Orbital Pathology Research Articles

Peculiarities of the morphogenesis and topography of the human orbit.

Background. Age dynamics of the orbit morphogenesis, stages of the topography formation of its structural components is a significant subject of the scientific search to elucidate the morphological underlying reason of stiopathogenesis of the congenital and acquired diseases of the organ of sight, accessory eye apparatus, muscular, vascular and nervous components of the orbit. Objective. To analyze the modern stage of studying morphogenesis and peculiarities of the age dynamics of the anatomical changes of the human orbit, to elucidate discrepant and not solved issues of morphology of its structures. Methods. Critical analysis of the domestic and foreign sources, dedicated to the human orbit morphology studying, realized 10 years ago. Results. The main stages of morphogenesis of the human orbit structures (bones, adipose tissue, muscles, blood vessels and nerves) have been analyzed in the review of the scientific literature. Human orbit is characterized with sexual-age and peculiar changeability, conformities’ elucidation of which will allow to individualize the operative treatment and prognosticate its possible complications. Data concerning anlage of the human orbit structures, morphogenesis peculiarities and sequence of topographic-anatomical changes of its structures are left to be fragmental and contradictory. Conclusion. Up-to-date data about morphogenesis and formation of topography of the muscular structures of the human orbit require a complex morphological investigation in the age dynamics of the structural and topographic-anatomical changes. The present data concerning prenatal development of the orbit are fragmentary and do not give complete conception about the sequence of the structural transformation during antenatal life. Information about sources, location, term and sequence of anlage of the human orbit structures as well as peculiarities of the change of the form, sizes, syntopy, variation anatomy in the age dynamics of ontogenesis require more precise definition. Determination of these important tasks by the scientists-morphologists will promote the morphological underlying reason formation to develop new methods of the operative treatment and diagnostics of the human orbit pathology.

Endoscopic orbital decompression for proptosis in non-thyroid eye disease.

Orbital decompression is an established surgical treatment option for a range of orbital conditions. We report the outcomes of endonasal decompression to recess the globe for conditions and pathologies other than thyroid eye disease. This was a retrospective case series of patients who underwent endoscopic orbital decompression for proptosis secondary to non-thyroid eye disease orbital pathologies. The procedures were carried out by oculoplastic surgeons across two hospital sites between January 2011 and July 2018. Information collected includes patient demographics, diagnosis, surgical details, pre- and postoperative clinical findings (including visual acuity, exophthalmometry readings, intraocular pressure, ocular motility and diplopia), complications and further treatment. There were seven cases of endoscopic decompression, each due to a different pathology. The reasons for decompression were proptosis secondary to optic nerve sheath meningioma (1); sphenoid wing meningioma (1); idiopathic myositis (1); axial myopia (1); chronic third nerve palsy (1); to protuberant keratoprosthesis (1); and Crouzon syndrome with corneal exposure (1). Visual acuity remained stable or improved in all patients postoperatively. There was an average reduction in proptosis of 3.5 ± 1.4mm (standard deviation - SD). Ocular motility remained stable in 100% (7/7). There were no intraoperative or postoperative complications, including no new cases of postoperative diplopia. Endoscopic orbital decompression can be performed for patients with proptosis associated with a large globe, facial dysplasia or medial and infero-medial orbital lesions.

Conjunctival lymphoma a case report

AbstractPurposeOrbital lymphomas are not frequent within orbital pathologies; they are commonly found associated to systemic diseases. Lymphomas affecting only the conjunctiva are even less frequent and their bilateral manifestation are uncommon. The characteristic lesion of conjunctival lymphomas is an orange‐pink mass at the bottom of the bag, without adhesion to deep planes. Patients are often asymptomatic but they may also complain of irritation of the eye. Painful proptosis or ptosis may appear if the affectation extends to the orbit. The average age of presentation is 60–70 years and it is more common in women. The diagnosis is confirmed by biopsy of the lesion.MethodsWe report the case of a 55‐year‐old woman with a conjunctival bilateral mucosa associated lymphoid tissue (MALT) lymphoma, not associated to systemic disease. The patient came to the service complaining of one month of epifora and itching in both eyes, with a salmon patch conjunctival mass in the temporal tarsal conjunctiva of the left eye, without any inflammatory signs or decreased visual acuity.ResultsA partial exeresis and biopsy of the left eye subconjunctival mass was performed. An extranodal lymphoma of the lymphoid tissue associated with mucosa was diagnosed (MALT lymphoma), CD20: positive, BCL2: positive and Ki67: 5%. Ocular ECO and MRI demonstrated infiltration of the external rectus muscle, being in contact with the superior rectus muscle, and PET CT confirmed a normal metabolic pattern. The patient was followed up for several months in the departments of Ophthalmology and Oncology, treatment was initiated with radical radiotherapy 30 Gy, fractionation cGy 200 in the left conjunctiva, which started on January 30 2017 and ended on February 18 2017.ConclusionBiopsy offers an early diagnosis for conjunctival lymphoma, being its prognosis very good. Because of this, ophthalmologists should be aware of this pathology, its characteristics and diagnosis.

