Disease Profiles: Other Visual Defects Flashcards
What is sympathetic opthalmia?
Penetrating injury to one eye results in exposure of intra-ocular antigens results in an auto-immune reaction in both eyes
Inflammation in both eyes may lead to bilateral blindness (from a unilateral injury)
Name 4 sight-threatening complications of ocular trauma
Tearing of intra-ocular structures
Dislocated lens
Retinal detachment
Commotio retinae (bruised retina)
Describe the management of a corneal abrasion
Remove any foreign bodies
Consider the need for analgesia or ocular lubricants
Consider prescribing chloramphenicol if risk of infection
Define anisometrophia
Significant difference between right and left ametropia
Describe the clinical presentation of cataracts
Gradual visual loss (‘hazy’/’blurred’)
What causes a subconjunctival haemorrhage?
Often appear after episodes of strenuous activity such as heavy coughing, weight lifting or straining when constipated
It can also be caused by trauma to the eye
An inward movement of the uncovered eye during a cover test indicates what type of strabismus?
Exotropia
Describe the management of hyperophia
Glasses with convex (positive) lenses
Name 3 risk factors for the development of cataracts
Hypertension, steroids, metabolic disorders e.g. diabetes
Which ocular muscle is most at risk of entrapment following an orbital blowout fracture?
Inferior rectus muscle - results in diplopia
Describe the clinical signs of a patient with a penetrating foreign body in their eye
Irregular pupil
Shallow anterior chamber
Localised cataract
Gross inflammation
What is traumatic uveitis?
Inflammation of the iris caused by eye trauma
What is a corneal abrasion?
Trauma resulting in the removal of a focal area of epithelium on the cornea
Name two risk factors for the development of glaucoma
Raised intraocular pressure is currently the only modifiable risk factor
Increased incidence with age
What can fluorescein help with in regards to a corneal abrasion?
Fluorescein stain can be used to aid in viewing of the abrasion through opthalmosope/slit lamp
What causes presbyopia?
Age-related degeneration of structures responsible for accomodation of the lens
Describe the management of astigmatism
Correction with cylindrical lenses
Describe the management of primary open-angle glaucoma
First line - prostanoids e.g. latanoprost (‘xalatan’)
Second line - β blockers, carbonic anhydrase inhibitors
Others - ⍺2 adrenergic agonist, parasympathomimetics, combination eyedrops
What is the definitive management of closed-angle glaucoma?
Laser peripheral iridotomy
Describe the clinical presentation of open-angle glaucoma
Usually asymptomatic, screened for by optometrists
Define ametrophia
Retractive error present, light focussed in front of retina or behind retina
What causes glaucoma?
Glaucoma occurs when there is a blockage in the drainage through the trabecular meshwork or in the Canal of Schlemm
What causes a corneal abrasion?
Abrasions usually occur when the eye is accidently poked with a finger, a foreign body flies into the eye or something brushes against the eye
An outward movement of the uncovered eye during a cover test indicates what type of strabismus?
Esotropia
What causes astigmatism?
Eye has unequal refractive powers at different meridians of curvature
Describe the management of acutely presenting closed-angle glaucoma
Lower IOP quickly with drops/oral medication to prevent the patient from going blind
How would you prevent an infant with strabismus from developing amblyopia (cortical blindness, ‘lazy eye’)?
Cover infant’s good eye with a patch for a few hours each day so that the brain must rely on signals from the bad eye
Helps the brain develop properly to process signals coming from both eyes until infant is old enough for surgery
Describe the clinical presentation of astigmatism
Causes distorted vision at all distances
What is a refractive error?
Refers to any abnormality in the focusing mechanism of the eye
Define cataracts
Opacifications within the lens
Describe the clinical signs of open-angle glaucoma
Visual field defect, may or may not have high IOP
A downward movement of the uncovered eye during a cover test indicates what type of strabismus?
Hypertropia
What causes hyperophia (far-sightedness)?
Abnormally decreased axial length of eye means light focuses in behind the retina
Describe the management of myopia
Glasses with concave (negative) lenses
At what age is strabismus most likely to develop?
