orbita, globo ocular, la conjuntiva capsula de tenon paredes orbitarias: superior ( techo): formada por el hueso frontal en su profundidad el ala menos del. Non-contrast CT is useful in the initial evaluation of orbital and globe trauma for the assessment of fractures, extra-ocular muscle herniation and. Aug 30, · “El torero Juan José Padilla sufre estallamiento de glóbulo ocular por cornada” EfektoTV Deportes: – Duration: Efekto Televisión 1,,
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Eye globe abnormalities can be readily detected on dedicated and non-dedicated CT and MR studies. A primary understanding of the globe anatomy is key to characterising both traumatic and non-traumatic globe abnormalities. The globe consists of three primary layers: The various pathological processes involving these layers are highlighted using case examples with fundoscopic correlation where appropriate.
The radiologist has an important role in primary diagnosis contributing to appropriate ophthalmology referral, thereby preventing devastating consequences such as vision loss. Majority of eye globe imaging is performed secondary to CT and MRI imaging of the brain for various reasons ranging from trauma to neoplasia. Recent advances in MR and CT technology that allows for detailed visualisation of the globe has resulted in frequent, incidental detection of abnormalities.
Non-contrast CT is useful in the initial evaluation of orbital and globe trauma for the assessment of fractures, extra-ocular muscle herniation and suspected globe rupture.
ALVARO LÓPEZ / LUPITA LÓPEZ TORERA
CT is the technique of choice for evaluating metallic or paramagnetic foreign bodies, whereas MRI is contraindicated due to potential migration and local heating. CT is also useful for evaluation of globe calcifications, especially in the case of retinoblastoma 1. MRI provides exquisite soft tissue contrast and the sclera can be distinguished from the choroid and retina.
Dedicated orbital MRI scans 1. Table 1 shows the common MRI characteristics of the various structures in the globe. High-resolution MRI facilitates evaluation of chorioretinal detachments and potential underlying neoplasms. The technique is limited by lengthy scanning time, increased cost compared to CT, and requirements for sedation in children and other non-compliant patient groups.
Eye Globe Abnormalities on MR and CT in Adults: An Anatomical Approach
In order to interpret the globe abnormality, a primary understanding of the globe anatomy is necessary. The differential diagnosis can be made easier and refined by categorising the abnormalities according to the layers and the compartments of the globe.
Knowledge of the imaging features of both traumatic and non-traumatic globe abnormalities is necessary to ensure appropriate ophthalmology referral and accurate diagnosis. In addition, knowledge of incidental degenerative changes, globe implants and fillers is important to prevent unnecessary work-up. The globe occupies one third of the orbital volume, with the vitreous humour representing two-thirds of the volume of the globe 2. The wall of the globe comprises three layers Fig. Lens black arrow and sclera white arrow show hypointense signal on all sequences.
Optic nerve is labeled dashed black arrow. Axial T1W image of right globe.
Occular and choroid appear as single hyperintense layer white arrow with enhancement on fat-saturated post contrast T1W image Cwhite arrow. Ciliary bodies form part of choroid dashed white arrows, B, C.
Approximate position of ora serrata is shown small white arrowheads. Anotated illustration of globe for comparison with MRI anatomy. The outermost fibrous coat constitutes the sclera and cornea. The sclera is enveloped by the fibroelastic Tenon’s capsule, which fuses with the bulbar conjunctiva and is perforated posteriorly by the optic nerve sheath. The episcleral space is a potential space that oculat extend between the fascia and the sclera 1.
corrida toreador – ZICC
The cornea is a key component of the refractive system and measures 0. On MRI, the cornea is a low signal intensity structure due to collagen but may be highlighted by an overlying slightly hyperintense tear film on T1W images. The sclera merges with the cornea at the limbus anteriorly. It is also composed of collagen, appearing hypointense on MRI and measuring up to 1 mm in thickness. The sclera maintains intraocular pressure and is the insertion site for the extra-ocular muscles.
The uveal tract consists of the iris, ciliary body and choroid. The uveal tract is highly vascular and contains pigmented melanocytes. The iris is a pigmented circular structure responsible for controlling the size of the pupil. It attaches to the ciliary body, which consists of the aqueous humour producing anterior pars plicata and the posterior pars plana. The ciliary body musculature attaches to the lens via the zonular fibers and is important for accommodation.
The choroid merges with the ciliary body at the ora serrata and extends posteriorly to the optic nerve head. This structure provides nourishment to the retina 4. The retina is the innermost sensory layer of the globe and consists of two layers.
The outer retinal pigment epithelium RPE is attached firmly to the choroid. The innermost sensory retina is responsible for visual perception. The layers are only tightly adherent at the optic disc and ora serrata where the RPE becomes continuous with the ciliary body. On MRI, the retina is in close apposition to the choroid in normal circumstances and cannot be discerned separately 1.
