3D assessment of morbidity associated with lower eyelid incisions in orbital trauma

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1 Int. J. Oral Maxillofac. Surg. 2007; 36: doi: /j.ijom , available online at Leading Clinical Paper Trauma 3D assessment of morbidity associated with lower eyelid incisions in orbital trauma Y. H. Nunu, A. Bell, S. McHugh, K. F. Moos, A. F. Ayoub Department of Oral and Maxillofacial Surgery, Glasgow Dental Hospital & School, 378 Sauchiehall Street, Glasgow G2 3JZ, UK Y. H. Nunu, A. Bell, S. McHugh, K. F. Moos, A. F. Ayoub: 3D assessment of morbidity associated with lower eyelid incisions in orbital trauma. Int. J. Oral Maxillofac. Surg. 2007; 36: # 2007 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. This study compared the morbidity associated with transconjunctival and transcutaneous approaches for orbital floor exploration with respect to the position of the lower eyelid following surgery. Two groups of 32 volunteers and 32 patients (12 transconjunctival and 20 transcutaneous) were recruited and three-dimensional (3D) imaging was carried out at 6 months following surgery. In the transcutaneous group, there were significant variations in the shape of the lower eyelid, with more medial displacement of the exocanthion. No significant differences were detected in the transconjunctival group compared to controls. The use of a 3D imaging system provided an objective method of assessing this aspect of morbidity associated with the use of lower eyelid incisions. Key words: eyelid incisions; orbital trauma; 3D imaging. Accepted for publication 10 May 2007 Available online 3 July 2007 Open reduction and internal fixation is normally the best treatment modality for displaced fractures of the zygomatic complex and for other fractures involving the orbital cavity. Surgical access to the inferior orbital rim or floor may be achieved through the lower eyelid, either through the skin (transcutaneous) or through the conjunctiva of the eye (transconjunctival). Since the design of and access provided by these two incisions are different, one would not expect the range of complications to be the same. The complications that may be seen include ectropion, entropion and excess scleral show; these have been previously investigated and described by others 2,5,6,17,19. There is little agreement in the literature on any association between the specific complications and the type of incision used. In fact, the results of various studies have been contradictory; one reason for this could be that most investigators have used subjective methods for the assessment of the outcome of different surgical incisions in relation to the position and shape of the lower eyelid 2,5,6,17,19. ROHRICH et al. 22 reviewed the literature with respect to transcutaneous incisions and concluded that no one incision was superior to the others. The mid-lower eyelid (subtarsal) incision was associated with a long-term lower incidence of eyelid malposition compared to the subciliary incision, but at the expense of the development of greater initial postoperative oedema and a more visible scar. With regard to the possible complications of the different types of lower eyelid incision, ectropion and entropion are the major concern. Ectropion is the eversion or turning forward of the eyelid margin 18, and it is thought to occur as a result of vertical shortening of the lower eyelid as the incision line heals. This complication is more frequently associated with the subciliary type of incision 2. HWANG et al. 12 postulated that scar contracture of the orbital septum or tarsal plate and the denervation of the pre-tarsal part of the orbicularis occuli muscle could contribute to complications such as ectropion or increased scleral show. Entropion is the excessive turning in of the eyelid margin 18. In addition to disruption of the orbital septum predisposing it to scarring and vertical shortening, iatrogenic damage to the tarsal plate through the incision or / $30.00/0 # 2007 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

2 3-Dimensional assessment of lower eyelid incisions 681 the use of cutting diathermy can cause scarring and shortening resulting in entropion of the lower eyelid 17, especially with a transconjunctival incision. Other complications of the various lower eyelid incisions include increased scleral show, tearing or laceration of the eyelid, conjunctival granuloma or inclusion cyst, lacrimal sac laceration, and postoperative haemorrhage 17,24, all of which are mainly associated with the transconjunctival approach. When the latter is carried out with a lateral canthotomy incision 2, lateral canthal malposition may occur as a complication. Any change postoperatively in the position of the eyelids should be noted and recorded. Ideally there should be an objective method for measuring changes following orbital surgery. This should provide a mechanism for the detection of subtle changes in the lower eyelids after the various lower eyelid incisions. In the past, the use of photographs for facial