Common conditions of the eye

Question 1

What is a hordeolum?

Answer 1

A hordeolum is a common disorder of the eyelid. It is an acute focal infection (usually staphylococcal) involving either the glands of Zeis or, less frequently, the meibomian glands

they can appear externally and internally

Question 2

a

Answer 2

superior rectus

Question 3

b

Answer 3

lateral rectus

Question 4

c

Answer 4

inferior rectus

Question 5

d

Answer 5

inferior oblique

Question 6

e

Answer 6

medial rectus

Question 7

f

Answer 7

superior oblique

Question 8

What is conjunctiva

Answer 8

thin vascular membrane that covers inner surface of eyelids and loops back over sclera.

Does not cover the cornea

Question 9

What is conjunctivitis, symptoms and treatment?

Answer 9

Self-limiting bacterial or viral infection of the conjunctiva

Red, watering eyes, discharge

No loss of vision as long as infection does not spread to cornea

Rx – antibiotic eye drops if likely to be bacterial

Question 10

What are the 2 types of stye or hordeolum?

Answer 10

External – affecting the sebaceous glands of an eyelash

Internal – affecting the meibomian glands

Question 11

Describe the histology of the cornea (5 layers)?

Answer 11

1. Epithelium - stratified squamous non-keratinised
2. Bowman’s membrane (basement membrane of corneal epithelium)
3. Stroma - regularly arranged collagen, no blood vessels
4. Descemet’s layer
5. Endothelium – single layer (normal - 2500 cells/mm2) - shown by arrow

Question 12

What are 2 types of pathology of the cornea?

Answer 12

1. Inflammatory – eg: corneal ulcers
2. Non-inflammatory – eg: dystrophies

Question 13

What can corneal pathologies commonly lead to?

Answer 13

Corneal pathologies frequently lead to opacification of the cornea. This might need to be treated by corneal transplant - Keratoplasty

Question 14

What may cause corneal ulcers?

Answer 14

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

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

Question 15

Non- Inflammatory dystrophies and degenerations are a group of diseases affecting the cornea which are what?

Answer 15

1. Bilateral
2. Opacifying
3. Non – inflammatory
4. Mostly genetically determined
5. Sometimes due to accumulation of substances such as lipids within the cornea

Question 16

What is the lcinical presentation of non- inflammatory dystrophies and degenerations

Answer 16

First to fourth decade

Most commonly - decreased vision

Start in one of the layers of the cornea and spread to the others

Question 17

Is a corneal transplant easier or harder to carry out and why?

Answer 17

The avascularity of the cornea is of 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

This has lead researchers to believe that the cornea is an “immune-privileged” site

(remember there are no lymphatics draining the eyeball; though lymph drains the eyelids)

Question 18

What is the most common disease affecting the eye?

Answer 18

cataract

Question 19

What is a cataract?

Answer 19

lens opacification

Question 20

Why do cataracts develop?

Answer 20

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

Question 21

WHat is the treatment of cataract?

Answer 21

Surgery – small day case – lens capsule opened – cataracteous lens removed by emulsification – plastic lens placed in capsular bag

Question 22

Where does aqueous humor drain?

Answer 22

angle of the anterior chamber through the trabecular meshwork into schlemms canal

Question 23

What is the 2nd global cause of blindness?

Answer 23

glaucoma

Question 24

WHat is the most commonly seen form of glaucoma?

Answer 24

Most commonly seen form of primary glaucoma is Primary Open Angle Glaucoma (POAG)

Question 25

What is glaucoma?

Answer 25

Raised intraocular pressure (IOP)

Question 26

How does glaucoma present and how is it picked up?

Answer 26

Bilateral Patient can be asymptomatic for a long period of time Picked up on routine eye exams

Question 27

What are the consequences of raised IOP?

Answer 27

Pressure on nerve fibres on surface of retina - die out - visual field defects optic disc appears unhealthy, pale and cupped This results in altered field of vision Ultimately all nerve fibres are lost, which results in blindness

Question 28

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

Answer 28

Question 29

What is the management of POAG?

Answer 29

Eye drops to decrease IOP ^{Prostaglandin analogues Beta-blockers Carbonic anhydrase inhibitors} Laser trabeculoplasty - used when eye drops are not working Trabeculectomy surgery

Question 30

What is experienced in angle closure glaucoma?

Answer 30

Sudden onset, painful, vision lost/ blurred; headaches (often confused with migraine) O/E – Red eye, cornea often opaque as raised IOP drives fluid into cornea AC shallow, and angle is closed Pupil mid-dilated IOP severely raised ^{pictures: Right eye: red and inflammed, cornea hazy, pupil mid-dilated Slit-lamp photo showing shallow AC compared to normal AC}

Question 31

Why does the angle close?

Answer 31

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

Question 32

What is the management of an acute eye episode?

Answer 32

1. Decrease IOP ^{IV infusion with or without oral therapy – carbonic anhydrase inhibitors (acetazolamide) Analgesics (reduce pain), antiemetics (reduce naeusa and vomiting) Constrictor eye drops – pilocarpine If no contraindication beta-blocker drops such as timolol Steroid eye drops (dexamethasone)} 2.Iridotomy (laser) - both eyes - to bypass blockage

Question 33

What is the difference between open angle and angle closure glaucoma?

Answer 33

open angle - gradual, painless build up of pressure closed angle - suddent increase in IOP leading to red eye, severe pain and patient usually presents as an emergency

Question 34

What is Uveitis?

Answer 34

inflammation of uvea

Question 35

What are the different types of uveitis?

Answer 35

Anterior uveitis - iris with or without ciliary body inflammed Intermediate uveitis - ciliary body inflammed Posterior uveitis - choroid inflammed

Question 36

What are the causes of uveitis?

Answer 36

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

Question 37

What is the pathophysiology of anterior uveitis?

Answer 37

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

Question 38

What happens in intermediate uveitis?

Answer 38

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

Question 39

What happens in posterior uveitis?

Answer 39

In posterior uveitis the choroid is inflammed Since the choroid sits under the retina, the inflammation frequently spreads to the retina causing blurred vision