Common Conditions of the Eye Flashcards

1
Q

What is the aetiology of cataract formation?

A

Lens fibres absorb harmful UV rays, preventing them from damaging the retina, but causing damage to themselves in the process. Damage to the fibres of the lens leads to opacification and cataract formation

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2
Q

How does the lens develop in basic terms?

A

Older embryological fibres are never shed from the eys and compact in the middle. They receive no blood supply, instead rely on diffusion for nutrition

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3
Q

Give some causes of secondary cataracts

A

Steroid-induced
Traumatic
Sutural & zonular - childhood

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4
Q

Do eye drops treat cataracts?

A

No

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5
Q

What is the treatment for cataracts?

A

Day case surgery, plastic lens in bag replaces damaged lens

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6
Q

What is the name for lens implant after cataract surgery?

A

Posterior Chamber Intra Ocular Lens - PCIOL

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7
Q

What is glaucoma?

A

Raised intraocular pressure
The 2nd most common global cause of blindness
Most common form is primary open angle glaucoma - POAG

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8
Q

What are the consequences of raised IOP?

A

Pressure on nerve fibres on surface of retina causes the retinal fibres to die out resulting in visual field defects
The nerve fibres die out and there is pressure on the optic nerve. When visualised the optic disc appears unhealthy, pale and cupped
The result is an altered field of vision, with the nerve fibre loss progressing until the result is total blindness

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9
Q

What is the ‘triad’ of signs for glaucoma diagnosis?

A

Raised IOP
Visual field defects
Optic disk changes on ophthalmoscopy

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10
Q

Management of POpenAG?

A

Eye drops to decrease IOP
Laser trabeculoplasty
Trabeculectomy surgery

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11
Q

What are the signs of angle closure glaucoma?

A

Sudden onset, painful, loss or blurring of vision, headaches - often confused with migraine
Red eye, cornea often opaque due to raised IOP driving fluid into cornea. Anterior chamber shallow, angle closed. Pupil mid-dilated, IOP severely raised

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12
Q

Management of acute angle closure glaucoma?

A

Decrease IOP - IV infusion with or without oral therapy, analgesics, antiemetics, constrictor eye drops, BBlockers if no contraindication, steroid eye drops
Iridotomy (laser) - both eyes, to bypass blockage

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13
Q

Why does the angle close and cause AC glaucoma?

A
  1. Functional blockage in a small eye - large lens
  2. Mid-dilated pupil -> periphery of iris crowds around angle and outflow is obstructed
  3. Iris sticks to the pupillary border (synechia) and fluid cannot reach AC. Iris balloons anteriorly and obstructs angle
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14
Q

Describe the process of POAG?

A

Drainage through the trabecular meshwork is impaired (in most cases). This leads to a gradual painless build up of IOP. NB: SOME FLUID CAN STILL ESCAPE SO IOP INCREASE IS GRADUAL

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15
Q

Describe the process of angle closure glaucoma

A

Some event on a predisposed eye leads to the peripheral iris blocking the angle, therefore aqueous humour cannot drain. Raised IOP is therefore sudden and leads to red eye and severe pain - usually present as emergency

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16
Q

What epithelium is found in the cornea?

A

Stratified squamous non-keratinised

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17
Q

Describe the layers of the cornea

A

Epithelium
Bowman’s membrane (basement membrane of epithelium)
Stroma - regularly arranged collagen, no blood vessels
Descemet’s layer
Endothelium - single layer

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18
Q

What are the two general forms of corneal pathology?

A

Inflammatory

Non-inflammatory

19
Q

What is keratoplasty?

