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CCTs Year 3 > Eyes and ears (3) > Flashcards

Eyes and ears (3) Flashcards

1
Q

What’s:

  • amblyopia
  • ametropia
A
  • Amblyopia: uncorrectable poor vision without a structural abnormality.
  • Ametropia: refractive error so eye is unable to make light focus on retina. (Includes myopia and hypermetropia)
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2
Q

What’s:

  • anisometropia
  • anisocoria
A
  • Anisometropia: large difference in refractive errors between eyes.
  • Anisocoria: unequal sized pupils.
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3
Q

What’s astigmatism?

A

Astigmatism: eye’s optical system cannot produce a point of focus because of irregular shape of cornea -> so horizontal/vertical planes do not all coalesce at a single point on retina

*Can usually correct with cylindrical lens.

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4
Q

What’s:

  • emmetropia
  • hypermetropia
  • myopia
A
  • Emmetropia: normal eye, with light focusing on retina.
  • Hypermetropia (or hyperopia) (long-sightedness) where light is focused behind retina
  • Myopia (short-sightedness), where light is focused in front of retina (causing blurry distance vision)
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5
Q

What’s:

  • keratoconus
  • presbyopia
A
  • Keratoconus: progressive thinning of the cornea; rare cause of myopia and astigmatism: best corrected by rigid contact lenses
  • Presbyopia: lens less flexible because of age-related changes. Unable to do close-up tasks (e.g. reading)
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6
Q

Is raised pressure (and how much) suggestive of glaucoma?

A
  • Approx 50% all glaucoma have normal IOP.(< 21mm Hg)
  • Approx 10% population (without glaucoma) have IOP ≥ 21 mmHg. (= ocular hypertension)

Raised IOP is risk factor for glaucoma. Glaucoma ≠ raised IOP. Raised IOP ≠ glaucoma.

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7
Q

Difference in pathophysiology of closed vs open- angle glaucoma

A

Closed angle (rare) = trabecular network (irido-corneal angle – where aqueous flows out between iris and cornea) is blocked -> painful red eye, loss of vision, often sudden

Open angle (common) = meshwork not blocked but there is still not free flow through it and IOP rises (or not!)

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8
Q

Closed angle glaucoma - symptoms and what can trigger an attack

A

Symptoms

  • severe pain in eye, often around eye and frontal headache
  • Blurred vision, coloured haloes around lights (can get in mild, subacute attacks).
  • Malaise (nausea, vom).
  • Attack precipitants – mid-dilated pupil snags on lens -> build up of aqueous beneath it -> pushes iris further forward and blocks trabecular meshwork. So mid-dilation of pupil can provoke attack (stress, excitement, watching TV in dim light, anticholinergics, topical mydriatics)
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9
Q

Closed-angle glaucoma signs

A
  • Signs of Closed – unwell.
  • Red eye (ciliary flush – redness more marked around periphery of cornea).
  • Hazy cornea /pl. mglisty/
  • Non-reactive (or minimally reactive)
  • mid-dilated pupil
  • Palpation - globe hard.
  • Acute attack usually unilateral but long term Mx is both eyes. Emergency!
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10
Q

Open- angle glaucoma -> signs and symptoms

A
  • Usually asymptomatic (until late stage)
  • Signs of Open: Tonometry – measures IOP
  • optic discs – ratio of diameters of cup (pale centre) to whole disc. normal cup:disc = 0.3 ( but up to 0.7 can be normal).increase in cupping over time suggests glaucoma.
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11
Q

Treatment of closed angle glaucoma

A
  • Closed angle glaucoma -> Refer immediately
  • topical glaucoma Rx: IV acetazolamide -> to reduce secretions and pilocarpine (cholinergic) -> to induce pupillary constriction
  • Lay supine
  • Then – surgery or laser to re-establish drainage
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12
Q

Treatment of open-angle glaucoma (general, classes no names)

A

Open - angle glaucoma Rx:

  • reduce IOP
  • Topical Beta Blockers (1st) – decrease aqueous production in eye
  • OR topical prostaglandin analogue (2nd) (increase outflow)
  • Then sympathomimetic or carbonic anhydrase inhibitor (topical or oral acetazolamide) –> decrease aqueous production
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13
Q

What’s are the risks associated with cochlear implants?

A

Cochlear implants – option for severe (or worse) deafness if normal aid not helped.

  • Very small increased risk bacterial meningitis - hence need pneumococcal vaccine (all children should now get routinely anyway)
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14
Q

What are ‘bone anchored’ hearing aids used for?

A

Bone Anchored Hearing Aids – for conductive / mixed loss

  • titanium implant just behind ear, uses direct bone conduction
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15
Q

What’s the principle of autoinflation? What is it used for?

A

Autoinflation

  • child learning to blow up a balloon through their nostril rather than their mouth -> to hold open their eustachian tube -> pressure in their middle ear to equalise with atmospheric pressure
  • can prescribe or buy OTC special devices (e.g. Otovents, about £7 from pharmacies or £4.90 to the NHS) that consist of a plastic nozzle and a couple of balloons. Can’t use normal balloons as they are too hard to blow up
  • Use it three times daily (ideally). One balloon lasts 3-4 days so a pack lasts 2 weeks.
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16
Q

What’s Meniere’s disease?

  • cause
  • some symptoms
A

Meniere’s disease

Meniere’s disease is a disorder of the inner ear of unknown cause. It is characterised by excessive pressure and progressive dilation of the endolymphatic system.