Ojo rojo

A red eye is the most common ocular disorder encounter in emergency department. This sign appearing in multiple disorders, thus an exhaustive examination allow us to approach the etiological diagnosis (conjunctival hemorrhage, corneal pathology, conjunctivitis, acute anterior uveitis, acute glaucoma, scleritis and orbital pathology). Treatment has to be focused on underlying pathogenic mechanism.

Development of a Modular Cadaveric Endoscopic Orbital Surgery Model.

Introduction Endoscopic orbital surgery requires the acquisition of unique skill set including endoscopic bimanual dissection of intra/extraconal lesions adherent to orbital fat and neurovascular structures. Our goal was to develop a modular cadaveric model used to train surgeons to resect orbital pathology within any desired orbital compartment. Methods Expansile superabsorbent polymer (SAP) beads (2 mm) were soaked in Omnipaque™ (Iohexol) solution for 15 minutes prior to transcaruncular orbital implantation using 10-gauge angiocath. Insertion depth was designed to implant beads in predetermined intraconal compartments corresponding to established orbital tumor stages. Beads were left to expand in situ over a period of 1 to 5 hours. Computed tomography scans were performed using the FUSION image guidance protocol. Model utility and learning curves were assessed by quantifying resection time over 8 sequential attempts. Results All 24 beads were successfully implanted in 8 orbits corresponding to CHEER stage II to IV lesions (n = 3 per orbit). Beads expanded from 2 mm to an average of 5.2 mm within 1 hour. During expansion, the beads interpolated into the adjacent fascia similar to in vivo tumors. Average insertion time was 5:53 minutes per orbit (range, 3:24–10:33 min) and average time to bead identification was 10:47 minutes. Across all beads, dissection times decreased in a nonsignificant manner over 8 consecutive attempts. Conclusion The directed implantation of expansile SAP beads in this cadaveric model accurately replicates the approach, identification, and resection of isolated orbital lesions. This orbital model can assist the endoscopic surgical team to develop further knowledge and technical skill sets to approach orbital lesions. Further ongoing studies to validate this model are currently underway.

Orbital Abscess Drainage Using Intravenous Cannula: Technique and Advantages

The orbital infections are known to be the most frequent primitive orbital pathology.
 Rhinosinusitis (RS) is the most common cause of orbital inflammation and infection, especially in the pediatric range. So far, the main orbital complication of RS is the preseptal cellulitis. The dissemination of the infection in the orbital retroseptal area may occur and is considered to be a serious complication requiring urgent diagnosis and treatment. It is usually seen as an orbital (OSPA) subperiosteal abscess adjacent to the infected sinus. The diagnosis of an OSPA is based on clinical evaluation as well as X-ray imaging. The CT scan is the preferred imaging modality for orbital abscess diagnosis. In most cases of OSPA, the surgery is often indicated and can be conducted by an external method, transnasal endoscopy or a combined method. In this article, we describe the technique of external drainage using an intravenous cannula (case report of 10 patients) as well as the results obtained.