assessment entailed the application of two-dimensional methods for recording the three-dimensional (3D) morphology of the face, and hence there were drawbacks. Photogrammetry was a process by which measurements could be obtained from standardised photographs 15. Various methods have been developed for recording the face in 3D including electromagnetic 3D digitisers 9, laser scanning 16, Moiré topography 14 and stereophotogrammetry 21 which has been further developed with the advances in computer technology 4.FERRARIO et al. 8 used an electromagnetic digitiser to study the morphometry of the orbital region in non-trauma cases by extracting age- and sex-related linear and angular measurements. The comparison between the right and left orbital dimensions revealed symmetry within each age and sex group. Mean values of paired linear distances differed by less than 1 mm except for the eye fissure length in young adult males, which showed a difference of slightly more than 1 mm between the right and left sides. The system used in the present study was based on the recent advances of stereophotogrammetry and consisted of two camera stations, each of which had a stereo-pair of digital cameras and special textured illumination. The system (Di3D) has been validated previously for its accuracy in recording facial morphology 3. The aim of this study was to compare the positional morbidity of the lower eyelid associated with the transconjunctival and transcutaneous approaches for orbital floor exploration using the Di3D imaging system. A group of patients who had sustained Fig. 1. Anatomical landmarks digitised on the face of one of the patients in the study. unilateral orbital trauma were examined postoperatively, and any changes between the traumatised and non-traumatised eye were assessed; taking into account the normal variation between the right and left eyes in a healthy control group who had not sustained any facial trauma. Materials and methods This investigation was conducted on 32 volunteers (25 males and 7 females) with no history of previous facial trauma or surgery. Their ages ranged between 19 and 49 years. The study group was made up of 32 patients (27 males and 5 females) with an age range of years. Twelve of the patients had transconjunctival incisions and 20 patients had transcutaneous lower eyelid incisions for the exploration of the orbital floor. In the transconjunctival approach, two stitches were applied to approximate the periosteum, and the conjunctiva was not sutured. Eyelid support was applied using steri strips for 24 h. In the transcutaneous cases the lower eyelid was closed in layers. Chloramphinicol eye drops were applied perioperatively and postoperatively for 24 h. To assess the morbidity associated with each approach, 3D facial imaging was captured using the established method of AYOUB et al. 3,4. The earliest appointment given for imaging following treatment was 6 months after the surgery and the latest was 16.5 months. Fifteen landmarks were digitised on each 3D facial model, the majority of which were located around the eyes (Fig. 1). Most of these landmarks were previously defined by KOLAR & SALTER 15 and FARKAS 7 (Table 1). Exclusion criteria for both groups included those with a history of previous trauma or surgery in the orbital region, and those patients with bilateral orbital trauma. The aim was to compare the traumatised eye with the non-traumatised side, and for this the patient s other eye acted as the control. Ethical approval was obtained for the study from the local ethics committee. The 15 landmarks were digitised 3 times (with a 3-day gap between each of the sessions) for 7 models chosen randomly from the control group of volunteers. The standard deviations of the x, y and z coordinates of each landmark at each session of digitisation were obtained and averaged on all seven volunteers. The standard deviations of each landmark (deviation around the centroid of the three sets of coordinates) were calculated. Several linear and angular measurements were taken (Table 2) in order to compare the measurements obtained from one eye with those taken from the other eye in the same subject in the volunteer group. This provided information on any difference between the right and left eyes in the control group. In the patient group, the same measurements were carried out comparing the traumatised eye with the normal eye. Subtracting the orbital measurements for the non-traumatised eye from the corresponding measurements for the traumatised eye for each of the linear and angular

