Orbit Anatomy and Ocular Injuries MCQs

Alkali (penetrate inside) burns are more severe as compared to acid(coagulate on surface) Corneal epithelial and stromal damage by coagulase enzyme released by damaged epithelium and cause a lot of inflammation. Limbal ischaemia results from loss of stem cells. Vascularisation and conjuctivalisation of cornea occurs. Severe cases can have corneal ulceration and perforation. Reference: 9th/e kanski chapter 22 trauma pg. 912 chemical injury

Chalcosis, also called chalcosis bulbi, is a chronic reaction to a copper-containing intraocular foreign body (IOFB) When copper enters the eye, it is oxidized from its uncharged elemental form, Cu, to Cu 2+ ions. Though the ions are free to diffuse throughout the vitreous, they have a propensity to deposit in intraocular basement membranes including Descemet's membrane of the cornea (KF ring) and the internal limiting membrane (ILM) Foreign bodies containing less copper ( 85%) show a generalized pattern of intraocular copper deposition and are associated with more devastating outcomes such as suppurative endophthalmitis and phthisis bulbi. Reference: 9th/e kanski chapter 22 trauma pg. 911 IOFB

Commotio retinae Commotio retinae is caused by concussion of the sensory retina resulting in cloudy swelling that gives the involved area a grey appearance. It most frequently affects the temporal fundus. If the macula is involved, a 'cherry-red spot' may be seen at the fovea. Severe involvement may be associated with intraretinal haemorrhage that can involve the macula. The prognosis in mild cases is good, with spontaneous resolution in around 6 weeks. Sequelae to more severe commotio may include progressive pigmentary degeneration and macular hole formation Reference: Kanski 8th edition/873

Intra ocular foreign body is due to penetrating injury. Other options mentioned here are due to blunt trauma. Reference: 9th/e kanski chapter 22 trauma pg. 899 blunt trauma

The depth of the orbit varies from 40 to 45 mm from the orbital entrance to the orbital apex. The distance to the apex becomes important in the dissection or excision of a tumor in the posterior orbit or in the repair of an extensive blowout fracture Reference : kurana 4/e, p. 48

Blunt trauma may result in a variety of retinal breaks including retinal dialyses, macular holes, giant retinal tears, horseshoe retinal tears, operculated retinal tears, and large, necrotic, sometimes posterior retinal breaks often associated with chorioretinitis sclopetaria. Retinal dialyses, however, are the most common retinal breaks found following blunt ocular trauma. Retinal dialyses resulting from blunt trauma are most often found in the inferotemporal and superonasal quadrants. All patients with a history of blunt trauma need to be given a careful retinal examination with scleral depression to look for retinal breaks after their pain, iritis, or hyphema, if any, has resolved. Reference: Kanski 8th edition/873

Medial orbital wall fractures often cause enophthalmos and/or medial rectus entrapment with restrictive strabismus, both of which are indications for surgical repair. Reference: Kanski 8th edition/866

The most common site of entry of an IOFB is the cornea (82.9%) followed by the sclera (11.4%), and the limbus (5.7%). The most common location of an intraocular foreign body lodged in the posterior segment is intravitreal (61%), followed by intra-retinal (14%) and sub-retinal(5%). Reference: 9th/e kanski chapter 22 trauma pg. 911 IOFB