The vitreous body is a gel-like fluid bounded by the posterior and anterior hyaloid membranes. The lens forms the posterior boundary of the anterior chamber and is attached to the ciliary body via the zonular fibers. Effusions due to infection or inflammation of adjacent structures, traumatic hemorrhage and neoplasms including metastases can distend the episcleral space Figs. Bilateral episcleral fluid collections white asterisks with distortion of globes are likely due to scleral degeneration or necrosis.
Disruption of the sclera can result from trauma globe rupture Figs. Episcleritis is typically a self-limiting idiopathic disorder; whereas, scleritis is a more serious condition associated with connective tissue diseases such as rheumatoid arthritis.
Scleritis may be complicated by exudative chorioretinal detachment and glaucoma Fig. Buckling and defect in superior sclera Bwhite arrow with loss of globe volume is consistent with globe rupture.
Hypointense material in vitreous is suggestive of hemorrhage. The sclera is altered in thickness and shape throughout life. Sustained intraocular pressure in childhood can lead to diffuse enlargement of the globe buphthalmos ; where as in adults, the more rigid sclera results in focal protrusions staphylomasespecially in myopia Fig.
Other globe shape abnormalities include colobomas congenital defects in the layers of the globe including the optic disc and phthisis bulbi representing an end-stage atrophic globe Figs.
Other scleral findings include scleral banding for treatment of retinal detachment Figs. Bilateral focal protrusions through thinned sclera posteriorly are consistent with posterior staphylomas white arrows. Bilateral bands of hyperdensity that do not conform to insertions of extra-ocular muscles, are consistent with prior bilateral scleral bands for treatment of retinal detachment. However, characteristic concavity at site of banding is not seen in this case.
These calcifications represent normal part of aging. Scleral bands would appear more linear, as compared to punctate calcifications observed. The distinction between choroidal and retinal detachment is not always possible with MRI despite several known patterns. Anteriorly, choroidal detachments commonly extend into the ciliary body, whereas, retinal detachments are limited by the ora serrata.
Posteriorly, choroidal detachments are limited by the insertions of the vortex veins; whereas, retinal detachments are limited by the optic disc producing a characteristic V shape 1.
Fundoscopy facilitates detection of retinal detachments, while contrast-enhanced MRI plays an essential role in the assessment of an underlying cause such as a neoplasm. Subretinal fluid accumulation can occur in nonrhegmatogenous detachments secondary to underlying neoplasms and hemorrhage.
Gradual visual loss is the most common clinical finding. Rhegmatogenous detachments are commonly secondary to vitreous degeneration and traction on the retina. Choroidal black arrow and retinal dashed black arrow detachment is seen in left globe with underlying subchoroidal and subretinal fluid, respectively.
Ciliochoroidal detachment extends anterior to expected location of ora serrata Awhite arrows. Enhancement of choroid is noted Bwhite arrowwhich is expected in detachment due to inflammatory response. Enhancing lesion suggestive of neoplastic cause is absent. Right choroidal detachment is seen limited posteriorly at expected location of vortex vein insertion white arrow and extending anterior to ora serrata black arrow.
Enhancement of detached choroid is also apparent as in Figure Likewise, enhancing lesion suggestive of neoplastic cause is absent. Retinal detachments can be treated using scleral bands Figs. This patient had undergone silicone oil injection for treatment of retinal detachment.
Gas is noted in anterior vitreous compartment consistent with pneumatic retinopexy typically used in treatment of superior rhegmatogenous retinal detachments.
No history estallamieto trauma was noted. Malignant melanoma represents the most common intraocular malignancy in adults and occurs in the pigmented uveal tract 3. Other globe neoplasms also predominantly involve the highly vascular uveal tract and include metastases commonly breast and lungbenign neoplasms such as hemangiomas, and inflammatory processes such as sarcoidosis 6.
Malignant melanoma oculr most commonly unilateral and may present with pain or decreased visual acuity. Uveal melanomas are much less common than the cutaneous form.
The appearance of melanoma is non-uniform on imaging due to the varying levels of melanin. Amelanotic tumors have a similar appearance to other neoplasms on MRI. Occular CT, melanocytic melanomas appear slightly hyperdense and show contrast enhancement.
Axial T1WI shows lobulated hyperintense lesion arising in anteromedial left globe with endophytic extension into vitreous. Corresponding photograph shows pigmented lesion arising from inferomedial globe wall with surrounding hemorrhage. Histology was consistent with uveal melanoma. The vascular uveal tract is the most common site for hematogenously disseminated metastases within the globe Fig. Breast and lung are the most common primary neoplasms leading to metastases.
T1W images are useful to distinguish metastases from melanocytic melanoma with the exception of hyperintense hemorrhagic or mucinous adenocarcinomas 6.
Medial lesion shows contrast enhancement. Considerations include metastases highly likely estlalamiento clinical history with amelanocytic melanoma no T1W hypointensity; images not shownless likely differential.