3 682 Nunu et al. Table 1. Definition of landmarks used for 3D facial analysis Landmark Definition Alar curvature (ac) (right and left) The most lateral point in the curved base line of each ala, indicating the facial insertion of the nasal wingbase Endocanthion (en) (right and left) The point at the inner commissure of the eye fissure (i.e. at the inner junction of the upper and lower eyelids) Exocanthion (ex) (right and left) The point at the outer commissure of the eye fissure (i.e. at the outer junction of the upper and lower eyelids) Inner limbus (ilim) * (right and left) The point on the lower eyelid margin constructed by dropping a vertical line extending from the tangent at the inner edge of the corneo-scleral junction or limbus to the lower eyelid Outer limbus (olim) * (right and left) The point on the lower eyelid margin constructed by dropping a vertical line extending from the tangent at the outer edge of the corneo-scleral junction or limbus to the lower eyelid Palpebrale inferioris (pi) (right and left) The point in the midportion of the free margin of the lower eyelid constructed by dropping a line from the mid-pupil to the lower eyelid y Palpebrale superioris (ps) (right and left) The point in the midportion of the free margin of the upper eyelid constructed by extending a line from the mid-pupil to the upper eyelid y Subnasale (sn) The midpoint of the columella base where it meets with the surface of the upper lip * Points defined by the author. y The author preferred to use these points on the lower and upper eyelids which corresponded to the same line passing through the mid-pupil, rather than the original definitions used by KOLAR &SALTER 15 and FARKAS 7, which indicated the lowest or highest concavities on the lower or upper eyelids, respectively. It was not feasible to locate the mid-pupil point itself on the models using the C3D imaging system because of the nonreflective surfaces of the pupils. Table 2. The linear and angular measurements used for orbital analysis, applied to both volunteer and patient groups Linear measurements in the coronal plane en ex Right and left eye fissure length ps pi Right and left eye fissure height at mid-pupil level ps ilim Right and left eye fissure height as a tangent to the inner limbus ps olim Right and left eye fissure height as a tangent to the outer limbus en pi Distance from (en) to (pi) for right and left eyes ex pi Distance from (ex) to (pi) for right and left eyes ac pi Distance from (ac) to (pi) for right and left eyes Angular measurements en pi ex Angle between (en), (pi) and (ex) for right and left eyes Antero-posterior measurements in the sagittal plane pi (enr-enl-sn) plane y Distance of right and left (pi) in relation to a plane (enr-enl-sn) y Positive values for this measurement indicated that the palpebrale inferioris (pi) point was anterior to the constructed coronal plane, whilst negative values indicated that the palpebrale inferioris (pi) point was posterior to the plane. measurements in the patient group produced either a positive or a negative value, depending on the change occurring at the traumatised eye. Positive values indicated that the linear or angular measurements for the traumatised eye were larger than the non-traumatised eye measurements, and that the palpebrale inferioris point in the traumatised eye was more anterior than that of the non-traumatised eye. In the volunteer group, the measurement from the left eye was subtracted from the corresponding measurement from the right eye, for each of the linear and angular measurements. The differences between right and left eyes and traumatised and non-traumatised eyes were first plotted to give a visual representation. The differences were then summarised using medians and inter-quartile (IQ) ranges. The Kolmogorov Smirnov two-sample test was used to compare the distributions of the difference data of each of the patient groups in turn to that of the volunteer group, for each of the measurements. The null hypothesis under test, for each measurement, was the equality of the distributions of the volunteer and patient groups. Results The extent of the error in the identification of the 15 landmarks in the x, y and z axes on 7 randomly chosen images can be seen in Table 3. Most of the landmarks had standard deviations below 0.5 mm, which was considered the cut-off limit between reproducible and non-reproducible registrations. The highest errors were found mainly along the y-axis of the landmarks around the nose (acr, acl, sn), whilst the lowest errors were found along the z-axis in general. The standard deviations of repeated extracted landmark coordinates around their centroids are shown in Fig. 2. One of the patients who underwent orbital exploration and reconstruction of an orbital floor fracture using a lower Table 3. Reproducibility of landmark identification showing the standard deviations (SD) of the x, y and z coordinates of the 15 landmarks Landmarks x-axis (mm) y-axis (mm) z-axis (mm) exr enr enl exl psl pil oliml iliml psr pir olimr ilimr sn acr acl