A

Corneal transplantation

20
Q

Describe a corneal ulcer

A

Inflammatory
Infection - of the cornea via viral/bacterial/fungal. Needs aggressive treatment to stop spread and scarring

Non-infectious - due to trauma, corneal degerations, dystrophy

21
Q

Describe corneal dystrophy

A

Non-inflammatory

Group of diseases which are all:
Bilateral
Opacifying
Non-inflammatory
Genetically determined (mostly)
Sometimes due to accumulation of substances such as lipids in the cornea
22
Q

Describe the clinical presentation of corneal dystrophies

A

First to fourth decade
Most commonly with decreased vision
Start in one layer of the cornea and spread to others

23
Q

Give two examples of corneal dystrophies

A

Lattice (stromal) dystrophy

Fuch’s endothelial dystrophy

24
Q

Describe lattice (stromal) dystrophy

A

The classic type is autosomal dominant

Results in deposition of amyloid material in the corneal stroma

25
Q

What is the clinical presentation of lattice (stromal) dystrophy?

A

Eye irritation, photosensitivity, pain, blurred vision

26
Q

What is shown on examination of patients with lattice (stromal) dystrophy?

A

Bilateral criss-crossing opacities in the stroma of the cornea

27
Q

What is the management for lattice (stromal) dystrophy?

A

Manage symptoms, in late stages keratoplasty

28
Q

Describe Fuch’s endothelial dystrophy

A

Asymmetrical bilateral progressive oedema of the cornea
Occurs in the elderly- 60-70yrs
Due to destruction and death of the endothelial cells
When the number of functioning cells falls below the critical number required to keep the cornea clear, oedema occurs and is followed by opacification of the cornea

29
Q

What special features does the cornea posses, of particular relevance to surgery?

A

The total lack of blood vessels makes the cornea an ‘immune-privileged’ site, greatly reducing the chance of foreign antigen recognition and subsequent rejection

30
Q

What structures make up the vascular layer of the eye (uvea)

A

Ciliary body - suspends the lens and produces aqueous humour
Iris - controls the diameter of the pupil and thereby controls the amount of light rays entering the eyeball
Choroid - supplies blood to the outer layers of the retina

31
Q

What is uveitis?

A

Inflammation of the uvea

32
Q

What are the three of uveitis?

A

Anterior - iris with or without ciliary body inflamed
Intermediate - ciliary body inflamed
Posterior - choroid inflamed

33
Q

What are the causes of uveitis?

A

Isolated illness
Non-infectious autoimmune causes
Infectious causes - chronic disease such as TB
Associated with systemnic diseases e.g. ankylosing spondylosis

34
Q

What are the features of anterior uveitis?

A

An inflamed anterior uvea (iris) leaks plasma and white blood cells into the aqueous humour. These are seen during slit lamp examination as a hazy anterior chamber and cells deposited at the back of the cornea. The eye is red and painful with visual loss

35
Q

What is hypopon?

A

Cells in the AC settling anteriorly, white plaque-like appearance on iris

36
Q

What are the features of intermediate uveitis?

A

The ciliary body is inflamed and leaks cells and proteins. This leads to a hazy vitreous humour. Patients complain of hazy vision and things floating across the eye

37
Q

What are the features of posterior uveitis?

A

The choroid is inflamed, and because the choroid sits just under the retina, the inflammation frequently spreads to the retina, causing blurred vision

38
Q

What are the conjunctiva?

A

Thin vascular membrane that covers the inner surface of the eyelids and loops back over the sclera. It does not cover the cornea

39
Q

Describe the two manifestations of a stye or hordeolum

A

External - affects the sebaceous glands of an eyelash
Internal - affects the meibomian glands

Both red and tender

40
Q

Describe a chalazion

A

Sterile, chronic inflammation that arises from a blocked meibomian gland. May develop form an internal stye/hordeolum

Hard, non-tender

41
Q

What is conjunctivitis?

A

Self-limiting bacterial or viral infection of the conjunctiva

42
Q

How does conjunctivitis present?

A

Red, watering eyes, discharge. No loss of vision provided infection does not spread to cornea

43
Q

What is the management for conjunctivitis?

A

Antibiotic eye drops if likely to be bacterial, eyelid hygiene