Flipped Classrooms - meags.pdf

FLIPPED CLASSROOMS 1 Coloboma Clinical presentation !"#$%&'%&$(%)%Incomplete formation of an ocular structure due to incomplete fusion of the optic fissure !"*+%,-*'%&$%.-/0(%)%Forms during the 5th-6th week of gestation while the optic fissure is closing. What causes colobo...

FLIPPED CLASSROOMS 1 Coloboma Clinical presentation !"#$%&'%&$(%)%Incomplete formation of an ocular structure due to incomplete fusion of the optic fissure !"*+%,-*'%&$%.-/0(%)%Forms during the 5th-6th week of gestation while the optic fissure is closing. What causes coloboma Abnormal changed genes that affect eye development External factors leading to trauma = mother drinking alcohol, drugs etc. Genetic ○ Won’t just affect the eye ○ Usually syndromic and have severe developmental defects Mostly unknown What eye structures can be affected? Iris 1&2&#/3%4-,3%)%54'*+6*%-.%7-+82*'%6#8'*%'*90*+$#2%6-+$/#6$&-+%-.%2*+' :*$&+#%)%1#+%*;$*+,%&,'?%@&'&-+(%)%Depends on lens, optic nerve, chorioretinal Will my next child have coloboma? Isolated colomba is usually not inherited Syndromic colomba is inherited *if inherited can be autosomal dominant/recessive or X-linked (rare) Germ layers involved Neuroepithelium (retina, iris, optic nerve) Surface ectoderm (corneal epithelium, lens) Extraocular mesenchyme (corneal stroma and epithelium, EOM, choroid, sclera) Other eye tests to perform Visual acuity Refraction (association with anisometropia) Slit lamp examination of the anterior segment Dilated fundus examination Visual fields (Age dependent) Check bilaterally (bilateral uveal coloboma, refer for systemic disorder check) 2 Orbital Fracture Clinical presentation Signs Periorbital oedema Lack of eye elevation Depression of the globe Enophthalmos – posterior displacement of globe Symptoms Pain (may develop numbness due to infraorbital nerve injury), teary, reduced vision, diplopia Which bone/bones are most likely to be affected? Bones of the floor (palatine, zygomatic, maxillary) Bones of the medial (maxillary, ethmoid, lacrimal, body of sphenoid, frontal) Which muscle/muscles are most likely to be affected? Inferior rectus and/or inferior oblique most likely ○ Entrapment is the most common (occurs when any orbital tissue is trapped due to the septa coursing the orbit) ○ Retrobulbar haemorrhage (leads to compression or ischaemia of the optic nerve) can also result in nonspecific, variable EOM abnormality. Superior rectus least likely ○ Palsy due to direct injury or CNIII palsy Which artery/arteries are most likely to be affected? Angular artery Facial artery Transverse facial artery Lateral palpebral artery Superficial temporal artery Inferior marginal arterial arcade Infraorbital artery Conjunctiva ○ The muscular, medial palpebral, and lacrimal branches of the ophthalmic artery ○ The anterior ciliary arteries, derived from the muscular branches serving the rectus muscles supply the perilimbal conjunctiva EOM ○ Ophthalmic artery branches to lateral muscular branch (superior) and medial muscular branch (inferior) 3 Eye Alignment: Phoria Testing eye-alignment Cover-uncover test ○ Watch for movement of the covered eye upon removing cover ○ Deviation from alignment when fusion is broken ○ Subject needs to fixate on a central point throughout the test 4 Conjunctival lumps and bumps Clinical presentation Condition Image Pinguecula Pterygium Conjunctival intraepithelial neoplasia (CIN) Squamous conjunctival carcinoma 5 Angle Recession What is it? Posterior displacement of the iris root. Separation between the longitudinal and circular muscle of the ciliary body (commonly caused by blunt injury to the eye) Pathophysiology Ocular blunt force trauma 1. Blunt force delivered initiates an anterior to post axial compression with equatorial expansion. 2. Transient anatomic deformity results in a shearing force applied to angle structures which disrupts the weakest points. 3. The common site involves the ciliary muscle. Ciliary body is torn, but longitudinal muscle remains attached to the insertion scleral spur, while pars plicata and iris root is displaced posteriorly. Summarised explanation: separation between longitudinal and circular fibres of the ciliary body muscle. Longitudinal muscle fibres remain attached to scleral spur. What angle structures are involved? Separation between the longitudinal and circular fibres of the ciliary body muscle Longitudinal muscle fibres remain attached to the scleral spur Leads to the posterior displacement of the iris roo What is the effect on intraocular pressure? Increase in IOP due to compromised drainage Caused by degenerative damage and subsequent inflammation of the trabecular