4 3-Dimensional assessment of lower eyelid incisions 683 Fig. 2. Bar chart showing the overall reproducibility of landmarks and the standard deviations shown in mm. that of the volunteer group, there were statistically significant differences for two of the measurements: (a) en ex (eye fissure length) and (b) ex pi (distance from exocanthion to midpoint of the free margin of the lower eyelid). The differences for these two measurements, for the transcutaneous and volunteer groups, are illustrated in Figs 5 and 6, respectively. Figure 5 suggests that there was slightly more variability in the transcutaneous group than in the volunteer group, for the en ex measurement. This was statistically significant with a P-value of (Table 6). For 5 of the 20 patients in the transcutaneous group, the traumatised eye measurement was greater than the corresponding non-traumatised eye measurement, whilst in the volunteer group 13 of the 32 subjects had a right eye measurement greater than the left eye measurement. Figure 6 illustrates that there was more variability in the transcutaneous group than in the volunteer group for the measurement ex pi. This was statistically significant with a P-value of (Table 6). In the surgical group, for 7 of the 20 patients the non-traumatised eye measurement was greater than the corresponding traumatised eye measurement. In the volunteer group, the left eye measurement was greater than the right eye measurement for only 2 of the 32 subjects. Fig. 3. (a) Scleral show of the left eye and slight entropion 12 months following transconjunctival approach for repair of fractured orbital floor. (b) 3D image of the same case with the application of a wireframe pattern. transconjunctival incision developed a persistent entropion and increased scleral show of the left eye. The 3D images of this patient are shown in Fig. 3a and b. The descriptive statistics of the differences for the volunteer (right left eye), and transconjunctival and transcutaneous surgical (traumatised non-traumatised eye) groups are given in Tables 4 6. Tables 5 and 6 also contain the P-values from the Kolmogorov Smirnov two-sample tests, comparing the distributions of the respective patient group to the volunteer group. For the measurement ps pi (eye fissure height at midpoint of lower eyelid) there was slightly more variability in the differences for the transconjunctival surgical group compared to the volunteer group (Fig. 4). There were no statistically significant differences between the distributions of the differences for the transconjunctival and volunteer groups, for any of the measurements. When comparing the distribution of the differences for the transcutaneous group to Discussion Previous studies that compared the results of the different types of lower eyelid incisions were somewhat contradictory due to the subjective nature of the facial assessment; this included clinical observation 5,23, the evaluation of preoperative and postoperative photographs 6,11,19 and patient questionnaires 19. The human face is three-dimensional, and this fact necessitates that any technique used for facial measurements should be able to record the face as a 3D structure. Two-dimensional photographs are not adequate, and even if the frontal and lateral profiles are viewed Table 4. Descriptive statistics of differences between right and left eyes of volunteers Volunteers (n = 32): right left (mm) Median IQ range Range en ex to to ps pi to to ps ilim to to ps olim to to en pi to to ex pi to to ac pi to to en pi ex to to

5 684 Nunu et al. Table 5. Descriptive statistics of differences between traumatised and non-traumatised eyes in patients in the transconjunctival surgical group Transconjunctival (n = 12): traumatised non-traumatised (mm) Median IQ range Range P-value * en ex to to ps pi to to ps ilim to to ps olim to to en pi to to ex pi to to ac pi to to en pi ex to to * P-values are from Kolmogorov Smirnov two-sample test, comparing the distribution of the data from the volunteers to the data from the appropriate surgical group (testing null hypothesis of equality of the two distributions). Table 6. Descriptive statistics of differences between traumatised and non-traumatised eyes in patients in the transcutaneous surgical group Transcutaneous (n = 20): traumatised non-traumatised (mm) Median IQ range Range P-value * en ex to to ps pi to to ps ilim to to ps olim to to en pi to to ex pi to to ac pi to to en pi ex to to * P-values are from Kolmogorov Smirnov two-sample test, comparing the distribution of the data from the volunteers to the data from the appropriate surgical group (testing null hypothesis of equality of the two distributions). together, they will still be lacking in the depth component of the facial structures. The rapid speed of the imaging process in the system used here, i.e. 50 ms for each image capture, made it superior to other 3D systems. Since the measurements were to be extracted from around the eyes, the subjects were instructed to keep their eyes open as normal. The speed of the system made this capture possible, since the speed Fig. 4. An illustration of the difference data for the measurement ps pi. of the image capture was faster than the blink reflex itself. On those rare occasions when the eyes were not fully open, the images were discarded and repeated. This research would not have been possible with other 3D imaging systems such as laser scanning since the latter would have necessitated that subjects eyes be closed and the capture time is almost 13 seconds. The reproducibility of