ophthalmic and otic disorders Flashcards
what is glaucoma?
a group of eye disorder in which there is a progressive damage to the optic nerve - characterised by structural abnormalities of the optic nerve head + associated patterns of visual field loss
how is glaucoma classified?
variations in the anterior segment of the eye and appearance of iridocorneal angle - resulting in elevated IOP
what are the 4 types of glaucoma?
- open-angle
- closed-angle
- secondary
- developmental
What is the pathophysiology of chronic open-angle glaucoma?
- overproduction/obstruction to outflow of aq humour through trabecular meshwork or schlemm’s canal
- Increase IOP + damage to optic nerve
What is the pathophysiology of acute angle-closure glaucoma?
- There is an obstruction to the outflow of aq humour
- Narrow angles between the anterior iris and posterior corneal surface, shallow anterior chambers and a thickened iris or bulging iris.
- Increase in IOP
What is the pathophysiology of secondary glaucoma?
trauma and surgery which may increase risk of obstruction of intraocular fluid outflow
clinical presentation of chronic open-angle
- Mild aching
- Pattern of visual field changes (due to compression of retinal rods and nerve fibres)
- Halos around lights
- Often missed as a diagnosis
- Slow progression, painless and irreversible
- Visual acuity and peripheral vision loss w/ mobility difficulties.
clinical presentation of primary angle closure
- Ocular pain
- Redness, blurred vision
- Photophobia, halos around lights
- Nausea and vomiting
- Medical emergency
drugs that may induce open-angle
- Ophthalmic corticosteroids (high)
- Systemic corticosteroids
- nasal/inhaled corticosteroids
- Ophthalmic anticholinergics
drugs that may induce closed-angle
- Topical sympathomimetics
- Systemic anticholinergics
- Antihistamines
- Ipratropium
- Benzodiazepines (low risk)
- Theophylline (low risk)
- Heterocyclic antidepressants
how is glaucoma diagnosed?
- Pressure measurement tonometry
- Fingertip tension - estimates IOP
- Gentle palpation of closed eyelids, one eye feels heavier than the other in acute)
- Gonioscopy - determines angle of eye’s anterior chamber = differentiates whether acute or chronic
- Ophthalmoscopy - shows cupping of optic disk in chronic
- Perimetry or visual field test
- Fundus photography
how is chronic open-angle glaucoma managed?
GOAL OF TREATMENT
- Slow or halt progression so that any visual loss has least impact on QOL
- Reducing IOP with treatment options
- Medications should be the first choice for most patients
- Laser therapy
what is the indication for treatment in chronic open-angled glaucoma?
INDICATION FOR TREATMENT:
IOP > 25 mm Hg
Vertical cup-disk ratio > 0.5
Central corneal thickness < 555 micrometer
what are the therapeutics for chronic open-angle glaucoma?
IOP is determined by balance between inflow and outflow of aq humour:
- inflow is decreased by alpha2, alpha and beta adrenergic blockers; dopamine blockers; carbonic anhydrase inhibitors and adenylate
- outflow is increased by cholinergic agents, prostaglandin analogs and alpha2-adrenergic agonists
initial treatment for chronic open-angle
prostaglandin analogues and beta-blockers eye drops - first line
if these cannot be tolerated or contraindicated - alpha2 adrenergic agonists or carbonic anhydrase inhibitor should be considered.
practice point for the initial treatment of chronic open-angle glaucoma
- treatment is recommended to begin in one eye only (worst eye), using other eye as a control to test for effectiveness
- response to lowering IOP should be checked within 2-6 weeks
subsequent treatment for chronic open-angle
- depending on response to first treatment - either change in medication (inadequate response) or add topical agent
- increase dose of initial agent NOT recommended - only increases ADE
- switch to alternative agent within class or alternative class
- prostaglandin analogues (structurally different to each other)
what happens if there is an inadequate response with initial medication for chronic open-angle
- additional medication is added - HOWVER not from same class
- no combination with prostaglandin analogues and best to use topical and systemic beta blockers
- if more than 2 topical medications are required, suggest surgery or laser therapy
glaucoma response to therapy
- target IOP is 30-50% reduction in pre-treatment IOP
- continuing evaluation of optic disk and visual field
who are recommended to undergo laser trabeculoplasty based on Australian Guidlines?
older patients with open-angle glaucoma that have high risk of visual loss, difficulty in administering eye drops and are unresponsive to medication alone or are poor candidates for incisional surgery
when is it recommended to undergo surgery in glaucoma
- when the target IOP is not being achieved with two or more medications
- adherence is problematic
- when laser therapy has failed or is not likely to succeed
treatment for acute closed angle glaucoma
- ophthalmic emergency
- referral to ophthamologist
- peripheral laser iridotomy
drug therapy for acute closed-angle glaucoma
- prostaglandin analogues OR topical beta-blockers
- pilocarpine (topical)
- acetazolamide (orally)
- mannitol (4) or oral glycerol
- antiemetics
6/ opioid analgesia
what is AMD - ophthalmic disorder
age-related macular degeneration which is a progressive disease affecting central vision