Commonly onset is in childhood, can start in adulthood but this is less common
Describe the clinical presentation of closed-angle glaucoma
1/3 present as an emergency - acute red eye and visual loss, headache and N+V
Name two complications associated with hyperophia
Complications related to smaller eyeball size - closed angle glaucoma
Describe the management of cataracts
Surgical removal with intra-ocular lens implant if patient is symptomatic
Define emmetropia
No refractive error, light focussed onto retina
An upward movement of the uncovered eye during a cover test indicates what type of strabismus?
Hypotropia
What is a subconjunctival haemorrhage?
Occurs when one of the small blood vessels within the conjunctiva ruptures and release blood into the space between the sclera and the conjunctiva
Describe the clinical presentation of myopia
Clear near vision, blurred far vision
Describe the management of presbyopia
Requires a supplementary convex or positive lens (i.e. reading glasses) in order to focus light from a near object onto the retina
What is an orbital blowout fracture?
Occurs when there is a fracture of one of the walls of the orbit but the orbital rim remains intact; typically caused by a direct blow to the central orbit from a fist or a ball
Name 3 risk factors for the development of strabismus
Premature birth, cerebral palsy and a family history of the condition
Describe the immediate management of a chemical burn to the eye?
Quick history, check pH, irrigate minimum 2L saline, or until pH normal, then assess using slit lamp
What causes strabismus?
Can occur due to muscle dysfunction, farsightedness, problems in the brain, trauma or infections
Describe the clinical presentation of hyperophia
Blurred near vision, clear far vision
In a patient with strabismus, corneal reflections will be _________
Asymmetrical
What causes a globe rupture?
More commonly occurs after direct penetrating trauma but if sufficient blunt force is applied to the eye the intraocular pressure can increase enough to rupture the sclera
Name two complications associated with myopia
Complications related to larger eyeball size - retinal detachment, primary open angle glaucoma
What causes myopia (short-sightedness)?
Abnormally increased axial length of eye or, less commonly, increased refraction means light focuses in front of the retina
Define strabismus (squint)
Ophthalmic condition in which the eyes do not properly align with each other when focusing to look at an object (i.e. poor fusion)
What causes open angled glaucoma?
Result of poor drainage through trabecular meshwork
Slow onset, often asymptomatic and now screened for
How do glaucoma drops work?
Either decrease aqueous production or increase drainage
What causes cataracts?
Many different causes, often age-related
Describe the fundoscopy findings associated with glaumcoma
Cupped disc (increased cup-to-disc ratio) indicates a reduced volume of healthy neuro-retinal tissue, which can occur in glaucoma
Define glaucoma
A group of chronic diseases characterised by a progressive optic neuropathy resulting in characteristic field defects
What causes closed angled glaucoma?
Drainage through meshwork is patent
Aqueous humour encounters resistance through iris/lens channel
Increased pressure gradient causes peripheral iris to bow forward, obstructing trabecular meshwork → pressure increases
Describe the clinical presentation of strabismus
Misalignment of the eyes
Reduced visual acuity
Diplopia
Asthenopia (i.e. eye strain, fatigue or pain), particularly in the afternoon or at the end of the day
Describe the management of strabismus
Depends on type of strabismus and the underlying cause; may include the use of glasses and possibly surgery
What is hyphaemia?
Blood in the anterior chamber, sign of fairly significant intra-ocular trauma
Describe the clinical presentation of presbyopia
Similar to hyperopia - blurred near vision, clear far vision
Preexisting myopia may temporarily compensate presbyopia, leading to better near vision
What might a pale optic disc indicate on fundoscopy of a patient with glaucoma?
A pale optic disc suggests the presence of optic atrophy, which can result from advanced glaucoma
Describe the clinical signs of closed-angle glaucoma
Red eye, cloudy cornea, dilated pupil
What causes rubeotic glaucoma?
New vessel formation in diabetic eye disease forms obstructive angle (rare and late complicatiom
How can diabetes predispose to the development of cataracts?
Changes to osmotic pressures and altering of fluid content in lens damages epithelial cells and fibres