landmark identification was similar to that reported by HAJEER et al. 10. The present study had a lower degree of error than that of FERRARIO et al. 9 who found an overall error of 2 mm. In the patient group, the ps pi (fissure height at midpoint of lower eyelid) measurement for the traumatised eye of one patient was found to be as high as 13.5 mm, whilst the average ps pi distance for the non-traumatised eye was 10.5 mm. This patient had a transconjunctival incision, and in his case the postoperative clinical diagnosis of an increased scleral show had been made. The absolute difference between the traumatised and non-traumatised eyes in this particular patient was the highest, measuring around 3.1 mm (Fig. 3), whilst the normal absolute difference between the right and left eyes in the volunteer group for the ps pi measurement was 0.49 mm. There were no statistically significant differences between the two surgical groups with regard to this measurement. ANTONYSHYN et al. 1 reported an abnormal ps pi measurement of 17 mm in one patient who had developed postoperative ectropion. Five out of 30 of their patients showed a postoperative difference of 2 mm or more between the right and left ps pi measurement following orbital fracture repair using a subciliary muscle-splitting incision. When the effects of the incision types were compared with the normal variation present in the volunteer group, statistically significant differences between the two groups were detected in two measurements, en ex (fissure length) and ex pi (exocanthion to palpebrale inferioris). For these two measurements the lower eyelid in the transcutaneous group showed statistically significant variations following surgery. This indicated that the transcutaneous incision resulted in a significant variation in eye fissure length compared with controls, and that there was a significant reduction in length from palpebrale inferioris to exocanthion following this incision. In the control group almost one in two people had one eye fissure length (en ex) longer than the other, i.e. the right was longer than the left. In the transcutaneous incision group this was reduced to only

6 3-Dimensional assessment of lower eyelid incisions 685 Fig. 5. An illustration of the difference data for transcutaneous and volunteer groups for the measurement en ex. Fig. 6. An illustration of the difference data for transcutaneous and volunteer groups for the measurement ex pi. one in four patients, where the fissure length in the traumatised eye was longer than in the non-traumatised eye. This may be the result of a reduction in total fissure length following the transcutaneous incision. This incision resulted in a significant variation in eye fissure length (en ex) compared to the control group, and this was not the case following the transconjunctival approach. The variation in fissure length between right and left eyes in the control group is borne out in other work. It was this measurement that showed differences between right and left eyes in the study by FERRARIO et al. 8. They examined a non-trauma population using an electromagnetic digitiser and found that eye fissure length differed by over 1 mm between the right and left side in young adult males. As already mentioned, there was a significant reduction in the pi ex measurement following the transcutaneous incision. Again, this was not seen in the transconjunctival group and would appear to support the findings in the literature that suggest there is a lower incidence of lower eyelid complications with the transconjunctival compared to transcutaneous incision 2,13,20. These findings suggest that the transcutaneous incisions resulted in some degree of alteration in the shape of the lower eyelid, and since pi en was not significantly altered the resultant variation must have been due to changes in the position of exocanthion. It is likely that this would manifest itself as the medial retraction of the lateral canthus. Displacement of the lateral canthus has been documented in the literature, especially when a lateral canthotomy is incorporated with a transconjunctival incision 2. In the present study none of the patients in either the transcutaneous or transconjunctival group underwent lateral canthotomy. The results suggest that exocanthion was displaced medially in a significant number of patients in the transcutaneous group, even without a lateral canthotomy incision. This is most likely the result of scarring of the incision. A longer term follow up, up to 2 years, is recommended before considering revision of the scarring of the lower eyelid. As mentioned, despite the fact that one of the cases in the transconjunctival group showed clear clinical scleral show, the differences in the vertical measurements (ps pi) between the traumatised and nontraumatised eyes for the group as a whole were not significantly different from those detected in the volunteer group. It is important to note that our sample sizes were relatively small making it difficult to draw firm conclusions. A future multicentre study of a large number of subjects would be beneficial. In conclusion, the findings suggest that the Di3D imaging system is an accurate, reliable and objective method of assessment of the changes occurring in the lower eyelids following surgical incisions in this area. There were statistically significant alterations in the lower eyelid secondary to the transcutaneous incisions in comparison with the transconjunctival approach. The study establishes a protocol for the use of the 3D imaging system in this area, and future similar studies with larger numbers of patients are recommended. Acknowledgements. Many thanks are due to all the consultants at the West of Scot-

