other visual defects Flashcards by Evie Mander

what is emmetropia

where there is no refractive error - light is focused onto the retina

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what is ametropia

light is focused before or after the retina

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what is anisometropia

where there is a significant difference between the refractive error of the left and right eye

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another name for myopia

short sightedness

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what causes myopia

abnormally increased axial length of the eye or increased refraction

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pathophysiology of myopia

light focuses before the retina

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management of myopia

glasses with concave (negative) lenses

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complications of myopia (2)

retinal detachment
open-angle glaucoma

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another name for hypermetropia

far sightedness

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pathophysiology of hypermetropia

abnormally decreased axial length of the eye means light focuses behind the retina

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management of hypermetropia

glasses with convex (positive) lenses

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complication of hypermetropia

closed-angle glaucoma

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what is an astigmatism

irregular corneal curvature

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pathophysiology of astigmatism

eye has unequal refractive powers at different meridians of curvature

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management of astigmatism

cylindrical lenses

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what is presbyopia

age-related generation of structures responsible for accommodation of the lens

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management of presbyopia

reading glasses

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what is another name for strabismus

squint

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what is strabismus

where the eyes don’t align with each other when focusing on an object

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when does strabismus usually start

childhood

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name 3 risk factors for strabismus

premature birth
cerebral palsy
family history

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what can cause strabismus (5)

muscle dysfunction
farsightedness
problems in the brain
trauma
infection

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clinical sign of strabismus

corneal reflections are asymmetrical

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investigation for strabismus

cover test

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outward movement of the eye in cover test

esotropia

inward movement of eye in cover test

exotropia

downward movement of eye in cover test

hypertropia

upward movement of eye in cover test

hypotropia

complication of uncorrected squint during childhood

lazy eye

what is cataracts

opacifications within the lens

name some risk factors for cataracts

cumulative UVB damage hypertension smoking steroids diabetes genetic predisposition post operative / trauma

clinical presentation of cataracts

gradual visual loss - hazy/blurred glare

clinical sign of cataracts

loss of fundal reflex

management of cataracts

surgical removal with intra-ocular lens implant

most common ages for males to present with ocular trauma

25-34

mechanism of injury of ocular trauma in males

assault or machinery injuries

most common age for females to present with ocular trauma

>60

mechanism of injury of ocular trauma in females

falls at home

what is a blowout fracture

when there is a fracture of one of the walls of the orbit but the orbital rim remains intact

what usually causes a blowout fracture

direct blow to the central orbit from a fist or a ball

what is the most common type of blowout fracture

inferior blowout

mechanism of clinical presentation of an inferior blowout fracture

orbital fat prolapses into the maxillary sinus and may be joined by prolapse of the inferior rectus muscle, resulting in diplopia

what is subconjunctival haemorrhage

when one of the small blood vessels within the conjunctiva ruptures and release blood into the space between the sclera and the conjunctiva

when does subconjunctival haemorrhage usually appear

strenuous activity such as heavy coughing, weight lifting or straining when constipated

how long does it take for subconjunctival haemorrhage to resolve

around 2 weeks

what is a globe rupture

rupture of the sclera usually due to a direct penetrating injury

what is hypahemia

blood in the anterior chamber

state 4 site-threatening complications of trauma

- tearing of intra-ocular structures - dislocated lens - retinal detachment - commotio retinae

what is another name for commotio retinae

bruised retina

mechanism of injury of a corneal abrasion

poking, foreign bodies, brushing against the eye

investigations for corneal abrasions

visual acuity fluorescein staining

what must always be done with potential intraocular foreign bodies

x-ray

state 4 signs of a penetrating foreign body

- irregular pupil - shallow anterior chamber - localised cataract - gross inflammation

pathophysiology of sympathetic ophthalmia (2)

- Penetrating injury to one eye results in exposure of intra-ocular antigens → auto-immune reaction in both eyes - Inflammation in both eyes may lead to bilateral blindness (from a unilateral injury)

what kind of chemical burn is worse

alkaline

management of a chemical burn to the eye

irrigate - minimum 2L saline, or until pH normal

name 3 complications of chemical burns to the eye

limbal ischaemia corneal scarring corneal vascularisation

what characterises glaucoma

progressive optic neuropathy resulting in characteristic field defects

name the only modifiable risk factor for glaucoma

raised intraocular pressure

when does glaucoma occur

when there is a blockage in the drainage of aqueous humour through the trabecular meshwork

what is the most common type of glaucoma

chronic open-angle

name some risk factors for chronic open-angle glaucoma

hypertension, DM, corticosteroids myopia Afro-Caribbean ethnicity increasing age

what happens in chronic open-angle glaucoma

impaired aqueous humor drainage through the trabecular meshwork, causing elevated intraocular pressure this damages the optic nerve and causes peripheral visual field loss

clinical presentation of chronic open-angle glaucoma

usually asymptomatic - diagnosed through screening tests

fundoscopy of a patient with glaucoma

optic disc cupping pale optic disc

first line management of chronic open-angle glaucoma

prostaglandin analogues

name 2 second line drugs used in management of chronic open-angle glaucoma

β blockers, carbonic anhydrase inhibitors

what happens in closed angle glaucoma

blockage or narrowing of the drainage angle formed by the cornea and the iris, resulting in a sudden increase in intraocular pressure

risk factors for closed angle glaucoma

hyperopia Asian or Inuit pupillary dilatation

symptoms of angle-closure glaucoma (4)

pain blurred vision haloes N+V

clinical signs of closed-angle glaucoma

red eye hazy cornea mid-dilated pupil

definitive management of closed-angle glaucoma

laser peripheral iridotomy

pharmacological management of acute presentation of closed-angle glaucoma

pilocarpine 4% drops