ICAR: endoscopic skull‐base surgery

Endoscopic skull-base surgery (ESBS) is employed in the management of diverse skull-base pathologies. Paralleling the increased utilization of ESBS, the literature in this field has expanded rapidly. However, the rarity of these diseases, the inherent challenges of surgical studies, and the continued learning curve in ESBS have resulted in significant variability in the quality of the literature. To consolidate and critically appraise the available literature, experts in skull-base surgery have produced the International Consensus Statement on Endoscopic Skull-Base Surgery (ICAR:ESBS). Using previously described methodology, topics spanning the breadth of ESBS were identified and assigned a literature review, evidence-based review or evidence-based review with recommendations format. Subsequently, each topic was written and then reviewed by skull-base surgeons in both neurosurgery and otolaryngology. Following this iterative review process, the ICAR:ESBS document was synthesized and reviewed by all authors for consensus. The ICAR:ESBS document addresses the role of ESBS in primary cerebrospinal fluid (CSF) rhinorrhea, intradural tumors, benign skull-base and orbital pathology, sinonasal malignancies, and clival lesions. Additionally, specific challenges in ESBS including endoscopic reconstruction and complication management were evaluated. A critical review of the literature in ESBS demonstrates at least the equivalency of ESBS with alternative approaches in pathologies such as CSF rhinorrhea and pituitary adenoma as well as improved reconstructive techniques in reducing CSF leaks. Evidence-based recommendations are limited in other pathologies and these significant knowledge gaps call upon the skull-base community to embrace these opportunities and collaboratively address these shortcomings.

Evaluation of Surgical-Navigation System in Management of Orbital Disorders

AbstractBackground: Surgical navigation guidance is primarily designed to assist with surgery on bony tissues and closed spaces, it is widely used in neurosurgery and sinus surgery. And since the limited mobility of the soft tissues of the orbit, as they are tightly contained within its bony walls, stereotactic navigation may be a useful tool in orbial surgeries such as tumor excisions, biopsies, orbital wall fractures, and orbital decopmression.Aim of Study: To evaluate whether the use of Frameless surgical navigation is useful and time efficient in removing orbital masses and repairing orbital wall fracture as known to be a helpful tool in Neurosurgery and sinus surgery.Patients and Methods: Prospective interventional non-controlled non-randomized case series study was coducted in Cairo Univeristy Hospitals from June 2013 to December 2014 on 15 patients with primary or recurrent post-septal orbital pathology using the Electromagnetic “FusionTM ENT Naviga-tion System” during the surgery. Primary outcomes were assessing time efficiency through operative times (Total Time, Operating Time and Maintenance Time), extent of mass excision and fracture repair. Secondary outcomes were im-provement in Hertel's readings and detecting complication related to the navigation system.Results: The mean of maintenance time percentage com-pared to the total operating time was 46.7% with SD ±6.1 that lead to relatively longer total operating time, but as more cases were performed, it decreased gradually. Complete excision was achieved in 70% of cases. The p-value for improved Hertel's reading was 0.016 and only one case had significant complications.Conclusion: Although promising results were seen in orbital wall fracture and well circumscribed orbital masses. The Surgical Navigation System cannot yet be considered the standard of care for patients with different orbital pathologies as it prolongs the total operating time. However, it is helpful and promising in complicated cases of recurrent and infiltrative masses and massive trauma, where the normal anatomical landmarks are compromised specially with the evolving updates in improving this technology.

P.102 Expanded endoscopic endonasal approach for orbital apex decompression

Background: The Endoscopic endonasal approach (EEA) has been gaining popularity in the past decade as an alternative to traditional transcranial and transorbital approaches. We have performed orbital apex decompression for a variety of pathological entities. Methods: We performed a retrospective chart review on patients who underwent EEA orbital apex decompression between January 1st 2010 and December 1st 2018 at McMaster University. Results: Eight patients underwent endoscopic endonasal orbital decompression at our center, including five male patients and three female patients. The mean age of our patients was 50.1 years. The different pathologies we treated included nasopharyngeal carcinoma, hemangioma, fibrous dysplasia, IgG4 disease, inverted papilloma, angioleiomyoma, and neuroendocrine paraganglioma. Five patients presented with visual symptoms. Postoperatively, one of these five patients improved to baseline, three had stable vision, another one had progressive visual decline despite surgical intervention. Conclusions: Endoscopic endonasal approach can be used as an alternative to decompress orbital apex pathologies in selected patients.