7 686 Nunu et al. land Oral and Maxillofacial Surgery Units for giving us access to their patients. Our thanks also go to Dr. Colin Urquhart from Di3D in Glasgow for providing and maintaining the imaging system used in this study. References 1. Antonyshyn O, Gruss JS, Galbraith DJ, Hurwitz JJ. Complex orbital fractures: a critical analysis of immediate bone graft reconstruction. Ann Plast Surg 1989: 22: Appling WD, Patrinely JR, Salzer TA. Transconjunctival approach vs. subciliary skin-muscle flap approach for orbital fracture repair. Arch Otolaryngol Head Neck Surg 1993: 119: Ayoub AF, Garrahy A, Hood C, White J, Bock M, Siebert JP, Spencer R, Ray A. Validation of a vision-based threedimensional facial imaging system. Cleft Palate Craniofac J 2003: 40: Ayoub AF, Siebert JP, Moos KF, Wray D, Urquhart C, Niblett TB. A visionbased three-dimensional capture system for maxillofacial assessment and surgical planning. Br J Oral Maxillofac Surg 1998: 36: Bahr W, Bagambisa FB, Schlegel G, Schilli W. Comparison of transcutaneous incisions used for exposure of infraorbital rim and orbital floor: a retrospective study. Plast Reconstr Surg 1992: 90: Baumann A, Ewers R. Use of the preseptal transconjunctival approach in orbit reconstruction surgery. J Oral Maxillofac Surg 2001: 59: FARKAS LG. Anthropometry of the Head and Face. 2nd edn. New York: Raven Press 1994: 3 56, 79 88, [appendix A: ; appendix A-1: ]. 8. Ferrario VF, Sforza C, Colombo A, Schmitz JH, Serrao G. Morphometry of the orbital region: a soft tissue study from adolescence to mid-adulthood. Plast Reconstr Surg 2001: 108: Ferrario VF, Sforza C, Poggio CE, Cova M, Tartaglia G. Preliminary evaluation of an electromagnetic threedimensional digitizer in facial anthropometry. Cleft Palate Craniofac J 1997: 35: Hajeer MY, Ayoub AF, Millett DT, Bock M, Siebert JP. Three-dimensional imaging in orthognathic surgery: the clinical application of a new method. Int J Adult Orthod Orthognath Surg 2002: 17: Holtmann B, Wray RC, Little AG. A randomized comparison of four incisions for orbital fractures. Plast Reconstr Surg 1981: 67: Hwang K, Lee DK, Lee EJ, Chung IH, Lee S. Innervation of the lower eyelid in relation to blepharoplasty and midface lift: clinical observation and cadaveric study. Ann Plast Surg 2001: 47: Jacono AA, Moskowitz B. Transconjunctival versus transcutaneous approach in upper and lower blepharoplasty. Fac Plast Surg 2001: 17: Kawai T, Natsume N, Shibata H, Yamamoto T. Three-dimensional analysis of facial morphology using Moiré stripes. Part I: methods. Int J Oral Maxillofac Surg 1990: 19: KOLAR JC, SALTER EM. Craniofacial Anthropometry (Practical Measurement of the Head and Face for Clinical, Surgical and Research Use). Springfield: Charles C. Thomas Publisher Ltd. 1997: 54 55, , [appendices: 309, ]. 16. McCance AM, Moss JP, Fright WR, Linney AD, James DR. Three-dimensional analysis techniques Part 2: laser scanning: a quantitative three-dimensional soft-tissue analysis using a colour-coding system. Cleft Palate Craniofac J 1997: 34: Mullins JB, Holds JB, Branham GH, Thomas JR. Complications of the transconjunctival approach: a review of 400 cases. Arch Otolaryngol Head Neck Surg 1997: 123: MUSTARDE JC. Repair and Reconstruction in the Orbital Region: A Practical Guide. 2nd edn. Churchill Livingstone 1980: , Netscher DT, Patrinely JR, Peltier M, Polsen C, Thornby J. Transconjunctival versus transcutaneous lower eyelid blepharoplasty: a prospective study. Plast Reconstr Surg 1995: 96: Patel PC, Sobota BT, Patel NM, Greene JS, Millman B. Comparison of transconjunctival versus subciliary approaches for orbital fractures: a review of 60 cases. J Cranio Maxillofac Trauma 1998: 4: Ras F, Habets LLMH, Van Ginkel FC, Prahl-Anderson B. Quantification of facial morphology using stereophotogrammetry: demonstration of a new concept. J Dent 1996: 24: Rohrich RJ, Janis JE, Adams Jr WP. Subciliary versus subtarsal approaches to orbitozygomatic fractures. Plast Reconstr Surg 2003: 111: Waite PD, Carr DD. The transconjunctival approach for treating orbital trauma. J Oral Maxillofac Surg 1991: 49: Westfall CT, Shore JW, Nunery WR, Hawes MJ, Yaremchuk MJ. Operative complications of the transconjunctival inferior fornix approach. Ophthalmology 1991: 98: Address: Ashraf F. Ayoub Glasgow Dental Hospital & School 4th Floor 378 Sauchiehall Street Glasgow G2 3JZ UK Tel: Fax: a.ayoub@dental.gla.ac.uk