angle from AL to IOF was 61.7 (SD, 7.61) degrees. These results were a little different from the results of some other populations. We found the IOFs located on the point of one-fifth proportion distant to the ALs along the vertical direction distance from AL to SOF, whereas the AOMs located on the point of three-fifths proportion distant from the AL. Our results may provide more detailed information to predict the location of the SOFs and IOFs and help to prevent nerve or vessel damage.

Morphometric and geometric anatomy of the caucasian orbital floor

INTRODUCTION

To describe the morphometric and geometric relationships of the orbital floor in a Caucasian population.

MATERIALS AND METHODS

Exenterations of 47 orbits from 24 formalin fixed cadavers were performed. Morphometric measurements were taken between anatomical landmarks located along the orbital floor and the orbital apex. The mean measurements were used to calculate geometric data. These results were analysed according to sex and side and compared to results from other ethnic populations.

RESULTS

The average distances from the infraorbital foramen to the nasolacrimal fossa, inferior orbital fissure, optic canal and inferior orbital rim were 20.67 mm (± 2.42), 25.40 mm (±2.70), 43.23 mm (±3.35) and 8.95 mm (± 1.53), respectively. The average distances from the tip of the infraorbital groove to the tip of the inferior orbital fissure, lateral aspect of the inferomedial strut, optic canal and the intersection with the inferior orbital fissure were 14.08 mm (±2.41), 12.12 mm (±2.42), 35.02 mm (±3.17) and 20.05 mm (± 2.87), respectively. The distances from the tip of the inferior orbital fissure to the optic canal and the intersection with the inferior orbital groove were 29.56 mm (±2.73) and 13.37 mm (±2.76), respectively.

DISCUSSION

Orbital surgeons should be aware of the morphometric relationships of the orbital floor due to the degree of variation that exists between different ethnic groups. Geometric data may be used to provide orbital surgeons with a navigational template that can be used to plan surgery and as a guide intraoperatively.

Inlay implanting technique for the correction of medial orbital wall fracture

BACKGROUND

For blowout fractures of the medial orbital wall, the goals of treatment are complete reduction of the herniated soft tissue and anatomical restoration of the orbital wall without surgical complications. Surgeons frequently worry about damage to the optic nerve caused by dissection when the part over the posterior ethmoidal foramen is fractured. The authors performed small incision and inlay implantation of porous polyethylene for reconstruction of medial orbital wall fractures.

METHODS

Between January of 2007 and December of 2009, 55 patients were included in an analysis of the outcome of corrected medial orbital wall fractures. For 55 patients with posterior comminuted fractures of the medial orbital wall, insertion of porous polyethylene into the ethmoid sinus was performed in multiple layers, through the transconjunctival approach.

RESULTS

In all cases, the orbital cavity was restored to its normal anatomical shape. The associated ocular problems disappeared except for mild enophthalmos in three patients and diplopia in one patient. There were no serious surgical complications associated with inlay implantation.

CONCLUSIONS

The advantages of the inlay technique include the anatomical reconstruction of the orbital wall, the avoidance of optic nerve injury, the simplicity of the procedure, and consequently the absence of surgery-related complications. This technique is presented as one of the preferred treatments for posterior comminuted fractures of the medial orbital wall.

Analysis of the orbital floor morphology

INTRODUCTION

For the repair of large orbital floor defects due to blow-out fractures or those involved by tumours, it is necessary to understand the detailed morphology. The purpose of the present study was to elucidate how age and gender affect its three-dimensional morphology.

METHODS

The 3-D computer tomography data of 305 orbits of 182 patients were included in the study. Using the CT data, the orbital floor angle (the angle between the orbital floor and the horizontal plane) and the location of the most inferior point of the orbital floor were measured. Patients were classified into subgroups according to their gender and age. Data were compared among the subgroups.

RESULTS

The orbital floor angle was greater in males than in females, and in children than in adults. The location of the lowest point of the orbital floor moves postero-inferiorly with increasing age.

CONCLUSION

The present study demonstrated that gender and age affects morphology of the orbital floor. These findings should be useful for reconstruction of the orbital floor.

Persistent diplopia after retrobulbar anesthesia

PURPOSE

To determine the causative factors of persistent diplopia after retrobulbar anesthesia.

SETTING

Strabismus Section, Department of Ophthalmology, Seoul National University, Seoul, South Korea.

METHODS

Prism and alternate cover tests in the diagnostic positions of gaze and ductions/versions were performed in 28 patients with persistent diplopia 6 months after retrobulbar anesthesia. The Lancaster test, Bielshowsky head tilt test, double Maddox rod test, fundoscopic examination for torsion, forced duction test, force generation test, tensilon test, thyroid function test, and/or orbit computed tomography were performed when necessary.