meshwork The greater the circumferential angle of ciliary body affected the greater the risk of increased IOP IOP typically becomes elevated either within the first year, or 10 years after the trauma Glaucoma only occurs in 7-9% of people with angle recession Corneal endothelium/Descemet’s may also be induced to grow over the angle 6 Iridocorneal endothelial (ICE) syndrome Clinical presentation What is it? A rare eye condition characterised by abnormal corneal endothelium Three clinical categories ○ Cogan-ReeseSyndrome ○ Chandler’s syndrome ○ Essential iris atrophy Pathophysiology Abnormal corneal endothelial cells proliferate and migrate to the anterior chamber angle and onto the iris surface. ○ Typically unilateral ○ Cause unknown, possibly triggered by Epstein-Barr virus or herpes simplex virus. Resulting in corneal swelling ○ Leads to peripheral anterior synechiae ○ Pleomorphism (variability in size and shape) and polymegathism (variability in size) of endothelial cells What angle structures are involved? Endothelial cells proliferate over ALL structures of the angle Proliferate over Schwalbe’s line, across trabecular beams, and over the scleral spur and ciliary body to the iris Peripheral anterior synechiae form What is the effect on intraocular pressure? Proliferation of endothelial membrane over the anterior chamber angle and progressive peripheral anterior synechiae formation Leads to reduced aqueous outflow Results in increased IOP and eventually glaucoma development 7 Diabetic cataract Clinical presentation Decreased distance and near vision Info Direct mechanism unknown Intralenticular accumulation of sorbitol ○ Major osmotic change due to increased sorbitol leads to water being drawn into lens (disrupts fibres) Osmotic stress !"#$%&##"&'()*+,#-./"%&$./0+0-"1"2%&&"%,(./,+"3&'&%,$.)' Osmotic stress from sorbitol accumulation in the lens"!",*)*$)#.#")2"+&'#"&*.$4&+.,+" /&++# 8 Diabetic myopic shift Decreased distance vision Info During hyperglycemia (increased blood sugar levels) there is usually a myopic shift in refraction Thought to be due to increased sugar levels in the lens (especially sorbitol) ○ Increased refractive index ○ Increased lens thickness ○ Increased lens curvature 9 Presbyopia Decreased distance vision Cause Ageing Due to increase in lens stiffness Ciliary muscle (inner apex moves forward with age, and more connective tissue between muscle fibres) Capsule (thicker, less extensible, and more brittle) Cortex (increased cortical fibres leads to increased axial thickness, increased stiffness) 10 Nuclear Sclerotic Cataract Clinical presentation Info Most common Yellowing & hardening of the centre (i.e. nucleus) of the lens May result in myopic shift (increase lens refractive power, causing myopia) Looking through a yellow filter 11 Cortical Cataract Clinical presentation Info Opacification of the lens fibre surrounding the nucleus Radial, spoke-like opacity originating from the outer lens. Progress towards lens centre Impact on vision dependent on proximity to visual axis 12 Posterior subcapsular cataract Clinical presentation Info Opacification of the lens at the posterior cortex, next to lens capsule More visually debilitating than nuclear or cortical cataract b/c cataract at nodal point of the eye Glare Faster progression 13 Visual Pathway 14 Visual Pathway - Case 1 Clinical tests History – ask about glaucoma med compliance Visual acuity Anterior eye? Gonioscopy? IOP Optic disk exam with slit lamp vs. direct ophthalmoscopy ○ Cup to disk ratio ○ ISNT rule Perimetry OCT – F/U if seen before Which eye? Left eye What has happened at the point indicated by the arrow? Notch (not a leaky optic disc whoever said that is stoopid (i think leaky is a reasonable explanation)) ISNT rule is not being followed in this eye The inferior portion of the optic nerve is thinner, while in a normal eye it is usually the thiccest Loss of retinal ganglion cell fibres in the neuroretinal rim Inferior loss corresponds to inferior macula/inferotemporal retina Almost complete loss as cup extends out towards edge of disc Possibly some sparing of fibres originating from further away from optic cup, as some outer neuroretinal rim is spared Effect on visual field Loss of peripheral vision 15 Visual Pathway - Case 2 Where is the lesion most likely? Bitemporal defect, respecting vertical midline Optic chiasm What is your reasoning 16 Visual Pathway - Case 3 Where is the lesion most likely located? Pre-chiasmal, as crosses vertical midline Therefore retina/optic nerve E.g. vascular incident near ONH can lead to an altitudinal defect Anterior ischaemic optic neuritis (ON) Branch retinal artery occlusion (retina) 17