Transorbital penetrating trauma caused by a fall on the antenna of a radio receiver: Case report and review

Summary We report the case of a patient who died after falling on the antenna of a radio receiver that was stood on the floor. External examination showed an orificial contuse wound, less than a centimetre in diameter, on the right upper eyelid. There was no ocular lesion. Full-body CT (computed tomography) scan imagery revealed a fracture of the roof of the right orbit and diffuse intra and pericerebral haemorrhages. Those haemorrhages had caused the death of the patient. Penetrating transorbital traumas represent a very small part of cranial traumas and orbital pathologies. They are usually linked to the high-velocity traumas associated with traffic accidents or penetration by firearm projectiles. Low-energy penetrating transorbital traumas are even less frequent; associated prognoses are rarely lethal and generally functional. These traumas cause minimal palpebral or periocular wounds that can seem insignificant upon external forensic examination, especially when the foreign body involved is fully intracranial or absent. Performing a cerebral scan, or even post-mortem angiography, thus appears to be a key-procedure, very useful to the medical examiner.

Examiner Position in Ocular Point-of-Care Ultrasound: A Proposed Technique.

Ocular point-of-care ultrasound (POCUS) is a fast and safe non-invasive procedure used to evaluate the structural integrity and pathology of the eye. Ocular POCUS can be used for evaluation of posterior chamber and orbital pathology, including retinal detachment, vitreous detachment or hemorrhage, foreign body, lens dislocation, and increased intracranial pressure. The purpose of this brief communication is to describe a technique for conducting an ocular POCUS that may in some cases be easier and more comfortable by adjusting the position of the sonographer relative to the patient. To our knowledge, this proposed technique has not been described in previous literature and may result in greater comfort for both sonographer and patient.

Orbital reconstruction for tumor-associated proptosis: quantitative analysis of postoperative orbital volume and final eye position.

Surgical resection of sphenoid wing tumors and intraorbital pathology carries the dual goal of appropriately treating the target pathology as well as correcting proptosis. Residual proptosis following surgery can lead to cosmetic and functional disability. The authors sought to quantitatively assess the effect of orbital volume before and after reconstruction to determine the optimal strategy to achieve proptosis correction. All surgeries involving orbital wall reconstruction for orbital or intracranial pathology that preoperatively resulted in proptosis between 2007 and 2017 were reviewed. Proptosis was measured by the exophthalmos index (EI): the ratio of the distance of the anterior limit of each globe to a line drawn between the anterior limit of the frontal processes of the zygomas, comparing the pathological eye to the normal eye. Postoperative radiographic measurements were taken at least 60 days after surgery to allow surgical swelling to abate. The orbit contralateral to the pathology was used as an internal control for normal anatomical orbital volume. Cases with preoperative EI < 1.10, orbital exenteration, or enucleation were excluded. Twenty-three patients (16 females and 7 males, with a mean age of 43.6 ± 22.8 years) were treated surgically for tumor-associated proptosis. Nineteen patients harbored meningiomas (11 en-plaque; 8 sphenoid wing), and one patient each harbored an orbital schwannoma, glomangioma, arteriovenous malformation, or cavernous hemangioma. Preoperative EI averaged 1.28 ± 0.10 (range 1.12-1.53). Median time to postoperative imaging was 19 months. Postoperatively, the EI decreased to a mean of 1.07 ± 0.09. Greater increases in size of the reconstructed orbit were positively correlated with greater quantitative reductions in proptosis (p < 0.01). Larger volume of soft tissue pathology was also associated with achieving greater proptosis correction (p < 0.01). Residual exophthalmos (defined as EI > 1.10) was present in 8 patients, while reconstruction in 2 patients resulted in clinically asymptomatic enophthalmos (defined as EI < 0.95). Tumor invasion into the superior orbital fissure sinus was associated with residual proptosis (p = 0.04). Proptosis associated with intracranial and orbital pathology represents a surgical challenge. The EI is a reliable and quantitative assessment of proptosis. For orbital reconstruction in cases of superior orbital fissure involvement, surgeons should consider rebuilding the orbit at slightly larger than anatomical volume.

Nontraumatic Orbital Emergencies

Non-traumatic orbital pathology can often have overlapping imaging features and challenging timely diagnosis. Prompt recognition is necessary due to potential risk of permanent visual loss. In this article we present systematic evaluation of non-traumatic orbital pathology with attention to key imaging features, pathogenesis and potential complications.