  • vertigo, tinnitus and hearing loss
  • Symptoms resolve between attacks -> but a degree of hearing loss may occur
  • Acute attacks last 5–15mins, then burn out leaving disequilibrium, tinnitus and moderate hearing loss
17
Q

Diagnosis of Meniere’s disease - what Ix and finding confirm it?

What further Ix are needed and why?

A
  • History and an audiogram showing low frequency hearing loss will make the diagnosis
  • Referral is recommended for MRI to rule out acoustic neuroma
  • DVLA must be informed if attacks are sudden and disabling
18
Q

What are the drugs that cause ototoxicity?

A

Drugs: aminoglycosides, cis-platinum, salicylates, quinine, some loop diuretics, macrolides

  • May have long term hearing impairment but if have associated balance disturbance that usually improves (central compensation)
19
Q

What happens in Otosclerosis? (pathophysiology)

A

Otosclerosis

Otosclerosis describes the replacement of normal bone by vascular spongy bone.

  • slowly progressing conductive hearing loss -> as stapes fixates on the oval window
  • may extend into cochlea -> mixed conductive and SN hearing loss
20
Q

Causes and risk factors of otosclerosis

A
  • Inherited - autosomal dominant, but variable penetrance plus environmental factors
  • measles can cause (incidence declining with vaccination)

Risk factors: white and Asian, women, age (teens to middle age), FH

21
Q

Symptoms suggestive of otosclerosis

A

Sx of *otosclerosis*:

  • progressive hearing loss and tinnitus
  • usually low tone loss
  • may have low volume speech due to enhanced bone conduction -> perceive own speech as loud
22
Q

Ix for otosclerosis

A

Ix in *otosclerosis*:

  • Audiogram - conductive hearing loss

Carhart’s notch = drop in bone conduction threshold of 20-30 dB esp at 2 kHz.

  • Tympanogram may show ‘stiffness curve’
  • CT
23
Q

What prostaglandins analogues (name examples) are used for Rx of glaucoma?

A

Prostaglandin Analogues

  • Latanoprost, bimatoprost, travoprost, tafluprost
  • work by increasing the outflow of fluid from the eye
24
Q

Side effects of prostaglandin analogues use in glaucoma Rx

A

Side effects include:

  • possible changes in eye colour and eyelid skin
  • stinging. itching, burning
  • blurred vision
  • eye redness
25
Q

What is the name of beta-blocker used to Rx glaucoma?

A

Beta blockers such as timolol are the second most often used class of topical medication for glaucoma

26
Q

MoA of B-blocker use in glaucoma

A

Topical beta-blockers -> reduce the intraocular pressure (IOP) by

  • blockade of sympathetic nerve endings in the ciliary epithelium -> a fall in aqueous humour production.
27
Q

Side effects of Timolol use

A

Timolol= beta-blocker used in glaucoma Rx

Side effects include:

  • low blood pressure,
  • reduced pulse rate
  • fatigue, shortness of breath

*rarely: reduced libido, depression

* The systemic side effects of beta blockers can be minimized by closing the eyes following application or using a technique called punctal occlusion that prevents the drug from entering the tear drainage duct and systemic circulation.

28
Q

What is the name of alpha-agonist that may be used in Rx of glaucoma?

  • MoA
  • side effects
A
  • Alpha agonist = brimonidine
  • MoA: work to both decrease production of fluid and increase drainage.

They act by decreasing aqueous humour secretion and increasing uveoscleral outflow

  • Side effects: burning or stinging, fatigue, headache, drowsiness, dry mouth and nose, relatively higher likelihood of allergic reaction
29
Q

Acetazolamide in glaucoma treatment

  • class
  • MoA
  • side effects
A

Acetazolamide - carbonic anhydrase inhibitor

  • Mechanism of action: for the reduction of Intraocular pressure

Acetazolamide inactivates carbonic anhydrase and interferes with the sodium pump, which decreases aqueous humour formation and thus lowers IOP .

  • Side effects: stinging, burning, eye discomfort
30
Q

Acetazolamide use in altitude sickness

A

Acetazolamide (or Diamox)

  • prophylaxis agent for high altitude illness
  • The medication is effective in preventing acute mountain sickness (AMS), high altitude pulmonary oedema (HAPE), and high altitude cerebral oedema (HACE).

MoA: inhibition of the carbonic anhydrase enzyme -> counteracts the respiratory alkalosis which occurs during ascent to altitude -> It facilitates the excretion of bicarbonate in the urine -> as a result, acetazolamide hastens acclimatization and helps prevent high altitude disorders

31
Q
A
32
Q

Features of Meniere’s disease

A
  • recurrent episodes of vertigo, tinnitus and hearing loss (sensorineural). Vertigo is usually the prominent symptom
  • a sensation of aural fullness or pressure is now recognised as being common
  • other features include nystagmus and a positive Romberg test
  • episodes last minutes to hours
  • typically symptoms are unilateral but bilateral symptoms may develop after a number of years
33
Q

Management of Meniere’s disease

A
  • ENT assessment is required to confirm the diagnosis​
  • acute attacks: buccal or intramuscular prochlorperazine (dopamine antagonist/anti psychotic). Admission is sometimes required
  • prevention: betahistine (H1 receptor agonist -> improves blood flow to the inner ear) and vestibular rehabilitation exercises may be of benefit
  • patients should inform the DVLA. The current advice is to cease driving until satisfactory control of symptoms is achieved

CCTs Year 3 (14 decks)

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