Eyes and ears (3)

Question 1

What’s:

• amblyopia
• ametropia

Answer 1

• 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)

Question 2

What’s:

• anisometropia
• anisocoria

Answer 2

• Anisometropia: large difference in refractive errors between eyes.
• Anisocoria: unequal sized pupils.

Question 3

What’s astigmatism?

Answer 3

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.

Question 4

What’s:

• emmetropia
• hypermetropia
• myopia

Answer 4

• 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)

Question 5

What’s:

• keratoconus
• presbyopia

Answer 5

• 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)

Question 6

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

Answer 6

• 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.

Question 7

Difference in pathophysiology of closed vs open- angle glaucoma

Answer 7

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!)

Question 8

Closed angle glaucoma - symptoms and what can trigger an attack

Answer 8

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)

Question 9

Closed-angle glaucoma signs

Answer 9

• 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!

Question 10

Open- angle glaucoma -> signs and symptoms

Answer 10

• 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.

Question 11

Treatment of closed angle glaucoma

Answer 11

• 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

Question 12

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

Answer 12

Open - angle glaucoma Rx:

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

Question 13

What’s are the risks associated with cochlear implants?

Answer 13

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)

Question 14

What are ‘bone anchored’ hearing aids used for?

Answer 14

Bone Anchored Hearing Aids – for conductive / mixed loss

• titanium implant just behind ear, uses direct bone conduction

Question 15

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

Answer 15

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.

Question 16

What’s Meniere’s disease?

• cause
• some symptoms

Answer 16

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

Question 17

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

What further Ix are needed and why?

Answer 17

• 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

Question 18

What are the drugs that cause ototoxicity?

Answer 18

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)

Question 19

What happens in Otosclerosis? (pathophysiology)

Answer 19

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

Question 20

Causes and risk factors of otosclerosis

Answer 20

• 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

Question 21

Symptoms suggestive of otosclerosis

Answer 21

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

Question 22

Ix for otosclerosis

Answer 22

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

Question 23

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

Answer 23

Prostaglandin Analogues

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

Question 24

Side effects of prostaglandin analogues use in glaucoma Rx

Answer 24

Side effects include:

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

Question 25

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

Answer 25

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

Question 26

MoA of B-blocker use in ***glaucoma***

Answer 26

**Topical beta-blockers -\>** reduce the intraocular pressure (IOP) by * blockade of sympathetic nerve endings in the ciliary epithelium **-\>** a fall in aqueous humour production.

Question 27

Side effects of ***Timolol*** use

Answer 27

***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.

Question 28

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

Answer 28

* **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

Question 29

***Acetazolamide*** in **glaucoma** treatment - class - MoA - side effects

Answer 29

***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

Question 30

***Acetazolamide*** use in altitude sickness

Answer 30

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

Question 32

Features of Meniere's disease

Answer 32

* **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

Question 33

Management of ***Meniere's disease***

Answer 33

* 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