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Flashcards in common conditions of the eye Deck (33)
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1
Q

where do optic vesicles grow?

A

outwards from diencephalic part of neural tube towards surface ectoderm.

2
Q

whaat is conjunctivitis?

A

Self-limiting bacterial or viral infection of the conjunctiva.

3
Q

symptoms of conjunctivitis?

A

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

4
Q

treatment of conjunctivitis?

A

antibiotic eye drops if likely to be bacterial

5
Q

what is a stye thats external called?

A

hordeolum externum

6
Q

what is a stye that is internal called?

A

hordeolum internum

7
Q

what is the treatment of styes?

A

warm compress, eyelid hygiene, may need surgical incision and curettage

8
Q

wht is the histology of the cornea?

A

Epithelium – stratified squamous non-keratinised.

Bowman’s membrane (basement membrane of corneal epithelium)

Stroma – regularly arranged collagen, no blood vessels

Descemet’s layer
Endothelium – single layer (normal - 2500 cells/mm2)

9
Q

whats the pathology of the cornea?

A

Inflammatory – eg: corneal ulcers

Non-inflammatory – eg: dystrophies
Corneal pathologies frequently lead to opacification of the cornea. This might need to be treated by corneal transplant - Keratoplasty

10
Q

psthology of a corneal ulcer

A

Infectious - Viral/ bacterial/ fungal infection of cornea. Needs aggressive management to prevent spread, scarring.

Non-infectious ulcers due to trauma, corneal degenerations or dystrophy.

11
Q

what are corneal dystrophies?

A

a group of genetic, often progressive, eye disorders in which abnormal material often accumulates in the clear

12
Q

what are the different types of corneal dystrophies?

A
Bilateral 
Opacifying
Non – inflammatory
Mostly genetically determined.
Sometimes due to accumulation of substances such as lipids within the cornea
13
Q

what is the significance of the avascularity of the cornea?

A

benefit to surgeons when performing a graft surgery as it means there is a lesser chance of foreign antigens from a corneal graft being recognised by the recipient, so lesser chance of a graft rejection.

14
Q

is there any lymphatics draining in the eyes/eyelids?

A

no

15
Q

what are some common disease cinditions of the eye?

A
cataract
glaucoma
age-related macular degeneration
diabetic retinopathy
corneal opacities
childhood blindness
trachoma
16
Q

why do cataracts develop?

A

Older (embryological, foetal) fibres are never shed – compacted in the middle

No blood supply to lens, which depends entirely on diffusion for nutrition

Absorbs harmful UV rays preventing them from damaging retina but in the process, get damaged themselves

Damaged lens fibres–> opaque —>CATARACT

17
Q

what is the management of cataracts?

A

Eye drops do not treat cataract!

Surgery – (day case) small incision lens capsule opened cataractous lens removed by emulsification (phacoemulsification) plastic lens placed in capsular bag

Lens implant after cataract surgery – PCIOL = Posterior Chamber Intra Ocular Lens

18
Q

what is the 2nd most common global cause of blindness?

A

glaucoma

19
Q

what is the most commonly seen from of primary glaucoma?

A

primary open angle glaucoma

20
Q

what is the consequence of raised intraocular pressure

A

Pressure on nerve fibres on surface of retina–> die out —> visual field defects

21
Q

what is the triad signs of glaucoma?

A

raised IOP
visual field defect
optic disc changes on ophthalmoscopy

22
Q

whats the management of POAG?

A

Eye drops to decrease IOP
Prostaglandin analogues
Beta-blockers
Carbonic anhydrase inhibitors

Laser trabeculoplasty

Trabeculectomy surgery

23
Q

what is angle closure glaucoma?

A

Sudden onset, painful, vision lost/ blurred; headaches (often confused with migraine)

24
Q

signs of angle closure glaucoma?

A

Red eye, cornea often opaque as raised IOP drives fluid into cornea
AC shallow, and angle is closed.
Pupil mid-dilated
IOP severely raised
Right eye: red and inflammed, cornea hazy, pupil mid-dilated

25
Q

what are the mechanisms for the angle closing?

A

Functional block in a small eye – large lens
Mid-dilated pupil periphery of iris crowds around angle and outflow is obstructed
Iris sticks to pupillary border (synechia) which prevents reaching AC. Leads to iris balooning anteriorly and obstructing angle.

26
Q

whats the management of an acute episode?

A

Decrease IOP
IV infusion with or without oral therapy – carbonic anhydrase inhibitors (acetazolamide)
Analgesics, antiemetics
Constrictor eye drops – pilocarpine
If no contraindication beta-blocker drops such as timolol
Steroid eye drops (dexamethasone)

Iridotomy (laser) - both eyes - to bypass blockage

27
Q

whats the difference between open angle and angle closure glaucoma?

A

In open angle glaucoma the drainage through the trabecular meshwork is blocked (in most cases)
This leads to a gradual, painless build up of intraocular pressure (IOP).
This type of Glaucoma is called Primary Open Angle Glaucoma (POAG)

In angle closure glaucoma, some event on a predisposed eye leads to the peripheral iris blocking the angle, therefore aqueous can’t drain.
So the increase in IOP is sudden leading to a red eye, and severe pain.
Patient usually presents as an emergency

28
Q

what is uveitis?

A

inflammation of uvea

29
Q

what are the different types of uveitis?

A

Anterior uveitis – iris with or without ciliary body inflammed

Intermediate uveitis – ciliary body inflammed

Posterior uveitis – choroid inflammed

30
Q

causes of uveitis?

A

Isolated illness
Non-infectious autoimmune causes – eg: presence of HLA-B27 predisposes to anterior uveitis
Infectious causes – chronic diseases such as TB
Associated with systemic diseases – eg: ankylosing spondylosis

31
Q

whats the pathophysiology of anterior uveitis?

A

An inflammed anterior uvea (iris) leaks plasma and white blood cells into the aqueous humor

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, painful, with visual loss

Cells in the AC may settle inferiorly – “hypopyon”

32
Q

pathology of intermediate uveitis

A

In intermediate uveitis the ciliary body is inflammed and leaks cells and proteins.
This leads to a hazy vitreous
Patient complains of “floaters” or hazy vision

33
Q

pathology of posterior uveitis

A

In posterior uveitis the choroid is inflammed.

Since the choroid sits under the retina, the inflammation frequently spreads to the retina causing blurred vision

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