Magnetic Resonance Imaging of the Orbital Cavity: Indications and Diagnostic Possibilities

Today, magnetic resonance imaging (MRI) is considered the diagnostic tool of choice for eye and orbital pathologies. In this article, the MR image characteristics of relevant pathologies are illustrated with case-based examples in the context of clinical findings. Vascular pathologies (such as capillary and cavernous hemangioma), inflammatory diseases (such as endocrine orbitopathy), and neoplasms (such as lymphoma, uveal melanoma, retinoblastoma, and ocular/orbital metastasis) are described. Additionally, the role of MRI in the acute clinical setting and in trauma are discussed. Technical aspects of MRI encompassing field strength and the utilization of receiver coils to optimize image quality and achieve high spatial resolution are explained. Next to the use of common sequences (T1- and T2-weighted sequences) used in standard anatomic imaging (sAI), the article demonstrates the potential of "multiparametric imaging" (diffusion-weighted imaging, DWI, and dynamic contrast-enhanced imaging, DCE). These innovative MRI sequences depict functional tissue features in addition to pure morphology and thus facilitate radiological assessment.

Computed tomography imaging-based normative orbital measurement in Indian population.

Purpose:This study aims to evaluate normal orbital structures with nonenhanced computed tomography (NCCT) and determine normative data for the Indian population.Methods:CT images of the orbits of 100 patients were retrospectively reviewed on a work station to record the normative data of the orbits. Clinical details of all patients were reviewed to ensure that they did not have ocular/orbital diseases. Both axial and coronal images were utilized to record the data.Results:The mean age of the population evaluated was 34.07 years, with male to female ratio of 1.77. The average orbital index for the left orbit was 97 and for the right side was 103. The mean thickness of left inferior rectus, lateral rectus, medial rectus, and the superior rectus was 3.36 mm, 3.14 mm, 3.80 mm, and 3.75 mm, respectively. The right inferior rectus, lateral rectus, medial rectus, and the superior rectus measured 3.46 mm, 3.14 mm, 3.83 mm, and 3.78 mm, respectively. The optic nerve sheath complex diameter varied between 3.05 mm and 7.17 mm for the left eye and 3.05 mm and 7.0 mm for the right eye.Conclusion:The study provides normative data on various orbital structures in an Indian population. This data is likely to be useful for diagnosing various orbital pathologies and in planning surgical orbital procedures.

Recommendations for ultrasound examination in ophthalmology. Part II: Orbital ultrasound.

Pathological processes within the orbits are a heterogeneous group of diseases of various etiologies, clinical pictures and therapy models. Due to poor access to the orbits in a clinical examination, imaging plays a significant role in both diagnosis and treatment monitoring in patients with an orbital pathology. One of such imaging modalities is ultrasonography. It is relatively well-available, rapid and safe for the patient. This paper enumerates indications for an orbital ultrasound scan, including functional ocular disorders (vision disorders, mobility disorders), autoimmune diseases, inflammatory conditions, proliferative processes, and others. The authors present Ossoinig’s standardized method which encompasses topographic, qualitative and kinetic echography, and may facilitate orbital ultrasound examinations. Moreover, the article shows management standards for ultrasound imaging of orbital pathologies with an emphasis on the relevance of equipment selection, scanning technique (transducer position, transocular technique, paraocular technique) and patient preparation for the examination, and indicates appropriate elements of an examination report. The authors discuss the ultrasound presentation of the orbital structures in physiological conditions and selected orbital pathologies, such as pseudotumor, thyroid orbitopathy, cancerous tumors of the optic nerve, and others. The ultrasonographic characteristics of the presented pathologies are shown taking into account A and B scans. Attention was paid to the evaluation of angle kappa in the A scan in echographic assessment of the orbits. Furthermore, the authors include referential values for extraocular muscle thickness and quantitative measurement of the severity of thyroid ophthalmopathy based on Ossoinig’s muscle index.

Evolution of thyroid eye disease decompression-dysthyroid optic neuropathy.

