Items tagged “eye”
66 results found
The abducens nerve is the sixth cranial nerve. It courses from its nucleus located in the dorsal pons to its innervation of the lateral rectus muscle and can be divided into four parts: nucleus and intraparenchymal portion cisternal portion cavernous sinus portion orbital portion Gross anat...
Calcification of the globe (differential)
Calcification of the globe has many causes, varying from the benign to malignant. When calcification is seen of the posterior half of the globe, it could relate to any of the layers (scleral, choroidal or retinal), as it is not possible to separate them out on CT. Retinal drusen: 1% population...
Ectopia lentis refers to subluxation or dislocation of the lens of the eye secondary to dysfunction or disruption of zonular fibres. Pathology Aetiology trauma systemic and syndromic disorders Marfan syndrome typically upwards and out most common spontaneous cause 2 homocystinuria - ty...
The orbit is a feature of the face and contains the globe and it's supporting structures, as well as many nerves and vessels. Gross anatomy In the adult, the orbit has a volume of approximately 30 mL, of which the globe occupies 6.5 mL. It has a roof, floor, medial and lateral wall. The orbit ...
Orbital pseudotumour is an idiopathic inflammatory condition that most commonly involves the extraocular muscles. Less commonly there is inflammatory change involving the uvea, sclera, lacrimal gland, and retrobulbar soft tissues. The exact aetiology is not known but an association with many inf...
Retinoblastomas are the most common intraocular neoplasm found in childhood, and with modern treatment modalities are, in most cases, curable. On imaging, they are generally characterised by a heterogeneous retinal mass with calcifications, necrotic components, and increased vascularisation on ...
Superior orbital fissure
The superior orbital fissure is the communication between the cavernous sinus and the apex of the orbit. It is straddled by the tendinous ring which is the common origin of the four rectus muscles (extraocular muscles). Gross anatomy Boundaries medial: body of sphenoid superior: lesser wing ...
The tendinous ring, also known as the annulus of Zinn, is the common origin of the four rectus muscles (extraocular muscles). The tendinous ring straddles the superior orbital fissure and through it (from superior to inferior) pass: superior division of the oculomotor nerve (CN III) nasocilia...
Published 22 May 2008
The ophthalmic artery (OA) is a branch off the C6 segment of the internal carotid artery (ICA). Gross anatomy Origin OA arises medial to the anterior clinoid process as the ICA exits the cavernous sinus. It originates from the antero- or supero-medial surface of the ICA. Course OA passes in...
Leukocoria (also spelled as leucocoria or leukokoria) refers to an abnormal white reflection from the retina of the eye. Despite its colour, the reflection is related to the familiar red-eye effect. Usually, when a light is shone through the iris, the retina appears red to the observer. In leuko...
Enophthalmos due to anorexia nervosa
Diagnosis almost certain
Published 02 Jan 2009
Coloboma is collective term encompassing any focal discontinuity in the structure of the eye, and should not be confused with staphylomas, which are due to choroidal thinning. Pathology Most commonly colobomas are due to failure of closure of the choroidal fissure posteriorly. Typically colob...
Multiple myeloma of the orbit
Published 15 Apr 2009
Coats disease of the eye
Diagnosis almost certain
Published 22 Apr 2009
Trilateral retinoblastoma refers to the combination of retinoblastoma (usually bilateral) and pineoblastoma. This relationship highlights the close relationship between these highly aggressive small round blue cell tumours. It affects only a minority of patients with retinoblastoma (1.5-5%) and...
Optic pathway glioma
Optic pathway gliomas are relatively uncommon tumours, with a variable clinical course and usually seen in the setting of neurofibromatosis type I (NF1). Histologically the majority are pilocytic astrocytomas. They are characterised on imaging by an enlarged optic nerve seen either on CT or MR...
Tram-track sign (orbit)
Tram-track sign refers to the parallel thickening and enhancement around the optic nerve, and is most frequently seen in the setting of optic nerve meningioma. It may however also be seen in 1: orbital pseudotumour perioptic neuritis orbital sarcoidosis oribtal leukemia orbital lymphoma or...
Exudative retinitis (also known as retinal telangiectasis or Coats disease) is a rare congenital disease affecting the eyes and is a cause of leukocoria. Epidemiology The exact aetiology is unknown and the disease is a non hereditary disorder. It occurs predominantly in young males, with the ...
Diagnosis almost certain
Published 05 Apr 2010