RESULTS

Most of the patients (26 patients, 93%) did not have diplopia before retrobulbar anesthesia. Of the 14 patients with extraocular muscles imbalance, 12 patients showed vertical rectus overaction (11 superior recti, 1 inferior rectus) and 2 patients, mild vertical rectus underaction. Nine patients were presumed to have a sensory strabismus related to the preoperative poor vision, but this went unnoticed preoperatively. Three patients showed a small vertical deviation without any specific causative factors.

CONCLUSIONS

Fifty percent of the cases of diplopia were associated with either direct trauma or anesthetic myotoxicity to the extraocular muscles, in which overactions were more common than underactions. Thirty-two percent of the patients were presumed to have sensory strabismus, which suggested the importance of preoperative examination for strabismus as well as providing an explanation about the risk of postoperative diplopia before surgery.

Anatomical variations of the frontal and supraorbital transcranial passages

In this study, 500 frontal and supraorbital transcranial passages were studied in 50 cadavers and 200 crania of 500 samples. One hundred six specimens had a frontal foramen (notch), and all the samples had a supraorbital foramen (notch). The frontal passage was a foramen in 7 samples and a notch in 99 samples. As for the supraorbital passage, it was found as a foramen in 133 of specimens and as a notch in 358 of specimens. In 9 of the specimens, there were double notches or foramina. The distances from the foramina (notches) to angulus oculi medialis were measured in the cadavers. The average distance from the angulus oculi medialis to the frontal foramen (notch) was 4.50 mm, and the average distance to the supraorbital foramen (notch) was 9.87 mm. The distances from the foramina (notches) to the midline were measured in the crania. The average distances from the midline to the frontal foramen (notch) and the supraorbital foramen (notch) were 20.24 mm and 25.23 mm, respectively. The average distance between the frontal foramen (notch) and supraorbital foramen (notch) was 5.37 mm in cadavers and 4.99 mm in crania. In 200 crania, the distances of the frontal and supraorbital transcranial passages to the midline were measured. Types of these passages were also evaluated, and frequencies were calculated. Measurements were made using a digital compass, and the student t test was used in the statistical evaluation of results.

The inferomedial orbital strut: an anatomic and radiographic study

PURPOSE

To study the anatomic and radiographic features of the inferomedial orbital strut (IOS), with particular emphasis on the region of the posterior IOS.

METHODS

Cadaver dissection study of the IOS was performed on 20 orbits of 10 fresh-frozen cadaver specimens. Radiographic volumetric analysis was performed on CT scans of 20 orbits to measure the volume available for decompression in the region of the posterior IOS.

RESULTS

The anterior IOS provided bony support to the orbit and served as a site of attachment for globe-supporting suspensory ligaments. The midportion of the IOS demonstrated a contiguous anatomic relation to the maxillary sinus ostium. The posterior IOS consisted of two components: the intraorbital process of the palatine bone and ethmoidal air cells that extended inferior and posterior to the IOS. Radiographic volumetric analysis demonstrated that there was an average of 2.1 mL of volume available for decompression in the region of the posterior IOS (range, 1.2 to 3.3 mL).

CONCLUSIONS

The findings of this anatomic and radiographic study of the inferomedial orbital strut support the concept of a posterior inferomedial orbital decompression. The region of the posterior IOS appears to offer significant volume for axial globe mobilization while minimizing the risk of globe dystopia and/or impairment of the maxillary sinus drainage.

Anatomic characteristics of the infraorbital foramen: a cadaver study

PURPOSE

The aim of this study was to document the variability in the position of the infraorbital foramen with relation to the facial midline, infraorbital rim, supraorbital notch, and maxillary teeth.

MATERIALS AND METHODS

Forty-seven cadavers (94 sides) were dissected, exposing the infraorbital foramen, supraorbital foramen, and orbital floor bilaterally. Measurements made included (A) distance between the infraorbital foramen and inferior orbital rim; (B) distance of the infraorbital foramen from the facial midline; (C) distance of the supraorbital foramen from the facial midline; (D) distance between the infraorbital foramen and supraorbital foramen. Means, standard deviations, and ranges were determined, and statistical differences were calculated between the left and right orbits and sexes by use of an unpaired sample t-test (P < .05).

RESULTS

In men, the mean distance between the infraorbital foramen and the inferior orbital rim was 8.5 +/- 2.2 mm. In women, this was 7.8 +/- 1.6 mm. The distance between the infraorbital foramen from the facial midline was 27.7 +/- 4.3 mm in males and 26.2 +/- 3.2 mm in females. The mean distance between the infraorbital foramen and supraorbital notch in males was 43.3 +/- 3.1 mm and in females was 42.2 +/- 2.4 mm. The average distance of the supraorbital notch from the midline was 26.5 +/- 3.5 mm in males and 26.3 +/- 3.3 mm in females. There were no statistically significant differences between the left and right sides or between sexes. The maxillary tooth most commonly found in the same vertical plane as the infraorbital foramen was the first premolar. Multiple ipsilateral foramina were found in 15% of cadavers.

CONCLUSION

These anatomic characteristics may have important implications for surgical and local anesthetic planning.