Orbital decompression surgery and medical therapy for thyroid eye disease (TED) have evolved over the past 150 years and afforded the opportunity to restore pre-disease appearance and visual function. This manuscript explores the past 150 years of surgical innovation for the treatment of TED. The "Age of Surgical Heroism" spans the time from 1888 to 1979 during which the pioneers of orbital decompression developed lateral orbitotomy, transcranial decompression, paranasal sinus decompression, and transantral decompression despite an incomplete understanding of the pathophysiology of both TED and a limited ability to non-invasively assess their patients. The "Age of Surgical Refinement" dawned with the development of computed tomography and represents the years 1979-2000. During this time, the "swinging eyelid" approach for two- and three-wall decompressions was introduced, a combined orbital-extradural four wall decompression procedure was developed, fat decompression was explored, and endoscopic decompression techniques were advanced. At the beginning of the 21st century, our understanding of the orbital pathophysiology of TED evolved significantly. Clinicians recognized the age-related phenotype of TED based largely on the relative contribution of extraocular muscle enlargement vs. orbital fat expansion. The "Modern Age" of Customized Orbital Decompression features both "medical decompression" during the active phase of TED and, in the stable phase, customized surgical plans incorporating individual patients' anatomy, orbital pathology, and surgical goals that collectively maximize therapeutic benefit while minimizing therapeutic morbidity.

Intraoral Approach for Reduction and Fixation of Infraorbital Rim Fracture

Various surgical approaches are widely used for exposure, evaluation, and treatment of orbital trauma and pathology in the orbital floor and infraorbital rim. They were conveniently categorized as either transcutaneous or transconjunctival. The purpose of this research is to assess the intraoral approach for reduction and fixation of the infraorbital rim in zygomatic fractures.Patients and methods:11 patients were subjected to reduction and fixation of infraorbital rim fracture through intraoral vestibular approach. Time of surgery, Post-operative edema and infraorbital nerve sensory function were evaluated. All patients were followed up for six months.Results: all cases included in the current study did not show any lower eyelid complications . postoperative numbness and edema were reported and subcided completely .Conclusion: Intraoral unilateral vestibular approach allows access to the zygomatico-maxillary buttress and infraorbital rim with only 1 incision, optimizes surgical time, decreases complication rates, and avoids periorbital scarring in the patient.

Gut Microbiome in BALB/c and C57BL/6J Mice Undergoing Experimental Thyroid Autoimmunity Associate with Differences in Immunological Responses and Thyroid Function.

Experimental models of hyperthyroid Graves' disease (GD) and Graves' orbitopathy (GO) are efficiently developed by genetic immunisation by electroporation with human thyrotropin hormone receptor (hTSHR) A-subunit plasmid in female BALB/c (H-2d) mice. We investigated susceptibility in C57BL/6 J (H-2b) animals to allow studies on disease mechanisms in transgenic and immune response gene knock-out mice. Higher numbers of female C57BL/6 J were positive for pathogenic thyroid stimulating antibodies, but induced hyperthyroidism remained at a low frequency compared to BALB/c animals. Assessment of hTSHR specific T cells showed reduced proliferation in C57BL/6 J animals accompanied with anti-inflammatory IL-10, with less pro-inflammatory IFN-γ compared to BALB/c. Whilst the orbital tissue from immune BALB/c mice showed inflammation and adipogenesis, in contrast C57BL/6 J animals showed normal pathology. We characterised the gut microbiota using 16 S ribosomal RNA gene sequencing to explore its possible pathogenic role in the model. Despite being housed under identical conditions, we observed significantly different organisation of the microbiota (beta-diversity) in the two strains. Taxonomic differences were also noted, with C57BL/6 J showing an enrichment of Operational Taxonomic Units (OTUs) belonging to the Paludibacter and Allobaculum, followed by Limibacter, Anaerophaga and Ureaplasma genera. A higher number of genera significantly correlating with clinical features was observed in C57BL/6 J compared to BALB/c; for example, Limibacter OTUs correlated negatively with thyroid-stimulating antibodies in C57BL/6 J mice. Thus, our data suggest gut microbiota may play a pivotal immunomodulatory role that differentiates the thyroid function and orbital pathology outcome in these two inbred strains undergoing experimental GO.

Ultrasonographic assessment of ophthalmic diseases in low-income countries.

We undertook a study between December 2016 and February 2017 on 1637 of 2101 patients with clearly documented findings. These underwent ocular B-scan ultrasonography (USG). Their ages were in the range of 10 days to 92 years; among these patients, 921 (56.26%) were male and 224 (13.68%) were children. Among the adults, 669 (40.86%) patients had anterior segment and 636 (38.85%) had posterior segment pathology. In addition, there were 108 (6.59%) with orbital pathology. Our experience is that USG is an effective, quick, low-cost and non-invasive diagnostic tool for the diagnosis of various ocular and orbital conditions in high patient volume centres (including children and adults) especially where resources are limited.